I am not going to go into the various methods of carbon capture and storage in this post. All I want to do is to give some very rough figures for the magnitude of the problem.

Although some argue that carbon capture is necessary to limit global heating to 1.5°C, what is necessary is not always possible.

There are two ways of capturing CO2 from fossil fuels. The first is to capture it at source (Carbon Capture and Storage – CCS) and the other to extract it from the atmosphere (Direct Capture).

What we call ‘oil’ and ‘coal’ refer to substances of quite a wide chemical composition. So to get an order of magnitude figure of the amount of carbon dioxide produced from burning fossil fuels, I am just going to use octane (C₈H₁₈).

Burning 1 litre of octane would produce 1,100 litres of carbon dioxide. Since CO₂ is only a small fraction of the atmosphere, you would have to process 2,600,000 litres of air to remove it. My calculation is given below, but you can skip it to the next section if you wish.

The Problem With Burning In Air

Most fossil fuels are just burnt in air. However, this immediately creates a problem since air is nearly 80% Nitrogen which has to be separated along with any oxygen that is not consumed during the combustion.

It is reasonably easy to remove most of the water, and the CO₂ can be compressed or reacted with other chemicals to produce solids or liquids. However, it is still a very large amount of material to handle to keep pace with current CO₂ emissions.

Scale Of The Problem

Globally, we emit over 34 billion tonnes each year¹. So even without trying to decrease the CO2 from the current levels, this is the mass that we have to deal with.

To put this in perspective, the world iron ore production is less than 2½ billion tonnes per year². Only 4.2 billion tonnes of cement are produced in the world annually³.

So we would need a carbon capture industry that is an order of magnitude larger than any industrial process we have at the moment – and we need it soon.

Alternatively, we could just keep it in the ground.

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¹ Global CO2 emissions from fossil fuels; Our World Our Data; 2023 (https://ourworldindata.org/co2-emissions)

² Iron Ore; US Geological Survey (https://pubs.usgs.gov/periodicals/mcs2020/mcs2020-iron-ore.pdf)

³ Cement and concrete around the world, Global Cement and Concrete Association; 2020 (https://gccassociation.org/concretefuture/cement-concrete-around-the-world/)