The carbon capture conundrum

Recent news that 2024 looks set to have an average temperature 1.5°C higher than the pre-industrial average is the latest warning that measures to avoid a climate catastrophe are urgently needed. And reducing carbon dioxide emissions – difficult though it is – will only be half the story. As well as stopping or slowing the rate at which we’re filling the bathtub, we also need to empty it out. And that means removing carbon dioxide from the atmosphere.

But how can we capture and store carbon dioxide without too great an economic or carbon cost?

With the price of renewable power falling, and its capacity increasing, hopefully the need for carbon capture and storage from fossil-based power generation will be fairly low in the future. Even so, it was good to see a recent local news story with a gas-fired power plant capturing its emitted carbon dioxide and purifying it to a food grade standard. This can then go on to be used to carbonate drinks, for example. The founder describes it as an example of the circular economy, but perhaps carbon neutral is more accurate; I’m not sure even the most committed of drinkers are capturing their personal methane emissions to be sent back to the power plant…

A recent paper aims to capture the carbon in the high temperature places where it is first emitted, such as the exhaust flues from the furnaces and kilns that produce steel and cement – both extremely carbon-intensive processes that are currently high emitters. 

Also in the news is the covalent organic framework material recently created by Omar Yaghi’s team at the University of California, Berkeley, in the US. COF-999 can capture and release carbon dioxide over many cycles – and unlike many similar metal–organic framework materials, contains only the abundant and cheap elements carbon, hydrogen, oxygen and nitrogen. This is important because many thousands of tonnes of the material would be needed to make a serious dent in current emissions or levels in the atmosphere. And of course, sourcing even those abundant elements and producing the material would come with its cost in both dollars and more emissions.

With the depressing realities of economics, chemistry and thermodynamics always apparent when it comes to carbon capture, it’s no surprise to read that industrial-scale progress in the area is very slow. There are concerns about technical problems including the necessary purity of the captured carbon dioxide – it may not seem like a problem if it’s going to be locked away in a cave or a disused oil field, but sulfates and nitrates could corrode the pipeline that gets it there. And of course cost is the over-riding issue, in spite of fairly impressive government funding available, both from the UK and EU.

On the one hand, it’s heartening to see that there are potential scientific solutions being pursued, and that political will – and funding – is being brought to bear on the problem. But with a hurricane season in the US that was fuelled by overheated seas, and catastrophic flooding in Spain exacerbated by how much more moisture warmer air could carry, we should all be concerned that any progress will be too little and too late.