Is the term “clean coal” an oxymoron? That’s a hot question for politicians, the energy industry and environmentalists, alike. While the words seem intuitively clear, the meaning of the term, as well as the feasibility of improving coal’s environmental impact, are in question.
First, some background. Coal is the major source of America’s energy. In fact, it provides half of the electricity produced in the U.S. However, its combustion is responsible for over 1/3 of our carbon dioxide emissions. With CO2 being targeted as one of the major causes of climate change, the coal industry has come under fire.
In response, the American Coalition for Clean Coal Electricity, a coalition of businesses including some of the country’s largest coal mining companies, electric utilities and railroad owners, is actively promoting what it calls “clean coal.” Through a multimillion-dollar advertising campaign, sponsorship of two presidential debates, and ongoing lobbying of high level governmental officials and candidates, it has turned the term into a household word, albeit one that is little understood.
Originally, “clean coal” referred to any number of techniques to reduce the negative effects of burning coal. Up until recently, this has meant reducing sulphur dioxide and other particulates that contribute to acid rain, as well as removing minerals and impurities which reduce the efficiency of combustion. Now, with increased concern about climate change, the term is more often used to describe a process that greatly reduces carbon dioxide emissions. The most commonly referred to method is carbon capture and sequestration (CCS), in which the CO2 from coal is isolated before being emitted into the atmosphere and is disposed of in a way that prevents its escape.
While there are several ways to capture CO2 from coal, in the U.S. the most promising way is via coal gasification. This process converts the coal into a gas by heating it with steam, air or oxygen, producing hydrogen, which is used as fuel, and CO2, which can be captured. The CO2 is then transported as a gas or liquid via pipelines to sequestration sites. Options for storage include declining oil fields, saline aquifers, unmineable coal seams, and even the ocean.
Many questions remain about possibilities of leakage of CO2 back into the atmosphere. The International Panel on Climate Change provides some encouragement, stating that at least 99% injected into appropriately selected and managed geological reservoirs is likely to remain there.
The questions, of course, are how to select and manage these sites responsibly, and at what cost. Ocean storage is considered more risky and problematic if leakages do occur, as CO2 in large concentration kills marine life and increases the acidity of seawater.
The issue of the cost of CCS is hardly insignificant. It is estimated that 25-40% additional fuel will be required to process the coal in a more environmentally sound way. Because the technology requires new coal-powered plants specifically designed for CCS, the cost of energy would be 20-50% higher than traditional coal-fired plants, depending on the sequestration method used.
Huge government subsidies, proposed by the Bush Administration, would be required to build power plants that could produce “clean coal.” Pundits far and wide opine that taxpayer money might be more appropriately spent on renewable energy, as well as cap and trade standards to reduce CO2 emissions.
On the political front, the financial concerns, as well as technical uncertainties, are proving to be a show-stopper. Never mind the fact that the words “clean coal” belie the definition. After all, where in the discussion is there recognition of what occurs before the coal reaches the power plant? The “cleanliness” of coal mining, with its toxic effects on the health of miners and the environment, also need to be considered.
This article was written by Abigail Rome