How Clean Is Your Electricity?


Inside this Article

United States map of subregional utility electric grids.
Twenty-six subgrids provide energy to various regions throughout the United States, though energy is often bought and/or sold between subgrids at different times of the day or year.
United States map of subregional utility electric grids.

On-gridders have plenty of reason to be concerned about where their electricity comes from these days. But exactly how much of it comes from miner-killing and mountaintop-removing coal; aquifer-polluting and fracked “natural” gas; radiation-producing nuclear; war-causing oil; or fish-killing dams? How much comes from carbon-free renewables—and just how “green” are they?

The Environmental Protection Agency’s Power Profiler ( is an online database that shows the fuel mix of the electricity you buy from the grid. By plugging in your ZIP code and electric utility’s name, you can find the fuel mix and pollution emissions of the electricity in your subregional grid (one of 26 generally independently functioning electrical grids in the United States) and compare it to the national average.

The 2009 data comes from the EPA’s Emissions & Generation Resource Integrated Database (eGRID, The eGRID summary tables are a great way to see how your subregional grid stacks up against the others.

You can also get EPA data on generation sources by state, but since electric energy is consumed on grids—which can be a subset or a superset of states (or parts thereof)—it’s most accurate to assess your electricity sources by including the entire subregional grid.

And, when it comes to being green, there are several important, but different, metrics—climate-friendly, earth-friendly, and human-friendly. By any measure, fossil fuel (coal, oil, natural gas, etc.) is not “green.”

Biomass, typically burned to produce electricity, produces emissions and causes air-quality issues. And carbon emissions from biomass-produced electricity is not much of a short-term winner for the climate.

Hydropower is renewable as long as the rain falls, but large dams have large environmental impacts, including decimating or eliminating wild runs of salmon and other fish, and destroy entire canyons and river runs.

Nuclear power generation doesn’t emit carbon dioxide into the atmosphere, but uranium mining, plant construction and decommissioning, and the manufacturing of their highly specialized equipment releases a lot of CO2. Plus there are the matters of catastrophic failures and storing radioactive waste.

Geothermal steam that is tapped to turn turbines to make electricity is fairly climate-friendly, but depending upon the rates of extraction, it may not be sustainable. Depending upon where it is located and the size of the facility, it may or may not have significant environmental impact.

Only a few generation sources come out tops in all categories. Photovoltaic (solar) electricity is tops for the climate and for earthlings, but it’s even more planet-friendly if distributed over thousands of roofs rather than having tens of thousands of PV modules clustered in one spot. Wind power, although also pollution-free, can be bad for birds if poorly sited.

In 2009, the most solar electricity as a percentage of a subregional grid (0.30%) was generated in California, with Hawaii following at 0.046%. (The Paradise State produces more than two-thirds of its electricity from burning oil.) Due to a boom in PV installations, however, the percentage of solar-generated electricity has increased dramatically.

Comments (6)

MAK2D4's picture

One comment I would like to make is a point that has significant merit in this article but was overlooked. As noted "nuclear power generation doesn't emit carbon dioxide into the atmosphere, but uranium mining, plant construction and decommissioning, and the manufacturing of their highly specialized equipment releases a lot of CO2." Photovoltaic or "PV" panels are in the very same category. The mining, plant construction, and manufacturing releases tremendous amount of CO2 as well as other toxic chemicals into the atmosphere and ground such as silicon tetrachloride (SiCl4). Silicon tetrachloride is highly reactive with water and is known to cause burns and irritations to the skin, respiratory system and eyes. Furthermore, sfter silicon is produced, sulfur hexafluoride (SF6) is used to clean the reactors. SF6 is the most influential greenhouse gas due to the magnanimity of its impact. The STVC claims that “it is imperative that a replacement for sulfur hexafluoride be found, because accidental or fugitive emissions will greatly undermine the reductions in greenhouse gas emission gained by using solar power.” SF6 and SiCl4 are just two of the worst pollutants created by the solar power manufacturing process—others include toxic flame-retardants, carcinogens, endocrine disrupters, and other harmful chemicals such as lead. In many countries where the the most panels are currently being produced such as China the regulations for safe disposal or handling of these dangerous chemicals are nonexistent. The final point I would like to present is there is truly "no free lunch", everything comes for something. Please be cognizant of the manufacturing process and when you consider your next purchase.

Andy Kerr's picture

MAK2D4 makes an important point that even products that produce clean energy can be dirtily made. Yes, everything has tradeoffs.

Yes, as a greenhouse gas SF6, is the most potent per molecule, with each SF6 molecule having the same potential to warm the atmosphere as 22,000 molecules of CO2. Collectively however, all those CO2 molecules are the most significant pollutant contributing to climate disruption. As Wikipedia notes: "Given the low amounts of SF6 released compared to carbon dioxide, its overall contribution to global warming is estimated to be less than 0.2 percent."

One also should be concerned about the back end of one's energy choice. With PV panels, one doesn't have to worry about a runaway reaction spewing radioactivity all about; not to mention having to worry about how to contain radioactive was for tens of thousands of years.

The only environmentally pure position on consumption is suicide and only then if one fully mitigates the climate impacts of disposing of the body.

MAK2D4's picture

No free lunch. Are you say save the planet and kill yourself? (In jest)

Andy Kerr's picture

For the record, I'm not in favor of suicide to save the planet. I supposed I should have ended that remark with something along the lines of: ;-) to indicate that such was in jest.

Ben Root's picture

In fact, not saving the planet is a kind of suicide. Save the humans!

Ben Root's picture

Thanks for for the real numbers Andy. It's like people saying that CFLs are bad because they contain mercury, but not realizing how much more mercury goes into the environment by using coal-powered incandescent lights. I do agree with MAKs concern about foreign (or domestic) industrial waste management practices. How can we guarantee the cleanliness of our products' production. International certification would be awesome.

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