An integrated gasification combined cycle (IGCC) is a technology that uses a high-pressure gasifier to turn coal and other carbon-based fuels into pressurized gas—synthesis gas (syngas). The system is also able to remove impurities from the syngas prior to the power generation cycle.

Some of these impurities, such as sulfur, can be turned into re-usable byproducts through the Claus process. This results in lower emissions of sulfur dioxide, particulates, mercury, and in some cases carbon dioxide. With additional process equipment, a water-gas shift reaction can increase gasification efficiency and reduce carbon monoxide emissions by converting it to carbon dioxide. The resulting carbon dioxide from the shift reaction can be separated, compressed, and stored through sequestration. Excess heat from the primary combustion and syngas fired generation is then passed to a steam cycle, similar to a combined cycle gas turbine. This process results in improved thermodynamic efficiency compared to conventional pulverized coal combustion.