26 MINING and the ENVIR ONMENT A c loser l ook at c lean c oal t echnologies Because coal is one of Americas most plentiful and readily available energy resource s research has been directed at fnding ways to use coal in a more efcient costefective and environmentally friendly manner The mining industry joined with the US Department of Energy in the Clean Coal Technology Program CCTP an industrygovernment partnership which has successfully developed and deployed more efcient and cleaner technologies in the marketplace to satisfy Americas need for electricity and a cleaner environment for years to come Advanced clean coal technologies can use coal more efciently with reduced emissions of sulfur and nitrogen oxides and carbon dio xide CO 2 while also providing distinct advantages over conventional coal systems Existing coal plants can of t en be retroftted with these new technologies and they can be used for new coal plants to reduce emissions to limits that may be required by new regulations Clean coal technologies typically fall into one of four categories precombustion the washing and sizing stage before coal is burned combustion where coal is combined with other substances in the boiler to improve efciency and remove impurities postcombustion where scrubbing chemical cleaning or use of precipitators remove sulfur other impurities and particulate matter from emissions going up the fue and conversion where heat and pressure convert coal to a gas or liquid that can be further refned and utiliz ed cleanly T he C C TP has developed advanced pollution controls such as low nitrogen oxide NO x burners now deployed at mor e than 75 percent of US coal power plants that help utilities comply with more stringent Clean Air Act requirements Other NO x control technologies such as Selective Catalytic Reduction demonstrate even more impressive air quality improvement capability As a result of advances pioneered in the program an additional 70 percent NO x emission reduction from 200 0 levels was achieved in 20 15 even though coal consumption incr eased ac c or ding t o the EP A Similarly the program redefned fue gas desulfurization FGD capabilities bringing to the market more efcient and costefective scrubber technology Fl u idized b ed c ombustion and i ntegrated g asifcation c ombined c ycle have entered the marketplace and ofer even greater operating efciency and air quality improvements According to the Depar tment of Ener gy each percentage improvement in operating efciency translates into a nearly equal percentage reduction in CO 2 emissions a factor important in addressing climate change In addition great advances have been made in technologies that enhanc e the potential to capture separate and store carbon Coupled with higher efciency power plants carbon captur e and s t or ag e t echnologies ofer a way to achieve reductions in CO 2 while allowing full utilization of plentiful domestic coal resources A dditionally n ew c oal c ombustion s y st ems using supercritical and ultrasupercritical technolog ies oper ate at higher temperatures and pressures to achieve bett er efciencies than conventional s y st ems in addition t o signifcant CO 2 reductions Supercritical steam cycle technology is curr ently c ommer cially a v ailable and in use in se v er al c ountries U ltrasupercritical units operating at even higher efciencies ar e curr ently being studied and ne w st eel allo y s de v eloped t o withstand the incr eased pr es sur e and t o r esist c orr osion