Clean coal could fight climate change
Rhett A. Butler, mongabay.com
March 13, 2006
A new chemical process for removing impurities from coal could lead to significant reductions in carbon dioxide emissions from coal-fired power stations say researchers sponsored by the Engineering and Physical Sciences Research Council, Britain’s main agency for funding research in engineering and the physical sciences.
Cleaner, more efficient use of coal could play a key role in addressing climate change, especially with the growing importance of coal as an energy source as world crude oil supplies are diminished in the future. Coal presently supplies about two-thirds of China’s energy and one-third of the energy demand in the United States but, due to its abundance, is forecast to become an increasingly important relative to petroleum around mid-century.
Currently, coal is used mostly for electricity generation, but is less thermally efficient than natural gas-fired power stations. Scientists say that identifying and deploying effective ways of harnessing coal at acceptable environmental and economic cost is an urgent priority for the global energy industry.
“A lot of research took place in the 1970s and 1980s to see if coal-cleaning was viable,” says lead researcher Dr Karen Steel of the School of Chemical, Environmental and Mining Engineering at the University of Nottingham. “The conclusion was that it was too expensive. With the environment high on the global agenda and coal certain to remain a key energy source for decades, it makes sense to see if the perception is still justified today.”
Her team of researchers at the University of Nottingham are developing a chemical process that cleans coal before it is burnt in an effort to reduce the formation of polluting particles during electricity production. The new approach uses chemicals to dissolve and filter out unwanted minerals in coal from around 10% to below 0.05%. The chemicals are easy to regenerate from the reaction products so they are constantly recycled, reducing the overall cost of the process while eliminating traditional sources of waste. Further, removing unwanted minerals before the coal enters the power plant helps protect the turbines from corrosive particles.
Current coal reserves. Source: US Department of Energy/Energy Information Administration
According to Dr Steel there are other potential uses for ultra-clean coal, apart from power generation, including the production of heavy fuel oil, graphite and carbon fibers. Steel says added benefits result from the process by which chemicals are being regenerated.
“As the chemicals are being regenerated, valuable additional products are made, e.g. pure silica — a raw material used in the manufacture of a huge range of products such as silicon chips and solar cells,” she says in a statement from the project. “The ultra-clean coal itself also has non-fuel uses. As a raw material for manufacturing high purity carbon-based products, e.g. electrodes for the aluminium industry, it could act as a substitute for oil.”
Dr Steel says if the process proves technically viable and economically competitive, it could help ensure that world coal reserves are harnessed with less impact on climate change.
Fossil fuel emissions are blamed by most scientists for increased concentrations of carbon dioxide (CO2) in the atmosphere. The scientific consensus says that higher CO2 levels are behind the recent rise in global temperatures.
This brief is based on a news release from the Engineering and Physical Sciences Research Council.