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,
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