Reducing methane emissions from the oil and gas sector
Federal agencies are pursuing regulatory and voluntary steps to reduce methane emissions from the oil and natural gas production system, the largest manmade source of this potent greenhouse gas.
On January 14, 2015, the Environmental Protection Agency (EPA) announced a goal to cut methane emissions from the oil and gas sector by 40–45 percent from 2012 levels by 2025.
As part of achieving this goal, it released proposed regulations on August 18, 2015, for new and modified sources of methane emissions from the oil and natural gas sector. These regulations will be finalized by summer 2016.
Separately, the Department of the Interior (DOI) has proposed regulations to be finalized in 2016 to reduce methane emissions from certain wells.
EPA also plans to work collaboratively with industry and states, including expanding its voluntary Natural Gas Star program, to reduce methane from existing oil and gas operations.
Steps to reduce methane from other sources, such as landfills and coal mines, are also part of President Obama’s Climate Action Plan.
What is methane?
Methane, or CH4, is the main component of natural gas. When combusted as fuel, natural gas produces half as much carbon dioxide emissions as coal, and one-third less than oil (per unit of energy produced). However, natural gas that is released into the atmosphere without being combusted is a potent greenhouse gas.
Why is it important to reduce methane emissions?
Methane is the second biggest driver of climate change. It is much more potent than carbon dioxide (CO2) at increasing the atmosphere’s heat-trapping ability, but it remains in the atmosphere a much shorter time (a little more than a decade compared with hundreds of years for CO2).
Averaged over a 100-year time frame, the warming potential of methane is about 21 times stronger than that of CO2. However, in a 20-year time frame, it is 72 times more potent. (The most recent report by the Intergovernmental Panel on Climate Change raises estimates of the global warming potential of methane to 34 times stronger than CO2 for the 100-year time frame, and 86 times stronger for the 20-year time frame. However, the earlier estimates are still used to maintain comparability among U.S. greenhouse gas inventory reports.)
Because methane is potent and short-lived, reducing methane emissions can have a more immediate benefit, and is especially important at a time of growing U.S. oil and natural gas production.
What are the primary sources of methane emissions in the United States?
Natural gas and petroleum systems are the largest emitters of methane in the U.S., according to EPA estimates. These emissions come from intentional and unintentional releases.
Agriculture, solid waste landfills, and coal mines are also major sources and are addressed by other EPA programs.
Figure 1: 2012 U.S. Methane Emissions, By Source
In 2012, U.S. methane emissions totaled 567 million metric tons of carbon dioxide equivalent.
Source: U.S. Environmental Protection Agency, “Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2012” (Washington, DC: U.S. Environmental Protection Agency, 2014), http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html.
How much methane is released in oil and natural gas production and how will this announcement improve the accuracy of measurements?
Methane is released unintentionally and intentionally from oil and gas systems. According to EPA, natural gas and petroleum systems were responsible for 29 percent of methane emissions in 2012. The rate of methane emissions from the sector has decreased in recent years, even as natural gas production has surged.
However, independent studies estimate a wide range of leak rates from natural gas production, from 0.71 to 7.9 percent. More comprehensive studies are needed for accurate results.
EPA has committed to examining options for applying remote sensing and other technologies to improve methane emissions data accuracy and transparency, and strengthening reporting requirements for methane in its Greenhouse Gas Reporting Program.
Why is methane intentionally released?
In the production process, small amounts of methane can leak unintentionally. In addition, methane may be intentionally released or vented to the atmosphere for safety reasons at the wellhead or to reduce pressure from equipment or pipelines.
How does EPA propose to address methane emissions from oil and natural gas production?
EPA proposed a rule in August 2015 under Section 111(b) of the Clean Air Act. It would require operators of new oil and gas wells to find and repair leaks, capture natural gas from the completion of hydraulically fractured oil wells, limit emissions from new and modified pneumatic pumps, and limit emissions from several types of equipment used at natural gas transmission compressor stations, including compressors and pneumatic controllers. EPA estimates that this proposal would prevent the emission of 340,000 to 400,000 short tons of methane in 2025, which is the equivalent of 7.7 million to 9 million metric tons of carbon dioxide. A final rule is expected in 2016.
EPA already regulates Volatile Organic Compounds (VOCs, which are ozone-forming pollutants) from new oil and gas production sources, which has the side benefit of also reducing methane.
In addition, on January 22, 2016, the Department of the Interior proposed a Methane Waste and Reduction Rule to reduce methane emissions from all wells on lands managed by the Bureau of Land Management and Indian lands. The proposal from DOI will update rules and require oil and gas producers to reduce methane emissions from operations. It proposes the first-ever limits for flaring of natural gas as well as increased disclosure requirements. The proposal would prohibit venting except in specified circumstances, require pre-drill planning for leak reduction, and increased use of leak-detection technology
What entities will be covered by the regulations?
The proposed rule would cover new and modified oil and gas production sources, and natural gas processing and transmission sources. Specifically, EPA notes it will look to reduce emissions from five specific sources:
- oil well completions
- pneumatic pumps and leaks from well sites
- gathering and boosting stations
- compressor stations.
In developing new standards, EPA says it will focus on in-use technologies, current industry practices, emerging innovations and streamlined and flexible regulatory approaches to ensure that emissions reductions can be achieved as oil and gas production and operations continue to grow.
The DOI proposal would affect all oil and gas wells on federally owned onshore lands, amounting to 100,000 wells responsible for 5 percent of US oil supply and 11 percent of gas supply.
How would the EPA’s proposed methane actions complement existing regulation?
The actions would work with EPA’s new source performance standards (NSPS) and hazardous air pollutant regulations, finalized in 2012. They already apply to oil and gas production and gas processing, transmission, and storage facilities, and the rule proposed in August 2015 would apply them directly to methane as well.
While primarily aimed at reducing smog-forming and toxic air pollutants, known as volatile organic compounds (VOCs), the NSPS rules also had the indirect effect of reducing methane emissions. They include the requirement to use "green completions" at natural gas wells to limit emissions from hydraulic fracturing, a rapidly growing means of drilling and production. In a “green completion,” special equipment separates hydrocarbons from the used hydraulic fracturing fluid, or flowback, that comes back up from the well as it is being prepared for production. This step allows for the collection (and sale or use) of methane that may be mixed with the flowback and would otherwise be released to the atmosphere. Because the same technologies in place to reduce VOC emissions would also be used to reduce methane, no additional steps would be necessary to reduce methane.
In its January 2015 announcement, EPA said it will develop new guidelines to assist states in reducing VOCs from existing oil and gas systems in areas that do not meet the ozone health standard and in states in the Ozone Transport Region. Like the earlier NSPS, these guidelines will also reduce methane emissions.
The proposed regulation of August 2015 will extend emission reductions further downstream from the 2012 rules and cover certain equipment used in the natural gas transmission sector in addition to equipment covered by regulation in 2012.
What other non-regulatory steps has the administration announced it will take?
The president will request $15 million for the Department of Energy (DOE) to develop and demonstrate more cost-effective technologies to detect and reduce losses from natural gas transmission and distribution systems, including leak repairs, and developing next-generation compressors. The president’s budget will also propose $10 million to launch a program at DOE to enhance the quantification of emissions from natural gas infrastructure for inclusion in the national Greenhouse Gas Inventory in coordination with EPA. Congress must appropriate funding for these programs for them to be implemented. DOE will also be responsible for other recommendations to reduce emissions from the natural gas system.