Negative emissions technologies

Definition

Carbon dioxide (CO₂) is a major driver of climate change. This is why technologies already exist today that capture CO₂ from industrial plants and power plants, collectively referred to using the term “carbon capture and storage” (CCS). Other processes such as direct air capture and storage (DACS) attempt to filter CO₂ directly from the air. Such technologies that capture and store CO₂ are known as negative emissions technologies (NETs). They include technical solutions such as CCS and DACS as well as biological and hybrid methods. Biological solutions include forest and soil management and biochar storage. A hybrid approach uses the fermentation of plants in sewage treatment plants. The CO₂ produced during fermentation is captured and stored.  

For NETs, it is crucial that the captured CO₂ is stored for the long term. However, the permanence of storage depends on the method used. CO₂ mineralised in concrete remains stored for a very long time, whereas the storage capacity of soils and plants, for example in forest management, depends on how the land is managed and usually lasts only a few decades.  

Current applications and opportunities

One of the first companies to use NETs commercially is Climeworks, a Swiss ETH spin-off founded in 2009. The company currently operates two plants in Iceland that filter a total of 40,000 tonnes of CO₂ from the air every year and store it in the ground. Climeworks is the only company in the world that operates DACS systems on a semi-commercial basis. 

More and more companies are capturing CO₂ directly from industrial exhaust air. ETH spin-off Neustark, for example, has developed a technology for the permanent storage of biogenic CO₂ from biogas plants whereby CO₂ is captured, liquefied and mineralised in concrete. Neustark already operates 29 plants in Switzerland, Austria, Belgium and Italy. A pioneer in CCS technologies is Norway, which established a repository for CO₂ captured from natural gas production in the North Sea in 1996. 

The legal framework in Switzerland has evolved rapidly over the last two years, with the Swiss Climate and Innovation Act (CIA) coming into force in 2025. This law stipulates that Switzerland must achieve net zero emissions by 2050. Greenhouse gas emissions are to be reduced as much as possible and remaining emissions are to be offset by NETs. From 2025 to 2030, the federal government will provide companies with up to 200 million Swiss francs per year in funding for climate-friendly innovations. Funding applications must include a roadmap showing how emissions will be reduced to net zero by 2050 at the latest. 

Owing to their high CO₂ emissions, waste incineration plants are key to Switzerland’s climate strategy. According to an agreement between the Federal Department of the Environment, Transport, Energy and Communications (DETEC) and the Association of Plant Managers of Swiss Waste Treatment Installations (VBSA), Swiss waste incineration plants must commission at least one CO₂ capture facility by 2030. The first facility is to be built at the Linth waste incineration plant in Niederurnen in the canton of Glarus, with more planned in Hinwil, Zurich and Basel. 

The development of NETs is primarily driven by industry, research and public authorities. At association level, the VBSA and cemsuisse, the Swiss cement industry association, are particularly active.  

Various initiatives are seeking to support NETs, including the Carbon Removal Booster from the funding agency Innosuisse. Germany has launched the research programme CDRterra (land-based CO₂ removal methods) and the research mission CDRmare (Marine Carbon Sinks as a Pathway to Decarbonisation). 

In addition, more and more companies are pursuing ambitious climate targets and participating in a voluntary market for negative emissions certificates, the Voluntary Carbon Market (VCM). Tech giant Microsoft alone covers 60 to 70 percent of the NET market, as the company aims to achieve net zero by 2030. 

Challenges

There are a number of challenges to NETs: 

• The catalysts used today for CO₂ capture require metals known as rare earth metals. There are doubts as to whether these raw materials are available in sufficient quantities to be used on a large scale worldwide. This is pushing scientists to search for and develop new materials for capturing CO₂ from the air. 

• DACS systems that filter CO₂ from the air are currently too expensive. Plants that capture CO₂ at source, such as cement production or waste incineration plants, perform better economically because the concentrations of CO₂ in the exhaust gas are higher than in the atmosphere. 

• The technology readiness level (TRL) of the processes varies greatly, and uncertainty is high owing to low CO₂ prices and a lack of regulation. Under the current conditions, the applications are not economically viable. 

• Some solvents used in carbon capture processes can emit toxic emissions, especially in amine-based processes. Volatile amines pose health risks. 

• The permanent storage of CO₂ presents a major challenge. There only are few suitable storage sites worldwide, including Iceland and the North Sea. 

• CO₂-intensive production branches could be relocated abroad. To prevent the import of unregulated cement, for example from Turkey, the EU is gradually introducing the Carbon Border Adjustment Mechanism (CBAM) by 2026, which aims to ensure fair prices for trading carbon-intensive goods. The cement industry in Switzerland is lobbying for similar tariffs. 

Focus on industry

Swiss industry is aware of the need to invest in NETs. This also brings economic benefits, for example through the marketing of products manufactured with a lower carbon footprint, which also has a positive impact on the reputation of companies. 

Depending on the area of application, employees require specific technical skills in areas ranging from the timber industry to CO₂ capture from the air. Systemic thinking is important because carbon removal has to work within the overall system. Skilled workers such as fitters, electricians and construction site managers are hard to find. To address this, more people with training in life cycle analysis, CO₂ monitoring and verification are needed. 

International perspective

The United States, Canada and Australia are leaders in the field of carbon capture technologies. In Europe, Norway is playing a pioneering role in the disposal of excess CO₂ from gas extraction in the North Sea. In May 2024, Switzerland and Norway signed a memorandum of understanding to intensify their cooperation in the areas of CCS and carbon dioxide removal (CDR). The aim is to promote the cross-border development of CO₂ transport and storage infrastructure. 

The European Union (EU) also wants to provide more support for NETs by 2050. At the end of 2024, the EU adopted the Carbon Removals and Carbon Farming Certification (CRCF) Regulation.  

Swiss institutions are involved in various European research programmes and cross-sector platforms. For example, the Swiss Federal Office of Energy and the Swiss National Science Foundation (SNSF) are involved in the Clean Energy Transition Platform (CETP), which supports transnational projects in the area of CO₂ capture, utilisation and storage (CCUS). Participation in these initiatives gives Switzerland access to European expertise and promotes the development of joint solutions in the field of CCS. 

There is a great deal of debate surrounding biochar, whose supporters believe that Switzerland is too hesitant about recognising and authorising biochar as a carbon sink. In other countries, carbon sequestration through biochar is being promoted more strongly. 

Future applications

By 2030, five to ten major DACS projects will be in operation across Europe. Developments between 2030 and 2035 will depend heavily on policies and incentives. In Switzerland, a dozen projects are planned for the cement industry, which could result in the storage of 10 million tonnes of CO₂ per year, equivalent to almost 20 percent of annual emissions. Interested companies, for example in pharmaceutical logistics, fear that the supply of carbon storage will be insufficient. They are therefore setting up in-house carbon removal departments. 

For Switzerland, NETs are an essential part of the climate strategy for achieving the net-zero target by 2050. These technologies are designed in particular to offset hard-to-avoid emissions from sectors such as agriculture, cement production and waste recycling. However, success depends on technological advances, economic viability and social acceptance.