Carbon sequestration has long been discussed as an essential tool in our quest for net zero. Given that we will likely rely on carbon capture methods to offset over half of the UK’s residual carbon footprint in 2050, it is important to examine the options available and the feasibility of their application over the coming decades.

There are two categories of carbon capture techniques: natural and artificial. The main methods in the former category involve afforestation and reforestation. Given that planting a forest the size of Greater London would over 100 years only offset the next two years of UK carbon emissions, it seems appropriate to focus mainly on the second group.

From extracting carbon dioxide from seawater in Devon, to heat-powered methods at Sizewell C, there are dozens of innovative carbon capture, usage and storage (CCUS) methods being funded by Government net zero investments. Issues only arise when we begin to evaluate the costs of these technologies versus the benefits they provide.

There are two key figures to examine. Firstly, the social cost of carbon: the present value of the damage done by a tonne of CO2 released into the atmosphere. William Nordhaus, 2018 Nobel laureate in Economic Sciences for his work on the economic implications of climate change, has called this “The most important single economic concept in the economics of climate change”, and estimated it in 2017 to be $31/tonne CO2. (It should be noted that there is disagreement around this figure, because of how we weigh impacts on future generations and developing countries. Most papers put the figure around $20-60.)

Secondly, is the price of extracting one tonne of carbon from the atmosphere by these methods. A report cited in 2019 by the BEIS committee stated a cost of £80-160/tonne of CO2 prevented from entering the atmosphere at gas-powered electricity plants.

Assuming a reduced dependence on fossil fuels, carbon capture will likely come from Direct Air Capture (DAC), rather than being attached to a power plant. A planned British DAC plant hopes to decrease costs to £200/tonne. The International Energy Agency has stated that in the best locations and using the best technology, DAC could fall below $100/tonne.

These prices must therefore fall by 50-90% in the next two decades for carbon sequestration to be cost-effective. This is unlikely since most of the cost is from the electricity required by the process, and excepting a breakthrough in nuclear fusion, the price of electricity is unlikely to fall much in the UK, if at all. If this does not happen, capturing carbon could cost more than leaving it in the atmosphere. Given the number of people still sceptical about climate change, funding cost-ineffective policies which will hurt them more than climate change will is not the way to convince them of the very real harms caused by CO2.

The UN Intergovernmental Panel on Climate Change’s latest report shows CCUS to be the most expensive of 31 mitigation options, and exhibiting the joint-lowest potential contributions to net emission reduction. Perhaps unsurprisingly, the Government has not included any discussion whatsoever of CCUS prices across 550 pages of Net Zero, CCUS Strategy or Clean Growth Strategy documents.

It is of course possible that we will succeed in reducing costs. However, there are currently no commercial applications of CCUS in the UK, and even if technology improves, the projects in Devon and at Sizewell C are predicted to bottom-out at £100 and £200/tonne of CO2 removed respectively.

If new methods are to be developed and carbon capture is to become a serious and cost-effective method for reaching net zero, it is far more likely to happen in the Middle East or China, which have comparative advantages in developing this technology. Given the UK’s reluctance to support large infrastructure developments within our own borders, it could be beneficial to partner with these nations and use British brains to aid them in developing these important technologies which, if successful, could then be applied here.

Given these realities it appears that without significant technological breakthroughs to lower capture costs, or unlikely catastrophic climactic changes to increase carbon’s costs, carbon sequestration is likely to be a net cost to our net zero strategy.