Capture or curtail: The potential and performance of direct air capture powered through excess renewable electricity

Abstract

• Discussion of the potential and costs of direct air capture powered using excess solar electricity. • Historic and forecasted values of excess electricity show tangible and scalable potential. • Use of excess solar electricity exhibits appealing environmental and economic performance in evaluated case study. • Direct air capture could offer carbon dioxide removal and excess electricity management alongside other discussed technologies. The widespread deployment of direct air capture is impeded by technology and scalability challenges, particularly resulting from high capital costs and energy demands. This paper posits that it is not possible to effectively evaluate the economic and environmental impacts of direct air capture without accounting for the spatial and temporal contexts in which it will be operated. Accordingly, the analysis aims to evaluate the near-term and medium-term (2030–50) potential of using excess renewable energy to power flexible deployment of direct air capture in California. Current systems would be able to sequester almost 1 million tonnes of carbon dioxide per year, an important benchmark target. For future systems, increased solar photovoltaic penetration could lead to potential carbon sequestration of 20–140 million tonnes during 2030–50. The environmental efficacy of excess electricity powered direct air capture is also estimated, which exhibits lower upstream energy consumption and net greenhouse gas emissions compared to the average range of carbon dioxide removal technologies. In terms of economic performance, the studied system is appealing across a wide range of capacity factors, thus showing large operational flexibility. Beyond this, the current study discusses a more fundamental premise, which is that different carbon dioxide removal approaches are uniquely suitable for different contexts that should be explicitly accounted for when evaluating their anticipated costs, benefits, and potential.