Energy From Coal Mine Ventilation Air Methane

MEGTEC Systems recently announced the inauguration of the first power plant in the world to use MEGTEC's technology to generate electrical power by using coal mine ventilation air methane (VAM) as its primary fuel. The power plant is now in full operation in Australia at the West Cliff Colliery of BHP Billiton, the world's largest diversified resources company.

Innovative Technology for Coal Mine Ventilation

The system is based on a patented combination of emission control and steam-cycle technologies. By using the compact and flameless VOCSIDIZER® regenerative thermal oxidizer (RTO) as an energy source, MEGTEC has made it possible to generate high grade, super-heated steam from a fuel with 0.9% methane content. The steam has the same quality as used at traditional power plants. It is used to drive a conventional steam turbine, which generates electricity that can be delivered to the state grid or directly to the mine.

Each hour, the installation is treating 0.9 % of methane content in 150,000 scfm (250,000 m3) of ventilation air. The energy produced from the methane is utilized to generate steam suitable for running a conventional 6 Megawatt turbine, resulting in this first power plant of its kind. The volume of ventilation air treated amounts to only 20 % of the total volume of ventilation air available from the ventilation shaft.

Methane as a Green House Gas

When coal is formed, so is methane. When the coal is excavated, methane is released. Since methane in air is explosive in concentrations between 5 and 15%, ventilation air is used to dilute the methane to levels below 1 % - well below the explosion limit. This safety measure leads to very large volumes of air with extremely low methane content being released to atmosphere.

Since methane emissions are a green house gas driving the global warming more than 20 times more potent than CO2, BHP Billiton can convert the emission reduction to carbon credits corresponding to 250,000 tons of CO2e (CO2-equivalents). A VAM Power Plant treating the full volume of ventilation air can generate approximately one million carbon credits.