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.
For nuclear power, the major concerns are low-probability but high-consequence accidents causing substantial harm to nuclear workers and the public, as well as long-term nuclear waste disposal. Whereas fossil fuel supply chains do not entail such risks, they are more likely to directly kill miners  and oil/gas workers  on an annual basis. Added to these direct occupational hazards are the public health effects of fossil fuel combustion  – both conventional air pollution, and the greenhouse gases that cause climate change and its associated impacts.
Oil use carries with it the risk of large spills during its extraction and transport. It also makes us dependent on a global oil supply that is concentrated in unstable regions of the world. Natural gas combustion pollutes the air less than oil or coal, but its transportation (especially when it requires liquefaction) presents safety and security risks.
Renewable energy sources like wind and solar involve much lower risks to workers and public health. However, the challenge with renewables is deploying them at sufficient scale to meet U.S. and global energy demand, particularly in light of issues such as the variability of wind and solar power.
We have learned to manage the risks of our energy system in a variety of ways. We set safety standards, rules and regulations for nuclear power plants, oil platforms and natural gas pipelines. We create regulatory agencies like the Nuclear Regulatory Commission, the Environmental Protection Agency, and the Occupational Health and Safety Administration, to ensure that workers and the public are protected.
We bring electricity into our neighborhoods and houses, but we know not to touch it. We odorize the natural gas that fuels our stoves and heaters so that we can smell it before it reaches dangerous levels. We locate large gas pipelines and high-voltage power lines in rights of way and tell people to keep away.
Our energy supply choices involve balancing many factors. In this blog we are focusing on health, environmental and safety risks, but all kinds of other considerations matter -- such as affordability, availability, price stability, reliability, and convenience. Based on what we know about the comparative risks, benefits and costs of our various energy systems, there is no consensus on which energy option is best. We now rely on a combination of energy sources to meet our needs, all of which have advantages and disadvantages, and that is likely to continue for the foreseeable future. Oil is by far the dominant fuel for transportation. In the U.S., almost half of our electricity comes from coal; natural gas and nuclear power each provide about one fifth of our electricity. In 2009, conventional hydropower provided 7 percent of U.S. electricity, with all other renewables providing 4 percent of total supply. Our electricity supply is much more diversified than our transportation fuel supply, making that sector less vulnerable to the risk and cost of any single energy source.
We need rules and regulators to make each and every energy source as safe as possible. With the right rules in place to address societal costs like climate change, air pollution, and nuclear accidents, we can then allow markets to judge which option has the lowest private costs. We must use the options we have as best we can and make public and private investments in new energy sources that will give us better choices (with lower social and private costs) in the future.
The only no-brainer in energy policy is energy efficiency. We will never completely obviate the need for energy supply, but there is abundant evidence  that we can dramatically and cost-effectively reduce our energy needs by reducing energy demand . The more energy efficient we are, the more money we save  on our energy bills, and the less risk we must bear from any of our energy supply options.
Oddly, a number of politicians who consider themselves conservative are going after efficiency standards. Yet what could be more conservative than conservation? Energy efficiency standards are not only effective and cost-effective for consumers, they save societal and governmental resources. By avoiding building new power plants, for example, we avoid the costs and difficulties of siting and overseeing energy facilities to safeguard environmental protection, worker safety, and public health. By using less gasoline, we can reduce the quarter of a trillion dollars  (yes I mean trillion) we send overseas each year to pay for foreign oil.
We may never achieve consensus on which energy supply option causes the least harm, but we ought to be able to agree to reduce the overall risk of our energy system by going after energy efficiency as aggressively as possible.
Judi Greenwald is Vice President for Innovative Solutions