Negative emissions technologies and practices: the way forward
According to the United Nations’ Intergovernmental Panel on Climate Change, the world must transform in complex and interconnected ways to limit global warming to 1.5 °C relative to pre-industrial levels. Emissions reductions and carbon dioxide removal (CDR) both reduce the amount of atmospheric greenhouse gases. As the urgency to mitigate climate change escalates and the speed with which the world adopts low-carbon processes lags behind, negative emissions technologies and practices (NETPs) are needed to complement the emission reductions. Negative emissions are created when more CO2 is removed from the atmosphere than is emitted and its storage is permanent. To be adopted and thus effective, NETPs must go beyond technological potential. The EU-funded NEGEM project, ending in May 2024, is evaluating the realistic potential of seven classes of NETPs in the context of their technical, environmental, social and commercial potential and challenges. The project’s science policy brief summarises the results to date and delivers key recommendations for EU climate policy.
Engineered and nature-based solutions for CDR
Engineered solutions abound. They include direct air capture and storage of CO2, bioenergy or other biomass-based processes combined with CO2 capture and storage, enhanced weathering and ocean-based solutions such as ocean liming. Nature-based solutions (NBS), a phrase put forth in the late 2000s and now enshrined in climate change dialogues, include afforestation, reforestation, biochar CDR, soil carbon sequestration, and ocean-based CDR including seaweed cultivation and sinking. The NEGEM project is studying all of these. According to Kati Koponen of the VTT Technical Research Centre of Finland: “Engineered solutions with storage on geological timescales provide permanent CDR and are necessary to reach climate neutrality. NBS are essential because they provide strong synergies between climate change mitigation and international targets for nature restoration and broader sustainable development goals.”
NETPs: technical, environmental, social and commercial aspects
The NEGEM analysis framework combines land use modelling, life-cycle assessment (LCA), cost optimisation and social acceptance evaluation. Essential new insight on NETPs deployment is emerging from combined modelling approaches, for example land use modelling and energy system modelling, and integrated assessment modelling that included the full portfolio of NETPs. The LCA results for more than 20 NETP cases revealed that none of the NETPs comes without trade-offs between different environmental goals. The social licence to operate varies across sectors and geographical regions for different NETPs. For example, NGOs and companies sometimes have opposing views on the acceptability of certain NETP solutions. In addition, tension exists in balancing CDR goals against other high-priority social or environmental goals. NEGEM also studied the market-based mechanisms for CDR. They found that the current mechanisms mainly support afforestation and soil carbon sequestration with minimal support for geological CDR. Overall, they are under-funded and provide too little incentive to enable a CDR portfolio that can achieve climate neutrality.
Climate policy requires a portfolio of solutions
Koponen summarises: “Based on the results of the scenario analyses, drastic and immediate emission reductions are needed to reach the 1.5-2.0 °C mitigation goals. In addition, NETPs will be needed as a complementary measure. A large portfolio of NETPs can help to respond to the environmental and social challenges. NETPs deployment should begin by the 2030s, underscoring the urgency to develop clear policies and regulations in the EU and globally.” To assist stakeholders, the NEGEM tools and data sets can be found on the project website that will continue to be updated throughout the project’s duration.
Keywords
NEGEM, NETPs, CDR, climate change, negative emissions technologies and practices, carbon dioxide removal, climate policy, nature-based solutions, NBS