Limestone captures carbon dioxide

Scientists at New Zealand based Industrial Research Ltd (IRL) are developing a new process that uses limestone to capture carbon-dioxide emissions from coal-fired power stations and other industries that emit significant amounts of the greenhouse gas.

IRL has been awarded NZ$350,000 (£159,000) over three years by the Foundation for Research Science and Technology to develop its technology further.

In the IRL process, limestone is first heated to around 900^oC to become lime, which is a very effective material for absorbing carbon dioxide. When post-combustion flue gas is passed through the lime in a fluidised bed, the CO₂ is captured. The process is then reversed to transform the lime back into limestone, which is then used again to capture more CO₂.

The CO₂ can then be compressed to about three per cent of its original volume and stored efficiently or used in another industrial process.

This process has been known for many years, but until now it has not been efficient enough to be considered commercially applicable.