Climate policy | Germany's shrinking CO2 stocks

The possibilities of storing CO2 under the seabed of the German North Sea are significantly lower than previously assumed. Photo: Unsplah/Robert Katzki A few days ago, the environmental organization Greenpeace wrote an open letter to the Federal Ministry for Economic Affairs and Energy. It says that the federal government's basic assumptions about CO2 storage can no longer be maintained in view of new research results.

The question is how much carbon dioxide can fit under the German part of the North Sea and what the limited capacities should be used for. The Geostor research association presented new calculations at the end of September. According to this, 0.5 to 1.5 billion tons of CO2 could actually be stored for use under the German North Sea.

The CO2 is to be captured at industrial sites, liquefied, transported via pipelines or ships to a storage facility and pressed into porous rock deep beneath the seabed. This is part of the federal government's strategy to achieve its goals in reducing greenhouse gas emissions.

“Deep beneath the German North Sea lie rock formations that have a storage potential of one to six billion tons of carbon dioxide,” Geostor wrote in its first study of the storage potential off the German North Sea coast. According to the researchers, only a fraction of this is actually usable. Large areas are already used for other purposes - for example for wind power and shipping, by the military or as protected areas.

What is important is not only the storage volume, but also how quickly CO2 can be stored there. Even under optimistic assumptions, the future demand of up to 70 million tons of CO2 per year assumed by the Ministry of Economic Affairs cannot be covered with the available storage facilities, according to Greenpeace. Geostor researchers had cited a possible annual injection rate of eight to 23 million tons.

Since other forecasts of “residual emissions” in 2045 assume 130 million tons or more, there remains a huge gap in the goal of climate neutrality. The new findings thus touch on a central component of the German “carbon management strategy”. In the key points decided in 2024, the federal government determined how the capture, transport and storage of CO2 - CCS for short - should be made possible. Central parts of this concept were cast into applicable law at the end of 2025 with the Carbon Dioxide Storage and Transport Act.

The assumption in the strategy that Germany would have “significant potential storage capacity for CO2” is no longer tenable in view of the new data, argues Greenpeace. The environmental organization is therefore calling for an immediate revision. This raises the main question of who should have access to the scarce storage facilities. Greenpeace demands that storage capacities be reserved exclusively for “demonstrably unavoidable residual emissions”.

However, which emissions fall into this category is not clearly defined. Process emissions from the cement, lime and chemical industries as well as waste incineration are prime examples. The “Carbon Management Strategy” states that CCS should be made possible “especially, but not only” for emissions that are difficult to avoid. The CCS law does not draw this limit either. In principle, all CO2 emissions are permitted, with the exception of coal-fired power generation.

“CCS must no longer be used as an excuse to delay decarbonization.”

Last year, the government rejected a request from the Federal Council to exclude gas power plants from the CCS law. Only state funding is limited to CCS projects with emissions that are difficult to avoid. There is a loophole here too – through climate protection agreements. The state wants to use these to offset the additional costs of a more climate-friendly production method for industrial companies.

According to Greenpeace, up to five billion euros could also benefit projects that use fossil natural gas. This is “not climate-neutral, but rather harmful to the climate.” Methane emissions from extraction and transport as well as incomplete capture rates - even modern CCS systems can usually capture around 90 percent of CO2 emissions - would cause significant residual emissions.

Greenpeace therefore warns against investing billions of taxpayers' money in an "economically unprofitable for the foreseeable future" and unsafe technology and thus creating false incentives. The Ministry of Economic Affairs is planning to set up an oversized CO2 pipeline network. “CCS must no longer be used as an excuse for delaying decarbonization,” says the open letter. Geostor currently assumes 100 to 300 euros per ton of captured and stored CO2. In EU emissions trading, a certificate for one ton of CO2 currently costs 75 euros.

Geostor researchers also urge people to use storage space carefully. There are still great uncertainties about the actual storage volume. It is only “during the CO2 storage itself” that it becomes clear how quickly the pore space is filled and the pressure in the storage rock increases.

It is not a new finding that there is often a world of difference between theoretical storage potential and actually usable deposits. An international study concluded last year that the size of global deposits is much smaller than previous estimates. Looking at Germany, the researchers came to a theoretical capacity of 27 billion tons on land and six billion tons under the North and Baltic Seas. When risks are taken into account, total capacity shrinks to 1.3 billion tonnes, three quarters of which lies under the sea. 

Greenpeace also argues that the development of underground deposits poses a threat to maritime ecosystems. Geostor also addresses the effects of noise pollution and acidification risks due to CO2 escaping in the event of leaks. The extent of the danger caused by cracks in the rock is currently being investigated.

There are also risks involved in the pressing process itself. The increase in pressure in the reservoir rock could even trigger minor earthquakes. Both Geostor and Greenpeace are therefore calling for strict requirements, controls and limits, for example for noise.

In Germany, the topic is likely to concern the Bundestag again soon. By the end of the year, the federal government wants to present its strategy for decarbonizing German industry. CCS will most likely play a major role in this.

Meanwhile, the federal government is pushing the issue further: At the first “Strategic Dialogue” of the Carbon Management Forum, State Secretary Frank Wetzel confirmed that the Ministry of Economic Affairs wanted to accelerate the ramp-up of CCS.

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