NEWS RELEASE JANUARY 2013
Pressurized Oxy-Combustion is Just One More Route to Clean Coal
Clean energy from coal is a multibillion dollar industry which will grow rather than shrink. This is the conclusion reached by McIlvaine in Fossil & Nuclear Power Generation: World Analysis & Forecast.
One of the biggest drivers for clean coal will be use where it is greener than solar or wind. This will occur when a combination of coal and biomass are burned in an oxy combustion system. All the gases (CO2) are sequestered and used for enhanced oil recovery. There are no emissions and there is a net reduction in the world’s CO2 in the atmosphere for every unit of energy generated.
The U.S. DOE as well as countries in Europe and Asia are funding programs to further oxy combustion. Two approaches in the U.S. include combustion at normal pressure and combustion at high pressure. Recent research shows that if combustion takes place at the pressures experienced by separating the oxygen from the air, there are multiple benefits including total parasitic energy reduction. The energy to compress CO2 is substantial, so eliminating this step is significant.
There is progress being made on ultra supercritical coal firing. This approach will significantly improve the conversion efficiency particularly when compared to older power plants operating in the U.S. and elsewhere. The biggest and quickest impact to make coal cleaner would be to replace all old power plants with ultra supercriticals. The capital cost would be more than offset by the 30 percent reduction in coal consumption. This new generation of power plants could be retired in twenty-five years and still provide a more economic bridge to renewables than retaining the old coal fleet.
The steam plume associated with coal plants is testimony to inefficiency. This plume can be eliminated and the heat efficiently used to make ethanol or heat sewage sludge. In fact, the co-location of sewage treatment plants and coal-fired generators should be the wave of the future. Existing coal plants can practice sewer mining and treat all the municipal sewage in the surrounding area. They can then use the treated wastewater for cooling and other purposes.
Coal complexes making power and liquid fuels are already a reality. In fact, there are large numbers of plants under construction. China is leading the way, but there are projects in many other countries. At the present price of oil, it is economically attractive to make gasoline from coal.
Many of these technologies can be applied to existing power plants. In fact many of the old coal-fired power plants are located in areas where there is a need to dispose of large quantities of municipal solid waste. This waste can be gasified and used as a reburn fuel in coal-fired boilers. The net effect is a big reduction in emissions compared to alternatives.
Generation of useful byproducts can more than offset the emissions of alternative production of those byproducts. Rare earths can be extracted from flyash. Sulfuric acid, hydrochloric acid, magnesium hydroxide and gypsum can all be economically produced along with power
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