What Is Carbon Capture And Storage?

Over the coming months you are likely to hear the words "carbon capture and storage" (CCS) more and more. It is potentially a game changer when it comes to the battle to avoid climate change, but what exactly is it?

In basic terms, it's technology that can be used to capture carbon dioxide at power stations etc. before it is emitted into the atmosphere, then store it somewhere safe.

It matters because it can potentially stop the whole carbon emissions problem at source. What's more, in theory, it throws oil, natural gas, and coal producers a lifeline, as there'd no longer be the urgency to replace their products with the cleaner alternatives.

However, it's early days yet. The tech could be years away from being ready to scale up and use across the world. The reason being that it is inefficient, and too expensive to be commercially viable at the moment.

This is why, a week or so ago, Norway opened up a new carbon capture and storage (CCS) test facility at Mongstad: To try to push the technology along. The facility has the capability of testing several CCS techniques at a time and should prove invaluable. It joins over 40 such test and demo sites around the world.

Carbon Capture

There are 3 broad methods for capturing: Post-combustion, where chemicals are used to strip out the CO2 from the emissions; pre-combustion, where the fossil fuel is oxidized, producing a 'syngas' for fuel whilst the CO2 is available for capture; and oxy-fuel combustion where the fuel is burned in oxygen instead of air, and CO2 can be removed from the flue gases.

Storage

There are also a number of ways the CO2 can be stored.

• The first way is to store it deep underground e.g. in old oil/gas fields, exploiting the geology to keep the gas where it is. 

• A second, more controversial way, is to store it by various means in the oceans. As far as I'm concerned, that's a non-starter. If you simply dissolve the CO2 into the water, it would add to the growing problem of acidification. Other methods just leave the problem for later generations to deal with.

• Then there's converting the CO2 into carbonates (various forms of limestone), so trapping the carbon 'forever'. This has been shown to be possible but whether it can work on an industrial scale remains to be seen.

• A couple of other promising ideas are to use the CO2 to feed algae that produce oil for plastics and even aviation fuel (Although I think this last one just moves the problem along to somewhere that doesn't use CCS).

I see CCS as something that could make a major contribution to cutting CO2 if fitted to all new coal and gas power stations, and retro-fitted to all existing ones, plus any other major emitters. However, it will take a major effort to bring the costs down to a level where this is feasible. Somehow I think the fossil-fuel industry will find a way, don't you?