To help deliver on net-zero promises, negative emissions technologies and processes (NETPs) which can capture CO2 from the air, such as direct air capture with CO2 storage (DACCS) or bioenergy with carbon capture and storage (BECCS), have been investigated. These technologies are still at the early stages of development and deployment but offer the promise of durable CO2 storage at scale so the main question is whether the costs, which are currently high, can be reduced to the point where these technologies can play an important role in carbon neutrality plans.
Reliable economic models projecting cost and upscaling pathways for DACCS and BECCS are needed by policymakers to design effective support mechanisms. These models require two types of inputs: the uncertainty surrounding relevant parameters and the expected best estimates for cost trajectories and the scale of deployment.
A recent study, by David Reiner, Manon Abegg, Lucrezia Nava and Zeynep Clulow, University of Cambridge, investigated the future costs and the uncertainties on deployment scale of DACCS and BECCS technologies in Europe in 2030, 2040 and 2050, as well as the implications for policy.
Carried out as part of NEGEM activities, this work gathered quantitative and qualitative insights from 34 DACCS and BECCS experts interviews. Experts were asked to estimate their 90% confidence intervals for future costs followed by their “best estimates”. Experts were also asked to estimate the expected scale of future deployment under two different policy scenarios, namely the IEA Stated Policies (STEPS) and Net Zero Emissions by 2050 (NZE) scenarios.
The experts’ best estimates suggest that, by mid-century, costs will fall to an average value of EUR 280/tCO2 for DACCS and EUR 153/tCO2 for BECCS (current assumptions are EUR 581/tCO2 for DACCS and EUR 172/tCO2 for BECCS). However, the uncertainty around future costs increases over time for both DACCS and BECCS and these best estimates hide a wide divergence in views, particularly for DACCS.
Most DACCS experts do believe that in the future new and better materials as well as economies of scale will reduce the costs of the technology although they differ widely in their assessment of the overall cost implications. On one hand, some believe that costs start and will remain very high for the foreseeable future, whereas others believe that even in the near-term costs are more moderate and will decline further.
By contrast, experts believe that BECCS, while currently significantly cheaper than DACCS, might struggle to scale up given the distinctive characteristics of each plant.
For both technologies, the uncertain future of European energy prices is perceived as a hurdle, and policymakers must prioritize securing a stable green energy system to reduce uncertainties linked to energy costs for DACCS and revenue streams for BECCS respectively.
In the expert view of what would be deployed, in the NZE or net-zero scenario DACCS is expected to be deployed at a scale that is nine times greater than in the STEPS (or ‘stated policies) scenario where governments do not move much beyond current policy ambitions (353 Mt CO2/year compared to 39 Mt CO2/y).
By contrast, BECCS is expected to be deployed at a smaller scale than DACCS in 2050, particularly in the NZE scenario, even though it has lower costs. (131 Mt CO2/y in the NZE scenario and 36 Mt CO2/y in the STEPS scenario).
Taken together, the average estimated combined capacity of DACCS and BECCS for 2050 amounts to only about a quarter of the CO2 removals the IEA envisions would be needed in its NZE scenario (1.9 GtCO2).
This reinforces the view expressed by several experts that an array of negative emission technologies and practices will be needed to meet net-zero ambitions. The deployment levels of both technologies depend on the successful implementation of early plants and that this requires negative emission technologies to be clearly defined in European policy frameworks.
For the STEPS scenario, BECCS deployment shows a higher potential scalability compared to DACCS, although limited to around 0.3Gt CO2/year. The higher uncertainty for the scalability of BECCS could be due to the need for one-of-a-kind plants and local supporting infrastructure.
This analysis reveals that there is a potential for both DACCS and BECCS to play a role in reaching net zero, together with other forms of greenhouse gas removal. However, there is a high uncertainty regarding future costs and the scale of deployment. Costs, as well as policy and regulations, are the most relevant limiting factors and there is deep disagreement among leading experts as to costs and hence the potential for the technologies (especially DACCS) to play a large role at scale.
To reveal whether the optimistic or more pessimistic views are actually manifest when the technologies scale up, concrete frameworks that define how negative emissions are accounted for, disposed of, and paid for, will be needed before these technologies can begin to be scaled up.