New Zealand miners planning to burn coal underground to extract useful gases say they don't expect their projects to cause the kind of environmental problems reported in Australia and North America.Solid Energy's underground coal gasification (UCG) manage
New Zealand miners planning to burn coal underground to extract useful gases say they don't expect their projects to cause the kind of environmental problems reported in Australia and North America.
Solid Energy's underground coal gasification (UCG) manager, Steven Pearce, said its $22 million pilot project due to start by next year in the company's Huntly West licence area will have gas wells cemented to avoid leakage into the environment.
"Water samples are taken routinely to monitor water quality and water pressure in the pilot plant area, and are tested by an independent body," he told NZPA.
An Australian company, Cougar Energy, was forced to shut down its Queensland underground coal gasification plant in July after a water contamination scare in nearby bores.
Traces of the toxic chemicals benzene and toluene were reported in groundwater at the site and at a neighbouring property.
In North America, researchers have reported two of 34 UCG pilot plants have caused groundwater contamination, though the problems could have been mitigated by proper site selection, good operational and abandonment practices and operator expertise.
In New Zealand, listed company L&M Energy Ltd (LME) has sought a prospecting permit for a 2112 square kilometre area containing over 2 billion tonnes of coal, south of Solid Energy's Huntly coal mines.
Both LME and Solid Energy want to burn coal underground to extract gas fuels and chemical feedstocks, while separating the carbon dioxide from the gas stream at relatively low cost. About a quarter of the coal's energy will be used during the UCG process but the syngas it produces could then be piped to Auckland for use in highly efficient gas turbine electricity plants.
The gas stream could also provide feedstocks for fertilisers, explosives, plastics and chemicals.
Mr Pearce said Solid Energy's UCG plant planned for the Waikato would not use hydraulic fracturing of the coal seam, and will not inject any chemicals, only air to fuel the fire.
"The wells are cemented into place to seal and isolate the process from the surrounding environment," he said.
Solid Energy's site was selected for the depth of its coal seams "which are hundreds of metres below and separate from aquifers that drinking water and agricultural water is drawn from".
Asked about other potential risks, such as subsidence, Solid Energy said it had a long history of managing subsidence in the Waikato coal fields in an environmentally-responsible way.
John Bay, petroleum managing director of LME, said that in the Queensland case, chemicals may have been released from the coal as it burned, which would mean the problem was confined to those specific coal deposits.
Should LME gain its exploration permit, it would "certainly undertake a rigorous evaluation of all of the potential issues" surrounding UCG development before committing to spend any significant capital on drilling.
