Clean Coal Technology

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Clean coal is the name attributed to coal chemically washed of minerals and impurities, sometimes gasified, burned and the resulting flue gases treated with steam, with the purpose of removing sulfur dioxide, and reburned so as to make the carbon dioxide in the flue gas economically recoverable. The coal industry uses the term "clean coal" to describe technologies designed "to enhance both the efficiency and the environmental acceptability of coal extraction, preparation, and use", with no specific quantitative limits on any emissions, particularly carbon dioxide.

The burning of coal has been shown to be one of the principal causes of anthropogenic climate change and global warming, according to the United Nations Intergovernmental Panel on Climate Change. The concept of clean coal is said to be a solution to climate change and global warming by coal industry groups, while environmental groups believe the claim is misleading and inaccurate. Greenpeace is a major opponent of the concept because emissions and wastes are not avoided, but are transferred from one waste stream to another. The 2007 Australian of the Year, paleontologist and environmental activist Tim Flannery made the assertion that "Coal can't be clean".

There are no coal-fired power plants in commercial production which capture all carbon dioxide emissions, making the process still theoretical and experimental and a subject of feasibility studies. It is has been estimated that it will be at least fifteen to twenty years before any commercial-scale clean coal power stations (coal-burning power stations with carbon capture and sequestration) are commercially viable and widely adopted. This time frame is of concern to environmentalist because of the belief that there is an urgent need to mitigate greenhouse gas emissions and climate change to protect the world economy Even when CO₂ emissions can be caught, there is considerable debate over the necessary carbon capture and storage that must follow.

Byproducts

The byproducts of coal combustion are very hazardous to the environment if not properly contained. This is seen to be the technology's largest challenge, both from the practical and public relations perspectives.

While it is possible to remove most of the sulfur dioxide (SO₂), nitrogen oxides (NOx) and particulate (PM) emissions from the coal-burning process, carbon dioxide (CO₂) emissions and radionuclides will be more difficult to address. Technologies do exist to capture and store CO₂, but they have not been made available on a large-scale commercial basis due to the high economic costs. For this reason renewable energy sources may be a more cost-effective and environmentally friendly alternative.

Potential cost of clean coal

A 2003 study conducted by the International Energy Agency (IEA) on greenhouse gases found that the cost of building a shell-designed IGCC plant that doesn't capture carbon could cost $1,371 per kW. A comparable system that captures carbon could cost $1,860 per kW."

Capturing and compressing CO₂ requires much energy, significantly raising the running costs of CCS-equipped power plants. In addition there are added investment or capital costs. The process would increase the energy needs of a plant with CCS by about 10-40%. The costs of storage and other system costs are estimated to increase the costs of energy from a power plant with CCS by 30-60%, depending on the specific circumstances.

Costs of energy with and without CCS (2002 US$ per kWh)

	Natural gas combined cycle	Pulverized coal	Integrated gasification combined cycle
Without capture (reference plant)	0.03 - 0.05	0.04 - 0.05	0.04 - 0.06
With capture and geological storage	0.04 - 0.08	0.06 - 0.10	0.06 - 0.09
With capture and Enhanced oil recovery	0.04 - 0.07	0.05 - 0.08	0.04 - 0.08
All costs refer to costs for energy from newly built, large-scale plants. Natural gas combined cycle costs are based on natural gas prices of US$2.80–4.40 per GJ (lower heating value based). Energy costs for PC and IGCC are based on bituminous coal costs of US$1.00–1.50 per GJ (lower heating value (LHV). Note that the costs are very dependent on fuel prices (which change continuously), in addition to other factors such as capital costs. Also note that for EOR, the savings are greater for higher oil prices. Current gas and oil prices are substantially higher than the figures used here. All figures in the table are from Table 8.3a in the IPCC Special Report on Carbon Dioxide Capture and Storage.

The cost of CCS depends on the cost of capture and storage which vary according to the method used. Geological storage in saline formations or depleted oil or gas fields typically cost US$0.50–8.00 per tonne of CO₂ injected, plus an additional US$0.10–0.30 for monitoring costs. However, when storage is combined with enhanced oil recovery to extract extra oil from an oil field, the storage could yield net benefits of US$10–16 per tonne of CO₂ injected (based on 2003 oil prices). However, as the table above shows, the benefits do not outweigh the extra costs of capture.

Resources

References

===Related SourceWatch articles

• Global warming
• Carbon Capture and Storage

External links

• IPCC Special Report on Carbon Dioxide Capture and Storage, Intergovernmental Panel on Climate Change.
• Carbon Sequestration News, recent news articles on CO₂ capture and storage.

Wikipedia also has an article on Clean Coal Technology. This article may use content from the Wikipedia article under the terms of the GFDL.