New solution to CO2 pollution

Coal gasification offers one of the most versatile and clean ways to convert coal into electricity, hydrogen, and other valuable energy products. The first coal gasification electric power plants are now operating commercially in the United States and in other nations, and many experts predict that coal gasification will be at the heart of the future generations of clean coal technology plants for several decades to come. Gasification, in fact, may be one of the best ways to produce cleanburning hydrogen for tomorrow's automobiles and power-generating fuel cells. Hydrogen and other coal gases can also be used to fuel power generating turbines. The environmental benefits of gasification stem from the capability to achieve extremely low COx SOx, NOx and particulate emissions from burning coal-derived gases. Sulfur in coal, for example, emerges as hydrogen sulfide and can be captured by processes presently used in the chemical industry. In some methods, the sulfur can be extracted in either a liquid or solid form and can be sold commercially. In an Integrated Gasification Combined-Cycle (IGCC) plant, the syngas produced is virtually free of fuel-bound Nitrogen. NOx from the gas turbine is limited to thermal NOx. Diluting the syngas allows for NOx emissions as low as 15 parts per million. Selective Catalytic Reduction (SCR) can be used to reach levels comparable to firing with natural gas if required, to meet more stringent emission levels. Coal gasification may offer a further environmental advantage in addressing concerns over the atmospheric buildup of greenhouse gases, such as Carbon dioxide. If Oxygen is used in a coal gasifier instead of air, Carbon dioxide is emitted as a concentrated gas stream in syngas at high pressure. In this form, it can be captured and sequestered more easily and at lower costs. By contrast, when coal burns or is reacted in air, 80 percent of which is Nitrogen, the resulting Carbon dioxide is diluted and more costly to separate. Efficiency gains are another benefit of coal gasification. In a typical coal combustion plant, heat from burning coal is used to boil water, making steam that drives a steam turbine-generator. In some coal combustion plants, only a third of the energy value of coal is actually converted into electricity, the rest is lost as waste heat. A coal gasification power plant, however, typically gets dual duty from the gases it produces. First, the coal gases, cleaned of impurities, are fired in a gas turbine - much like natural gas - to generate one source of electricity. The hot exhaust of the gas turbine is then used to generate steam for use in a more conventional steam turbine-generator. This dual source of electric power, called a "combined cycle," is much more efficient in converting coal's energy into usable electricity. The fuel efficiency of a coal gasification power plant, in this type of combined cycle, can potentially be boosted to 50 percent or more. Future concepts that incorporate a fuel cell, or a fuel cell-gas turbine hybrid, could achieve efficiencies nearly twice today's typical coal combustion plants. Higher efficiencies translate into more economical electric power and potential savings for rate-payers. A more efficient plant also uses less fuel to generate power, meaning that less Carbon dioxide is produced. In fact, coal gasification power processes, under development by the US Energy Department, could cut the formation of Carbon dioxide by 40 percent or more per unit of output, compared to today's conventional coal-burning plants. The capability to produce electricity, hydrogen, chemicals, or various combinations - while eliminating nearly all air pollutants and potentially greenhouse gas emissions - makes coal gasification one of the most promising technologies for energy plants of the future.