Throughout this past election season we heard both major-party candidates give a lot of love to “clean coal.” The phrase sounds great to Americans concerned about our dependence on foreign oil, and the U.S. has enough coal to generate our electricity for hundreds of years – if it’s “clean”, why not? But what do “clean coal” technologies really entail, and can an ancient energy source responsible for 40% of U.S. CO2 emissions really clean up its act?

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Anyone concerned about the effects of human activity on the environment should be immediately skeptical of the phrase “clean coal.” The first clue should have been the usage of the term by the American Coalition for Clean Coal Electricity, an advocacy group for coal mining and utility companies. The exact meaning of “clean” in “clean coal technology” is slippery, but ACCCE’s web site defines it this way:

Clean coal technology: Any technology to reduce pollutants associated with the burning of coal that was not in widespread use prior to the Clean Air Act Amendments of 1990.

So “clean” really means “cleaner.” It refers to any techniques that improve on practices that were less regulated before 1990.

The Clean Air Act of 1990

Coal-fired plants are currently responsible for about 40% of the U.S.’s CO2 output, and they produce sulfur dioxide and nitrogen oxide, mercury, carbon dioxide, and fine particulates commonly called “soot.”

Sulfur dioxide and NOx are the causes of acid rain. The 1990 amendments required plants to reduce sulfur dioxide emissions by 50% of the levels emitted in 1980, and gave them 10 years to do so. The amendments also established a commission that created regulations in 1994 to reduce NOx emissions by 55 to 65% of 1990 levels.

Mercury is a toxin that bioaccumulates as it moves up the food chain. Humans can be affected by eating contaminated fish and shellfish. Mercury affects fetal development. The 1990 amendments called for more research, and emissions regulations were not finalized until December of 2004.

Particle pollution, or soot, can cause respiratory and heart problems when inhaled by humans. The 1990 amendments called for a 95% reduction in particulate pollution by coal-fired plants.

The 1990 amendments ignored the issue of carbon dioxide. As a result of a ruling by the Bush Administration, carbon dioxide is not currently classified as a dangerous pollutant and can’t be regulated by the Clean Air Act.

Can Coal Clean up Its Act?

Based on this summary of the 1990 amendments, we get some idea of the state of coal cleanliness in 1990. The amendments were very concerned about soot, which is visibly dirty and obviously harmful, but they were not interested in carbon dioxide emissions. The amendments were moderately concerned about acid rain, and slow-moving with regard to mercury. So it follows that coal-fired plants have since implemented technology that regulated pollutants with rigor corresponding to the level of national concern reflected in the amendments.

The ACCCE praises any technology that reduces pollutants that was not in widespread use before 1990 as “clean” – low standard. However It is possible to reduce most of the dangerous emissions from coal-fired plants to near-zero levels.

The smoke can be pumped through a “baghouse,” which captures the particulates in mesh bags. The smoke can be run through a spray of water which combines with the sulfur to form sulfuric acid, which then falls into the “scrubber” without entering the atmosphere. Activated charcoal particles can be ground up and sprayed into the baghouse, where the mercury will get caught on the particles and be trapped in the mesh.

The hardest part is reducing CO2 emissions. There is research into methods for isolating the CO2 and sequestering it. A popular idea is carbon capture, which involves injecting the CO2 under rock formations that would keep it trapped indefinitely in the earth. MIT estimates this technology won’t be possible on a commercial scale until 2030. It would also be costly and the consequences of sequestering the gas underground alarms some environmentalists.

Another idea is integrated gasification, which involves pulverizing the coal and heating it until it becomes a gas. But gasification plants have issues with reliability and require more maintenance. Environmentalists say it results in contaminated wastewater and that it’s too expensive to be practical.

Is it clean?

With vigilance and commitment, yes.

But is it green?

No. The goal of successfully reducing carbon dioxide emissions is undermined by the absence of full support and high costs. The highest cost is time. Rather than waiting for the technology to become available and then waiting longer for it to be phased in, we should pursue alternative sources of energy that are less hostile to the environment. Implementing wind and solar power on a wide basis is preferable to jumping through hoops to accommodate the nasty byproducts of an antiquated electricity source just because it’s cheap.

+ American Coalition for Clean Coal Electricity

+ U.S. Clean Air Act