TECHNOLOGY AND COST OF RECOVERING AND STORING CARBON-DIOXIDE FROM AN INTEGRATED-GASIFIER, COMBINED-CYCLE PLANT

A broad range of measures can be applied to reduce the net carbon dioxide emissions to the atmosphere and hence diminish the expected increase of the greenhouse effect. The method discussed here concerns the recovery of carbon dioxide from gases with a high carbon content. After recovery, the carbon dioxide is disposed of in exhausted natural gas (NG) fields. In an integrated-gasifier, combined-cycle (IGCC) power plant, coal is converted to an intermediate synthesis gas. The carbon can be recovered from this synthesis gas in three steps: (i) conversion of the carbon monoxide to carbon dioxide, (ii) extraction of the carbon dioxide by a physical absorption process and (iii) compression and drying of the carbon dioxide. The method reduces the emission of carbon dioxide by about 88%. Application of this process might decrease the net energy-conversion efficiency from 43.6% in the original IGCC base configuration to 38.1% in the low-carbon-dioxide-emission integrated-gasifier, combined-cycle (LCE-IGCC) plant. Assuming a fuel price of 4 Dutch guilders (Dfl)/gigajoule (GJ) for coal, the recovery of the carbon dioxide costs 25 Dfl/metric tonne (t) of carbon dioxide avoided, while electricity-production costs increase from 7.0 to 8.7 Dutch cents (Dct)/kW(e)h for the disposal of carbon dioxide. Storage in exhausted NG fields is a suitable option in The Netherlands. Upon exhaustion, the Dutch gas fields could store 40 times the total current Dutch annual carbon dioxide production. This disposal is likely to cost about 3.5 Dfl/t CO2, which increases the electricity-production costs by 0.3 Dct/kW(e)h. It is estimated that the removal of about 88% of the carbon dioxide from an IGCC power plant will cost 28.5 Dfl/t carbon dioxide avoided and lead to an increase of < 30% in the electricity-production costs.