The Bulga Complex is aiming to significantly reduce its greenhouse gas impact through initiatives that include the capture and use of methane to generate electricity, abating ventilation air methane and improving energy efficiencies.
As the world’s largest producer of export thermal coal and a significant consumer of energy, Xstrata Coal is actively targeting a reduction in emissions, as well as investing in and supporting low emission coal technologies.
Draining methane from the coal
In an underground mine, removing the gas from the coal prior to mining is crucial to the safety of underground employees. Gas that is not drained from the coal prior to mining can cause a safety hazard as well as delays in production.
Bulga Underground Operations also undertakes post draining once the coal has been removed to remove gas which accumulates in the goaf (the area behind the longwall).
Once we have drained the gas, we burn the methane to reduce our greenhouse gas footprint. Combusting the captured gas is called flaring which is done at a central flaring facility. Flaring methane to produce carbon dioxide and water vapour reduces the methane greenhouse gas impacts by 21 times.
Power Generation – utilising the gas
We aim to utilise the gas collected by our gas drainage system for power generation. In 2010, Bulga Underground Operations received approval to construct and operate a 25MW power plant which will produce electricity from the methane. The Bulga Complex has commenced construction of the 9MW first stage which consists of 3 generator units. Each unit will produce 3MW of electricity which will be used on site.
The power plant has the capacity to produce up to 25 megawatts of power which will be used either on site or supplied to the public power grid.
Ventilation Air Methane (VAM) Abatement System
Mine ventilation air can contain up to 2% methane. At our Blakefield South operation, mine VAM is normally maintained below 1% and is often as low as 0.3%. Although the methane concentration within the ventilation air is low, the total volume of ventilation air is large and therefore the amount of methane discharge is substantial.
The Bulga Complex has commenced construction on a pilot VAM system which will oxidise the low percentage of methane contained in the mine ventilation air that cannot be captured and used in the power station of flares. Called a Regenerative After Burner (RAB), the VAM RAB directs ventilation air through a chamber where it is heated to around 1000◦C. Using this oxidation technique, almost all of the methane is converted to carbon dioxide and water, significantly reducing our greenhouse gas impact. The VAM RAB is being constructed at Rutherford and will be trucked to Blakefield South for final construction.
The pilot plant will allow us to understand how efficiently this system can oxidise the levels of methane from the mine ventilation air.
Energy efficiency initiatives – reducing our energy use
Bulga Coal Surface Operations and Bulga Underground Operations have Energy Actions Savings Plans in place that ensure we are operating as efficiently as possible. Energy efficiency is a key requirement in the procurement of plant, equipment and technology at the Bulga Complex.
The Energy Actions Savings Plans identify projects which will lead to a reduction in energy consumption and is reviewed annually at both operations.
Xstrata’s Key Initiatives
Xstrata is helping to fund research and deployment of low emission technologies within the power generation sector. Coal is an essential part of the world’s energy mix and will remain so for many years to come.
The coal industry is actively involved in the global collaborative effort and long-term commitment towards achieving low or near zero greenhouse gas emissions from the use of coal in electricity generation.
COAL 21 Fund
Coal 21 is a world first industry approach to greenhouse gas abatement. The scheme, funded by a voluntary levy, will raise over $1billion over ten years and aims to support research, development and demonstration of clean coal technologies to combat climate change. Xstrata Coal will contribute approximately US$150 million to support the demonstration of low emission coal technologies in Australia.
CS Energy Oxyfuel Project
Oxyfuel combustion is one of the three key low emission coal capture technologies for coal used in power generation combined with carbon storage. This technology has the capacity to be retrofitted to existing power stations. Xstrata Coal is a corporate contributor to the US$170 million project in Queensland.
Otway Pilot Project and Centre for Greenhouse Technologies Research Centre
This project will demonstrate carbon storage up to 80,000 tonnes in depleted gas reservoir in Otway Basin in Victoria and will assist the development of monitoring and verification protocols for this technology. Xstrata Coal is a corporate contributer to the project.
Global Carbon Capture and Storage Institute
The institute will provide international policy and management oversight to the goal of delivering at least 20 commercial scale CCS plants around the world by 2020. The Australian Government has a commitment to provide US$85 million per annum to fund the Institute. Xstrata Coal is a foundation member.