BECCS and afforestation in comparison

Which method can remove CO₂ from the atmosphere more efficiently – BECCS or afforestation? This question was investigated by our STEPSEC team in a new study.

In order to achieve the climate targets of the Paris Agreement to limit global warming to well below 2°C, CO₂ emissions must be reduced and CO₂ must be removed from the atmosphere. In nearly all future scenarios that are compatible with the Paris climate targets, both afforestation and bioenergy with carbon capture and storage (BECCS) play an important role.

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In a recently published study, a team led by the researchers Sabine Egerer and Julia Pongratz from our STEPSEC project investigated which of these two methods can store carbon more efficiently and thus remove it from the atmosphere. The study was recognised by the co-editor of the journal Biogeosciences as a ‘highlight paper’ of particular importance.

They considered various aspects of both methods within a sustainable future scenario: land consumption, the development over time, the extent to which bioenergy leads to a reduction in fossil fuels, and the proportion of biomass that is permanently stored in geological reservoirs.

To simulate the effects of climate and land use conditions on carbon storage, the authors used the land surface model of the Max Planck Institute for Meteorology in Hamburg, JSBACH. They analyzed global large-scale afforestation and the cultivation of bioenergy crops in the same areas. In particular, they considered Miscanthus, which is known as a second-generation bioenergy plant and can therefore store carbon more efficiently than maize or rapeseed, for example.

Lead author of the article: CDRterra researcher Dr Sabine Egerer

The researchers found the following main results:

BECCS has a higher removal potential over longer periods of than afforestation, as afforestation reaches saturation of carbon storage over time, while bioenergy plants for BECCS are replanted and harvested every year. However, BECCS will not make a significant contribution to achieving short-term climate mitigation targets. This is partly because reforestation is more efficient over shorter periods and partly because CCS (carbon capture and storage) technology cannot be scaled up so quickly.
There are significant regional differences due to different regional soil and climate conditions: While afforestation is more efficient in China, for example, more carbon is stored through the application of BECCS in the South American grasslands and south-eastern Africa.
The efficiency of BECCS compared to ‘nature-based solutions’ such as afforestation will depend crucially on the upscaling of CCS facilities, whether fossil fuels are replaced by bioenergy in the future and whether bioenergy crops are grown in suitable locations that do not harm biodiversity, impair water retention or compromise food security.

‘The study shows that a comprehensive consideration of the local, temporal and socio-economic boundary conditions is necessary to assess the potential for terrestrial CO₂ storage. It thus creates the requirements for political decision-makers to develop strategies that are compatible with the Paris climate targets,’ summarizes lead author Sabine Egerer.

Publication:

Sabine Egerer, Stefanie Falk, Dorothea Mayer, Tobias Nützel, Wolfgang A. Obermeier, and Julia Pongratz: How to measure the efficiency of bioenergy crops compared to forestation. Biogeosciences 2024. https://doi.org/10.5194/bg-21-5005-2024.

Sabine Egerer, Tobias Nützel, Julia Pongratz and Wolfgang Obermeier are part of the CDRterra consortium STEPSEC.

To the study