COAL-GASIFICATION FOR ELECTRIC-POWER GENERATION

Since proven world coal resources are sufficient to produce electricit y until well into the twenty-second century, coal will remain the prim ary fossil fuel for power generation. Growing concern about environmen tal pollution will inevitably lead to more advanced and cleaner cycles . Basic considerations for advanced coal fired plants are maximum avai lability and efficiency minimum environmental emissions, optimal total costs (investment, operational and maintenance costs) and maximum uti lization of waste products. The currently applied pulverized coal fire d steam cycle plant will further develop From supercritical units in t he early 1990s (27.5 MPa, 545 degrees C, 570 degrees C) to ultrasuperc riticar double reheat units in the next century (35.0 MPa, 600 degrees C,600 degrees C). By additional improvements, such as increased feed- water temperature, improved turbine blading, waste heat recovery devic es and better back-end designs, the net thermal efficiency can be incr eased further. Gas turbines and fuel cells provide a new basis for eff iciency improvement early next century. Combined cycle techniques base d on pressurized fluidized bed combustion or gasification and pressuri zed entrained bed gasification are expected to be the competitive tech nologies for the next decades. The coal gasification technology has ad vantages over the coal combustion technology. First, the potential to exploit a high gas inlet temperature for the gas turbine (high efficie ncy) and second, the ability to utilize the sygas for high efficiency cycles such as the fuel cell technology or in combination with chemica l processes during night shift (powerplex principle). Finally, the rem oval of CO2 from the syngas is potentially economically feasible. Disa dvantages of coal gasification are the high capital costs and the comp lexity of the installation, Integrated gasification combined cycle pla nts are close to commercialization. They promise major reductions in e missions and interesting options for improved efficiency. Materials ar e a key element in further development.