UCG with Carbon Capture & Storage
In a carbon constrained world, UCG must be able to demonstrate that carbon in the fuel gas, when combusted at surface, can be prevented from entering the atmosphere as CO2. A key area of future research is the study of UCG with local CO2 storage. UCG creates voids in the coal and a highly stressed area above it. Under the right conditions, these could be suitable for permanent CO2 storage, and possible storage receptors for CO2 are the deeper coal seams in the vicinity of the UCG process and the use of the abandoned cavity and surrounding stressed area.
In addition, the production gases are also open to pre-combustion capture, and can benefit from the high concentration and pressure of the CO2 in the product gas. UCG is unique as a gasification process in producing CO2 and methane as well as the carbon monoxide and hydrogen found in surface gasification. This is because lower temperatures and higher temperatures in parts of the UCG cavity favour the formation of methane. Much of the CO2 from UCG can be captured more cheaply than in other applications, and UCG has the option of supplying either pure hydrogen or methane/hydrogen mixtures. The latter have favourable burning properties in turbines and the costs of transmission are lower than for hydrogen alone.
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| Stressed area above UCG Cavity |
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