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Carbon capture and storage (or sequestration) – CCS – is a process that involves capturing carbon dioxide and storing it in underground structures where it should remain indefinitely. Storage options include depleted oil and gas fields and deep saline aquifers. It is thought that these sites will hold the carbon dioxide for more than a thousand years with minimal leakage.
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Carbon capture and storage
Unfortunately, the use of coal to generate electricity is set to increase greatly over the coming decades, particularly in developing countries. Scientists and engineers are thus working on ways to make coal cleaner by capturing and storing the carbon dioxide produced in a coal-fired station before it can get into the atmosphere.
This technology has been called “carbon capture and storage” (or carbon capture and sequestration) (CCS). The process involves capturing the carbon dioxide and storing it in underground structures where it should remain indefinitely. Storage options include depleted oil and gas fields and deep saline aquifers. It is thought that these sites will hold the carbon dioxide for more than a thousand years with minimal leakage.
A few small CCS trial projects are presently underway at various sites around the world but the technology is not anywhere near industrial scale testing at this stage. Billions of dollars in research funding are being applied to commercialising this technology, particularly in the United States and Australia. At this time, however, its not clear whether CCS will turn out to be practical and cost-effective in time to be incorporated into the many hundreds of new coal-fired generation stations now in the pipeline. This does appear unlikely – for instance the United States Department of Energy’s aims to have a 275 MW demonstration CCS plant operating by 2020 at the earliest. CCS could also be used to capture emissions from gas-fired generation plants, although applying it to coal plants is the most critical application at this time.
What are the opportunities for CCS in New Zealand?
New Zealand has a vast coal resource – known deposits amount to about 15 billion tonnes. This would supply New Zealand’s needs for 2000 years at current production rates. However, 70% of these deposits are lower grade lignite, which means their carbon dioxide emissions are high when burned to produce electricity.
If CCS were applied to lignite-fired generation plants in New Zealand large carbon dioxide capture systems would be required and large amounts of carbon dioxide would need to be stored. Suitable storage reservoirs have not yet been identified near the lignite reserves in Southland. There may, however, be potential for storage in unminable coal seams.
Given New Zealand’s vast renewable energy resources, it is questionable whether CCS will prove economical relative to existing renewable generation options in the foreseeable future. Nonetheless, New Zealand coal producer, Solid Energy, is participating in CCS research lead by the Australian-based Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC). Solid Energy has committed more than A$2 million towards the research of the Centre, which is part of a 20-year NZ$100 million investment the company is making in clean coal technology and new energy developments.
For more details on CO2CRC see:
http://www.co2crc.com.au/
See the following website for more information on carbon capture and storage:
http://www.co2captureandstorage.info/whatisccs.htm
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