Achieving climate goals: Which CO₂ removal technologies are in circulation?

Researchers warn: climate targets cannot be achieved without increased CO₂ removal

Hundreds of billions of tons of carbon dioxide must be removed from the atmosphere. According to researchers, this is necessary in order to achieve the climate goals. They took stock of CO₂ removal for the first time – and identified an enormous need to catch up.

A carbon dioxide reservoir under the sea floor – that could help Germany to achieve its climate goals. It would be a kind of CO₂ repository. Locked in there, the greenhouse gas could no longer harm the climate. Federal Minister of Economics Robert Habeck (Greens) plans to use the so-called “Carbon Capture and Storage” technology, or CCS for short, in Germany as well. He intends to introduce a corresponding law before the end of this year.

Storing CO₂ underground sounds like science fiction at first. But in order to limit global warming to 1.5 degrees Celsius, as stipulated in the Paris Climate Agreement, forms of carbon dioxide storage are needed in the short and long term in addition to significantly lower CO₂ emissions. Hundreds of billions of tons of the gas must be removed from the atmosphere over the course of the century. The first points to this Status report on CO₂ removal “State of Carbon Dioxide Removal” in which more than 20 international experts have contributed.

Air conditioning check

Receive the most important news and background information about climate change – new every Friday.

See also  Archaeology: The Economic Power of the Viking Women

Trees as natural carbon sinks

“CO₂ removals are a necessity,” emphasized Jan Minx, author of the report and head of the research group Applied Sustainability Research at the Mercator Research Institute on Global Commons and Climate Change, in an interview with the Science Media Center (SMC). “They won’t fall from the sky, we have to take care of them.”

CO₂ is already being removed from the atmosphere, primarily through conventional land-based methods such as afforestation. Trees are natural carbon sinks. They need the gas to grow and bind it in the wood as they do so. The researchers estimate that reforestation and sustainable soil management would remove around two gigatonnes of CO₂ from the atmosphere every year. In order to achieve the 1.5 degree target, CO₂ removal would have to double by 2050 compared to 2020.

New CO₂ removal methods are hardly ever used

According to the report, conventional extraction methods alone would not be sufficient. New extraction technologies would also have to be promoted and expanded. These include:

• Bioenergy with Carbon Capture and Storage (BECCS): Fast-growing plants are cultivated that remove CO₂ from the atmosphere. They are harvested, burned in plants, whereby energy is generated and the CO₂ released in the combustion process can be permanently stored.
• Biochar: It can be used as a fertilizer in agriculture, which improves soil quality and binds CO₂ in the soil for thousands of years.
• Accelerated Weathering: In the process, crushed minerals are spread over land areas, which help to chemically bind CO₂ from the air.
• Direct Capture of CO₂ from Air and Storage (DACCS): This is a large fan and filter system. This sucks in air, passes it through a chemical solution that removes the CO₂. After that, the air is added back to the atmosphere. The separated CO₂ can, for example, be pumped into the ground via pipelines and stored underground.

So far, these newer processes have only accounted for a tiny proportion of CO₂ removal. The researchers assume that an estimated 0.002 gigatonnes of CO₂ per year will be removed from the atmosphere in this way. “We’re really still at the beginning,” said Minx. “We’re almost at zero.” Which is probably also due to the fact that these methods are still viewed with suspicion. Their use should actually increase massively – by a factor of 1,300 by 2050, as the status report shows.

CO₂ withdrawals are not a panacea

“We’re really lagging behind when it comes to CO₂ removals,” stressed Minx. And the gap between what countries plan to remove in terms of CO₂ and what is needed to reach the 1.5 degree target and become carbon neutral by 2050 is not narrowing. Only a few countries want to significantly increase their CO₂ removals, let alone introduce new technologies. According to Minx, carbon storage is currently not a technological but a political problem because the necessary framework to expand the methods and options is missing.

However, according to the status report, CO₂ removal is not a panacea. In the end, both are needed: far-reaching reductions in emissions as well as conventional and new technologies for CO₂ removal. It’s no longer an either/or, explained Oliver Gerden, also an author of the report and a senior fellow at the Stiftung Wissenschaft und Politik in Berlin, to the SMC. He called on countries that have set net-zero emissions targets to report how much CO₂ they plan to remove from the atmosphere in the future, what methods they intend to use and who will pay for it. “If you don’t have an answer to that, you really can’t take your net-zero goal seriously.”

The researchers plan to regularly publish a new status report on CO₂ removal. Also to improve knowledge about carbon dioxide storage and make it accessible to more people step by step. “Twenty years ago, renewable energies were a niche sector,” write the authors. “Today the picture is completely different. (…) The CDR (Carbon dioxide removal, i.e. the removal of CO₂, d’s note. editor) stands at the beginning of a similar journey.”