Plastering over the cracks: The flaws in industry’s bid to class cement and concrete as delivering carbon removals – Updated

The EU must ignore lobbying efforts from industry to certify the storage of carbon dioxide in cement or concrete as carbon removals.

Image: Pawel Czerwinski, Unsplash 

Interest in carbon dioxide removals has been growing in recent years, and has sparked a debate on what constitutes carbon removals. In response, the European Commission proposed a Carbon Removal Certification Framework (CRCF) in November 2022 as a voluntary scheme within the EU. 

The development of the CRCF has served as a platform for discussions on the definition of carbon removals, with various industries vying for their sectors to be considered potential sources of removals. The critique which is most commonly levelled against many of these sectors is that the carbon they extract will not be additional, will not be more than the emissions they cause, will not come from the atmosphere and/or will not be permanently stored.

Concrete proposals 

A recently published position paper by Cembureau, the European cement association, exemplifies this trend. It claims that the EU cement industry can remove carbon in three distinct ways: Use of sustainable biomass as feedstock in cement plants, with the resulting emissions captured; the injection of atmospheric or biological carbon into cement during the production process (so-called enhanced carbonation); and the natural absorption of carbon by cement throughout its lifetime (so-called natural carbonation) if the cement is produced in what the paper calls a ‘carbon neutral’ way.

However, on deeper examination, it becomes clear that concrete and cement are unlikely to deliver real and durable carbon removals, at least not for the foreseeable future. All three of these potential and theoretical carbon removal benefits from the production and use of cement come with major caveats and risks.

Carbon cycles

This is principally because for a process to count as a carbon removal that contributes to achieving the Paris Agreement target of keeping global heating below 1.5°C, it must actually remove more carbon from the atmosphere than it generates throughout its lifetime and store this for at least a few centuries. This means that only a full life-cycle assessment can determine whether an activity actually results in carbon removals and how many. In the case of these three cement industry proposals, the likelihood of actual removals being delivered is extremely low, especially in the short term. This is why the CRCF should ignore these in favour of real and proven removals techniques. 

Cembureau’s position paper lays out a blueprint for achieving negative emissions in the long term by integrating carbon capture and storage (CCS) across the sector and transitioning increasingly to biogenic feedstock, i.e. burning fuels derived from organic matter which are supposedly “carbon neutral” because the biomass is presumed to grow back, and then capturing and storing the resulting emissions. This vision is problematic for a number of reasons.

Organic growth

First, biomass is expected to become a scarcer and scarcer resource. Supply is likely to drop due to soil degradation and diminishing crop yields as the planet heats up. Meanwhile demand is expected to as much as double by 2050. As a long-term strategy, transitioning to biogenic energy is, therefore, not a realistic pathway for the cement sector.

Second, even in the unlikely event of a massive future supply of sustainable biomass that the cement industry can access, the life-cycle of that biomass needs to be taken into account to ensure that there is an actual net removal from the atmosphere, which is far from a foregone conclusion. 

While biomass contains CO2 captured through photosynthesis, substantial amounts of energy are consumed to grow, harvest, process and transport the bio feedstock, all of which result in emissions.This also needs to include direct and indirect land use changes caused by greater demand for biomass. Ignoring the full lifecycle emissions could have unintended and dangerous consequences, such as accounting for the captured emissions as removals while the atmospheric greenhouse gas concentrations actually rise due to these overlooked or ignored sources.

A third concern is the overreliance on carbon capture and storage (CCS). A modern CCS installation would only reduce life-cycle concrete emissions by a modest 40%, while raising energy use by up to 40%. CCS would still only capture up to 90% of production emissions and involves a risk of CO2 leakage.  

When all the extra emissions and leaks are totted up, Cembureau’s vision of negative emissions takes on the semblance of a mirage caused by hot air that distorts the light. 

The trouble with carbonation

Cembureau argues that the injection of atmospheric or biogenic CO2 into concrete during the production process (enhanced carbonation) should be treated as a permanent removal. This can, however, only be considered a true removal if it leads to lower atmospheric concentrations of carbon. This would require enhanced carbonation to suck more carbon out of the air than is generated by the entire cement value chain – which is an unlikely proposition. 

The cement lobby group also advocates that natural carbonation should be considered as a carbon removal “when arising from the production of carbon neutral cement”. This argument rests on the premise of cement being a carbon sink due to its natural absorption of carbon throughout its lifetime. For currently produced cement, that means that some of the greenhouse gases emitted during production are slowly absorbed back into the cement, which is more akin to a delayed emission reduction than a carbon removal. 

Moreover, carbon-neutral concrete and cement are still at the pilot stage. It is deceptive and premature to demand that natural carbonation and carbon neutral cement together should already be recognised as carbon removals. 

In addition, natural carbonation occurs naturally in all concrete structures, so the CO2 absorption by the built environment is not delivering any additional benefits to the climate. Non-additional actions do not require further policy support as they will happen anyway, and the EU’s draft Carbon Removal Certification Framework recognises this by excluding non-additional activities (see article 4 of the European Commission proposal, where natural carbonation would be part of the baseline of a removal activity).

Diverting attention

The case of Cembureau’s position paper shows the need to keep an eye on how industries are jumping on the carbon removals bandwagon as a distraction from questioning the root of the problem –  their highly polluting and energy-intensive production methods. Giving policy space to theoretical solutions based on hypotheses and unproven assumptions is a slippery slope. To avoid hyped-up ideas stealing the oxygen from real solutions, the CRCF must unambiguously define carbon removals as permanent, additional and cover the full lifecycle of the removal and production process.

Cementing change

A recent CMW report  outlined numerous actions available for the European cement sector that can substantially slash emissions both in the short term and the long term. These include the use of low-carbon cement (using less limestone to lower process emissions), reducing the clinker-to-cement ratio (the clinker acts as the binder and constitutes the majority of CO2 emissions from cement manufacturing) and increasingly adapting a circular business model with material reused and repurposed. Some of theses actions are already implemented successfully by companies.

On the policy level, our analysis found that the allocation of free pollution permits under the Emissions Trading System has slowed down industrial decarbonisation. To tackle this, these freebies must be phased out more rapidly.

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This article has been revised to take into account feedback and comments from Cembureau, whom we thank for their engagement.

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