Underground coal gasification

Paul Boughton
Despite the ongoing trend towards greater use of renewable energy sources, the fossil fuels, and coal in particular, will continue to be a major source of energy for some time to come. But many of the world’s coal reserves are unusable simply because they lie too deep for profitable extraction. On the other hand, using fossil fuels contributes to the rising СО2 concentration in the atmosphere and the resulting global climate change.
Bulgaria’s largest privately owned gas company, Overgas Inc AD, acting in a consortium of partners from five European countries, has signed an agreement for financial support to a research project on underground coal gasification (UCG) and subsequent sequestration of the CO2 thus liberated. This project is being supported by the European Union with a three million euro grant, awarded in the context of the Research Fund for Coal and Steel (RFCS).
The coal is first to be converted into gas far underground and then routed to the surface where the energy is ultimately utilised. The waste greenhouse gases are then to be stored in the cavities formed by mining and in surrounding rock.
Overgas is the leader and coordinator of the initiative. Among the partners in the project are renowned European academic organizations and businesses, including DMT GmbH & Co. KG in Essen. DMT will be conducting geological evaluations of the deposits. In addition to economic and environmental aspects, technical procedures in regard to dual use of the drill holes will be in the foreground. Among the documentation to be generated is a “Best Practice” manual covering final closure of the drill holes and long-term monitoring.
The international team of engineers and scientists is to explore the setting prevailing for the realization of the procedure in Bulgaria. If the results of the study, expected to be completed in 2013, are favorable, then plans for a subsequent field test will be worked out with industry.
The idea for gasification of coal underground is not new – the process has been the target of extensive development over the past ninety years. Several large-scale power schemes were constructed in the 1980s in the former Soviet Union. Commercial exploitation of this technology is underway in Australia, the United States, Canada, South Africa and China. Offshore UCG permits have been issued in the UK.
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