September 24, 2021

I, Science

The science magazine of Imperial College

Capturing carbon dioxide at coal power stations is a great way of reducing greenhouse gas emissions, but energy companies are put off by the high cost of technology.  Could a new type of carbon-filtering membrane be the economical answer?

According to recent estimates, it costs $150 to remove one tonne of CO2 from power station outflow. Researchers from Canada and South Korea claim their new microporous organic polymers (MOPs) would catch carbon for just $15 per tonne.

Globally, coal-fired power plants emit around 2 billion tons of carbon dioxide every year.  Some stations use carbon capture technology to remove CO2 from smoke as it rises through the chimney – around 80% of the gas ­can be caught this way.  But current amine-cycling methods cost a lot to install and need large amounts of power to work effectively.

Much research has gone into membranes that separate CO2 from other gases, but until now these have either proved ineffective or too expensive.

The team, led by Dr Naiying Du, added tetrazole groups – rings of four nitrogen atoms and one carbon atom – to microporous polymer membranes.  They then exposed the membrane to a mixture of gases typical of coal power station emissions.  Results published in this month’s Nature Materials show that the polymers let through up to 40 times more CO2 than other gases.

Work still needs to be done to make the new MOPs thin enough for industry, but according to Dr Du, membranes could soon be smashing the US Department of Energy’s targets for carbon capture cost.