Carbon dioxide removal, or carbon removal for short, is a controversial and widely misunderstood topic. Harnessed properly, it can help cool our planet and combat global heating. Misused, it can be reduced to an exercise in greenwashing and creative climate bookkeeping that enables polluters to continue polluting with impunity. Wijnand Stoefs explains.
Carbon removal means extracting greenhouse gases from the atmosphere and storing them on land, underground, or in the oceans. Vitally, this storage must be permanent (i.e. lasting centuries) to ensure that the removed gases do not seep back into the atmosphere and make the situation worse instead of better.
This removal can be achieved through technological solutions, such as direct air capture, which soaks up greenhouse gases from the air and stores them deep under the ground. There are also natural processes, such as forestation, as long as the trees are not in danger of being chopped down, burning or dying off quickly,
These methods have the potential to enable humanity to actively lower the concentration of greenhouse gases (GHGs) in the atmosphere from their current dangerous levels. In the coming century, this can help us to mitigate the worst impacts of the climate emergency, and even return the atmosphere to a stable state.
Air of clarity
For carbon removal to help solve the climate crisis, we need to get it absolutely right. Any manipulations or mistakes risk intensifying, rather than easing, global warming. To deliver on its promise, four key principles have to be met.
Firstly, carbon dioxide must be physically removed from the atmosphere, and not from, say, fresh emissions produced by industrial installations. Secondly and crucially, the sequestered gas must be stored permanently and securely. Thirdly, all greenhouse gas emissions associated with the removal process (both upstream and downstream) must be accurately calculated and accounted for in the emission balance. These include emissions from the energy used to capture the carbon and the land used to store it.
Fourthly and logically, the total quantity of atmospheric carbon dioxide taken out of the atmosphere and permanently stored must be greater than the total quantity of gas emitted during the removal process.
Finally, the storage sites must be monitored by independent monitors, and it must be clear who is liable in case the storage turns out not to be permanent.
Carbon capture or corporate capture
These four principles are straightforward and help differentiate carbon removal from the far more problematic carbon capture and storage (CCS) and carbon capture and utilisation (CCU). Keeping these topics separate is critical to limiting the confusion between them and ensuring policies are focused on the right area.
Carbon removal can rely on technologies and processes also used for CCS (including for the capture and/or storage of atmospheric carbon), but they are not the same thing. Carbon capture and storage is not used to take greenhouse gases out of the atmosphere, but rather from power plants or factories. That means it does not mop up past emissions but partially prevents present or future emissions. This is what makes it so problematic.
CCS not only does nothing about excess carbon dioxide already in the atmosphere, it can never capture all emissions from a site and is incredibly energy-intensive. CCS can actually increase emissions, as most CCS is used to extract more fossil fuels (through so-called Enhanced Oil Recovery, where captured CO2 is used to increase oil production) and the energy used is sourced from fossil fuels. In addition, CCS has a bad track record of living up to its promise: globally, over 90% of CCS projects ever proposed in the power sector were never built.
There are similarities though: storage needs to be equally permanent and monitored with clarity on liability in case of leaks from storage sites.
Another related but critically different process is carbon capture and utilisation (CCU). This is when captured carbon is used in production processes to make, for example, synthetic fuels, building materials or plastics.
There are two key differences between carbon removals and CCU. First is the source of the carbon. For carbon removal, the carbon has to come from the atmosphere but for CCU, it can come from anywhere, and will very likely be captured from industrial smokestacks because it is far easier and cheaper to capture it from industrial sites than ambient air.
Second, carbon removal focuses on permanent storage while CCU focuses on storing the carbon only until it is (re)used. In a CCU process, the storage can last from minutes to years. Synthetic fuels, for example, are meant to be burned, releasing the captured carbon again. In general, emissions are merely delayed, making CCU a false climate solution in general.
Industrial lobbyists have tried to blur the lines between carbon removal and CCU with the aim of reducing the cost of polluting under the EU carbon market and even in the hope of acquiring subsidies for investing in CCU technologies greenwashed as carbon removals. Such companies want to continue polluting with impunity while creative CCU accounting hides their continued contribution to the climate crisis.
Policymakers need to understand and be keenly aware of the differences between these concepts if carbon removal processes are to be developed, incentivised and rolled out in the right way. CCU and CCS are false solutions for removing carbon already in the atmosphere. They are being promoted by certain industrial interests which are seeking to not only pay less for their own pollution, but even receive public subsidies for investing in greenwashing. This is not only bad for the climate, it makes a mockery of the polluter pays principle.
In order to reach climate neutrality, the EU needs to focus its efforts almost exclusively on reducing emissions as deeply and as rapidly as possible, while using carbon removals to compensate for any last remaining residual emissions. The other technologies are, at best, a distraction and, at worst, will fuel global heating further.