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By Rose Ragsdale
For Mining News 

Technology evolves with CO2 emission cuts

United States boasts 28% of world's known coal deposits; demand for greenhouse gas reductions spurs unprecedented research

 

Last updated 2/28/2010 at Noon



As researchers around the world strive to shrink the level of greenhouse gases pouring into the atmosphere from fossil fuel combustion and other sources, one aspect of the challenge is taking on new dimensions.

Coal has long been recognized as a dirty and deadly fuel. Researchers conducting autopsies in the 1800s found the lungs of infants to be black, sparking early fears that coal emissions were toxic.

Yet it took more than 170 years for scientists to develop methods to remove toxic gases from coal combustion emissions that were both effective and economic for industry.

Meanwhile, the use of coal continues to increase because the soft black rock is abundant and cheap, making it a fuel of choice for power companies and other commercial users.

Many people in developed countries see the pervasive burning of coal, especially in highly populated and poorly regulated countries such as China and India, as a climate forcer that could accelerate warming to a critical tipping point.

But it is here at home that we could face the biggest threat and perhaps, the biggest opportunity. The United States has more coal than any other country and as our most plentiful fossil fuel, it accounts for more than a quarter of all known coal reserves in the world. The United States, in fact, is called the "Saudi Arabia" of coal, likely because we have more of it than the entire Middle East has oil.

Of the world's known 929 billion tons of coal reserves in 2006, the United States had 28 percent, or roughly 260 billion tons, of it, according to the U.S. Energy Information Administration. Other countries with vast coal reserves include Russia (19 percent), China (14 percent) and Australia-New Zealand (9 percent).

Coal use in the United States totaled 22.5 quadrillion Btu in 2006 - more than 90 percent of total coal use in North America and nearly half (48 percent) of coal use around the world.

Half of U.S. coal goes into power production. Electric companies and businesses with power plants burn coal to make the steam that turns turbines and generates electricity.

At its current rate of consumption, the United States is capable of meeting its domestic demand for coal for more than 200 years.

Industry wants to build on success

But growing concern about global warming is driving increased demand for more stringent controls on pollutants from power plant emissions, including carbon dioxide, the greenhouse gas believed to be responsible for about 50 percent of climate forcing.

Government and industry scientists have responded with ongoing research and development generally known as "clean coal" technology.

"Clean coal" initially described technology aimed at curbing levels of carbon monoxide, volatile organic compounds, sulfur dioxide, nitrogen oxide and particulate matter in the exhaust generated by burning coal.

It was defined in this excerpt from U.S. Senate Bill 911 from April 1987: "The term 'clean coal technology' means any technology … deployed at a new or existing facility which will achieve significant reductions in air emissions of sulfur dioxide or oxides of nitrogen associated with the utilization of coal in the generation of electricity."

From 1970 to 2005, researchers, working with more than $50 billion in investment from industry and government, developed clean coal technology that succeeded in reducing the value of toxic emissions from coal combustion in large power plants to 6,970 short tons per billion kilowatt-hours from 30,510 short tons per billion kilowatt-hours - a reduction of 77.15 percent, according to the U.S. Environmental Protection Agency.

Curbs on CO2 emissions just beginning

Critics, however, argue that "clean coal" is a misnomer. They say the nation's more than 600 coal-fired power plants are not only still producing toxic emissions, but none of them are carbon-free or even close to it. They say the viability of an environmentally sustainable future for coal is questionable, and so is the coal industry's commitment to cleaning up itself.

As evidence, they note that the biggest coal companies in the United States have spent only a fraction of their multibillion-dollar profits developing technologies to curb carbon emissions from coal-fired power plants. Advertising, lobbying and other public clean coal activities are designed to delay global warming solutions without suffering a public relations black eye, according to The Center for American Progress, a progressive Washington, D.C.-based think tank.

To counter these charges, the American Coalition for Clean Coal Electricity representing 40 companies from the electricity generation and transportation sectors, coal producers and other manufacturers and vendors point to the track records of its members, their earlier successes and ongoing research.

Carbon capture and storage targeted

In the 1990s, industry and government scientists began to investigate what they described as the next generation of advanced clean coal technologies - those that capture and safely store carbon dioxide.

Naturally occurring carbon dioxide is relatively harmless, making up about 5 percent of the earth's atmosphere. As animals and other sources expel CO2, plants absorb the compound.

Trouble arises when large quantities of CO2 enter the atmosphere, throwing off that natural balance. CO2 found in coal deposits in the ground is released when coal is burned and otherwise combusted.

Using advanced technology and some existing techniques employed by the oil and gas industry, researchers believe they can recapture the CO2 released in coal combustion and return it to the ground before it enters the atmosphere.

In a 2009 study by researchers at Columbia University's Earth Institute and the U.S. Geological Survey, scientists reported mapping 6,000 square miles of ultramafic rock formations in the United States that could be used to store 500 years worth of U.S. carbon dioxide emissions.

After a decade of research, DOE's National Energy Technology Laboratory reported in 2007 that North America has enough storage capacity for more than 900 years worth of carbon dioxide at the current rate of production of 3.8 billion tons of CO2 each year. This storage capacity is located deep underground across the continent in varying types of geological formations - including coal seams that cannot be mined and oil and gas reservoirs.

More than $12 billion in new clean coal research is under way in 43 states along with a slew of other projects around the globe. Thanks to substantial funding from the U.S. Department of Energy, via the American Recovery Act, in recent months more research has entered the pipeline.

 

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