Underground coal Gasification
The process of converting hard coal into gas has been around for nearly 200 years. The first practical application of gas derived from gasifying mined coal at the surface was in London's Street lighting system in 1807.
As early as 1812, the Gas Light and Coke Company of London were formed and, by the mid 19th Century, surface coal gasification was a major industry in most of the rapidly developing industrialised nations.
UCG clean coal technology uses a similar process to that used in surface gasification. The main difference between both gasification processes is that in UCG the cavity itself becomes the reactor so that the gasification of the coal takes place underground instead of at the surface.
POWER GENERATION Electricity can be generated using Underground Coal Gasification (UCG) syngas as feedstock by the following methods:
- Combustion in a Gas Turbine Generator (GTG)
- Combustion in a boiler to produce steam to drive a steam turbine
The main advantage of UCG syngas as feedstock for power generation, as opposed to solid coal, is that syngas can be used as feedstock for gas turbines allowing the combination of gas and steam cycles into combined cycles. The higher efficiency achieved by combined cycles compared to coal fired power stations not only means higher returns on investment but also lower greenhouse gas emissions.
Several companies have developed a range of gas turbine applications including Alstom, GE, Hitachi, Mitsubishi and Siemens.