Robust BECCS deployment strategies under deep uncertainty : A case study of Stockholm Exergi

Abstract: The most recent IPCC assessment shows that negative emissions (NEs) and carbon dioxide removal (CDR) technologies are becoming increasingly important in scenarios that limit global warming to 2 °C or lower. In these scenarios, one key set of CDR technologies is bioenergy carbon capure and storage (BECCS). However, real-life BECCS projects are not being deployed at the rate required to meet the climate targets. Previous research has argued for the need to consider multi-dimensional and/or deep uncertainties of BECCS implementation to enable accelerated and robust CDR strategies. To this end, this work applies decision making under deep uncertainty (DMDU) methods to systematically consider deep uncertainties and to potentially improve the robustness of BECCS deployment strategies, using Stockholm Exergi (SE) as the studied case. Mixed DMDU methods were applied in the study: Dynamic Adaptive Planning (DAP) through semi-structured expert interviews, and Robust Decision Making (RDM) through an exploratory model, supported by the open source Python library Rhodium. Through DAP, 29 vulnerabilities, 19 opportunities and 79 corresponding adaptive actions were found. These covered political, economical, social, technological, regulatory and environmental dimensions. Through RDM, the Net Present Value (NPV) and Regret (a relative performance metric) of two options, Investing in BECCS or Waiting, were explored in 40 000 futures/states of the world. The two options were evaluated across three robustness criteria: satisficing domain, relative satisficing domain and min-max Regret, and critical uncertainties and scenarios were identified. The main conclusions were: most critical, and often deep, uncertainties of BECCS deployment are political or regulatory, and external to SE. These are linked to economic performance, and require external adaptive actions by SE. The major uncertainties are the NE claiming rules under Article 6 of the Paris Agreement, and the future of biomass regulation. Furthermore, Investing in BECCS is more robust than Waiting for SE in trends of low electricity prices (mean of 5-35 €/MWh between 2024-2050) across all three robustness criteria. In more vulnerable energy price trends, Investing still performs better than Waiting in 78 % of futures if actions are taken to allow co-claiming and selling of NEs before 2032, and if liquid market prices of NEs are likely to increase in the coming years. Between 2024-2050, mean NE prices higher than 150 €/tCO2 would likely be necessary.