Cincinnatus BLOG *** Political Commentary - Social Commentary

Coal, which is by far the dirtiest fossil fuel, generates half of the electricity in the United States and 82% of the carbon dioxide emissions created by power production. Since it is abundant and cheap, it is likely to continue to play a major role in electricity generation for the foreseeable future. In the rhetoric of its champions, The United States is the Saudi Arabia of coal. Despite the introduction of wind, solar and other clean technologies, the Department of Energy in its Annual Energy Outlook 2008 projects a small, 0.03% annual increase, in coal utilization through 2015. Surprisingly, maybe shockingly, they expect that growth rate to accelerate to 1% from 2015 to 2030 unless there are restrictions on carbon dioxide emissions or new clean technology replaces inexpensive coal.

Can coal be used cleanly? Coal gasification could be the answer. In a modern gasifier, coal or any carbon feedstock is exposed to steam and carefully controlled amounts of air or oxygen under high temperature and pressure. Under these conditions, molecules in coal break apart, initiating a chemical reaction that produces “syngas” a mixture of hydrogen and carbon monoxide and other gaseous constituents. Sulfur impurities in the feedstock are converted to hydrogen sulfide and carbonyl sulfide, from which sulfur can be easily extracted, typically as elemental sulfur or sulfuric acid, both valuable commercial byproducts. Nitrogen oxides, another potential pollutant, are not formed in the oxygen-deficient (reducing) environment of the gasifier; instead, ammonia (NH₃) is created by nitrogen-hydrogen reactions. The ammonia can be easily stripped out of the gas stream.

Source US Department of Energy

Efficiency gains are an additional benefit of coal gasification. Higher efficiencies mean that less fuel is used to generate the rated power, resulting in better economics and the formation of fewer greenhouse gases.  A 60%-efficient gasification power plant can cut the formation of carbon dioxide by 40% when compared to a typical coal combustion plant. One of the salient selling points for gasification is that the process generates hydrogen, which could ultimately be used for hydrogen-powered cars.

Gasification is not just theoretical but practical, small commercial power plants have been built; e.g. The Polk Power Station near Mulberry, Florida, is the Nation’s first commercial gasification combined cycle power station. Capable of generating 313 megawatts of electricity - 250 megawatts of which are supplied to the electric grid - the power plant is one of the worlds cleanest. The plant’s gas cleaning technology removes more than 98 percent of the sulfur in coal, converting it to a commercial product. Nitrogen oxide emissions are reduced by more than 90 percent.

Gasification has just recently made its commercial debut and only time will tell how important a role it will play in producing cleaner, inexpensive energy. Coal faces many hurdles, not the least of which is that certain groups are so inherently opposed to coal that no technological breakthrough could win them over. The ultimate role of coal gasification will be directly related to our ability to produce large quantities of electricity with alternate clean technology. Given the current state of development, coal will be with us for many decades and the best solution may be to learn to use it cleanly.