Carbon dioxide recovery using a dual gas turbine IGCC plant

A new scheme is described for electricity production based on coal gasificiation with recovery of CO₂. Coal is gasified into a synthesis gas, mainly consisting of hydrogen and carbon monoxide. After clean-up, this synthesis gas is separated by a membrane into a carbon-rich gas and a hydrogen-rich gas. The hydrogen-rich gas is fed to a conventional gas turbine. The carbon-rich gas is fed to another gas turbine, where it is fired in a mixture of oxygen and CO₂. The exhaust of the latter is almost pure CO₂ and can be stored outside the atmosphere. The CO₂ emissions of this plant are about 10% of the emissions of an IGCC plant without CO₂ recovery, and the conversion efficiency is approx. 6% lower. A first estimate is that the electricity production costs are about one third higher. It is found that the specific emission reduction costs can be limited to about $16 per tonne of CO₂ avoided. The main technical problem of this new scheme is the development of a new type of gas turbine with CO₂ as working fluid.