CO2: The Goal Is Negative Emissions
Author: Michael Vogel
Without the use of technologies for carbon capture, utilization, and storage, humanity will struggle to slow down and ultimately reverse the rise of atmospheric CO2. Crucial for implementation: trust along the entire process chain.
In 2021, “Orca” went into operation, followed by “Mammoth” in 2024. Both facilities are a response to climate change, as they extract CO2 from the atmosphere. They are located in Iceland due to the availability of abundant, low-cost renewable energy and the suitability of the local rock formations for permanently storing the captured CO2. The two facilities are operated by Swiss company Climeworks, an ETH Zurich spin-off. With its technology, Climeworks aims to help reduce the concentration of CO2 in the atmosphere.
The technology is called Direct Air Capture. A specialized material collects CO2, which is then carefully extracted in a second step for secure storage—a reusable filter for the greenhouse gas. Airlines such as Lufthansa, Swiss, and British Airways are now Climeworks customers, hoping this will help them sustainably reduce their net CO2 emissions. Currently, Climeworks operates the largest-capacity Direct Air Capture facilities worldwide. However, these capacities remain limited, with a total annual maximum of 40,000 tons. For comparison, this is equivalent to the yearly CO2 emissions of just under 30,000 compact cars driving 15,000 kilometers each.
CCS and CDR – What’s behind these terms?
When discussing the technical reduction of CO2 emissions, two acronyms frequently appear that are related but not identical: CCS and CDR. Carbon Capture and Storage (CCS) involves capturing CO2 from industrial emissions. The idea is to permanently store the captured CO2 in geological formations, the ocean, biomass, or durable products. Carbon Dioxide Removal (CDR), on the other hand, includes all human-made measures to extract CO2 directly from the atmosphere and store it permanently using the same methods. “All these technologies offer crucial opportunities for decarbonizing industries in which this is particularly challenging,” says Sebastian Bartels, Head of Global Sustainability Services at DEKRA. Examples include the production of cement, steel, and certain basic chemicals.
For a long time, removing CO2 from the air was politically and socially controversial, as there were concerns that technologies like CCS might slow down the sustainable transformation of the economy. However, opinions are increasingly shifting, recognizing that atmospheric CO2 concentrations have progressed so far that humanity will likely have to rely on every available opportunity for reduction.
Net-zero scenario – Is it achievable?
According to the International Energy Agency (IEA), the adoption of carbon capture, utilization, and storage (CCUS) “has fallen short of expectations in the past but has gained significant momentum in recent years, with more than 700 projects in various stages of development along the value chain.” However, even at this level, the deployment of these technologies remains far below the requirements of a net-zero scenario—a state of carbon-neutral living and economic activity.
“CDR is good for the climate and can have positive effects on ecosystems and biodiversity. All methods are also economically appealing, and every country has CDR potential,” emphasizes Chris Sherwood, Secretary General of the Negative Emissions Platform (NEP). The advocacy group supports and promotes technologies for removing CO2 from the atmosphere. It includes many start-ups developing specialized technologies, such as Climeworks, as well as companies like Microsoft and energy giants E.ON and RWE. Sherwood stresses the importance of distinguishing between CDR and CCS: “CCS helps prevent things from getting worse. CDR, on the other hand, repairs the damage!” Through CDR, the concentration of CO2 in the atmosphere can decrease again. This, Sherwood says, “gives people hope”.
Achieving negative emissions with biochar
There are various approaches to achieving negative emissions. Biochar is one example: Instead of composting biological waste, it can be converted into charcoal using appropriate processes that release significantly less CO2. This charcoal can then be used in agriculture, for filtering pollutants, or even as electrode material in batteries. Direct Air Capture, as seen with Climeworks’ facilities, is another CDR approach. A further method is coupling bioenergy production with carbon capture, which allows the process to become carbon-negative, as the CO2 absorbed by plants during growth is captured during energy generation. The IEA puts it this way: “Bioenergy with carbon capture is the only CO2 removal method that can also provide energy.” Another example is the accelerated weathering of rocks, which also removes CO2 from the atmosphere. And the list of approaches does not end there. “Of course, they vary in their level of technological maturity,” says Sherwood. “Direct Air Capture is among the most advanced, and in the near future, biochar will also be an important CDR method.”
Of course, all of this is not just about technical and economic questions but also about regulatory frameworks. In the EU, these are now well-advanced for Direct Air Capture and bioenergy with carbon capture. There is also a regulation for European biochar certificates. This year, the European Parliament agreed on a regulation concerning carbon removal and carbon management.
The path for the start-ups organized in the NEP has not always been easy, says Sherwood: “They may have funding for research, development, and pilot projects, but not for scaling their technologies to an industrial level. To attract investors, the political signals need to be clearer.”
Building trust in the process chain
“For CCS and CDR methods, it’s essential to build trust along the entire process chain – all the way to the investors,” says Sebastian Bartels. “Everyone involved needs to be able to verify whether standards are being met or how much CO2 has actually been captured. Independent verification is key.” He notes that many new players will enter the field who inevitably lack decades of experience in risk management and mitigation. The ambitious goal of reducing carbon emissions will not be limited by national borders, which is why technologies and processes must be interoperable across economic regions, industries, and energy sources, Bartels adds. “DEKRA sees its role in providing technical expertise in the areas of safety, risk prevention, and sustainability, supporting companies in complying with regulations, and conducting the final verification of processes and products.”