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AS THE WORLD STRUGGLES TO CONTROL EMISSIONS of greenhouse gasses fueling global warming, many have touted the concept that coal can be burned without inordinate pollution of the environment. “Clean coal” is based on the speculative theory that massive amounts of carbon dioxide produced during coal combustion can be captured and safely “sequestered,” injecting it deep into the earth. The article to right posits such technology is too expensive, unproven and dangerous to be employed on a large scale.

Coal-fired power is the largest single source of greenhouse gas emissions in the U.S. and the world, producing two-thirds of sulfur dioxide pollution (“acid rain”), 30-40 percent of mercury, and a host of hidden problems like coal combustion waste and coal mining waste. 

Any discussion of “clean” coal has to start with “mountaintop removal,” where 8 percent of our country’s coal comes from.  Mountaintop removal refers to literally blowing the tops off mountains with enormous amounts of explosives. About 40 percent of U.S. coal comes from the Powder River Basin in northeastern Wyoming. Colorado is the sixth largest coal-producing state in the U.S.

This is perhaps why, in sunny Colorado, 72 percent of our electricity comes from coal – far more than the U.S. average of 50 percent. In view of the preceding statistics, it may be hard to believe, but Colorado is about to increase its CO2 output from coal, thanks to a large new coal plant coming online in Pueblo. Two-thirds of the new facility is owned by Xcel Energy, and about 20 percent is owned by Tri-State Generation and Transmission Association.

So what exactly is “clean” coal?

“Clean” coal implies that more air pollutants will be trapped by filters during the energy production process – but what the “clean” coal lobby won’t tell you is that those pollutants don’t magically disappear – they are simply moved from the air to water or solid waste. A recent New York Times story revealed that many coal plants in the U.S. are dumping their wastewater into rivers and streams, violating federal and state emissions standards.

What the “clean” coal people don’t like to tell us is that matter can’t be created or destroyed, only changed.

The trick to “clean” coal is that the CO2 from burning coal can be “captured” and then “sequestered.” Sequestration implies storing CO2 for at least 500 years, because 25 percent of CO2 stays in the atmosphere for 500 to 1,000 years.

While it’s easy to talk about capturing CO2, it’s much harder to actually do it.  The capture process alone requires 20 percent of a coal plant’s energy. This means that for every four “clean” coal plants, another plant will be needed just to provide enough electricity to run the capture equipment.

The captured CO2 is then compressed to 1/600th its volume, and chilled to minus 240 degrees Fahrenheit to remain in a liquid state. The liquid CO2 is then either pumped into the ground on site, or transported to another location. There are very few existing coal plants with the correct type of geology to support injecting liquid CO2 onsite. Most situations require that the gas be put into a pipeline and shipped to an adequate sequestration site. 

Injecting CO2 into the earth requires drilling holes thousands of feet deep.  Careful review of the injection site to determine if the geology can accommodate the addition of highly pressurized gasses is complex since every location is unique. 

There’s another potential problem area that complicates the concept of sequestration: liability. Who will be liable if the CO2 leaks or migrates? 

In 1986, a deep volcanic lake in the Republic of Cameroon in Africa released a large amount of CO2 that had been trapped deep in Lake Nyos. What caused the release is unknown, although seismic activity is suspected. It came up in a mixture of gas and water droplets and settled on a village on the lake, driving out the air.

Nearly everyone in the village was suffocated, including cattle. Over 1,700 people and 1,100 head of cattle died.

Here in Colorado, liquid waste from the Rocky Mountain Arsenal was injected under the Denver Basin aquifer from 1962-1966. My father, George E. Bardwell, did a study for geologists at the time and concluded that there was a link between the injection and later earthquakes.

When the injection of liquids stopped, the earthquakes ceased as well.

Who will be liable in case of explosion or leakage? Without a limitation of liability from the government, industry cannot afford to insure against this type of accident.

OK, so it will take a lot of energy to do this and it’s risky. What else?

We mine and burn about a billion tons of coal per year in the U.S. – a huge amount. Every day, 100 one-mile-long trains of coal leave the Powder River Basin in Wyoming to travel as far as Georgia to deliver coal. 

So if we use even more coal-fired power to store the emissions from the coal-fired power, we must mine and burn even more coal. This means more mercury, more coal waste, more coal ash, more particulates, more arsenic, more asthma, more heart attacks and more global warming.

Coal mining and coal combustion account for the first- and second-largest waste streams in the U.S. Dozens of studies have linked mercury with fetal deformities and learning disabilities. Coal plants lose two-thirds of their energy as heat loss. Many old and dirty coal plants have been “grandfathered” from the Clean Air Act requirements, and the coal industry has been gorging at the public trough of subsidies for many decades.

Every pound of coal burned creates about 2.5 pounds of CO2, so 1 billion tons of coal emits about 2.5 billion tons of CO2 per year, roughly equal to the CO2 emissions of the entire transportation sector: cars, planes, trains, etc.

Longtime energy professor Vaclav Smil has estimated that to capture and store 10 percent of the world’s CO2 emissions from coal plants would require an infrastructure roughly equal to the pipelines and other infrastructure that moves our oil.

What about cost? Estimates are that a new “clean” coal plant will cost 9-11 cents/kWh (kilowatt-hour) to build, and a recent Harvard University study says, 8-20 cents per kWh to capture and store the CO2. 

So the total cost is about 17-31 cents/kWh. The problem is that no one really knows what it will cost because it hasn’t been done. The cost could be greater still.

In contrast, new wind energy costs 3-8 cents/kWh, solar photovoltaics (PV) cost 18-22 cents/kWh, and concentrating solar power with molten salt storage is 12-14 cents/kWh. Wind and solar PV use no water, and solar PV close to load does not need new transmission.

It would appear that clean coal is to science what Santa Claus is to children. It might feel good to believe, but the science just doesn’t support it.

Dr. Robert A. (Andy) Bardwell is a third generation Coloradan and principal of www.BardwellConsulting.com and a pro bono public interest intervener at the Colorado Public Utilities Commission. For more information about Xcel’s Pueblo coal plant, visit www.cleanenergyaction.org.