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European UCG Trial (1992-1999)

The European Working Group on UCG recommended in 1989 that a series of trials should be undertaken to evaluate the commercial feasibility of UCG in the thinner and deeper coal seams, typical of Europe. The first would be at an intermediate depth of around 500m to test the feasibility of the previously developed technology at this greater depth. If successful, later trials would follow to test UCG operations at ~1000m depth, and evaluate power generation from the resultant production gas. The first of these proposed trials became the Spanish trial 1992-1999.

The trial was undertaken by the Spain, the UK and Belgium, and was supported by the European Commission.

A suitable site at "El Tremedal" in the Province of Teruel, NE Spain was chosen on the grounds of its geological suitability, coal seam depth (550m) and the availability of extensive borehole data. The objectives were to test the use of directional in-seam drilling to construct the well configuration and to evaluate the feasibility of gasification at depths greater than 500m.

The Spanish trial was completedsuccessfully (although operating hours were low) and it demonstrated the feasibility of gasification at depth, the viability of directional drilling for well construction and intersection and the benefits of a controllable injection and ignition point (CRIP- controlled retractable injection point).

The operating and drilling experience provided a number of useful lessons for future trials in terms of the detailed engineering design of the underground components, the control of the in-seam drilling process and the geological selection of trial sites. The problems identified during the Spanish trial are relatively easy to solve, and a further trial of sustained channel gasification would lay the technical foundations for commercial operations, and provide a basis for a detailed economic assessment of the process of UCG.

UK Programme for UCG (1999 to date)

Largely as a result of the Spanish trial results, The Department of Trade & Industry Technology identified UCG as one of the potential future technology for the development of the UK's large coal reserves.

Technology targets got UCG development were set in the DTI's Energy Paper 67 (1999), as follows;

• Improved accuracy of in-seam drilling
• Assessment of the implications of burning UCG gas in a gas turbine
• Estimates of the landward reserves of coal that could be technically suited to underground gasification
• Identification of a site for a semi-commercial trial of UCG
• Identification of the parameters that underground coal gasification would have to meet to compete with current North Sea gas production costs.
• A pre-feasibility study for the exploitation of underground coal gasification offshore in the southern North Sea.

An initial pre-feasibility study was completed in January 2000 by the DTI in conjunction with The Coal Authority, and work then began on the selection of a UK site for a drilling and in-seam gasification trial. Detailed work has been done on the geological and hydrogeological criteria for UCG, the evaluation of suitable sites, and the legislative regime, mainly European, that would apply to an onshore UCG scheme.

This work, now largely complete, has emphasised the growing importance of environmental issues and a thorough investigation of these issues will be undertaken before legislative approval of a test site is sought. It is summarised in a report entitled "Review of the feasibility of undeground coal gasification in the UK", September 2004, which is available on the DTI website, see report 

In addition to the work on a trial site, paper feasibility studies have been initiated into the technology of UCG, and the potential of the UK coal resources Independent consultants have also undertaken a review of the technological advances in UCG (see references and web links).

People's Republic of China (late 1980's to date)

China has the largest on-going UCG programme currently underway. 16 trials have been carried out or currently operating since the late 1980's. The work uses abandoned galleries of disused coal mines for the gasification. Vertical boreholes are drilled into the gallery to act as the injection and production wells. A system of alternating air and steam injection is used to improve the production of hydrogen.

The UCG centre at the China University of Mining and Technology, Beijing, is testing UCG in abandoned coal mines.

A project due to start in Shanxi Province this year will use UCG gas for the production of ammonia and hydrogen production, Small scale power production schemes using converted coal boilers or gas turbines are also under consideration. A technology transfer study between the UK and China on UCG is currently underway.

A technical centre for UCG has been set up in the University of Beijing, and a technical exchange of information on UCG is taking place with the UK.

Australia (mid 1990's to date)

CSIRO are undertaking feasibility studies of UCG, and are currently evaluating cavity models in association with the University of Sydney. CSIRO have also been examining the process and power implications of UCG.

A trial burn of UCG by a private company, Linc Energy, was initiated in December 1999 in a coal seam in Chinchilla, Queensland, and the process was still in operation at the end of 2001. The results are currently being evaluated, and studies are underway of a larger gasification project combined with power generation. Gas turbine manufacturers have examined the product gas composition from Chinchilla and have concluded that units such as the GE Frame 6B, can operate satisfactorily on air blown UCG gas. They have extensive test experience on low CV gas to support this view.(see references and web links).

Japan

Japan, which has substantial coal interests overseas has UCG in its future research plans for coal exploitation, and has been maintaining a low level programme for many years. Economic and technical studies have been produced, and there are reports that a Japanese sponsored trial, possibly overseas will be undertaken in the near term.

The University of Tokyo undertakes technical and economic studies of UCG, and maintains a watching brief on behalf of NEDO. Japanese coal companies are interested in the technology as a possible export opportunity.

Other Countries

Feasibility studies have been undertaken recently by New Zealand, and a small trial burn was initiated at Huntley in 1994 with US technical advice.

India, Pakistan and some Eastern European countries, like Ukraine and Romania maintain an interest in UCG, and developments may already be underway.

Russia maintains technical expertise in UCG at the Russian Academy of Sciences in Moscow, and it is understood that one of the original schemes, developed in the Soviet era, is still in productionThe following graph shows the current schemes as a function of seam depth.

UCG Trials as function of coal seam depth

MBG September 2004