Area demand quantification for energy system-integrated negative emissions based on carbon dioxide removal portfolios

Abstract Climate change mitigation will most likely rely on large-scale carbon dioxide removal (CDR). Often, only a few technology options are used, principally bioenergy, carbon capture and sequestration, as well as afforestation and reforestation. If climate change mitigation is based on energy crops, the impact of CDR on area demand may be significant. The CDR-specific area demand is usually not presented. This study compares a CDR technology portfolio prioritising biomass-based solutions to portfolios prioritising low cost, low energy demand, high security, low area demand, and high technology readiness in terms of area demand. The CDR portfolio model is linked with an energy system model to include the area required for solar photovoltaics and wind power for the energy supply of the whole energy–industry–CDR system. A quantitative and qualitative comparison is made using the definitions of gross and net area demand, and the differentiation of CDR routes into biogenic, bio-technical, and technical options. Gross and net area demand differentiate the total area, including spacing or gathering areas (gross) and built-up areas (or areas unsuitable for biodiversity) (net). We consider total CDR demands of 500 GtCO 2 for a 1.5°C climate target and 1750 GtCO 2 for a 1.0°C climate target by 2100. The results indicate the advantage of technical CDR options regarding area demand compared to biomass-based CDR from energy crops. Including the energy supply for the whole energy–industry–CDR system does not lead to significant area demand. The net area demand can be kept at ca. 1.0% (1.5°C) and below 1.4% (1.0°C) of the total land area, except for the biomass-prioritising portfolio, which has a 3% net land area demand for both climate targets. Biogenic and biotechnical CDR options are estimated to require up to 9.7% of today’s global cropland by the end of the century (net area). The additional net area demand for the 1.0°C target versus the 1.5°C target is comparably small.