CO2 capture and storage – five technologies point the way to net zero

If Switzerland is to achieve its target of reducing its greenhouse gas emissions to net zero by 2050, it will be reliant on the use of negative emission technologies – processes which capture and permanently store CO2 from the atmosphere. Although negative emission technologies can contribute towards achieving climate targets, there are still many unanswered questions: in practice, some of these technologies are untested, technically complex and costly and currently have limited potential for upscaling. There is also relatively little public awareness of the opportunities and limitations of negative emission technologies.

On behalf of TA-SWISS, the Oeko-Institut and Empa therefore evaluated five negative emission technologies of relevance for Switzerland. The analysis, which was conducted with expert input from stakeholders, shows that none of these methods is the sole decisive solution; rather, all of the technologies are required. Reducing CO2 emissions is still the highest priority, as preventing emissions is a more cost-effective option than removing CO₂ from the atmosphere at a later stage.

The TA-SWISS study aims to inform policy-makers and the public about the opportunities, limitations and risks associated with various carbon capture and storage methods. It considers aspects such as feasibility, climate impact, costs, resource consumption and effects on the environment and society.

The five technologies are:

• CO2 storage in biomass in forests, with subsequent utilisation of wood
• CO2 storage in humus in soils, with use of biochar
• use of bioenergy with carbon capture and storage (BECCS)
• direct air capture and carbon sequestration (DACCS)
• accelerated weathering of demolition concrete and rock (carbonation)

Each of the five negative emission technologies was evaluated on the basis of current knowledge, with expert input collected in in-depth interviews. Opportunities, risks, synergies and conflicts of interests were identified and assessed from a systemic perspective. On this basis, utilisation options, general recommendations and detailed recommendations for the individual technologies were formulated and discussed with a range of stakeholders.

The study’s key recommendations:

• So that negative emission technologies will be able to make an environmentally and socially sustainable contribution towards the net zero target, policy-makers and society should engage with the topic at an early stage, as recommended by the study. Above all, this will require a knowledgeable and fact-based social debate on the application of negative emission technologies in Switzerland.
• There is a need for a comprehensive strategy on the use of limited resources, as well as a financing strategy to support the development and implementation of negative emission technologies.
• Further studies are required to assess the various technologies’ potential.
• To provide a suitable evaluation framework, a transparent and straightforward accounting method for CO2 permanently captured from the atmosphere is required; this should ensure that the same CO2 is not counted multiple times.
• There is a need for further reflection on the permanence of CO2 storage.
• The application of negative emission technologies should be a complementary option for achieving the net zero target. It is therefore important to set separate targets for CO2 emissions reductions and for CO2 capture.
• Switzerland currently plays a lead role in the development of negative emission technologies. It is important to reinforce this competitive advantage by promoting research and development in this field and supporting demonstration projects.

In addition to these general recommendations, the study sets out detailed recommendations for each of the five negative emission technologies. The research study report is published by vdf and can be purchased at book stores. It is also available for free download as an open access e-book: http://www.vdf.ch

Chancen und Risiken von Methoden zur Entnahme und Speicherung von CO₂ aus der Atmosphäre [Opportunities and risks associated with methods for capture and storage of CO2 from the atmosphere]: Study by the Oeko-Institut and Empa