Episode 12: End storage of greenhouse gases?

Wood, humus or high-tech for long-term carbon storage.

19.01.2023

About ten percent - that's how many greenhouse gas emissions will remain from the current ones if Germany is climate neutral by the middle of the century. This is because there will be unavoidable emissions that will have to be compensated. This works, for example, by removing carbon dioxide (CO₂) from the atmosphere and storing it permanently. But where should the CO₂ go? And which CO₂ extraction processes are at all promising?

(only in German)

„For our 2050 vision - and this is an optimistic vision - we have said for the peatlands and organic soils, we re-water everything we have in Germany and thereby achieve CO₂ avoidance in agriculture.“
Dr. Nadine Mengis, Geomar Helmholtz Centre for Ocean Research Kiel

Currently, only forests and wood products form a so-called carbon sink in Germany. Through their metabolism, trees bind about seven percent of German CO₂ emissions. Worldwide, the figure is more than 25 percent. That is why hopes on the path to a climate-neutral lifestyle rest primarily on forests. However, great potential is also attributed to agriculturally used soils, because humus, for example, is also one of the carbon reservoirs.

Possibilities and ideas for man-made CO₂ sinks are, on the one hand, increased building with wood, because carbon can remain fixed in durable wood products for many decades. On the other hand, there are longer-term ideas, such as combining bioenergy with "capture and storage". The carbon dioxide would then be captured and stored directly at the chimney instead of being released into the surrounding air. The targeted stabilisation of plant biomass through the production of pyrolysis charcoal is also being discussed as a possible long-term carbon sink. Last but not least, there are ideas and attempts to pull carbon dioxide out of the atmosphere or even the sea with the help of CO₂ filter systems and then store it geologically, for example in disused natural gas reservoirs.

What contributions to carbon storage agriculture and forestry can actually make, why peatlands and oceans play such an important role in CO₂ storage, what possibilities CO₂ filter plants offer and why there is nevertheless no way around avoiding greenhouse gas emissions are discussed by our guests in this episode: Dr Nadine Mengis from the Geomar Helmholtz Centre for Ocean Research Kiel, Prof. Andreas Krause from the Thünen Institute of Wood Research and Prof. Heiner Flessa from the Thünen Institute of Climate-Smart Agriculture.

Sources and further readings

Study on the carbon storage potential of soils
Climate Protection through CO₂ Certificates for Humus
Thünen explains: Why Forest Use is also Climate Protection
Project: Potentials of biochar as negative emission technology
MacDougall AH, Mallett J, Hohn D, Mengis N. (2022) Substantial regional climate change expected following cessation of CO₂ emissions. Environmental Research Letters, 17 (11). Art.Nr. 114046. DOI 10.1088/1748-9326/ac9f59
Evaluation of potential CO2 removal processes

Our guests

Climate physicist Dr Nadine Mengis is an expert in the evaluation of CO₂ removal processes. She heads the Emmy Noether working group of the FOOTPRINTS project at the Geomar Helmholtz Centre for Ocean Research Kiel. Together with researchers from the Helmholtz Climate Initiative, she has calculated how Germany can achieve net zero CO₂ emissions by 2050.

Professor Andreas Krause heads the Thünen Institute of Wood Research. He conducts research primarily on wood composites and deals with possibilities for permanent CO₂ storage in wood, such as the possibility of storing tree trunks in disused mines.

Professor Heinz Flessa, head of the Thünen Institute of Climate-Smart Agriculture, is primarily concerned with agriculture and climate protection. As a soil specialist, he knows the dynamics of carbon and nitrogen in soils and researches soils as sources and sinks for climate-relevant trace gases.