Coal mine emissions make up about 6.7% of Australia's total greenhouse emissions, with environmentally toxic methane gas emissions from underground coal mines contributing to 5.7%.
Toxic emissions from the spontaneous combustion of waste coal contribute an unknown further percentage of total greenhouse gas. With Australia's underground coal mines typically producing around 800,000 tonnes of waste coal per mine per year, all of it vulnerable to spontaneous combustion, there is an urgent need to reduce these emissions.
The coal industry has explored many processes for removing methane from the mine drainage and ventilation systems, including the potential for converting methane in the ventilation system to fuel, but because methane concentrations are usually too low for self-sustaining combustion, and the levels too fluctuating for the constant fuel supply needed to generate power efficiently, the solution has remained to date in the too hard basket.
Although several waste coal burning coal technologies already exist, ComEnergy designed and developed a plant with new technology that allows waste coal and methane to be burnt efficiently to produce electricity.
It is a simple, flexible and inexpensive process, with a typical plant producing 10 megawatts of electricity, which can be used to power the mine's own operations, and the surplus fed back into the power grid for general consumption.
The system has the potential not only of reducing emissions from coal mines, but also significantly reducing greenhouse effects by displacing hundreds of megawatts of electricity already in the power grid with electricity fuelled by burnt methane.