Carbon capture and storage (sequestration) would enable coal and gas fired power stations to be mostly green (90 % reduction in CO2 probably).
A significant reduction in CO2 emissions, from coal or gas power stations, can be made by capturing most carbon dioxide from the flue (in addition to dust and SO2), compress it, liquefy it and store it permanently underground in deep saline aquifers or depleted oil reservoirs (ref 126)(ref141). Perhaps 90% of CO2 emitted from a power station can be captured and stored permanently (ref135).
The process would cost an extra 20-30% probably bringing it in line with renewable sources and extra power required to make up power used in the process.
The Global Geological site potential for CO2 storage is between 1000 and 10,000 Giga tonnes (Gt) of CO2. The potential for CO2 capture is around 2.6 to 4.9 Gt CO2 (0.7 to 1.3 Gt of carbon) per year (ref 160). The total of all global emissions in 2001 was 24 Gt of CO2 (6.5 Gt of carbon) which is estimated to rise to 38 Gt by 2030 so this process could help for many years to reduce CO2 in the air.
Potential in UK North Sea areas is for 40 giga tonnes of CO2 to be liquefied and stored over 200+years in sandstone (porous) capped with mudstone at 3 mile depth. (ref ST p6 news 16 08 09)
The brine filled aquifer (brine in pore spaces) UTSIRA is solid rock 500 km X 50 km and 200 meters thick, 1000 meters beneath the sea bed under the Sleipner Norwegian oil field. 0.8 million tonnes of CO2 per year has been pumped into the pore spaces for ten years. (One power station would provide 4 million tonnes of CO2 per year) ( ref 127).
An alternative is to inject underground, at least 800m (2600feet) where CO2 takes on a liquid form so is unlikely to escape. (Ref 1 p292). It dissolves into saline water and may eventually become solid mineral carbonates.
More on Sequestration of CO2
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