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| CSIRO | SOLVE | Issue 6 Feb 06 | |
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ARTICLE
ENERGY TRANSFORMED:
Coal Captures a Cool Way to Keep Clean By Ava Bentley
New technology will allow energy producers, particularly coal-fired power stations, to cut greenhouse gas emissions from existing facilities. Greenhouse gas emissions (GGEs) and nature’s response – Cyclones and rising temperatures – are important global issues, with most countries interested in reducing output. In Australia, fossil fuel combustion, including the burning of coal for electricity, is responsible for 48 per cent of the nation’s gas emissions, with further increases of 0.6 per cent per year to 2010 estimated by the Australian Greenhouse Office.
This growth (measured from 1990) equates to a 46 per cent increase in GGEs produced by the energy sector alone. It is clear that using coal for power, despite being Australia’s most affordable current option for electricity, has a significant influence on global warming. In fact, in a report released by the International Energy Agency’s Coal Industry Advisory Board (CIAB) in 2005, it was admitted that coal’s “environmental performance needs to improve” if realistic GGE reductions are expected in the near future. One of the key messages of CIAB’s report Reducing Greenhouse Gas Emissions, The Potential of Coal is that research and development into clean coal technologies, such as Post Combustion Capture (PCC), is vital for a sustainable future and a reduction in GGEs. The PCC technology, currently of interest in many countries, involves the capture of carbon dioxide (CO2) at power stations followed by storage underground. Finding ways to reduce the energy sector’s GGEs is an important initiative for CSIRO. An extensive collaborative research program, led by the Energy Transformed Flagship, is underway and involves leading scientists from across four divisions of CSIRO. Several universities and industry partners are also expected to join the research program. Dr Louis Wibberley, leader of the PCC project team, says that PCC works by treating the flue gas at power stations to capture the CO2 emissions before release into the atmosphere. “The process involves cooling the flue gases (which typically contain five to 17 per cent CO2) and then capturing the CO2 by contacting the flue gas with a water-based solvent. This contacting occurs in a wash tower called an absorber. The water solution containing CO2 is pumped from the bottom of the absorber to a steam stripper. “This device strips the CO2 from the water-based solvent, allowing it to be recycled to the absorber. The stripped CO2 is dehydrated and compressed to produce a liquid CO2 which can be pumped underground for permanent storage. We hope to be able to reduce GGEs from power stations by 95 per cent using PCC.” Dr Wibberley says that capturing CO2 from power stations is the only way that Australia can significantly reduce its GGEs from electricity supply in the foreseeable future. “Expected reduction targets for GGEs from electricity generation require CO2 capture and storage from both existing and new coal- and gas-fired power plants. There are three approaches for capturing CO2; precombustion capture using coal gasification, oxygen combustion and PCC. Only PCC is readily adaptable to both existing and new installations, with the alternative approaches being restricted to new plant.” This is a significant advantage over other options, the importance of which is not lost on the energy sector. According to Dr Peter Cook, the Executive Director of the CRC for Greenhouse Gas Technologies, PCC is “one of the most promising options that we now have for decreasing CO2 emissions, whilst enabling us to continue to benefit from access to widely available, low-cost fossil fuels”. Mark O’Neill, executive director of the Australian Coal Association, agrees. His view is that “the range of technologies associated with CO2 capture, and geological storage, are identified as the key to achieving deep cuts or even near-zero emissions in coal-based electricity generation.” PCC will be put through its paces at a pilot plant being built by CSIRO at the Energy Centre in Newcastle. The two tonnes per day plant is transportable, to enable test work to be carried out at a number of power stations by treating a small slipstream from the flue gases before they enter the chimney. This will enable R&D for new solvents and technologies to reduce the cost of capture. These power plant tests will be backed by research into the science of capture in PCC laboratories being established by the Energy Transformed Flagship. The laboratories also include replicate reactors from key overseas research groups, to support a range of collaborative work which began late last year. Until recently the accepted wisdom was that the cost of reducing the GGEs by PCC was simply too high to be considered practical. However, following the advent of newer and more affordable sorbents and technologies, there is every expectation that with further research, demonstration and uptake, PCC will be a very realistic, cost-effective option for reducing GGEs in the Australian energy sector and globally. APPLICATION PCC can be fitted to new and existing power stations to capture carbon dioxide and store it underground For further information contact: |
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