The updated German climate law requires negative emissions technologies (NETs) and carbon removal from the atmosphere (read all about that in our previous article). Here we want to answer the question, which of the solutions could be used in Germany and what their potential might be. The main take-away: Nature-based and technological carbon removal solutions will both be necessary at the Megatonne scale.
New studies confirm need for carbon removal
Two new reports that model pathways of how Germany can achieve climate neutrality by 2045 have been published in October 2021. The dena-Leitstudie “Towards Climate Neutrality” by the German Energy Agency and the Ariadne report as part of the Kopernikus Project funded by the German Ministry of Education and Research both make clear that substantial amounts of negative emissions are required to balance certain land use, agricultural or industrial emissions. Figure 1 extends our findings about how much annual negative emissions will be needed in Germany in 2045 including the data from the latest studies.
Generally, the latest numbers are similar to those from earlier studies. However the various studies still disagree on how much carbon Germany needs to remove from the atmosphere by a large margin. The resulting figures range between 40 and 100 Mt CO2-eq. The average between all studies points at annual carbon removal needs of a bit over 74 Mt CO2-eq at the point where Germany wants to be climate neutral.
Not only the scientific community alone is stressing the need of negative emissions, but increasingly industry groups and associations take the issue seriously. In a recent open letter to the new federal government a range of large corporations under the Stiftung 2 Grad stressed the need for developing a political framework for actively managing the carbon cycle and start developing solutions for capturing CO2 from industrial facilities and storing it underground (CCS).
Which negative emissions technologies are needed?
Broadly we can differentiate between nature-based carbon removal solutions and technological ones. The predominant nature-based solutions is re-, and afforestation, but also the renaturation of peatlands, the enhanced sequestration of carbon in soils through different agricultural practices or growing kelp in the sea fall into that category.
On the technological side, the main focus currently lies on DACCS (direct air capture and storage). Of course also hybrid solutions exist, such as BECCS (bioenergy with carbon capture and storage) or the production biochar which uses biomass and utilizes a technical process to sequester or bind the carbon in a non-reactive form.
We explain and compare a range of those NETs here. Figure 2 shows which of the various NETs are being foreseen to help Germany to achieve climate neutrality by 2045 based on selected studies. The answer to the question which NETs and carbon removal solutions are needed is simple: all of them!
The different nature-based solutions are summarized into the land use, land use change and forestry (LULUCF) category in Figure 2, which takes up the largest share of necessary carbon removal in most studies and in many cases is not split up into more detailed removal pathways and sinks in the studies.
In addition, most studies foresee the need for substantial technical removals via BECCS and DACCS. Especially in case the nature-based solutions would not be able to deliver the large CO2-capturing capacities, technological solutions are required.
More exotic carbon removal solutions such as enhanced weathering do not feature prominently. The usage of carbon dioxide from the atmosphere as feedstock for green naphtha or methanol production and in long-lived plastic products goes into the 10 MtCO2-eq range. It is worth noting that the different studies do not necessarily agree on the potential or capacity of the different NETs. This is also due to the fact that not all studies consider the entire range of possible NETs or focus on specific technologies or sinks.
And just as a reminder: In 2018 the LULUCF sector in Germany only delivered 18 MtCO2-eq of negative emissions (source: dena). That means within the next 23 years a doubling to tripling of the annual carbon removal capacity through forests, swamp renaturation and soil carbon sequestration needs to be achieved. Otherwise the reliance on technological solutions that are as of now not scaled-up will be even higher.
Negative emission potential in Germany
As seen above, a silver bullet or one NET to take out the excess carbon to make Germany truly climate neutral by 2045 does not exist. Much more, all solutions and technologies will be needed. To give a better overview of how such a carbon removal portfolio on the country level can look like, we used the numbers from the Ariadne project report and compared the potentials across the different NETs. Figure 3 shows the shares of different NETs in Germany in 2045 according to the report of the Ariadne project with a total potential of almost 110 MtCO2-eq.
The light green wedge taking 46 per cent of the total carbon removal potential represents the LULUCF sector, which can then further be split into re-and afforestation, soil carbon sequestration and carbon storage through changed agricultural practices such as agroforestry. Technological solutions such as BECCS and DACCS make up 37 per cent of the entire carbon removal potential, whereas biochar and enhanced weathering add up 17 per cent in total.
The way forward
The most recent results from climate and energy system modeling from a variety of different research groups are clear: Carbon removal from the atmosphere will be important for Germany to reach its climate targets. In 2045 the capacity to remove 10 per cent of the greenhouse gas emissions Germany emitted in 2020 from the atmosphere has to be in place.
That is not an easy feat, especially considering that carbon removal from the LULUCF sector today only has the capacity of providing a fifth to a quarter of the required negative emission capacity. In addition, climate change might impede the carbon storage capacity of nature-based solutions further during the coming decades. If natural carbon sinks cannot deliver, then technical or hybrid carbon removal solutions such as BECCS, DACCS or biochar become more relevant.
The most recent studies under consideration in this article arrive at different carbon removal capacity and needs for different NETs, as figure 2 demonstrates. Starting a structured conversation about how the recent reports arrive at their negative emission capacity for different technologies would be important. In that way science can develop an understanding about assumptions and the potential for an integral negative emissions modeling framework.
At the political level, devising a framework for active carbon management alongside capacity building measures and restarting a public dialogue on carbon removal and CO2-storage as necessary and important parts towards climate neutrality are the most important steps. Furthermore, a process on revising current regulations on CO2-storage and -transport, possibly across borders in a European context has to start. German climate targets should accommodate the differences between genuine emission reduction and carbon removal (as already being started in the UK and Sweden).
The take-away for the private sector: A new industry is forming and it needs to be scaled rapidly. Forward-looking companies and industries can be on the forefront of that development if they seize the opportunity. This holds for technology providers, project developers and emitting industries that can provide and utilise NETs. However, also companies with climate targets can demonstrate more credible climate action by neutralizing part of their difficult-to-abate emissions via negative emissions or carbon removal credits instead using less permanent and less credible offsetting projects.
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