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
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
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
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
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
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, 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
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
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