How Do Clean Coal Advocates Justify the Use of the Word Clean?

Ask a Scientist - Januray 2013

E. Bockian from Fullerton, CA, asks “Recent advertisements have been pitching the use of 'clean coal,' claiming that it is abundant and cheap. Even the President has used the term. My understanding is that both the production and use of coal as an energy source is very polluting. How do they justify using the word 'clean'?” and is answered by Steve Clemmer.

The term “clean coal” has been pushed hard by the coal lobby which has run $35 million advertising campaigns promoting the notion in each of the past two presidential elections. But you are right to note that it has always been more of a myth than a reality.

Coal power plants are the single largest source of heat-trapping carbon dioxide emissions in the United States. They are also a major source of pollution that causes acid rain, smog, and mercury contamination. When people talk about “clean” coal, they are usually referring to expensive, high-tech coal plants that are designed to reduce the vast amounts of pollution and carbon emissions coal causes when it is burned. Pollution-scrubbing and carbon-capture technologies do exist that can lessen coal’s air emissions. But, even with such technologies, coal is a lot dirtier than other energy sources when you consider the whole fuel cycle.

The environmentally destructive practice of mountaintop removal mining, for example, has already ravaged vast tracts of land in Appalachia.  This coal extraction practice involves stripping all the trees from a mountaintop, blasting away the top several hundred feet of the mountain with explosives to reach a thin seam of coal underneath, and then dumping the rock debris into the adjacent valleys, burying streams and destroying everything that once grew there.  According to an Environmental Protection Agency (EPA) study, mountaintop removal mining has already buried more than 700 miles of biologically diverse streams, with another 1,200 miles directly affected by the sediment.  The EPA estimates that another 1,100 miles of waterways will be adversely affected in the next 10 years.

To make matters worse, mountaintop removal mining operations often build dams to create slurry ponds in which the extracted coal is separated from the rest of the debris with water and solvents, producing a huge amount of wet coal slurry that contains all sorts of toxins and heavy metals.  There are more than 700 of these slurry ponds in Appalachia today, each containing hundreds of millions of gallons of mine waste. These ponds pose a serious environmental hazard. When one such impoundment burst in 2000, for instance, it flooded the town of Inez, Kentucky with 300 million gallons of toxic sludge, leading to a disaster 30 times the size of the Exxon Valdez oil spill that contaminated local groundwater and completely destroyed the aquatic life in a tributary of Kentucky’s Big Sandy River.

No matter what kind of technology is used when burning coal to generate electricity, there is simply no way such mining procedures can be considered environmentally “clean” by any stretch of the imagination.

Of course, there are many other fuel cycle considerations as well. Coal power plants represent the largest source of human-made mercury emissions. Transporting coal represents another huge environmental impact. Our current annual consumption of more thanover 1 billion tons of coal per year in the United States makes up roughly 40 percent of the total freight moved in the nation, adding further to coal’s pollution and emissions profile. And, in an issue with increasing consequences in parts of the country with water constraints, the nation’s coal plants pull from lakes, rivers, and other water sources on the order of 100 billion gallons of freshwater per day —more than is withdrawn by the entire agricultural sector. This water, used primarily for cooling in coal plants, can have devastating consequences for fish populations, both when fish are killed in water intake structures and when they die from the higher-temperature water the coal plants return to the nation’s waterways.

The fact is, even if you leave aside such considerations, our recent analysis shows that increasingly coal can’t compete economically with other energy sources. Our “Ripe for Retirement” report shows that the vast majority of our nation’s coal plants are more thanover 30 years old and 17 percent are more thanover 50 years old. On economic grounds alone, we find that many of these older plants ought to be shut down. According to our analysis, retrofits to meet modern emissions and public health standards will simply not be cost effective for at least one third of our nation’s coal generators.  It makes more economic sense to retire these aging coal plants and replace them with cheaper and cleaner alternatives such as wind power, energy efficiency, and natural gas.

Our analysis also shows that by 2020, existing state renewables and efficiency policies will generate or save more electricity than would be lost through the closure of these old, inefficient coal-fired generators. Such clean energy gains would exceed the amount of power generated in 2009 by these coal units in most regions of the country. And when combined with a greater utilization of existing natural gas plants, we can replace these coal plants with minimal impact on the reliability of the nation’s electricity grid.

Today, while coal’s portion of the overall energy picture in the United States is shrinking, parts of our nation remain heavily reliant on coal for electricity. Because of this, it is important to consider and implement strategies to make this energy source less damaging to the planet. Often, though, the best strategy is simply to use cleaner and cheaper alternatives. The coal lobby will no doubt continue to tout the “clean coal” oxymoron. But that can’t alter the fact that greater reliance on renewable energy sources like wind and solar combined with increases in efficiency offer a far more sensible path to a cleaner environment and more stable climate.


As director of energy research, Steve Clemmer conducts research on the economic and environmental benefits of implementing renewable energy technologies and policies at the state and national levels. He also manages UCS's coal and Midwest renewable energy projects and serves on the steering committee of the National Wind Coordinating Collaborative. Mr. Clemmer holds a M.S. in energy analysis and policy from the University of Wisconsin-Madison and a B.A. in political science and history from Gustavus Adolphus College in St. Peter, Minnesota.


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