Bryan Leyland: Things you know that ain't so - carbon capture

“Things you know that ain't so - carbon capture and sequestration (CCS) will soon be an effective way of reducing emissions of carbon dioxide”

CCS involves removing carbon dioxide from the exhaust gas of coal and gas-fired stations and sequestering it underground or under the sea. Some people believe it will cut man-made CO2 emissions by 80% and so prevent a climate catastrophe.

Initially, hope centred on coal gasification combined cycle (IGCC) power plants that cook the coal to form a synthetic gas from which the CO2 can be extracted, allowing the remaining gases, mostly hydrogen, to be burned in a gas turbine to generate electricity. The process is complicated and expensive. Three such units have been built in the United States at a cost of over $6,000 per kW, or about what it costs to build a new nuclear power plant.

Experiments have also been done on capturing CO2 from the stack gas of conventional coal-fired and natural gas power plants. They showed that coal-fired power plants must be derated by about 30% due to the very high electrical loads consumed by the plant that captures and liquefies the CO2. You get 210 MW out of a nominally 300 MW power station!

Natural gas power plants will need to be derated by more than 30% because the waste steam includes less CO2, making it more difficult to capture CO2.

One can conclude that the cost of capturing carbon dioxide is impossibly high.

The captured CO2 must be disposed of underground. So the carbon dioxide as to be liquefied at high pressures and piped to where it can be disposed of underground by injecting it into an appropriate geologic formation.

The largest underground sequestration operation is the Sleipner gas field where one million metric tons of CO2 are injected annually into the saline aquifer under the North Sea.

To sequester the gas from 80 % of the coal-fired stations in United States 1,800 times the amount sequestered in the Sleipner gas field would need to be pumped into the ground.

The quantity staggering and there is no certainty that the CO2 would remain underground for the thousands of years people believe that is needed to prevent a postulated climate catastrophe.

The massive costs associated with CCS, the large increase in generating capacity needed to drive the process plant, the uncertainty that the CO2 would remain sequestered underground for centuries and increasing evidence that man-made carbon dioxide does not cause dangerous global warming leads to the conclusion that CCS is an expensive and risky solution looking for a problem.