Geospatial cost comparison of thermal energy technologies: a sorbent-based direct air capture case study

Introduction Decarbonizing energy production is essential for achieving greenhouse gas mitigation goals. To date, most of the work on decarbonizing energy has been focused on electricity. The decarbonization of heat is also critical, as the heat demand from current industries is expected to grow and be supplemented by demand in emerging sectors (e. g. carbon dioxide removal). Despite this need, heat decarbonization has received little attention compared to electricity. Methods In this study, we use detailed process models for heat generated from sedimentary basin geothermal, concentrated solar, and a heat pump to generate geospatial results across the US, and explore the key parameters that make each energy source preferred. We use sorbent-based direct air capture (DAC) as a case study heat application and examine both the levelized cost of heat (LCOH), and the levelized cost of carbon removal (LCOR). Results and Discussion Our results indicate that each of these thermal energy sources is sometimes preferred, depending on the location and the metric used. We find that geothermal heat has the lowest LCOH and LCOR when the geothermal resource has sufficient depth, temperature, and transmissivity (as low 16/MWh compared to a minimum of 31/MWh for concentrated solar or 39/MWh for a heat pump). When that is not the case, concentrated solar is often preferred over a heat pump (median LCOH of 47/MWh for concentrated solar vs 58/MWh for a heat pump) because electricity in the US is typically too carbon-intensive (increasing LCOR) and expensive (increasing LCOH and LCOR). Overall, our results show that it is essential to choose the appropriate metric and consider geospatial factors when studying decarbonized heat.