In the Climate Protection Act, Germany committed to becoming greenhouse gas neutral by 2045. However, it is no longer enough to reduce greenhouse gas emissions. In addition, CO2 must be removed from the atmosphere. The CDRterra research consortium has now evaluated various options for this, from reforestation to geochemical and technical processes such as artificial photosynthesis. All procedures have advantages and disadvantages; some increase competition for space, others have so far failed due to legal hurdles. But according to the researchers, if politics, business and the population work together, the climate goal can still be achieved – and synergies can even arise that benefit the climate and society.
Germany currently emits around 650 million tons of CO2 equivalents every year. According to the Climate Protection Act that came into force in 2019, Germany should become greenhouse gas neutral by 2045. But even with ambitious programs to reduce CO2 emissions, it is estimated that 60 to 130 million tons of residual emissions will still remain in 2045, including from agriculture, industry and waste management.
Reduce emissions, store carbon
“In order to compensate for these residual emissions, processes are needed that actively remove CO2 from the atmosphere and store it permanently,” explains the CDRterra research consortium. In the project funded by the Federal Ministry of Research, Technology and Space (BMFTR), more than 100 researchers spent four years investigating various options for removing CO2 from the atmosphere. In English, these processes are called Carbon Dioxide Removal, or CDR for short.
According to the researchers, biological methods such as reforestation and forest protection represent an important but limited component. Until 2018, forests in Germany were a significant CO2 sink, absorbing around 50 million tons of the greenhouse gas every year. But due to droughts, forest fires and bark beetle infestations, German forests are now releasing more CO2 than they absorb. “We have to restore the forest depression,” says CDRterra spokeswoman Julia Pongratz from the Ludwig Maximilian University of Munich. “But we also have to expand the portfolio and scale everything up.”
Combination of different procedures
One of the measures examined at CDRterra is to use CO2-binding materials such as the deep rock gabbro when constructing new buildings. As it weathers, this reacts with the CO2 and binds it permanently in mineral form. In addition, innovative building materials such as bio-based carbon fibers and biochar layers could be used. They could help save cement, which releases large amounts of CO2 during its production. This would allow the traditionally very emissions-intensive construction sector to create new CO2 sinks and complement technical approaches to CO2 capture from the air.
In agriculture, too, a combination of biochar and ground rock could ensure that the soil stores more CO2. At the same time, this process would improve nutrient availability for plants, which in turn incorporate CO2 into their biomass as they grow. Artificial photosynthesis can also be used. In laboratory experiments, researchers have succeeded in converting CO2 into carbon flakes using solar energy – even more efficiently than natural photosynthesis. “The process could reduce land and water consumption in the future compared to energy crops,” reports the CDRterra consortium.
Challenge in implementation
From the researchers’ point of view, the biggest challenge lies not in the techniques, but in the implementation. Many of the nature-based processes increase competition for space. Careful considerations and close communication with everyone involved are required in order to find viable solutions. “A functioning portfolio combines methods to balance climate benefits, biodiversity and land use and minimize risks,” writes the research team. Ideally, CO2 removal can even make agriculture more resilient and more reliable.
According to the report, there is currently a lack of suitable transport and storage infrastructure for technical methods of CO2 capture. “In short: the methods are there – the structures are often not yet,” say the researchers. In order to become greenhouse gas neutral by 2045, such structures must be established as quickly as possible. It is also important to develop uniform procedures to measure how much CO2 a technology actually removes from the atmosphere and how long-lasting the effect is.
The research team emphasizes that CO2 removal is not a license for uncontrolled emissions. “It complements but does not replace emissions reductions.” Only if greenhouse gas emissions are drastically reduced and CO2 is removed from the atmosphere through biological, geochemical and technical means will there be a chance of achieving the net zero target by 2045. “Without ambitious emissions reductions and CO2 removal, we will miss our climate goals,” says Pongratz. “In order to ramp up CDR, we need clear rules, the development of new methods, the protection of natural sinks – and dialogue with society.”
Source: CDRterra, Synthesis fact sheet 2021-2025