Energy & Technology

Nuclear Power

Quick Facts

  • Unlike conventional fossil fueled electricity generation, nuclear power can provide electricity without direct greenhouse gas (GHG) emissions and with very low lifecycle emissions.
  • In 2012 nuclear power provided nearly one fifth of total U.S. electricity and constituted 61 percent of the nation’s total non-GHG-emitting electricity generation.[1] The United States is the largest generator of nuclear power, accounting for about 27 percent of global nuclear generation in 2011.[2] However, absent new policies to reduce GHG emissions and promote non-emitting electricity generation, U.S. nuclear power is not expected to grow substantially in coming decades.
  • Globally, nuclear power provides roughly 13 percent of total electricity generation and 39 percent of global non-fossil fueled electric power generation.[3] The United States, France, Russia, South Korea and China account for a little more than 60 percent of global nuclear power generation; and China is rapidly expanding its fleet of nuclear power plants.[4]
  • Under new policies to reduce GHG emissions, nuclear power could be an important source of low-carbon electricity, with some analyses suggesting that nuclear power could provide more than 40 percent of U.S. electricity and nearly a quarter of global electricity by mid-century.[5],[6]
  • The 2011 accident at the Fukushima Daiichi power plant in Japan illustrated some of the risks of nuclear power. Addressing the threat of climate change through expanded nuclear power will require continued improvements in the safety of nuclear technology, thorough industry regulation and oversight, and a commitment to safety and security on the part of the nuclear industry.


Electric power generation is a major source of greenhouse gas (GHG) emissions, primarily carbon dioxide (CO2) from fossil fuel combustion. In the United States, electricity generation is responsible for roughly one third of total GHG emissions (80 percent of which come from coal use).[7] Globally, electricity generation accounts for more than 27 percent of total CO2 emissions and more than one fifth of total GHG emissions.[8] Given the magnitude of GHG emissions from the electricity sector, low-carbon electricity generation technologies are crucial for achieving the significant GHG emission reductions necessary to avoid dangerous climate change.

Nuclear power is one option in the portfolio of low-carbon electricity generation technologies, which also includes renewables (e.g., wind, solar, and biomass) and fossil fuels coupled with carbon capture and storage (CCS). Nuclear power emits no GHGs from electric power generation, and its overall lifecycle GHG emissions profile is low and similar to that of solar power.[9] In addition, nuclear power is already a widely deployed technology and can—like coal-fueled generation—provide reliable baseload electric power.

Currently, nuclear power is by far the largest source of low-carbon electricity in the United States. In 2012, nuclear power provided nearly one fifth of total U.S. electricity, which was more than 50 percent higher than the generation from all renewable sources (including conventional hydropower).[10] The United States has 100 operating nuclear reactors at 62 plants in 31 states; there are 4 to 6 new units expected to come online before 2020.[11] Globally, nuclear power generates roughly 13 percent of total electricity.[12]

In order for nuclear power to significantly expand domestically and globally, the United States and the rest of the world must adopt policies to promote low-carbon technology deployment and adequately address concerns about nuclear power safety, nuclear weapons proliferation, and the long-term handling of spent nuclear fuel.


Current nuclear power technology harnesses the energy released by nuclear fission. Atomic nuclei consist of protons and neutrons held together by a strong energy bond. In nuclear fission, a neutron strikes the nucleus of a very heavy atom and splits it apart into lighter atoms, releasing additional neutrons and energy as well. These neutrons, in turn, can fission other atoms. Under precise, controlled conditions, this nuclear fission process can occur as a continuous chain reaction that releases heat in useful amounts.

  • Nuclear Fuel: Nuclear power plants predominantly use U-235, a fissile isotope of uranium, as their fuel. Uranium is a naturally occurring heavy metal whose most common isotope is the non-fissile U-238. To make reactor fuel, mined uranium must be enriched to a higher concentration of U-235.[13] Some of the U-238 in nuclear fuel is transformed to fissile plutonium during the nuclear chain reaction, and some of this Pu-239 is, in turned, fissioned to produce useful energy.[14] At regular intervals, nuclear reactors’ fuel must be replaced with fresh fuel when the fuel is spent—i.e., no longer capable of supporting an adequate chain reaction. This spent nuclear fuel consists mostly of uranium (up to 96 percent) mixed with certain highly radioactive elements—namely, fission products (e.g., cesium and strontium) and transuranics (e.g., plutonium and americium). The decay heat and radiotoxicity of spent nuclear fuel is dominated by the fission products for roughly the first hundred years and then by the transuranics for subsequent millennia.[15] Currently, in the United States, spent nuclear fuel is stored first in pools of water at nuclear plants to cool the waste and provide protection from its radiation for at least 10 years; subsequently, spent nuclear fuel can be housed onsite in dry casks made of steel and/or concrete while it awaits permanent disposal or reprocessing (see below).[16]
  • Nuclear Reactors: All operating U.S. nuclear power plants are light water reactors (LWRs)—so called because they use ordinary water to transfer heat generated by the reactor to a turbine-generator which produces electricity—and LWRs are the only type of reactors under consideration for the proposed new plants in the United States.[17],[18] There are two types of LWR, the boiling water reactor (BWR) and the pressurized water reactor (PWR).[19] Roughly seventy percent of U.S. nuclear reactors are PWRs.[20] Nuclear reactors are often classified in terms of their reactor generation, or stage of reactor technology development:[21]
    • Generation I: these reactors were the prototypes and first commercial plants developed in the 1950s and ‘60s of which very few still operate.
    • Generation II: these are the commercial reactors built around the world in the 1970s and ‘80s.
    • Generation III/III+: Gen III reactors were developed in the 1990s and feature advances in safety and cost compared to Gen II reactors. Gen III+ reactors are the most recently developed reactor designs and have additional evolutionary design improvements. Only a few Gen III/III+ reactors have been built, but currently planned reactors in the United States are of this type.
    • Generation IV: refers to the advanced reactor designs anticipated for commercial deployment by 2030 and expected to have “revolutionary” improvements in safety, cost, and proliferation resistance as well as the ability to support a nuclear fuel cycle that produces less waste.[22]
  • Nuclear Fuel Cycles: The conventional, once-through fuel cycle involves nuclear reactors that use enriched uranium as fuel and that discharge spent nuclear fuel for disposal. This is the current approach in the United States. There are two alternative fuel cycles—the current, single-pass recycle option and a fully closed fuel cycle that would use anticipated advanced technology. The single-pass recycle option, which is the approach used in France, involves “reprocessing” spent nuclear fuel to separate fissile uranium and plutonium from other nuclear waste. This uranium and plutonium can then be recycled as fuel in existing nuclear reactors. This fuel cycle reduces the volume of nuclear waste that requires disposal but not necessarily the decay heat and radiotoxicity of the waste.[23] A recent Massachusetts Institute of Technology (MIT) study concluded that the cost of this single-pass recycle option is unfavorable compared to a once-through cycle and that the waste management benefits from a closed fuel cycle do not outweigh the attendant safety, environmental, and security considerations and economic costs.[24] In a proposed fully closed fuel cycle, spent nuclear fuel could be reprocessed with the separated uranium, plutonium, and other long-lived radioisotopes recycled as fuel. This could reduce the long-term burden on the final nuclear waste repositories by reducing long-term decay heat and radioactivity. However, it would not eliminate the need for long-term disposal because there are long-lived fission products and wastes from processing operations that will still require permanent geological disposal. A fully closed fuel cycle, however, requires advanced “fast” burner reactors that are not yet commercially available. In theory, SNF from these “fast” reactors could be repeatedly reprocessed until all the useable fuel was fissioned while also converting nearly all the uranium in the fuel cycle to useful fuel.[25]

Environmental Benefit/Emission Reduction Potential

Many analyses that look at the lowest-cost options for decarbonizing the electric power sector (e.g., via a GHG emissions pricing policy) project a substantial role for new nuclear power plants in meeting demand for non-emitting electricity generation.

In its 2014 outlook for “business as usual” (i.e., a scenario with no new policies), the U.S. Energy Information Administration (EIA) projects no net increase in nuclear generating capacity from now through 2040.[26] Over the same period, EIA projects that total electricity demand will grow by 28 percent.

In contrast, EIA also modeled an economy-wide carbon price and projected that such an emission reduction policy would spur the deployment of 53 GW of additional nuclear generating capacity above the “business as usual” case by 2040.[27]

As one indicator of the significant potential role for nuclear power in global GHG abatement, the International Energy Agency (IEA) estimated that nuclear power could provide 6 percent of total energy-related emission reductions compared to “business as usual” by 2050 (and 19 percent of emission reductions from the power sector).[28] IEA projected that, in this scenario, nuclear power would increase from about 14 percent of global electricity generation currently to nearly one fourth of total power generation by mid-century.


Nuclear power requires very large upfront capital investments in constructing the power plant (e.g., a new 1 gigawatt nuclear power plant might cost $7 billion including the cost of financing). For nuclear power, the capital cost of the plant constitutes roughly three fourths of the levelized cost of electricity, with fuel and operations and maintenance (O&M) costs making up the remainder of the cost in roughly equal proportions.[29],[30] In contrast, capital costs account for roughly 40 percent of the levelized cost of electricity from a new coal power plant, and fuel costs account for about 80 percent of the levelized cost of electricity from a natural gas power plant.[31] In short, nuclear plants are relatively expensive to build but relatively inexpensive to operate.

The cost of new U.S. nuclear power plants is uncertain due to a long hiatus in the construction of new nuclear plants in the United States, and cost estimates have been trending upward. In 2010, EIA increased its annually updated estimate of the capital cost of a generic new nuclear power plant by 37 percent, citing a trend of rising costs for capital-intensive power sector projects, higher global commodity prices, and the relative scarcity of engineering and construction firms capable of undertaking such complex projects.[32] In a 2013 update to this report, the overnight capital costs for new nuclear plants were unchanged.[33]

During the 1980s and early ‘90s, new nuclear power plants experienced long delays in construction schedules and massive cost overruns, which makes potential lenders see new nuclear power plants as riskier than other power plant investments and thus makes new nuclear plant construction more expensive to finance. Given the capital-intensity of nuclear power, financing is challenging for new plants.

EIA’s latest estimates for the levelized cost of electricity from new power plants using various electricity generation technologies put nuclear power at roughly the same cost as electricity from new coal plants but roughly 60 percent more costly than electricity from new natural gas combined cycle plants.[34] This cost differential makes new nuclear power plants hard to justify without a policy that changes the relative costs of different types of electricity generation based on GHG emissions.

The once-through nuclear fuel cycle is currently the least costly approach to nuclear power.[35]

Current Status of Nuclear Power

More than 90 percent of U.S. nuclear capacity came online in the 1970s and ‘80s before cost overruns, construction delays, and safety concerns ended this wave of nuclear plant construction. Whereas the build-out of the existing U.S. nuclear fleet saw a large number of companies building a variety of idiosyncratic nuclear plant designs with a regulatory licensing process that allowed for significant delays, a new wave of new nuclear plants in the United States is foreseen to include a small number of firms with nuclear power experience building a limited number of standardized plant designs under a new licensing framework that front-loads much of the regulatory risk.

The Energy Policy Act of 1992 overhauled the nuclear licensing process, which used to require two licenses—one to build the plant and another to operate it. Under the new process the U.S. Nuclear Regulatory Commission (NRC) can: 1) pre-approve a prospective site for a new nuclear plant, 2) certify a new reactor design, and 3) issue a single combined construction and operating license (COL).[36]

In 2005, Congress enacted new financial incentives (mainly federal loan guarantees) to help spur the first wave of a new generation of nuclear power plants. Subsequently, U.S. electricity providers did begin to pursue new nuclear plants. Currently, COLs have been issued to South Carolina Electric & Gas for Summer (Units 2 and 3) and to Southern Company for Vogtle (Units 3 and 4). There are nine additional license applications under active review by the NRC for up to 14 new reactors, with all of the license applications filed since 2007.[37]

Nonetheless, the high capital costs of new nuclear plants, the relatively lower cost of new natural gas generation following the domestic “shale gas revolution,” and continuing lack of federal policy to reduce GHG emissions and incentivize low-carbon energy technology all limit enthusiasm for new nuclear projects in the United States. As of April 2013, five new nuclear units are actively under construction. Watts Bar Unit 2 in Tennessee is expected to come online in December 2015.[38]  Additionally, construction is well underway at Vogtle Unit 3 in Georgia and V.C. Summer Unit 2 in South Carolina.[39], [40] The U.S. Department of Energy (DOE) has conditionally awarded a federal loan guarantee to one new nuclear plant (Vogtle) and is negotiating with three other projects.[41] The process of licensing and building the first few new nuclear plants is expected to take approximately 9-10 years, with 4-6 new units expected to start commercial operation by 2020.[42], [43]

Industry experts consider successful on-time, on-budget completion of this handful of new reactors crucial for creating confidence that new reactor construction can avoid the pitfalls of the past and enabling subsequent nuclear project developers to obtain financing from the private sector without government backing.

Nuclear power also faces potential political and public acceptance hurdles. After decades, the United States still has yet to resolve the issue of long-term handling of spent nuclear fuel. The Obama Administration withdrew the license application for the long-awaited Yucca Mountain geologic repository and appointed a blue-ribbon commission to reassess the options for long-term spent fuel management. The commission delivered its report in January 2012, and it is now up to the Administration and Congress to decide how to proceed.[44] Presently, the United States is pursuing a once-through nuclear fuel cycle. A fully closed fuel cycle would require not just advanced reprocessing and recycling technology but also the capability to manufacture a new type of reactor fuel from the reprocessing outputs.[45] According to the nuclear industry, the new generation of reactors necessary for a fully closed fuel cycle is decades away from commercial development.[46]

In March 2011, a catastrophic earthquake and resultant tsunami struck Japan and led to the failure of reactor and spent fuel storage cooling systems at the Fukushima Daiichi nuclear power station and subsequent damage to the reactors and fuel rods and releases of radioactivity. Global responses to the accident have been mixed. In the immediate aftermath of the disaster, Japan had decided to shut down all of its reactors as well as discontinue a plan to build 14 new nuclear reactors by 2030.[47] However, Prime Minister Abe plans to enhance safety standards and restart reactors.[48]  German policymakers are pushing ahead with a plan to shut down all nuclear reactors by 2022, and Switzerland has also decided to not replace its five existing reactors.[49], [50] In the United States, the Nuclear Regulatory Commission has identified several lessons learned from the accident and is implementing safety enhancements in the existing fleet.[51] The accident is not expected to impact current U.S. nuclear construction activities. Overall, the use of nuclear power is expected to increase with an increased focus on nuclear safety driven by developing countries, especially China and India.

Worldwide, 67 new reactors are currently under construction in 13 countries. 28 of these reactors are in China, which has only 17 reactors operating now.[52] , [53] Other countries currently building multiple new reactors are Russia, India, South Korea, and the United States.

Obstacles to Further Development or Deployment of Nuclear Power

  • Lack of Policies to Reduce GHG Emissions from Electricity Generation

In the absence of regulation of GHG emissions, new nuclear power is typically more expensive than existing or new conventional fossil fueled electricity generation.

  • Challenges to Financing Initial Nuclear Builds

The up-front capital investments required for nuclear power plants make financing difficult for U.S. electric power generators given their relatively small market capitalizations, especially in restructured electricity markets. Many of the existing nuclear plants proved to be far more expensive to build than expected and faced long delays in construction schedules.[54] Commercial lenders are thus reluctant to finance new nuclear plants on a project finance basis at a cost of capital comparable to other power generation technologies until “first-mover” firms demonstrate that new nuclear plants can be built on time and within budget.

  • Long-Term Nuclear Waste Policy

Experts have concluded that geological repositories can safely isolate nuclear waste over the long term; however, so far no country has successfully implemented such an approach for spent nuclear fuel and high-level nuclear waste.[55] final waste disposal facilities ,[57] The United States currently has over 60,000 tons of nuclear waste at more than 100 temporary sites (primarily nuclear power plants) around the country, and the fleet of existing nuclear power plants generates approximately 2,000 tons each year.[58] Moreover, even the proposed fully closed fuel cycle that may be a future option will still necessitate long-term geological waste disposal.

Under the provisions of the 1982 Nuclear Waste Policy Act, the federal government has responsibility for managing spent nuclear fuel produced by commercial reactors. The federal government has been collecting fees from nuclear power generators as part of contracts that originally required DOE to begin taking spent nuclear fuel for long-term disposal in 1998.[59] In 1987, Congress designated Yucca Mountain in Nevada as the sole candidate for a federal long-term geological repository for nuclear waste. However, the site engendered intense political opposition from Nevadans, and the Obama Administration has terminated the Yucca Mountain nuclear waste repository program.[60] Given current law, indefinite storage at reactor sites and other existing temporary facilities is the only alternative to Yucca Mountain absent additional congressional action.[61] Given the challenges encountered in opening a long-term geological repository, DOE has not yet begun taking spent nuclear fuel from nuclear plants and is not expected to do so for several years.

Several states—including California and Wisconsin—have laws that effectively ban the construction of new nuclear plants until a federal long-term waste disposal repository is operating.[62] Elsewhere, the lack of a solution for long-term spent nuclear fuel management creates uncertainty for new nuclear power plant sponsors. However, the NRC has determined that spent nuclear fuel can be safely stored at reactor sites for 30 years after a reactor shuts down, and NRC has proposed at least 60 years of storage after reactor shut-down as a safe period.[63]

  • Supply Chain and Workforce Constraints

The industrial resources and supply chains needed to build and operate nuclear plants may present challenges to a significant expansion.[64] Moreover, the current nuclear workforce is aging and retirements may exceed new entries resulting in a loss of experienced operator and maintenance personnel.[68]

  • Safety and Security

The global nuclear power industry has experienced four serious nuclear reactor accidents—at Windscale (1952) in the United Kingdom, Three Mile Island (1979) in the United States, Chernobyl (1986) in the former Soviet Union, and Fukushima Daiichi (2011) in Japan—and several fuel cycle facility incidents.[69] Neither the Windscale nor Chernobyl facility utilized a modern containment structure. Nuclear reactor damage is a potential threat to public health as it can lead to release of radioactivity to the air and groundwater. To date, the United States has had no immediate radiological injuries or deaths among the public attributable to accidents involving commercial nuclear power reactors.[70] Following the Three Mile Island accident, improvements were made to plant safety equipment, procedures, and training in U.S. reactor operations which significantly increased the safety of the U.S. nuclear fleet.[71] Moreover, new reactor designs have projected risks—particularly vulnerability to loss-of-coolant accidents—that are one to two orders of magnitude less than those of operating LWRs.[72] Nonetheless, the recent Japanese nuclear accident has once again focused attention on the safety of existing and planned nuclear reactors. However, it is important to stress that there have been no deaths attributable to radiation exposure from the Fukushima accident to date.

In addition to accidents, intentional attacks on nuclear power plants by terrorists could theoretically lead to nuclear reactor damage. Following the September 11th terrorist attacks, security at nuclear power plants came under increased scrutiny, and new regulations from the NRC increased the level of protection against terrorist attacks.

  • Nuclear Weapons Proliferation

The nuclear proliferation risk stems principally from the potential for countries to covertly use uranium enrichment or spent nuclear fuel reprocessing plants to generate materials for use in nuclear weapons, and theft of poorly secured nuclear materials could result in transfer to a dangerous state or terrorist group.[73] In particular, current commercial reprocessing technology generates separated plutonium that is directly usable in nuclear weapons.[74]

Policy Options to Help Promote Nuclear Power

  • Carbon Price

A policy, such as cap and trade (see Climate Change 101: Cap and Trade), that puts a price on GHG emissions would discourage investments in traditional fossil-fuel use and spur investments in a range of low-carbon energy technologies, including nuclear power.

  • Clean Energy Standard

A policy that required electric utilities to supply increasing percentages of low-carbon electricity (e.g., a clean energy standard) would likely substantially increase investments in new nuclear power.

  • GHG Performance Standards

Policymakers could rely on performance standards to drive nuclear deployment by enacting new regulations that establish maximum allowable CO2 emission rates for power plants (California, Washington, and Oregon have such standards).[75] If stringent enough, such standards could lead power generators to turn to nuclear power and other non-emitting technologies.

  • Loan Guarantees and other Financial Incentives for Initial New Nuclear Projects

The Energy Policy Act of 2005 included provisions for loan guarantees, production tax credits, and standby insurance for “first-mover” new nuclear power plants.[76] Commercial lenders have indicated that the first wave of new nuclear plants built in the United States without assured cost recovery from electricity ratepayers would be difficult or impossible to finance without federal loan guarantees owing to the perceived high risk of such projects in light of the poor track record of constructing the existing U.S. nuclear fleet.[77] With the current level of federal loan guarantees available for new nuclear power plants, two or three “first-mover” nuclear plants could obtain financing backed by federal loan guarantees and—if they demonstrate success in on-time, within-budget construction and operation—lower the perceived risk of investing in new nuclear power plants and make subsequent plants’ financing easier and less costly. An expanded loan guarantee program could support more “first-mover” nuclear projects.[78]

  • Defining a Long-Term Policy for Nuclear Waste

In January 2010, President Obama established the Blue Ribbon Commission on America’s Nuclear Future, a step also supported by congressional leaders and the nuclear industry. The commission was tasked with evaluating alternatives and recommending a new plan for managing the back end of the nuclear fuel cycle (i.e., the storage, processing, and disposal of spent nuclear fuel). The commission’s final report was issued in 2012.[79] Implementation of the commission’s recommendations will likely require congressional action as the only option for long-term waste management under current federal law is Yucca Mountain.

  • Research and Development

MIT’s 2003 report on nuclear power recommended several avenues for research, including: advanced LWRs and high temperature gas reactors; lab-scale research on reprocessing technologies with the potential for lower cost and greater proliferation resistance; establishment of a large nuclear system analysis, modeling, and simulation project; and a global uranium resource evaluation.[80] Several other expert reports have also suggested that efforts related to reprocessing focus on R&D rather than deployment, including reports by the Government Accountability Office, the National Academy of Sciences, and the directors of the Department of Energy’s national laboratories.[81]

  • Safety and Security

The NRC and nuclear plant owners can continue to advance nuclear plant safety via adequate regulation and oversight, continuous improvement based on operating experience, and an emphasis on safety culture. In particular, regulators and the nuclear industry will have to learn from and take steps necessary to minimize the risks exposed by the Japanese nuclear accident.

  • Non-Proliferation Policies

R&D investments in and international collaboration on technical safeguards—i.e., the technologies used to monitor and protect nuclear materials from proliferation threats domestically and under international agreements—and the inclusion of increased proliferation resistance in next-generation nuclear reactor designs can limit the risk of nuclear proliferation.[83] The MIT nuclear report and the directors of the national laboratories recommend that nuclear supplier states (e.g., the G-8) offer fuel cycle services to nations developing new nuclear capabilities on attractive terms in order to slow the process of additional nations, especially new users with only a few reactors, building enrichment and reprocessing facilities.[84] In December 2010, the International Atomic Energy Agency (IAEA) approved the creation of such an international fuel bank, which will be funded in part by the United States.[86]

  • Supply Chain / Workforce

The federal government can foster a robust nuclear workforce via increased educational funding for relevant graduate and undergraduate university education and certification programs at community colleges.[87] Grants for job retraining could also help displaced workers transition into nuclear and other growing energy industries.

Related Business Environmental Leadership Council (BELC) Company Activities



DTE Energy

Duke Energy





Rio Tinto

Related C2ES Resources

Climate Change 101: Technological Solutions, 2011.

A Performance Standards Approach to Reducing CO2 Emissions from Electric Power Plants, 2009.

The U.S. Electric Power Sector and Climate Change Mitigation, 2005.

Further Reading / Additional Resources

Blue Ribbon Commission on America’s Nuclear Future.

Congressional Budget Office (CBO), Nuclear Power’s Role in Generating Electricity, 2008. 

Congressional Research Service (CRS)

  • Advanced Nuclear Power and Fuel Cycle Technologies: Outlook and Policy Options, 2008.
  • Nuclear Energy Policy, 2008.
  • Nuclear Waste Disposal: Alternatives to Yucca Mountain, 2009.

International Atomic Energy Agency (IAEA).

International Energy Agency (IEA)

Keystone Center, Nuclear Power Joint Fact-Finding, 2007.    

Massachusetts Institute of Technology (MIT)

National Research Council of the National Academy of Sciences, Disposition of High-Level Waste and Spent Nuclear Fuel: Continuing Societal and Technical Challenges, 2001.

Nuclear Energy Agency (NEA).

Nuclear Energy Institute (NEI).

U.S. Department of Energy (DOE)

U.S. Nuclear Regulatory Commission (NRC).


[1] U.S. Energy Information Administration (EIA), Electric Power Monthly, April 2013, see Table 1.1.

[2] EIA, International Energy Statistics, 2011 data.

[3] EIA, International Energy Statistics, 2011 data.

[4] EIA, International Energy Statistics. In 2011 data.

[5] U.S. Environmental Protection Agency (EPA), EPA Analysis of the American Power Act of 2010, June 2010, ADAGE Model Scenario 2.

[6] International Energy Agency (IEA), Energy Technology Perspectives 2010: Scenarios and Strategies to 2050, 2010, BLUE Map Scenario.

[7] EPA, Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2011, 2013. See Tables ES-7 and 2-13.

[8] Intergovernmental Panel on Climate Change (IPCC), "Introduction." In Mitigation of Climate Change. Contribution of Working Group III to the Fourth Assessment Report. Cambridge: Cambridge University Press, 2007. 

[9] Fthenakis, VM and HC Kim, “Greenhouse-Gas Emissions from Solar Electric- and Nuclear Power: A Life-Cycle Study,” Energy Policy 35: 2549-2557, 2007.

[10] EIA, Electric Power Monthly, April 2013, see Table 1.1.

[11] World Nuclear Association, Nuclear Power in the USA, June 2013. All of 100 U.S. nuclear reactors were ordered between 1963 and 1973.

[12] EIA, International Energy Statistics, 2013 data.

[13] For a helpful overview of the basics of nuclear power, see EIA’s Introduction to Nuclear Power.

[14] Massachusetts Institute of Technology (MIT), The Future of Nuclear Power, 2003. For a helpful overview of nuclear fuel and the nuclear fuel cycle, see “Appendix Chapter 1 – Nuclear Fuel Cycle Primer.”

[15] Government Accountability Office (GAO), Global Nuclear Energy Partnership: DOE Should Reassess Its Approach to Designing and Building Spent Nuclear Fuel Recycling Facilities, April 2008.

[16] MIT, 2003.

[17] Holt, July 2008.

[18] Nuclear Energy Agency (NEA), Nuclear Energy Outlook 2008. About 20 percent of current nuclear plants today use heavy water as a moderator and coolant (mostly in Canada and India), while the United Kingdom has 18 gas-cooled reactors.

[19] In a BWR, the water heated by the energy released during the nuclear fission chain reaction in the reactor core turns directly into steam to power the turbine-generator (for an explanation of a BWR, see EIA’s Boiling-Water Reactor). In a PWR, the water passing through the reactor core is kept under pressure so that it does not turn to steam but rather is used to exchange heat with a separate water loop to create steam and power a turbine-generator (an explanation of a PWR, see EIA’s Pressurized-Water Reactor and Reactor Vessel).

[20] EIA, U.S. Nuclear Reactors.

[21] NEA, 2008.

[22] Gen IV International Forum.

[23] MIT, 2003.

[24] MIT, Update of the MIT 2003 Future of Nuclear Power, May 2009.

[25] Holt, July 2008.

[26] EIA, Annual Energy Outlook 2013, April 2013. EIA projects 11 GW from new plants and 8 GW of the capacity growth from uprates at existing plants, while there are around 6 GW of plant retirements expected.

[27] EIA, Annual Energy Outlook 2013: Greenhouse Gas $15, April 2013.

[28] IEA, 2010. IEA developed the BLUE Map roadmap for achieving a 50 percent reduction below current GHG emission levels in order to stabilize atmospheric CO2 concentration at 450ppm.

[29] The levelized cost of electricity is an economic assessment of the cost of electricity generation from a representative generating unit of a particular technology type (e.g. wind, coal) including all the costs over its lifetime: initial investment, operations and maintenance, cost of fuel, and cost of capital.

[30] Du, Yangbo and John Parsons, Update on the Cost of Nuclear Power, MIT Center for Energy and Environmental Policy Research, 2009, see Figure 1.

[31] Du and Parsons, 2009.

[32] EIA, Updated Capital Cost Estimates for Electricity Generation Plants, November 2010.

[33] EIA, Updated Capital Costs Estimates for Utility Scale Electricity, April 2013.

[34] EIA, Levelized Cost of New Generation Resources in the Annual Energy Outlook 2013, April 2013.

[35] MIT, 2009.

[36] Nuclear Energy Institute (NEI), Status and Outlook for Nuclear Energy in the United States, May 2009.

[37] U.S. Nuclear Regulatory Commission, Combined License Applications for New Reactors, Jun 2012. Available at:

[38] TVA, Watts Bar Unit 2 project construction update. April 2013.

[39] Southern Company, Construction Video and Photos, June 2013.

[40] SCE&G, New Nuclear Development, March 2013.

[41] NEI, April 2011.

[42] NEI, April 2011. NEI reports that this 9-10 year process breaks down as follows: approximately two years to prepare an application to the NRC for a COL, approximately three and a half years for NRC review and approval of the COL, and 4-5 years for construction. NEI expects that subsequent plants might have a licensing and construction timeline of only about six years.

[43] World Nuclear Association, Nuclear Power in the USA, June 2013.

[44] Blue Ribbon Commission on America’s Nuclear Future, January 2012.

[45] NEI, Advanced Fuel-Cycle Technologies Hold Promise for Used Fuel Management Program, Jan 2009.

[46] NEI, Jan 2009.

[47] Fackler, Martin, “Japan to Cancel Plan to Build More Nuclear Plants,” New York Times, 10 May 2011.

[48] Tabuchi, Hiroko, “Japanese Nuclear Regulator Announces an Overhaul of Safety Guidelines.” New York Times, 19 June 2013.

[49] BBC, Germany: Nuclear power plants to close by 2022, 30 May 2011.

[50] BBC, Swiss to phase out nuclear power. 25 May 2011. Switzerland will continue to utilize nuclear power until the end of the reactor’s operative lifetime. Its five units will be retired between 2019 and 2034.

[51] NRC, Japan Lessons Learned, June 2013

[52] WNA, World Nuclear Power Reactors & Uranium Requirements, June 2013.

[53] Xu, Wan, “China to Erect Nuclear Reactors to Match U.S.,” Wall Street Journal, 27 May 2009.

[54] MIT, 2009.

[55] MIT, 2003.

[56] The United States has built and operates the Waste Isolation Pilot Plant, a geological repository for defense-related transuranic waste.

[57] NEI, “Sweden Picks Location for Its Used Fuel Repository,” Nuclear Energy Insight, July 2009.

[58] Vogel, Steve, “Controversy Over Yucca Mountain May Be Ending,” Washington Post, 4 March 2009.

[59] Wald, Matthew, “As Nuclear Waste Languishes, Expense to U.S. Rises,” New York Times, 17 February 2008.

[60] Vogel, 2009.

[61] Holt, Mark, Nuclear Waste Disposal: Alternatives to Yucca Mountain, CRS, February 2009.

[62] NEI, “State Bills Promote New Nuclear Plants,” May 2008.

[63] Nuclear Regulatory Commission (NRC), “Waste Confidence Decision Update,” December 2010.

[64] Directors of DOE National Laboratories, A Sustainable Energy Future: The Essential Role of Nuclear Energy, Aug 2008.

[65] Klein, Dale, “Perspectives and Challenges of the Nuclear Renaissance,” Address by NRC Chairman to the American Nuclear Society, Raleigh, NC, 31 January 2008.

[66] NEI, “New Nuclear Plants Create Opportunities for Expanding US Manufacturing,” August 2008.

[67] U.S. Department of Energy (DOE), DOE NP2010 Nuclear Power Plant Construction Infrastructure Assessment, 2005.

[68] Keystone Center, Nuclear Power Joint Fact-Finding, 2007.

[69] MIT, 2003. See the MIT report for examples of fuel cycle facility incidents.

[70] Keystone, 2007.

[71] Keystone, 2007.

[72] Holt, July 2008.

[73] Nuclear Energy Study Group of the American Physical Society (APS) Panel on Public Affairs, Nuclear Power and Proliferation Resistance: Securing Benefits, Limiting Risk, 2005.

[74] APS, 2005.

[75] For more information on CO2 emission performance standards for electric power plants, see Rubin, Edward, A Performance Standards Approach to Reducing CO2 Emissions from Electric Power Plants, prepared for the Pew Center, June 2009.

[76] NEI, May 2009.

[77] Roy, Rukmini et al., Loan Guarantees for Advanced Nuclear Energy Facilities: Bankers' Viewpoints on DOE Implementing Regulations, Letter to DOE Secretary Bodman, March 2007.

[78] To illustrate the potential unmet demand for loan guarantees, project sponsors submitted 10 full applications for nuclear loan guarantees. See Slocum, John and John Reed, “Maximizing U.S. Federal Loan Guarantees for New Nuclear Energy,” Bulletin of the Atomic Scientists, 29 July 2009.

[79] Blue Ribbon Commission on America’s Nuclear Future, January 2012.

[80] MIT, 2003.

[81] Holt, July 2008.

[82] Directors of DOE National Laboratories, 2008.

[83] APS, 2005.

[84] MIT, 2003.

[85] Directors of DOE National Laboratories, 2008.

[86]IAEA Approves Global Nuclear Fuel Bank,” World Nuclear News, 6 December 2010.

[87] APS, Readiness of the U.S. Nuclear Workforce for 21st Century Challenges, 2008.

An overview on the use of nuclear power for electricity generation

An overview on the use of nuclear power for electricity generation

Let's Ride the EV Wave

This post also appeared in the National Journal Energy & Environment Experts blog in response to a question about oil use and the future of electric vehicles.

Whether or not electric vehicles (EVs) take off will ultimately depend on consumer acceptance of new technology. But public policy and technological progress are just as important, as we highlight in our new report on the transportation sector.

Indeed, electric drive vehicles powered by batteries or hydrogen fuel cells could revolutionize transportation in the United States, saving considerable amounts of oil while also reducing the sector’s impact on our global climate. And the EVs on the market now are off to a great start, winning national and international awards.

Nearly all major automakers are planning to introduce these vehicles in the coming years, and I applaud automakers like Ford that have committed to building alternative drivetrains in significant number for the long haul. Companies like Ford understand climate change and the need to reduce our impact on our global environment while not sacrificing our mobility. For EVs to achieve that goal, we need policies like a clean energy standard that aim to decarbonize our electrical grid. I’m sure Ford is also investing in this space because they see a market opportunity.

The private sector has invested billions of dollars in developing, manufacturing, promoting, and distributing EVs in the last decade. From a map on our website, you can see that policymakers across the country are supporting EVs because they want their region to benefit from this burgeoning market.

Policymakers should rely on private capital as much as possible to build out the EV charging infrastructure so we can balance the desire to support alternative vehicles while also tackling our nation’s budget deficit. To that end, we should coordinate policy related to EV purchase and home charging nationwide so private players can enter new markets more easily. The most efficient way to “refuel” these vehicles is not yet clear, and we should use policy to help provide the foundation to let the market work.

Another element that is critical to the success of these vehicles is its most expensive component – the battery. Not only do we need aggressive R&D to develop batteries with much higher energy density, we also need to figure out what to do with these batteries at the vehicle’s end-of-life. About 80 percent of the battery’s capacity is still usable at this point, resulting in the largest untapped resource in this space today.

If we achieve the right mix of policy, technological progress, and consumer acceptance, there’s little reason to doubt that alternative vehicles will have a significant impact on the car market in this decade. It appears that it will be tough to kill the electric car this time.

Eileen Claussen is President

Energy Uses

C2ES develops low-carbon solutions that aim to reduce greenhouse gas (GHG) emissions from all the major-GHG emitting sectors of the economy. Click on a sector below or on the menu on the left for more details:

2012 greenhouse gas emissions by sector according to the U.S. Environmental Protection Agency.

Moving Our Cars Off Oil

This post first appeared in Txchnologist.

It is too early to pick the ultimate car of the future. Plug-in electric, hydrogen fuel cell, and biofuel vehicles are currently in contention, but it is quite possible that no single alternative will dominate the future the way that gasoline-powered cars own our roads today. The competition will be fierce because these new technologies will not only be competing against each other, but also against the ever-improving internal combustion engine. By 2035, it’s quite possible a new gasoline-powered car will get 50 mpg and a hybrid-electric car (like the Toyota Prius) will achieve 75 mpg.

Whatever technologies win out, it is clear the societal costs of oil are too high. The price at the pump fails to include all the national security and environmental costs of exploration, extraction, distribution, and consumption of oil. Since oil appears cheaper to the consumer than its true cost to society, we end up consuming more than we should. We send hundreds of billions of dollars out of our economy each year – $330 billion in 2010 alone – to oil producers with monopoly power instead of investing the money here at home.

Lighting Efficiency

Quick Facts

  • Lighting accounts for about 11 percent of energy use in residential buildings and 18 percent in commercial buildings.
  • Both conserving lighting use and adopting more efficient technologies can yield substantial energy savings. Some of these technologies and practices have no up-front cost at all, and others pay for themselves over time in the form of lower utility bills. In addition to helping reduce energy use, and therefore greenhouse gas emissions, other benefits may include better reading and working conditions and reduced light pollution.
  • New lighting technologies are many times more efficient than traditional technologies such as incandescent bulbs, and switching to newer technologies can result in substantial net energy use reduction, and associated reductions in greenhouse gas emissions. A 2008 study for the U.S. Department of Energy (DOE) revealed that using light emitting diodes (LEDs) for niche purposes in which it is currently feasible would save enough electricity to equal the output of 27 coal power plants.


Nearly all of the greenhouse gas (GHG) emissions from the residential and commercial sectors can be attributed to energy use in buildings (see Climate TechBook: Residential and Commercial Sectors Overview). Embodied energy – which goes into the materials, transportation, and labor used to construct the building – makes up the next largest portion. Even so, existing technology and practices can be used to make both new and existing buildings significantly more efficient in their energy use, and can even be used in the design of net zero energy buildings—buildings that use design and efficiency measures to reduce energy needs dramatically and rely on renewable energy sources to meet remaining demand. The Energy Independence and Security Act of 2007 (EISA 2007) calls for all new commercial buildings to be net zero energy by 2030.[1] An integrated approach provides the best opportunity to achieve significant GHG reductions because no single building component can do so by itself and different components often interact with one another to influence overall energy consumption (see Climate TechBook: Buildings Overview). However, certain key building elements can play a significant role in determining a building’s energy use and associated GHG emissions.

Lighting accounts for about 11 percent of energy use in residential buildings and 18 percent in commercial buildings, which means it uses the second largest amount of energy in buildings after heating, ventilation, and air conditioning (HVAC) systems (see Figure 1).[2]

Figure 1: Residential Buildings Total Energy End-Use (2008)

* This chart includes an adjustment factor used by the EIA to reconcile two datasets.

Source: U.S. Department of Energy,2010 Buildings Energy Data Book, Section 2.1.5, 2010.

Adjustments to lighting systems can be straightforward and achieve substantial cost savings. Consequently, addressing lighting can be a simple way to reduce a building’s energy use, and related GHGs, in a cost-effective manner. Reducing energy use from artificial lighting can be achieved in two ways:

  • Conservation

Conservation efforts minimize the amount of time that lights are in use and can include behavioral change, building design, and automation, such as timers and sensors.

  • Efficiency

Efficiency improvements reduce the amount of energy used to light a given space, generally using a more efficient lighting technology.


This section briefly describes some of the most common ways to reduce the amount of energy consumed by lighting systems. The following options illustrate a range of conservation options—from small adjustments in daily habits to larger building design elements—that can reduce the use of artificial lighting:

  • Behavioral Change

Turning off lights when they are not being used reduces energy use, GHG emissions from electricity, and utility bills. This practice may include turning off lights in unoccupied rooms or where there is adequate natural light. Adjusting artificial light output can also provide energy savings; for example, using task lighting (e.g., a desk lamp) rather than room lighting can reduce the number of fixtures in use, and dimmers allow lights to be used at maximum capacity when necessary and at low capacity when less light is needed, such as for safety lighting, mood lighting, or when some daylight is available.[3]

  • Technologies that reduce lighting use

Timers and sensors can reduce light usage to the necessary level; these options use technology to mimic the behavior described above. Sensors come in a variety of models that serve different purposes, and certain types of sensors and light fixtures are more appropriate together than others. For example, lamps that take a long time to start are not suitable for sensors that turn off and on frequently.

  • Occupancy sensors help ensure that lights are only on when they are being actively used. Infrared sensors can detect heat and motion, and ultrasonic sensors can detect sound. Both must be installed correctly to ensure that they are sensitive to human activity rather than other activity in the vicinity (such as ambient noise). Some estimates suggest that occupancy sensors can reduce energy use by 45 percent, while other estimates are as high as 90 percent.[4],[5]
  • Photosensors use ambient light to determine the level of light output for a fixture. For example, photosensors might be used to turn outdoor lights off during daylight hours.
  • Improving building design to maximize natural light

Building designs that incorporate a substantial amount of natural light also reduce the need for artificial lighting; in these cases, artificial light may become a supplement for use during the night or when otherwise needed. Architects and land planners can play a role by designing buildings to include skylights or windows and orienting these toward the south or west. Designers and building occupants can choose light paint colors that maximize reflectance, and they can orient furniture to take advantage of available light.

When addressing GHG emissions through building design, it is important to take a holistic approach that considers not just how design affects natural light, but also the heating and cooling requirements for the building. Increasing the amount of sunlight a building receives may also lead to high levels of heat intake, which can have important implications for the building’s HVAC system. For example, large windows that reduce artificial lighting might also result in heat gain that requires more air conditioning in warm climates, or the same heat gain in a colder climate might reduce the need for additional heating.[6] In some cases, special coatings on windows can help maximize or minimize solar heat gain, depending on the desired effect (see Climate TechBook: Building Envelope). Coordinating window selection, building design, and lighting effectively can result in maximum solar light intake with the desired level of heat intake.

When artificial lighting is necessary, choosing efficient technologies can effectively reduce electricity use and related GHG emissions. In choosing among the available technologies, it is important to consider several factors, including the quality of lighting needed, the frequency of use, and the environment in which the light is being used (e.g., indoor or outdoor). The following types of lighting and fixtures are most common in buildings:

  • Incandescent bulbs

These bulbs emit light when an electrical current causes a tungsten filament to glow; however, 90 percent of the energy used for the bulb is emitted as heat rather than light, making these bulbs the least efficient for most household purposes when evaluating them on a lumen (amount of light emitted) output to energy input basis. Halogen bulbs are a type of incandescent that are slightly more efficient than standard incandescent but less efficient than most other alternatives.

  • Compact fluorescent lamps (CFLs) and fluorescent tubes

These emit light when an electric current causes an internal gas-filled chamber to fill withTabg ultraviolet (UV) light, which is then emitted as visible light through a special kind of coating on the tube.[7] All fluorescent bulbs require a ballast, a component that regulates the current going through the lamp. Ballasts can be integrated into the bulb, as is the case for most CFLs (allowing them to be used interchangeably with most incandescent bulbs) or non-integrated, which require the ballast to be part of the fixture, as is the case for many fluorescent tubes used in schools and offices. Ballasts come in two varieties: magnetic (which are older and less efficient) and electronic (which are newer and much more efficient). Efficiency upgrades for fluorescent tube lights require consideration of the ballasts because they contribute significantly to the overall energy draw of the fixture.

Both CFLs and fluorescent tubes come in a variety of shapes, sizes, and efficiencies (see Figure 2 for a diagram of a typical CFL bulb).[8] They generally use 75 percent less energy than incandescent light bulbs.[9] A CFL produces between 50-70 lumens per watt, compared to the 10-19 lumens per watt for an incandescent bulb.[10] They are also long-lasting products, with a lifetime of 10,000 hours for CFLs and a lifetime of 7,000-24,000 hours for tubes.[11] Incandescent bulbs, by comparison, have a lifetime of 750-2500 hours.[12]

Figure 2: Diagram of a Compact Fluorescent Bulb

Source: U.S. EPA/ DOE Energy Star Program. “Learn About Compact Fluorescent Light Bulbs”

  • High-intensity discharge (HID) lamps

HID lamps come in several varieties with widespread applications. They emit light when a current—also regulated through a ballast—is passed between two electrodes on either end of a gas-filled tube. Mercury, sodium, or metal halide gas can be used, each with different color outputs, lifetimes, and applications. These types of lights are not appropriate for all types of areas and use; for instance, HID lamps have a long start-up period—up to ten minutes—and are best used in areas where lighting must be sustained for several hours (e.g., on sports fields or for street lights). In general, HID bulbs are 75-90 percent more efficient than incandescent bulbs and have a long lifetime, with metal halide and high-pressure sodium bulbs being far more efficient than mercury vapor bulbs.[13]

  • Low-pressure sodium

Though these types of lamps are among the most efficient available for outdoor use, they are only useful for certain applications because of their long start-up time, cool-down time, and poor color rendition.[14] Low-pressure sodium lamps are typically used for street or highway lighting, parking garages, or other security lighting. Because of their niche application, they are not typically considered as a substitute for other types of less efficient bulbs.[15] See Table 1 for a comparison of HID and low-pressure sodium lighting.

Table 1: Characteristics of High-Intensity Discharge and Low-Pressure Sodium Lighting Types


Efficacy (lumens/watt)

Lifetime (hours)


Mercury vapor (HID)




Metal halide (HID)




High-pressure sodium (HID)




Low-Pressure sodium





Source: U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy “High-Intensity Discharge Lighting.”;
“Low-Pressure Sodium Lighting.”

  • Light Emitting Diode (LED)

In light-emitting diodes, electrons and electron holes (atoms that lack an electron) combine, releasing energy in the form of light. This technology has been around for several decades, but many applications of LEDs for lighting have only recently become available commercially as improved color renditions have been developed and costs reduced. LED fixtures use 75-80 percent less electricity than incandescent bulbs, and can have a lifespan 25 times longer than incandescent light bulbs.[16] LEDs produce in the range of 27-150 lumens per watt, depending on the type of LED.10 LEDs have small, very bright bulbs and because of their size, LED fixtures are often found in specialty applications such as decorative lamps as well as functional lamps in difficult-to-reach areas, such as for strip lighting, outside lighting, display lighting, stairway lighting, etc. (see the DOE website for more information about current LED applications). LEDs are more durable than most other lighting alternatives and are more controllable because the light can be focused in a particular direction and the LED can be dimmed.[17] Figure 3 shows the components of a typical LED.

Figure 3: Diagram of a Light Emitting Diode

Source: U.S. EPA/ DOE Energy Star Program. “Learn About LEDs”

The development of LEDs has generated a new field of lighting technology: solid-state lighting. Through the use of LEDs and similar products, researchers are developing an array of lighting options that use solid objects—rather than energy passed through a vacuum or gas—to produce light. The continued development of solid-state lighting will enable an even more widespread, general-use application for these types of products. At the moment, no other lighting technology offers the same level of potential to reduce energy use in the future.[18] The DOE estimates that energy savings in 2030 from solid-state lighting could reach 190 terawatt-hours, the annual electrical output of 24 large power plants (1,000MW). This would result in a 31.4 million metric ton reduction of carbon and $15 billion in energy savings in 2030 alone.[19]

  • Hybrid Solar Lighting

In this emerging technology, a roof-mounted solar collector sends the visible portion of solar energy into light-conducting optical cables, where it is piped to interior building spaces. Controllers monitor the availability of solar light and supplement it as necessary with fluorescent lights to provide the desired illumination levels at each location. Early experiments show that hybrid lighting is a viable option for lighting on the top two floors of most commercial buildings.[20]

This technology has other promising benefits as well. The solar collector on the rooftop can separate visible light from infrared radiation; the visible light can then be used for lighting, and the infrared radiation can be used for other purposes, such as to produce electricity, for hot water heating, or for a space heating unit. Because the energy is split, less heat energy is wasted in lighting—it is instead used for other energy-consuming items within the building.

While hybrid solar lighting systems have been developed and demonstrated in various facilities, they are currently not cost-competitive with most other lighting options. Research is underway with the goal of achieving commercial viability.

Environmental Benefit / Emission Reduction Potential

Through conservation and efficiency measures, GHG emissions associated with lighting can be reduced significantly. At the level of individual households and businesses, conservation and efficiency measures can provide lower utility bills, but widespread adoption at the societal level can result in broader GHG emission reductions and environmental benefits from the reduced demand for electricity. A range of options exists to address lighting efficiency, and using less artificial light altogether or using more efficient technologies can realize substantial environmental benefits. CFLs use 75 percent less energy and LEDs use 75 to 80 percent less energy than incandescent light bulbs; substituting these products for traditional lighting technologies, for example, can reduce net energy use.9,16

Widespread application of efficient lighting technologies will be essential for GHG emission reductions. A 2008 study for the U.S. DOE revealed that replacing LEDs for niche purposes in which LEDs are currently feasible would save enough electricity to equal the output of 27 coal power plants (see Figure 4). Though this represents only one percent of total energy consumption for lighting according to the most recent DOE estimates, savings from LED technology will increase as it is implemented on a more widespread basis.[21] McKinsey & Co’s Pathways to a Lower-Carbon Economy, for example, projects significant energy savings from switching from incandescent and CFL bulbs to LED technology by 2030;[22] this would not only provide GHG emission reductions from lower energy consumption, but it is also cost-effective over the lifetime of the bulbs.

Figure 4: Electricity Saved and Potential Savings of Selected Niche Applications

Source: U.S. Department of Energy (DOE). Energy Savings Estimates of Light Emitting Diodes in Niche Lighting Applications, Figure ES.1, 2008.

Greater GHG emission reductions can be achieved through integrated approaches that consider the entire building as a whole. Improving lighting may increase ambient heat (as in solar heat gain from daylighting) or decrease heat (such as reduced heat loss from inefficient bulbs), and depending on the region, season, and building design, this may relieve pressures on HVAC systems as well.

In addition to the climate benefits of efficiency and conservation in lighting, other benefits may include better reading and working conditions, reduced light pollution, and lower utility bills.


Some conservation efforts to reduce GHG emissions associated with energy use for lighting, such as turning off lights that are not in use, have no cost at all and provide immediate savings from lower utility bills. Newer technologies are more expensive up-front than incandescent light bulbs, but make up for the extra cost in savings within a months, depending on lighting use. For new buildings, incorporating design features that maximize natural light can also be an important, cost-effective element of constructing a net zero energy building.

Other conservation and efficiency measures require an upfront cost that is later recouped through lower utility bills, including:

  • Installing timers and sensors

The upfront price of timers and sensors varies depending on the type and scale of installation,[23] and overall savings depend on the net reduction in electricity consumption that results from the use of these technologies. Installation can result in net savings through lower utility bills.

  • Replacing incandescent bulbs with CFLs

CFLs are more expensive than incandescent bulbs, but they provide cost savings over the lifetime of the bulb through lower electricity bills. An ENERGY STAR® CFL, for example, saves about $40 over the lifetime of the bulb compared to an incandescent light, and the payback time can be just months, depending on light bulb use.[24],[25]

  • Replacing incandescent or CFL bulbs with LED bulbs

LEDs range from $25 to $60 for small bulbs,[26] but their efficiency and lifetime provide longer term savings. LEDs are currently available for certain types of lighting, such as residential downlights, portable desk lights, and outdoor area lighting.[27] Compared to incandescent bulbs, payback periods for LEDs can range from 1.7-3.4 years, depending on the lighting use. Payback periods for LEDs compared to CFLs can range from 4.5-12.9 years.[28]

As new and emerging technologies, such as hybrid solar lighting, become commercially available, consumers will have more options for lighting indoor and outdoor spaces using less energy, resulting in lower GHG emissions. As these technologies improve and become more widely adopted, their costs are expected to decline.

Current Status

Behavioral changes to conserve energy from lighting are among the most important options for achieving emission reductions from lighting, and many of these opportunities can be realized without adopting new technology at all (for example, by turning off the lights when they are not in use). When artificial lighting is necessary, many efficient lighting products are currently available. Replacing incandescent bulbs with CFLs, for example, is both accessible and affordable. McKinsey & Company’s Pathways to a Low Carbon Economy also projects significant savings over the lifetime of the bulb by switching from outdated florescent tube bulbs to more efficient models.22

In addition to those technologies that are now widely available, a variety of new and emerging highly efficient lighting systems are currently under development to improve the technology and reduce production costs. Some technologies that are promising but not yet commercially viable, include:

  • Hybrid Solar Lighting (HSL)

The technology has existed for decades, but cost considerations have thus far made widespread implementation infeasible. Currently, at least 25 facilities in the United States have installed HSL systems. Researchers are still trying to develop lower-cost systems that are marketable on a wider basis. Most research has been undertaken at the Oak Ridge National Laboratories in conjunction with DOE.[29]

  • Light Emitting Diodes (LEDs)/Solid-state Lighting.

DOE has developed a multi-year strategy to advance the research, development, and deployment of solid-state lighting technology for applications beyond the current niche opportunities for LEDs. DOE’s program includes public- and a private-sector participants, and focus areas include basic and applied research, product development, manufacturing and commercial support, and standards development.[30]

Obstacles to Further Development or Deployment

The obstacles to increasing conservation and improving efficiency for lighting are similar to those faced by buildings broadly. These barriers include upfront cost concerns, market barriers, public policy and planning barriers, and customer barriers, such as behavioral change. Up-front costs pose a particularly notable barrier: while efficient lighting technologies and practices can pay for themselves over time, some of them – particularly cutting edge technologies – have significant up-front costs that consumers, businesses, or municipalities may be unable or unwilling to pay. Payback periods also vary in length, and building occupants may be reluctant to install efficient lighting technologies if they will be vacating the building before they can reap the full benefits of these technologies (while new occupants would realize benefits immediately).

Certain lighting technologies face unique challenges, including the following:

  • Sensors/Lighting Control
    • Sensors are not always able to detect and match the needs of the occupant. This is because sensors react to different wavelengths, such as visible light, ultraviolent radiation, and infrared radiation, and because they are often located far from the area of occupancy. For example, photosensors are often located on the ceiling and cannot necessarily gauge lighting needs closer to the ground.[31]
    • Motion and occupancy sensors are not widely utilized because of logistical difficulties and consumer preference. Implementation in existing structures can be problematic because of the need for new fixtures, other wiring problems, and initial costs. Occupants may also object to automatic switch-off technology if it is poorly installed and is prone to premature switching; this can be remedied by more careful installation.[32]
  • Compact Fluorescent Lamps
    • Skepticism about the quality of CFL bulbs has deterred many consumers. Consumers may install the common spiral or A-shape CFL in an enclosed, recessed fixture without recognizing that only certain CFLs were built with reflectors to withstand the resultant heat, leading to shorter CFL lifespan.[33],[34] Moreover, manufacturers have been able to address other technical problems with early CFL models, including the start-up time, buzzing sounds, and less-appealing color temperature (a measurement that refers to the hue of light). Newer models can start in less than a second, are nearly noiseless, and are available in a variety of color temperatures.
    • Concerns about mercury may be a deterrent to some consumers. CFLs contain a very small amount of mercury in each bulb—less than 1/100 of the amount in an older thermometer.[35] However, as incandescent light bulbs require more energy and because mercury is emitted in the coal-burning process, the use of incandescent bulbs powered by coal-fired electricity generation results in mercury emissions that far exceed those of a CFL, particularly if the CFL is recycled.[36],[37]

Policy Options to Help Promote Lighting Efficiency

Because lighting efficiency can be improved through many different technologies, a broad set of policies is needed to spur the development of new, highly-efficient technologies as well as to promote the adoption of existing efficient ones. Lighting standards are an important policy for driving innovation in lighting efficiency. The Energy Independence and Security Act (EISA) of 2007, for instance, contains mandates for energy efficiency standards for incandescent bulbs; these standards phase out light bulbs that do not meet a certain efficiency standard. Lighting manufacturers have since created more efficient versions of the incandescent bulb, recognizing their popularity and the policy-driven need for efficiency. While these more efficient incandescent bulbs have not approached the level of efficiency that is possible with CFLs, the phase-out of inefficient bulbs from these federal standards and the subsequent development of more efficient technology has illustrated the role federal standards can play in driving innovation.

Other policies can facilitate the adoption of efficient existing lighting technology. Loan programs and tax credits are two examples of policies that can enable people to opt for more efficient lighting as opposed to less efficient lighting options with a lower up-front cost.

Broader building policies can also inspire building owners, managers, and occupants to examine lighting systems and practices in order to reduce both costs and GHG emissions. Such policies include updated building codes, financial incentives, information and education campaigns, lead-by-example initiatives, and research and development assistance. (For more information about each of these options, see Climate TechBook: Buildings Overview.)

Related Business Environmental Leadership Council (BELC) Company Activities

Related C2ES Resources

Climate TechBook: Buildings Overview, 2009

Climate TechBook: Residential and Commercial Sectors Overview, 2009

MAP:Commercial Building Energy Codes

MAP:Green Building Standards for State Buildings

MAP:Residential Building Energy Codes

Corporate Efficiency Project

Further Reading / Additional Resources

DOE, Office of Energy Efficiency and Renewable Energy

Environmental Defense Fund, Make the Switch: How to Pick a Better Bulb

U.S. Environmental Protection Agency (EPA) and U.S. Department of Energy (DOE), ENERGY STAR®

National Institute of Building Sciences’ Whole Building Design Guide

[1] One Hundred Tenth Congress of U.S. Energy Independence and Security Act of 2007. Sec, 422. 2007

[2] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Buildings Energy Data Book. 2010

[3] Fluorescent bulbs, which use devices called “ballasts” to regulate current through the bulb, require special ballasts that can work with dimmers.

[4] A Consumer’s Guide to Energy Efficiency and Renewable Energy. U.S. Department of Energy. Toolbase Services. Tech Set 4: Energy-Efficient Lighting.

[5] California Department of General Services: Green California. Building Maintenance—Lighting and Occupancy Sensors.

[6] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Energy Performance Ratings for Windows, Doors, and Skylights.

[7] The phosphor coating on fluorescent bulbs gives them their distinctive white color.

[8] For more information, please refer to the U.S. Department of Energy (DOE) Energy Savers and U.S Environmental Protection Agency (EPA) and DOE EnergySTAR® programs.

[9] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. New Light Bulbs: What’s the Difference?

[10] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Types of Lighting.

[11] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Fluorescent Lighting.

[12] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Incandescent Lighting.

[13] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. High-Intensity Discharge Lighting. The Energy Policy Act of 2005 outlawed mercury vapor; these lights are being phased out.

[14] Color rendition is a measure of the quality of color light indicating how colors will appear under different light sources, devised by the International Commission on Illumination (CIE). General Electric. GE Lighting.

[15] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Low-Pressure Sodium Lighting.

[16] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Lighting Choices to Save You Money.

[17] Toolbase Services. LED Lighting.

[18] U.S. Department of Energy. Office of Energy Efficiency and Renewable Energy. Solid-State Lighting.

[19] U.S. Department of Energy. Office of Energy Efficiency and Renewable Energy. Solid-State Lighting Portfolio.

[20] U.S. Department of Energy, Office of Renewable Energy and Energy Efficiency. Hybrid Solar Lighting Illuminates Energy Savings for Government Facilities. 2007

[21] Navigant Consulting, Inc. Energy Savings Estimates of Light Emitting Diodes in Niche Lighting Applications. Prepared for the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy. 2008.

[23] Lighting Controls.

[24] EPA and DOE. ENERGY STAR®: Compact Fluorescent Light Bulbs.

[25] The payback period is the amount of time it takes for the cost savings of the more energy efficient bulb to equal the difference in initial bulb costs. To calculate the cost of switching to CFL bulbs based on the current average price of electricity, please visit the EPA’s CFL Calculator.

[26] Toolbase Services. LED Lighting.

[27] Recessed downlights are the most commonly installed type of lighting fixture in residential new construction. Please see the DOE’s Solid-State Lighting webpage for more information about specific applications.

[29] Maxey, Curt. Hybrid Solar Lighting. June 2008.

[31] Lighting Research Center at the Rensselaer Polytechnic Institute. Recommended Solutions—Photosensor Dimming: Barriers.

[32] Lighting Research Center at the Rensselaer Polytechnic Institute. Recommended Solutions—Automatic Shut-off Controls: Barriers.

[33] U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy. Compact Fluorescent Lighting.

[37] Many convenient collection sites are available across the country—see the EPA’s Lamp/Bulb recycling site for more information.


Saving energy through conserving lighting use and adopting more efficient lighting technologies

Saving energy through conserving lighting use and adopting more efficient lighting technologies

Changing Planet Series

Changing Planet is a three-part series of town hall events intended to encourage student learning and dialogue about climate change by gathering scientists, thought leaders, business people, and university students to discuss the facts of climate science, the dynamics of its impact and to brainstorm solutions. The series is prodiced in partnership between NBC Learn (the educational arm of NBC News), the National Science Foundation (NSF), and Discover magazine.

The first town hall event, Changing Planet: The Impact on Lives and Values, was hosted at Yale University and moderated by NBC News Special Correspondent Tom Brokaw. The discussion explored themes of human health, national security, economic opportunity and competitiveness, moral or religious values, environmental justice, and what climate change means for youth. The panelists were Linda Fisher, Dupont’s chief sustainability officer; Rajendra Pachauri, director of the Yale Climate and Energy Institute and a Nobel Prize laureate; Billy Parish, founder and coordinator of the youth-oriented Energy Action Coalition; and Katherine Hayhoe, associate professor in the Department of Geosciences at Texas Tech University and an expert on the intersection between Christian fundamentalism and climate change.

NBC Learn/Weather Channel Make an Impact highlight

A second Changing Planet: Clean Energy, Green Jobs and Global Competition town hall was hosted at George Washington University on April 12, and focused on the economic advantages of climate change solutions, including clean energy policies and technologies and creation of market green jobs. Tim Juliani, Director of Corporate Engagement, was a panelist and provided our  perspective on the clean energy debate. Other panelists included: Ken Zweibel, a professor at GWU, Phaedra Ellis-Lamkins (head of Green for All),  and Chris Busch (director of Policy and Programs at the Apollo Alliance). NBC News reporter Anne Thompson moderated this event.

Read Discover Magazine's story on Building a Green-Collar Economy with a full transcript of the Changing Planet: Clean Energy, Green Jobs and Global Competition town hall.

The third town hall will be held at Arizona State University in the fall of 2011, and its suggested focus will be “Keeping It Fresh: Our Water Future,” impacts of  how communities are adapting, or preparing to adapt to, changing availability of fresh water..

In addition to the Changing Planet town halls, NBC Learn and NSF worked together to produce a series of 12 online video reports looking at the impact of climate change in various locations around the world. From Bermuda’s tropical seas to the Arctic Ocean, each story follows scientists in the field who are studying the dramatic impacts of rising temperatures in the air, in the water, and on land. The series is narrated by Anne Thompson, Chief Environmental Affairs Correspondent for NBC News. Watch the full video series here.

Geothermal Electricity

Quick Facts

  • Geothermal electricity generation is a commercially proven technology that harnesses the nearly inexhaustible heat of the earth’s core to continuously generate nearly zero-emission renewable electricity at a cost that is competitive with, and in many cases lower than, traditional fossil fuel power generation.
  • Geothermal energy is available twenty-four hours a day, seven days a week, which avoids problems of variability associated with other renewable technologies like wind and solar.
  • While it constitutes 8 percent of U.S. non-hydroelectric renewable electricity generation, geothermal energy currently provides less than 1 percent of total U.S. electricity.[1],[2]
  • Currently, nine states produce electricity from geothermal plants, with more than 80 percent of total geothermal generation capacity in California.[3]
  • While the United States currently has about 3,000 megawatts (MW) of geothermal electric generating capacity, the U.S. Geological Survey estimates the United States possesses 39,000 megawatts MW of geothermal potential, including identified resources and resources that are hidden or undetectable at the surface.[4],[5],[6]


Geothermal energy can be used for electricity generation, heat pumps, or direct applications. This document focuses only on the traditional, commercially available technologies that produce electricity by exploiting the naturally occurring heat of the earth. Enhanced geothermal systems, which utilize advanced, and often experimental, drilling and fluid injection techniques to augment and expand the availability of geothermal resources, are the subject of a separate factsheet (see Climate TechBook: Enhanced Geothermal Systems).

Unlike other sources of renewable energy, such as wind and solar, geothermal power generation can operate steadily nearly twenty-four hours a day, seven days a week. Continual production makes geothermal an ideal candidate for providing nearly zero-emission renewable baseload power.

In 2011, the 15.3 billion kilowatt-hours (kWh)  of geothermal electricity generated in the United States constituted 8 percent of the non-hydroelectric, renewable electricity generation, but only 0.4 percent of total electricity generation.[7],[8] The same year, five states generated electricity from geothermal energy (CA, HI, ID,  NV, and UT), but California alone accounted for 82 percent of U.S. geothermal electric generation.[9] Geothermal plays an important role in some of the states where it is installed. Geothermal facilities satisfy 6 percent of California’s electricity consumption and 2 percent of Hawaii’s. [10],[11]

Despite its current limited application, geothermal energy has a very large potential for expansion. As Figure 1 illustrates, most of the U.S. geothermal potential is in the western states. The U.S. Geological Survey estimates that current technologies could harness nearly 40,000 MW of geothermal resources in America’s West, compared to a current U.S. electric generating capacity of roughly 1 million MW.[12]

Figure 1: Distribution of U.S. Geothermal Resources

Source: Roberts, Billy J. National Renewable Energy Laboratory. October 2009.


Geothermal energy taps into the natural heat of the earth to produce electricity. More specifically, conventional geothermal energy draws on the earth’s hydrothermal resources (underground heated water and steam). After drilling into these reservoirs, geothermal plants extract hot water and steam from the earth’s crust to drive electricity-generating turbines, a process called “heat mining.”[13]

The various techniques currently used to produce geothermal energy include the following (see Figure 2 for illustrations of these techniques):

Dry Steam

Dry steam plants draw steam directly from under the earth’s surface to a turbine that drives a generator. The steam then condenses into water and is reinjected into the geothermal reservoir.

Flash Steam

Flash steam plants extract geothermal water exceeding 350°F under extremely high pressure. Upon surfacing, a sudden reduction in pressure causes a portion of the heated water to vaporize, or “flash,” into steam. That steam turns a turbine, which drives a generator, after which the water is reinjected into the geothermal reservoir.

Binary Cycle

Binary cycle plants operate in areas with substantially lower-temperature geothermal water (225°F). Rather than using hydrothermal resources to drive a turbine, binary cycle plants use the earth’s heated water to vaporize a “working fluid,” any fluid with a lower boiling point than water (e.g., iso-butane). The vaporized working fluid drives a turbine that powers a generator, while the extracted geothermal water is promptly reinjected into the reservoir without ever leaving its closed loop system.

Figure 2: The Three Most Common Techniques Used for Geothermal Electricity Generation

Illustration of a Dry Steam Power Plant - Geothermal steam comes up from the reservoir through a production well.  The steam spins a turbine, which in turn spins a generator that creates electricity.  Excess steam condenses to water, which is put back into the reservoir via an injection well.

Source: U.S. Department of Energy. Geothermal Technology Program. Hydrothermal Power Systems. November, 2010.

Geothermal energy also depends on advanced hard-rock drilling technology. While oil and gas drilling techniques apply to geothermal drilling, temperatures above 250°F found in geothermal reservoirs complicate the process. The high heat increases the probability of well failure due to collapse, mechanical malfunction, and casing failure.[14],[15] Extensive research has gone into understanding the geological characteristics of geothermal reservoirs and how to adapt drilling technologies to these conditions.[16]

Environmental Benefit and Emission Reduction Potential

Environmental benefits from geothermal energy include near-zero greenhouse gas emissions from plant operations and low freshwater use and contamination. Traces of carbon dioxide (CO2) and other greenhouse gases are found dissolved in some hydrothermal reservoirs. Using those hydrothermal resources with dry steam and flash steam geothermal plants does allow these dissolved greenhouse gases to escape into the atmosphere.[17] [18]A geothermal plant will emit only zero to four percent as much CO2 as a traditional coal-fueled power plant per unit of electricity generated.[19] Geothermal plants also emit significantly less conventional air pollutants (nitrogen oxides, sulfur dioxide, and particulate matter) than coal power plants, as these emissions are virtually nonexistent.[20]

A market-based policy to reduce greenhouse gas emissions and spur the deployment of clean energy technology could lead to much more rapid growth in geothermal electricity generation. For example, in its analysis of a 2010 greenhouse gas cap-and-trade proposal, U.S. Energy Information Administration projected that, geothermal electricity generation could grow more than twice as fast with such a policy in place.[21]

Globally, the International Energy Agency (IEA) estimates that geothermal electricity generation provided about 0.3 percent of total electricity in 2010. With current policies, IEA projects that geothermal sources will provide only about 0.5 percent of global electricity by 2035. However, with coordinated international action to keep greenhouse gases emissions in the atmosphere below 450 parts per million, IEA projects that geothermal electricity generation could provide about 1.4 percent of global electricity generation by 2035.[22]


There are at least two categories of costs associated all types of electricity generation: capital costs and operating and maintenance costs. The capital cost for a geothermal plant can vary significantly depending upon the conversion technology, the depth of the wells, and the temperature of the hydrothermal resource. The capital cost of a geothermal plant can range from $1,000 to more than $6,000 per kilowatt (kW) of capacity.[23]

While the capital cost of a geothermal plant can be either comparable to or much higher than that of a traditional fossil fuel power plant, the full cost of generating electricity includes operating and maintenance costs. Unlike a coal or natural gas plant, geothermal facilities do not need to purchase fuel to generate electricity. Accounting for this fact through a levelized cost analysis reveals that geothermal plants can produce electricity for 6 to 9 cents per kilowatt-hour (kWh), a rate competitive with traditional fossil fuel generation.[24] Depending on tax incentives, the EIA expects that the levelized cost of geothermal energy will remain competitive with fossil fuels.[25]

Geothermal plants harnessing high-temperature resources tend to be less expensive than those relying on low-temperature resources. This is because in high-temperature areas, more electricity can be generated from each unit of geothermal water, reducing the number of wells required. Therefore, flash steam geothermal plants, which generate electricity using hotter geothermal fluids and fewer wells, are likely to have lower capital costs than binary geothermal plants, which use cooler geothermal fluids and more wells. This correlation is pictured in Figure 3. The capital costs of flash steam plants range from $1,000 to $2,000 per kilowatt installed, while the capital costs of binary plants range from $2,000 to $6,500 per kilowatt.[26],[27]

With time, experts expect the cost of geothermal energy to drop as firms gain experience installing geothermal plants. Costs will also fall as new drilling technologies improve the exploration and well drilling phase, which constitutes, on average, 37.5 percent of a geothermal plant’s total capital cost.[28]

Figure 3: Relationship between Capital Cost of Geothermal Plants and Resource Temperature

Source: National Renewable Energy Laboratory, 2012. Renewable Electricity Futures Study.

Current Status of Geothermal Energy

From the early 1970s to the early 1990s, geothermal electricity generation saw rapid growth, with an average annual growth rate of more than 16 percent.[29] From the early 1990s until the present, however, geothermal generation has been relatively flat. As of February 2013, the United States possessed about 3,386 MW of installed geothermal capacity.[30] An additional 175 geothermal projects across fifteen states are currently under development.[31] According to the EIA, under current policies geothermal generation is projected to increase much more quickly than total electricity demand, with an annual growth rate of 4.3 percent between 2011 and 2035.[32]

Legislation and government incentives may help jumpstart the expansion of the geothermal industry. In 2012, the U.S. Department of Energy (DOE) provided $62 million for research in geothermal technologies.[33] Geothermal energy also received a production tax credit (PTC) through 2013.[34]

Geothermal energy plays an important role in some countries. Iceland, for example, generates over 80 percent of its electricity from geothermal sources.[35] The United States leads the world in terms of total installed geothermal capacity.[36] Global electric generation from geothermal sources is projected at an annual growth rate of 4.8 to 6.3%, depending on climate and energy policies.[37]

Obstacles to Further Development or Deployment of Geothermal Energy

High-Risk Exploration Phase

The exploratory phases of a geothermal project are marked by not only high capital costs but also a 75-80 percent chance of failure for exploratory well drilling, due to uncertainties regarding reservoir geology.[38] The combination of high risk and high capital costs can make financing geothermal projects difficult.[39]

Investment Uncertainty

Changes in government funding for geothermal generation and uncertainty over future climate-related regulations create uncertainty for potential project developers. Certainty is especially important in geothermal projects, which take an average of ten years to move from exploration to generation.[40] In the past, Congress has allowed the federal Production Tax Credit (PTC) to expire before renewing it. In addition, after years of moderate funding, the 2007 budget contained no provision to continue funding geothermal research. More recent federal budgets have, however, provided some funding to promote geothermal research and development, including $62 million from the DOE’s Energy Efficiency and Renewable Energy (EERE) fiscal year 2012 budget appropriated by the U.S. Congress.[41]

Geographic Distribution and Transmission

Some of the most promising geothermal resources lie great distances from regions of large electricity consumption, or load centers. The need to install adequate transmission capacity can deter investment in geothermal projects. For example, in 2002, MidAmerica Energy abandoned its geothermal project near California’s Salton Sea primarily due to lack of available transmission resources.[42]

Permitting Delays

Delays in permitting can increase the amount of time it takes to bring new geothermal facilities on-line, and increase project costs and developer risk.

Policy Options to Help Promote Geothermal Energy

Price on Carbon

A price on carbon, such as that which would exist under a greenhouse gas cap-and-trade program, would raise the cost of electricity produced from fossil fuels relative to the cost of electricity from renewable sources, such as geothermal energy, and other lower-carbon technologies.

Electricity Portfolio Standard

Electricity portfolio standards generally require that electric utilities obtain specified minimum percentages of their electricity from certain energy sources. Thirty-one states and the District of Columbia have renewable portfolio standards or alternative energy portfolio standards.[43] Congress has also considered federal renewable electricity standards and clean energy standards. Electricity portfolio standards encourage investment in new geothermal power and can guarantee a market for its generation.

Tax Credits and Other Subsidies

The federal Production Tax Credit (PTC) for geothermal electricity generation expires at the end of 2013. The PTC can lower the after-tax, levelized cost of electricity from geothermal by as much as 30 percent.[44] Geothermal developers can also choose to substitute their PTC benefits with the Investment Tax Credit (ITC). The ITC would provide tax credits equivalent to 10 percent of their investment costs in geothermal technologies. The ITC credits will expire at the end of 2016 unless the legislation is renewed.[45]

Development of New Transmission Infrastructure

Improving transmission corridors to areas with geothermal reservoirs would facilitate investment in geothermal energy. Policies to build new transmission to areas with significant renewable energy resources are already proposed for accessing the wind-rich regions of the central plains and the extensive solar resources of the desert in the Southwest United States. Such policies could also promote expanded transmission to reach the geothermal fields of the West.

Related Business Environmental Leadership Council (BELC) Companies


DTE Energy


Johnson Controls


Related Pew Center Resources

Climate Change 101: Technology Solutions, 2011

The Case for Action: Creating a Clean Energy Future. 2010

Deploying Our Clean Energy Future. 2009

Further Reading / Additional Resources

Blodgett, Leslie, and Kara Slack. 2009. Geothermal 101: Basics of Geothermal Energy Production and Use. Geothermal Energy Association.

Geothermal Energy Association. Deloitte. 2008. Geothermal Risk Mitigation Strategies Report. Department of Energy, Office of Energy Efficiency and Renewable Energy Geothermal Program.

Energy Information Administration. Geothermal Explained. 2011.

Fridleifsson, I.B., R. Bertani, E. Huenges, J. W. Lund, A. Ragnarsson, and L. Rybach. 2008. “The Possible Role and Contribution of Geothermal Energy to the Mitigation of Climate Change.” In: O. Hohmeyer and T. Trittin (Eds.) IPCC Scoping Meeting on Renewable Energy Sources, Proceedings, Luebeck, Germany, 20-25 January 2008, 59-80.

Geothermal Technologies Program. 2008. Geothermal Tomorrow 2008. U.S. Department of Energy, Energy Efficiency and Renewable Energy.

Geothermal Technologies Program. 2008. Multi-year Research, Development and Demonstration Plan: 2009-2015 with program activities to 2025. U.S. Department of Energy, Energy Efficiency and Renewable Energy.

Idaho National Laboratory. 2007. The Future of Geothermal Energy. The U.S. Department of Energy National Laboratory operated by the Battelle Energy Alliance.

International Geothermal Energy Association.

Union of Concerned Scientists. 2009. How Geothermal Energy Works.

Salmon, J. Pater, J. Meurice, N. Wobus, F. Stern, and M. Duaime. 2011. Guidebook to Geothermal Power Finance. National Renewable Energy Laboratory.

Williams, Colin, Marshall Reed, Robert Mariner, Jacob DeAngelo and S. Peter Galanis. 2008. Assessment of Moderate-and High-Temperature Geothermal Resources of the United States. United States Geological Survey.

Williams, Eric, Rich Lotstein, Chrisopher Galik and Hallie Knuffman. July 2007. A Convenient Guide to Climate Change Policy and Technology. Duke University.



[1] Energy Information Administration (EIA), Electric Power Annual Report. 2013. Table 3.1.B.

[2] EIA, Electric Power Annual. 2013. Table 3.1.A.

[3] Matek, Benjamin. Geothermal Energy Association. 2013. 2013 Annual US Geothermal Power Production and Development Report.

[4] Ibid.

[5] Williams, Colin, Marshall Reed, Robert Mariner, Jacob DeAngelo and S. Peter Galanis. 2008. Assessment of Moderate-and High-Temperature Geothermal Resources of the United States. United States Geological Survey.

[6] Represents a 50 percent chance of at least this amount.

[7] EIA, Electric Power Annual. 2013. Table 3.1.B.

[8] EIA, Electric Power Annual. 2013. Table 3.1.A.

[9] EIA, Electric Power Annual. 2013. Table 3.19.

[10] Ibid.

[11] EIA, Electric Power Annual. 2013. Table 3.6.

[12] EIA, Electric Power Annual. 2013. Table 4.3.

[13] Tester, Jefferson, et. al. 2006. The Future of Geothermal Energy: Impact of Enhanced Geothermal Systems (EGS) on the United States in the 21st Century. Massachusetts Institute of Technology.

[14] Casing is the pipe that connects the geothermal well to the generation facility, and prevents the mixing of hot geothermal fluids with groundwater at other depths. High temperatures can cause the steel piping to expand or buckle if not properly enforced with cement, a process referred to as “casing failure”.

[15] Geothermal Technologies Program. 2011. Multi-year Research, Development and Demonstration Plan: 2009-2015 with program activities to 2025. U.S. Department of Energy, Energy Efficiency and Renewable Energy.

[16]For an example of this work, see Blankenship, Douglas, David Chavira, Joseph Henfling, Chris Hetmaniak, David Huey, Ron Jacobson, Dennis King, Steve Knudsen, A.J. Mansure, and Yarom Polsky. 2009. Development of a High-Temperature Diagnostics-While-Drilling Tool. Sandia Report 2009-0248.

[17] Kagel, Alysa, Diana Bates, and Karl Gawell. 2007. A Guide to Geothermal Energy and the Environment. Geothermal Energy Association. []. See Williams, Eric, Rich Lotstein, Chrisopher Galik and Hallie Knuffman. July 2007. A Convenient Guide to Climate Change Policy and Technology.

[18] The gases released through geothermal energy production would have eventually entered the atmosphere, regardless of production in the area; however, the timing of their release is material to near-term climate forcing.

[19] Binary plants emit 0 lbs. of CO2 per MWh, flash plants emit 60 lbs. of CO2 per MWh, and dry steam plants emit 88.8 lbs. of CO2 per MWh.

[20] Williams, Eric, Rich Lotstein, Chrisopher Galik and Hallie Knuffman. July 2007. A Convenient Guide to Climate Change Policy and Technology. Duke University.

[21] Energy Information Administration. July 2010. Energy Market and Economic Impacts of the American Power Act of 2010. The text compares EIA’s “Reference” and “APA Basic” cases.

[22] International Energy Agency (IEA). 2011. World Energy Outlook 2012.

[23] Augustine, C.; Denholm, P.; Heath, G.; Mai, T.; Tegen, S.; Young. K. (2012). "Geothermal Energy Technologies," Chapter 7. National Renewable Energy Laboratory. Renewable Electricity Futures Study, Vol. 2, Golden, CO: National Renewable Energy Laboratory; pp. 7-1 – 7-32.

[24] Ibid.

[25] EIA. 2013. Annual Energy Outlook 2013. Available at:

[26] Costs are given in 2009 dollars.

[27] Augustine, et al. 2012

[28]Augustine et al, 2012.

[29] EIA. 2012. Annual Energy Review. See Table 8.2b.

[30] Matek, Benjamin. Geothermal Energy Association. 2013. 2013 Annual US Geothermal Power Production and Development Report.

[31] Ibid.

[32] Energy Information Administration. 2013. Annual Energy Outlook 2013. See Table 16.

[33] U.S. Department of Energy. 2012. Fiscal Year 2012 Agency Financial Report.

[34] HR1: The American Recovery and Reinvestment Act. THOMAS.

[35] Williams, 2008.

[36] Matek, 2013.

[37] IEA. 2012. World Energy Outlook 2012.

[38]Geothermal Technologies Program. 2008. Geothermal Tomorrow 2008. U.S. Department of Energy, Energy Efficiency and Renewable Energy.

[39] Deloitte, 2008.        

[40] Williams, 2007.

[41] U.S. Department of Energy. 2012. Fiscal Year 2012 Agency Financial Report.

[42] See footnote 9 in Tester et. al, 2006.

[43] For more information on state RPSs, see

[44] Owens, Brandon. 2002. An Economic Valuation of a Geothermal Production tax Credit. National Renewable Energy Laboratory.

[45] DSIRE. 2013. Business Investment Tax Credit (ITC).

Focus on conventional methods of generating electricity from the earth's heat

Focus on conventional methods of generating electricity from the earth's heat

Building Envelope

Quick Facts

  • Residential and commercial buildings account for almost 39 percent of total U.S. energy consumption and 38 percent of U.S. carbon dioxide (CO2) emissions.[1]
  • Space heating, cooling, and ventilation account for the largest amount of end-use energy consumption in both commercial and residential buildings. In the commercial sector they are responsible for 34 percent for energy used on site and 31 percent of primary energy use[2]. In the residential sector, space heating and cooling are responsible for 52 percent of energy used on site, and 39 percent of primary energy use.[3]
  • The building envelope – the interface between the interior of the building and the outdoor environment, including the walls, roof, and foundation – serves as a thermal barrier and plays an important role in determining the amount of energy necessary to maintain a comfortable indoor environment relative to the outside environment.


Nearly all of greenhouse gas (GHG) emissions from the residential and commercial sectors can be attributed to energy use in buildings (see Climate TechBook: Residential and Commercial Sectors Overview). Even so, existing technology and practices can be used to construct “net-zero energy” buildings ­ buildings that use design and efficiency measures to reduce energy needs dramatically and rely on renewable energy sources to meet remaining energy demand. The Energy Independence and Security Act of 2007 (EISA 2007) calls for all new commercial buildings to be net-zero energy by 2030. An integrated approach provides the best opportunity to achieve significant GHG reductions from the buildings sector, because many different building elements interact with one another to influence overall energy consumption (see Climate TechBook: Buildings Overview). However, certain key building elements can play a significant role in determining a building’s energy use and associated GHG emissions and merit a more in-depth consideration.

The building envelope is the interface between the interior of the building and the outdoor environment, including the walls, roof, and foundation. By acting as a thermal barrier, the building envelope plays an important role in regulating interior temperatures and helps determine the amount of energy required to maintain thermal comfort. Minimizing heat transfer through the building envelope is crucial for reducing the need for space heating and cooling. In cold climates, the building envelope can reduce the amount of energy required for heating; in hot climates, the building envelope can reduce the amount of energy required for cooling. A substantial part of “weatherization” includes improvements to the building envelope, and government weatherization programs often cite energy and energy bill savings as a primary rationale for these initiatives.


The building envelope can affect energy use and, consequently, GHG emissions in a variety of ways:

  • Design of the building envelope

The overall design can help determine the amount of lighting, heating, and cooling a building will require. Architects and engineers have developed innovative new ways to improve overall building design in order to maximize light and heat efficiency, for example through passive solar heating, which uses the sun’s heat to warm the building when it is cold without relying on any mechanical or electrical equipment.[4] Local climate is an important determinant for identifying the design features that will result in the greatest reductions of energy needs. These may include such things as south-facing windows in cool climates and shading to avoid summer sun in hot climates.[5]

  • Building envelope materials and product selection
  • Embodied energy

Embodied energy refers to the energy required to extract, manufacture, transport, install, and dispose of building materials, including those used in the building envelope. Efforts to reduce this energy use and associated emissions, for example through the substitution of bio-based products, can be made as part of a larger effort to reduce emissions from buildings.

  • Insulation and air sealing

Heat naturally flows from a warmer to a cooler space; insulation provides resistance to heat flow, thereby reducing the amount of energy needed to keep a building warm in the winter and cool in the summer. Insulation is frequently discussed in terms of its ability to resist heat flow, or its R-value. A variety of insulation options exist, including blanket, concrete block, insulating concrete forms, spray foam, rigid foam, and natural fiber insulation.

Adding insulation strategically will improve the efficiency of the building; however, it is only effective if the building is properly sealed. Sealing cracks and leaks prevents air flow and is crucial for effective building envelope insulation. Leaks can generally be sealed with caulk, spray foam, or weather stripping.[6]

  • Roofs

Roof design and materials can reduce the amount of air conditioning required in hot climates by increasing the amount of solar heat that is reflected, rather than absorbed, by the roof. For example, roofs that qualify for ENERGY STAR®[7] are estimated to reduce the demand for peak cooling by 10 to 15 percent.[8] Proper insulation is also important in attics and building cavities adjacent to the roof.

In addition, roofs also offer several opportunities for installing on-site generation systems. Solar photovoltaic (PV) systems can either be installed as a rooftop array on top of the building or a building-integrated photovoltaic system can be integrated into the building as roofing tiles or shingles (see also Climate TechBook: Solar Power).

  • Walls

Like roofs, the amount of energy lost or retained through walls is influenced by both design and materials. Design considerations affect the placement of windows and doors, the size and location of which can be optimized to reduce energy losses. Decisions regarding the appropriate material can be more complicated because the energy properties of the entire wall are affected by the design. Importantly, material selection and wall insulation can both affect the building’s thermal properties.

A building’s thermal mass – i.e., its ability to store heat – is determined in part by the building materials used. Thermal mass buildings absorb energy more slowly and then hold it longer, effectively reducing indoor temperature fluctuations and reducing overall heating and cooling requirements. Thermal mass materials include traditional materials, such as stone and adobe, and cutting edge products, such as those that incorporate phase change materials (PCMs). PCMs are solid at room temperature and liquefy as they absorb heat; the absorption and release of energy through PCMs helps to moderate building temperature throughout the day.

  • Windows, doors, and skylights

Collectively known as fenestration, windows, exterior doors, and skylights influence both the lighting and the HVAC requirements of a building. In addition to design considerations (the placement of windows and skylights affects the amount of available natural light), materials and installation can affect the amount of energy transmitted through the window, door, or skylight, as well as the amount of air leakage around the window components. New materials, coatings, and designs all have contributed to the improved energy efficiency of high-performing windows, doors, and buildings. Some of the advances in windows include: multiple glazing, the use of two or more panes of glass or other films for insulation, which can be further improved by filling the space between the panes with a low-conductivity gas, such as argon, and low-emissivity (low-e) coatings, which reduce the flow of infrared energy from the building to the environment.

In residential buildings, using optimum window design and glazing specification is estimated to reduce energy consumption from 10 to 50 percent below accepted practice in most climates; in commercial buildings, an estimated 10 to 40 percent reduction in lighting and HVAC costs is attainable through improved fenestration.[9]

  • Interactions with other building elements

The building envelope can affect the lighting, heating, and cooling needs of the building. These interactions are important to consider when retrofitting or weatherizing buildings to reduce their energy use in the most cost-effective manner. For example, with a new building it may be more cost-effective to choose a design with a more costly, high-performance building envelope that significantly reduces the need for heating and cooling with a smaller, less-costly HVAC system. For existing buildings, it may be more cost-effective to add insulation to a building than to install a more efficient heating system.

Environmental Benefit / Emission Reduction Potential

Improvements to the building envelope have the potential to reduce GHG emissions from new and existing buildings in the residential, commercial, and industrial sectors. The building envelope can significantly affect the amount of required lighting and HVAC, the two largest end uses of energy in both the residential and commercial sectors. Local climate influences the appropriateness and cost-effectiveness of many decisions pertaining to building envelope design and product selection.

Greater GHG emission reductions can be achieved through integrated approaches that consider the entire building as a whole. Significant improvements in energy efficiency are attainable and can reduce building-related emissions to very low levels or, when coupled with renewable energy sources, to zero.

In addition to the climate benefits, many building envelope improvements also result in a variety of benefits for consumers, including lower energy bills, as well as improved thermal comfort, moisture control, and noise control.


Improvements to the building envelope have the potential to be cost-effective for both new and existing buildings. From a climate perspective, improvements to the building envelope should be pursued because they reduce GHG emissions; from a consumer perspective, improvements to the building envelope should be pursued because they can result in both a more comfortable indoor environment and reduced energy costs. The ENERGY STAR® program provides estimates of cost savings associated with several building envelope elements, for example:

  • Windows

For a typical home, an ENERGY STAR® window will save $126 to $465 per year when replacing single-pane windows and $27 to $111 per year when replacing double-pane windows.[10]

  • Insulation and air sealing

By sealing air leaks and adding insulation from average values to recommended values, the average home in the northern United States can save 12 percent on its total utility bill (19 percent of heating and cooling costs) and the average home in the southern United States can save 11 percent on its total utility bill (20 percent of total costs).[11]

Energy audits can be conducted to identify the most cost-effective ways to improve energy efficiency in existing buildings. New buildings can be cost-effectively built to have lower energy needs, and the Commercial Building Initiative, a public-private collaboration, has a goal of having marketable net-zero commercial buildings beginning in 2025.[12] Importantly, these whole-building efforts include, but are not limited to, improvements to the building envelope.

Obstacles to Further Development or Deployment

In broad terms, the obstacles to improved building envelopes are the same as the obstacles faced by buildings broadly. These barriers include cost concerns, market barriers, public policy and planning barriers, and customer barriers. More narrowly, these obstacles pose different barriers to new and existing buildings, as well as to each of the different building envelope elements. The cost-effectiveness of certain building envelope improvements, such as improved insulation and sealing of air leaks, has not led to widespread implementation. Insulation retrofits, for example, would not only reduce GHG emissions, but they would also reduce energy consumption and consumer energy bills, improve air quality, and reap a variety of public health benefits.[13] These kinds of energy efficiency projects are part of the low-hanging fruit for reducing GHG emissions.

Policy Options to Help Promote Building Envelope Improvements

Like the obstacles to building envelope improvements, the available policy options fall into the same general categorization as buildings overall. Some policy and program interventions focus on improvements to a single building-envelope element, such as insulation. Tax incentives and other programs can change annually. A number of organizations track buildings-related policies; see below for a sample of useful references:

  • Standards and codes

Regulatory policies include mandatory and voluntary building codes passed by states and localities.

  • U.S. Department of Energy (DOE) Building Energy Codes Program – provides state-by-state information on residential and commercial building codes.
  • Financial incentives

Financial incentives include tax credits, rebates, low-interest loans, energy-efficient mortgages, and innovative financing, all of which address the barrier of first costs. Many utilities also offer individual incentive programs, because reducing demand, especially peak demand, can enhance the utility’s system-wide performance.

  • Weatherization Assistance Program – provides low-income families with weatherization services, including insulation, air sealing, and windows.
  • Database of State Incentives for Renewables and Efficiency (DSIRE) – tracks federal and state incentives for renewable and energy efficiency programs, including summary maps and tables, as well as a searchable database.
  • Information and education

While many businesses and homeowners express interest in making energy-efficiency improvements for their own buildings and homes, they often do not know which products or services to ask for, who supplies them in their areas, or whether the actual energy savings will live up to claims. A variety of programs provide useful information on building envelope improvements and other energy efficiency measures.

  • ENERGY STAR® – a joint program of the U.S. Environmental Protection Agency (EPA) and DOE provides information on and standards for energy efficient products and practices.
  • Energy Savers – a government program that provides information on ways to save energy at home, while driving, and at work.
  • Lead-by-example programs

A variety of mechanisms are available to ensure that government agencies lead by example in the effort to build and manage more energy-efficient buildings and reduce GHG emissions.

  • Research and development (R&D)

R&D programs provide funding and support for advanced building materials and practices. Government funding is important because the fragmented and highly competitive market structure of the building sector and the small size of most building companies discourage private R&D, on both individual components and the interactive performance of components in whole buildings.

Related Business Environmental Leadership Council (BELC) Company Activities

Related C2ES Resources

Climate TechBook: Buildings Overview, 2009

Climate TechBook: Residential and Commercial Sectors Overview, 2009

MAP:Commercial Building Energy Codes

MAP: Green Building Standards for State Buildings

MAP: Residential Building Energy Codes

Additional Resources

DOE, Office of Energy Efficiency and Renewable Energy. 2009 Buildings Energy Data Book, 2009

Whole Building Design Guide

[1] U.S. Department of Energy (DOE). 2009 Buildings Energy Data Book. Prepared for U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by D&R International, Ltd. Silver Spring, MD. October 2009.

[2] Primary energy use defined as, “energy used at the source (including fuel input to electric power plants)”. Ibid.

[3] Ibid.

[4] For more information on passive solar design, see the DOE’s site on Passive Solar Home Design, The National Renewable Energy Laboratory also provides case studies of passive solar homes in a variety of climates,

[5] The DOE has developed the Building America Best Practices Series that includes five climate-specific sets of building best practices that focus on reducing energy use and improving housing durability and comfort. Learn more at; also see the Whole Building Design Guide on Passive Solar Heating

[7] ENERGY STAR® is joint program of the U.S. Environmental Protection Agency (EPA) and U.S. Department of Energy (DOE) that provides information on and standards for energy efficient products and practices. For more information, see

[8] For more information on ENERGY STAR® qualified roof products, visit

[9] Ander, G. D. “Windows and Glazing.” Whole Building Design Guide, updated 18 June 2010.

[10] For more information on ENERGY STAR® windows, see

[11] See ENERGY STAR® Methodology for Estimating Energy Savings from Cost-Effective Air Sealing and Insulating.

[13] Levy, J. I., Y. Nishioka, J. D. Spengler. “The Public Health Benefits of Insulation Retrofits in Existing Housing in the United States.” Environmental Health: A Global Access Science Source 2: 4 (2003). 


The interface between the building's interior and the environment, e.g., walls and windows

The interface between the building's interior and the environment, e.g., walls and windows

Regulatory Reality vs. Rhetoric

First there was the warning about a construction moratorium – all new major stationary sources would come to an immediate halt because of EPA’s new source review requirements for greenhouse gas emissions (GHGs). Soon after the alarm went out about the approaching regulatory “train wreck” that would result from a series of EPA rules impacting electric utilities. A large number of power plants would shut down, the reliability of our energy supply would be sacrificed, and consumers would face skyrocketing costs.

There was only one problem with these warnings – they were made before anybody knew what the actual regulations would require. Now that EPA has issued several of these rules, it is useful to revisit these doomsday scenarios and see if the reality of the proposals matches the rhetoric before the fact.

All Energy Sources Entail Risk, Efficiency a No-Brainer

At the moment, our attention is riveted by the events unfolding at a nuclear power plant in Japan. Over the past year or so, major accidents have befallen just about all of our major sources of energy: from the Gulf oil spill, to the natural gas explosion in California, to the accidents in coal mines in Chile and West Virginia, and now to the partial meltdown of the Fukushima Dai-ichi nuclear reactor. We have been reminded that harnessing energy to meet human needs is essential, but that it entails risks. The risks of different energy sources differ in size and kind, but none of them are risk-free.

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