Carbon removal is not the main lever to reach Swiss Net Zero, yet properly understood it can accelerate decarbonization and improve biodiversity, concludes new paper


Is carbon removal the solution to the climate crisis we’ve been looking for? Or a desperate distraction as we are collectively unable to stop burning fossil fuels?

Please open today’s newspaper. You may read about converting CO2 into liquid fuels, instantly making airplanes or petrol cars climate-neutral. Or planting X trillion trees to absorb all excess carbon. Or international agreements promising plentiful, cheap compensation, suggesting net zero could be just around the corner, at a countrywide cost of just several hundred million francs. Is this all too good to be true?

We, both from the EPFL Laboratory of Environmental and Urban Economics, look into this complex and widely misunderstood area. We examine the promise, limitations and conditions for successful deployment of carbon removal, which includes carbon capture, utilization and storage (CCUS) and negative emission technologies (NET).

Carbon removal is part of the 7 types of climate action, from sufficiency, efficiency, and clean energy, to CCUS and NET, to solar radiation management (SRM) and climate adaptation. No action alone can solve the climate crisis; all are needed, with the exception of SRM, due to its unpredictable side effects, such as possibly making whole countries uninhabitable.

Carbon Capture and Storage (CCS) captures CO2 before it reaches the atmosphere, and stores it safely underground, in saline formations, or as in the past in depleted oil fields to enhance oil recovery. CCS is energy-intensive. Installations with CCS need more fuel for the extra energy of capturing and compressing CO2. When burned, this extra fuel pollutes more (PM2.5, sulphur dioxide, benzene, ozone, nitrogen oxides, carbon monoxide), as CCS only captures CO2. There are 26 large CCS plants over 0.1 Mt CO2/year in the world today. Together they remove 40 Mt CO2 per year. Since CCS started in 1972 and until today, the main use has been to extract more oil, which when burned emits more than the stored CO2, so the total effect has been bad for the climate.

Carbon Capture and Utilization (CCU) can use the CO2 for carbonated drinks or to help plant growth in greenhouses, but most uses require separating carbon and oxygen. As CO2 is a very stable molecule, this requires a lot of energy. There are no large-scale CCU installations yet.

The paper also reviews NETs, which remove CO2 from the air. Nature has been doing this for billions of years. The “fast” natural carbon cycle uses photosynthesis to capture and store carbon in biomass, mostly trees and soils. The “slow” cycle chemically binds carbon in rocks. NETs try to improve natural processes, by restoring degraded ecosystems, keeping more carbon in the soils, or crushing rock to accelerate “weathering” and store more carbon. This acceleration works well at small scales, and can improve ecosystem resilience and biodiversity. In Switzerland, the most promising methods are wetland restoration and storing carbon in soils, which would also improve agricultural practice. There is limited excess biomass in crop residues and forests, which could be used for electricity and heat, and the resulting CO2 could be stored underground, assuming the needed geological storage is developed.

Direct air capture and storage (DACS) is an entirely artificial process to remove CO2 from the air using chemical sorbents, and store it underground. It works at very small scales and has a very high energy and financial cost. Contrary to accelerated natural NETs, DACS in theory has few limits related to biomass, water or space, which makes it attractive at the first look. The paper quantifies practical limits and concludes that DACS is unlikely to scale anytime soon in our energy-constrained world.

How to pay for the relatively high cost of carbon removal? Under the polluter pays principle, CO2 emitters, past or present, should pay, not taxpayers. First, let’s consider the timing. Emissions are high now, and must decrease over the next 2-3 critical decades to stabilize the climate and reach the Paris Agreement commitments. Carbon removal needs to be developed, which takes time to identify and prepare ecosystem restoration sites, build the infrastructure, train people, develop methods, governance, financing, and monitoring. This looks like a temporal mismatch. It is preferable to disconnect the collection of the contribution and the payment of removal costs. What we propose is a Swiss Climate Cleanup Fund, to collect payments from polluters and fund all future carbon removals. 

This allows reaching net zero before 2050, and funding the removal of all excess carbon emissions beyond what IPCC shows as safe to stay below 1.5°C. This threshold will be exceeded late 2027 or early 2028; all further emissions will be removed, paid for by the Fund.

Other than choosing the right mix of methods and finding the money, what else do we need to be successful? Having the right goal in mind is essential. Carbon removal is not a substitute for deep cuts in emissions of at least 90% by 2050. It is not a way to extend the fossil era, or prolong the life of polluting installations, or find new markets for fossil fuel companies.

Deep decarbonization is the result of individual and collective action leading to higher wellbeing for all with less resources, especially energy, completely rethinking mobility, habitat, nutrition and consumption. Carbon removal will then cover the residual emissions. 

We believe that the remaining open questions should not delay urgent climate action, and carbon removal is clearly one of several good 10% solutions. It must not be seen as the solution to the climate crisis.

In this context, the E4S Center plans to contribute to societal dialogue with events, discussions, research, teaching, and pilot projects. Come and join us!

Sascha Nick and Philippe Thalmann