Transition to a low-carbon building stock. Techno-economic and spatial optimization of renewables-hydrogen strategies in Spain

Europe has set ambitious targets to reduce the final energy consumption of buildings in concerning the degree of electrification, energy efficiency, and penetration of renewable energy sources (RES). So far, hydrogen is becoming an increasingly important energy vector, offering huge opportunities to promote the share of inter-mittent RES. Thus, this manuscript proposes an energy model for the complete decarbonization of the estimated electricity consumed by the Spanish building stock in 2030 and 2050 scenarios; the model is based on the combination of photovoltaic and wind primary sources and hydrogen technologies considering both distributed and centralized configurations, applying also geospatial criteria for their optimal allocation. Large-scale RES generation, centralized hydrogen production, and re-electrification, along with underground hydrogen storage, result in the lowest levelized cost of energy (LCOE), hydrogen production costs (HPC), and the highest overall efficiency (mu SYS). Wind energy is mainly harvested in the north of Spain, while large PV farms are deployed in the mid-south. Furthermore, reinforcement of underground hydrogen storage enhances the overall system perfor-mance, reducing surplus energy and the required RES generation capacity. Finally, all the considered scenarios achieve LCOE below the Spanish utility grid benchmark, apart from accomplishing the decarbonization goals established for the year 2030.