Carbon capture isn't just a disaster for the environment, it's entirely unworkable

In terms of symbolism, it was perfect for Rishi Sunak to fly in a private jet from London to Aberdeenshire to announce a new carbon capture project.

A private jet is one of the most climate-destructive modes of travel that is enjoyed by a tiny fraction of humanity. How can such an oversized environmental footprint be justified? With carbon dioxide removal. The argument goes that if we plant lots of trees as a result of that flight, then as the trees grow they will absorb the hundreds of kilogrammes of carbon dioxide that the aircraft put into the atmosphere.

Typically, this is called carbon offsetting and it is now quite common to be asked by an airline if you would like to offset your emissions.

Unfortunately, there is now overwhelming evidence that carbon offsetting schemes have systemic problems, with the vast majority of them doing absolutely nothing to reduce climate impacts. The fundamental issue is one of timescales.

When fossil fuels are burnt, they release carbon into the air that has previously been locked up in rocks for millions of years. In carbon dioxide form, it has a warming effect on the climate. This warming effect can last for centuries. Most carbon offsetting schemes are “deferred emissions”. That is, you pay for someone or some organisation to not destroy a forest.

Keeping say 100kg of carbon in trees that are not going to be cut down allows you to put 100kg into the air via a jet aircraft trip. Unsurprisingly, this has produced schemes of questionable quality, e.g. pristine forests at no risk of destruction that continue to produce carbon credits used by individuals and corporations to carry on polluting.

Even schemes that plant new trees are not a long-term solution. Having a tree store carbon in its roots and leaves isn’t much help if the tree burns down after a few years or decades. The carbon needs to be removed from the atmosphere and stored somewhere where it cannot get back out.

What the Prime Minister was announcing in Scotland was that the UK Government was supporting the Acorn carbon capture and storage project that would do just that. This news was announced at the same time as the UK Government granting new licenses for oil and gas extraction in the North Sea.

Mr Sunak claimed that this does not mean the UK is backsliding on its net-zero commitments. Just like offsetting his private jet flight, the UK can offset the millions of tonnes of carbon dioxide that would be released from all the extra drilling with carbon capture and storage. Moreover, this would create thousands of new jobs for Scotland and the rest of the UK.

You can understand carbon capture and storage as running the fossil fuel industry in reverse. Rather than extracting carbon, companies such as Shell – one of the Acorn project’s partners – will capture carbon dioxide from industrial processes or even directly from the atmosphere, then pipe it down into empty oil and gas deposits.

The good news is that this avoids all the issues with trees and land use that besets traditional offsetting. The bad news is it doesn’t work.

Shell is involved in the Gorgon carbon and storage pilot project in Western Australia. This facility is billions over budget and years behind delivery. It was recently disclosed that is only operating at about one-third capacity. It is proving very difficult to pump concentrated carbon dioxide deep into the ground and have it stay there.

Direct capture of carbon dioxide is currently very energy intensive. One study concluded that deploying it at scale could cost hundreds of trillions of dollars while consuming a quarter of global electricity generation. Projects that use biomass burning to generate electricity and then capture the carbon dioxide would further accelerate forest destruction.

Wouldn’t it be much easier to simply not put the carbon dioxide into the atmosphere in the first place? Yes it would. But that risks the future profits of fossil fuel giants like Shell who recently announced that they would be continuing large-scale oil and gas exploration and development.

The Acorn project, just like all proposed carbon dioxide capture and storage endeavours, is essentially a buy-now-pay-later scheme. It allows politicians like Mr Sunak to continue to claim they are keeping their climate promises while facilitating the pumping up of more oil and gas.

They argue that we can reap the benefits of fossil fuels now, while others will pay for the clean-up later. The “others” here are our children and people not even born yet, because they will need to run carbon removal schemes for decades, potentially centuries, in order to drag concentrations back down from dangerous levels.

Today’s announcements further demonstrate that carbon dioxide removal is a dangerous flight of fantasy.

James Dyke is an associate professor in earth system science at Exeter University