Coalgas (U.K.) Ltd., Mansfield, U.K., has begun gas production from two abandoned coal mines and plans to bring 40 more small coalbed methane (CBM) projects into operation in the next 5 years.
The company found a novel way of exploiting coalbed methane that seeps from derelict coal mines by pumping gas from vent shafts rather than by drilling into coal seams (OGJ, June 29, 1998, p. 38).
In February, Coalgas began gas production from a vent in the former Markham mine near Mansfield, and in March, it began delivering gas to an electricity utility from the nearby former Steetley mine.
Cameron Davies, managing director of Coalgas, told OGJ that it is currently working to begin coalbed methane production on the site of the former Shirebrook mine, again near Mansfield.
"In the past year," said Davies, "we have inventoried 140 mines, and we want to bring 40 into production over the next 5 years. In these 12 months, the coal authorities have changed their perception of coalbed methane, thanks in part to the Markham and Steetley projects. Now they realize its potential and have come on board, providing us with tremendous cooperation."
Gas from the Markham mine is extracted at a rate of up to 1,300 cu m/hr and delivered through a 650-m pipe- line to local smokeless fuel manufacturer Coalite.
Coalite uses the gas to provide process heat on one production line. Previously, the company burned heavy fuel oil, and it plans to further upgrade burners at the plant to use gas, so that, after mid-July, Coalgas`s deliveries will double.
Davies said the company is currently engineering a Y-piece for installation in the pipeline to the Coalite plant to enable gas to be delivered to a second boiler house.
The company has also secured planning permission to build a 6-MW electricity generating station alongside its Markham gas extraction unit. Coalgas is in discussions for supply of Mark- ham gas to a local utility, which is looking to build and operate a generating plant at the site.
A coalbed methane extraction system was installed over a vent at the former Markham coal mine near Mansfield, U.K. Operator Coalgas (U.K.) Ltd. pumps vent gas from abandoned coal seams for delivery by pipeline to a local smokeless fuels producer, whose plant is in the background. Photo courtesy of Coalgas.
Steetley, Shirebrook projects
At the Steetley gas extraction unit, Coalgas delivers gas directly to utility Independent Energy plc, which provides electric power generated onsite to local industry, using refurbished transformers and cabling from the former mine.
Coalgas delivers gas at a rate of up to 2,000 cu m/hr to Independent, which in turn exports electric power at 415 v to the transformer station, where the voltage is boosted to 16 kv for delivery via the local power grid.
At Shirebrook, Coalgas is currently landscaping the area around the entrance to an old drift that leads to the main shaft. Near the entrance, it is laying foundations for a pumping station and a generator house.
Gas will be sucked from the coal seams up the main mine shaft and along the drift, into a gathering chamber that Coalgas is building above the entrance to the drift.
Coalgas has contracted to deliver enough gas to an undisclosed utility (Coalgas and the utility are finalizing contracts before details can be released) for the generation of 9 MW of electric power. The generator house will contain five 1.9-MW capacity sets.
The Shirebrook site will generate electric power for delivery to the national grid via the original mine cabling and transformer stations. First commercial operation is scheduled for November.
Among new projects under consideration, Davies cited a government scheme to build a "millennium village" commercial and residential development in the Castleford-Pontefract area of Yorkshire, to the north.
On one of Coalgas`s license areas there, Davies said there are two mine vents giving out large quantities of gas, which Coalgas has proposed as the feedstock for a combined heat and power (CHP) and district heating scheme for the village.
"This would be an ideal project from our point of view," said Davies. "Not only would we be able to sell methane, but also the 10-15% CO2 content of the gas from this mine could be cleaned and used in greenhouses planned on the village site.
"Plants grow more quickly in a CO2-rich atmosphere. In the Netherlands, many growers have mini-CHP plants on their farms, using methane to heat their greenhouses and piping (recovered) CO2 into the greenhouses."
Coalgas has begun discussions with the Leeds City Council and other local and energy authorities regarding the supply of coalbed methane to the millennium village and hopes to begin work on the scheme this year.
This would be one of six coalbed methane projects that Coalgas has lined up for development over the next year. After these, Coalgas aims to develop eight extraction projects per year.
Of the 40 lined up for development over the next 5 years, 15 would be vented gas projects, as with the Markham and Steetley schemes, while the rest would need to be drilled.
"Some of the shafts on these other mines were filled and capped rather than left open and capped as at Markham and Steetley," said Davies. "On some of these sites, we are planning to suck gas through the fill material."
Near yearend, Coalgas plans to drill a "gob gas" well at Cronton mine at Merseyside. This will be drilled into the big hole behind the worked-out coal face-known by miners as a gob-to enable depletion of gas that gathers there, Davies said: "This is very much a pilot project. It will be interesting to see if it takes off."