Gas reduction

The US Department of Energy (DOE) has joined in sponsoring the first US test of a system that may make a major contribution to reducing greenhouse gas emissions.

Using a new application of existing technology, engineers will attempt to capture methane in underground coal mine air, and if successful could limit emission of a greenhouse gas with more than 20 times the warming potential of CO2.

Methane in underground coal mine air constitutes approximately five percent of all US methane emissions and is the equivalent of about 32 million tons of CO2 per year.  The test will evaluate the long-term technical and economic feasibility of reducing methane emissions from underground coal mining.

The test is being conducted by CONSOL Energy and MEGTEC Systems in a closed mine near West Liberty, WV, for a period of eight months.  The $2.1 million undertaking is sponsored by DOE and the US Environmental Protection Agency and the operational phase has just begun.

The test will be a new application of a device called a full-scale thermal flow reversal reactor.  As coal mine air moves through the device, its internal temperature increases and the methane is oxidised.   The air flow is reversed at a specified interval and excess heat may be transferred for local heating needs or for producing electric power.

Trade-named VOCSIDIZER, the technology uses a large bed of ceramic material in an airtight steel container.  Through a series of steps, the electrical heating elements warm the centre of the bed to 1,800 degrees Fahrenheit and flow reversal keeps the centre hot.

The operating reactor is a single-bed commercial-size unit using coal mine methane obtained from a bore hole from a closed mine that is diluted with air to simulate ventilation air in a mine.

Following the operation period, performance data will be analysed to determine the feasibility and economics of using this system to reduce methane emissions and to recover usable energy.