Constraints to Energy Transition in Metropolitan Areas: Solar Potential, Land Use, and Mineral Consumption in the Metropolitan Area of Madrid

Amidst the backdrop of the fossil fuel energy crisis, the development of renewable energy sources is experiencing an unprecedented acceleration in Spain and focusing in metropolitan areas. This study investigates the potential for photovoltaic energy development in Spanish metropolitan areas, specifically Madrid and its surrounding region. Recognizing the inherent challenges of land use and material scarcity associated with this development, the research aims to quantify the maximum achievable photovoltaic capacity for the region, along with the corresponding land occupation and material consumption requirements. A Material Flow Analysis (MFA) methodology is employed to project these parameters to 2050. The analysis estimates a potential production capacity of 32,163 GWh/year, representing 76.81% of the projected electricity consumption in 2050 (and 39.94% of final energy consumption). This capacity would necessitate the utilization of 32,169 hectares of land (4.01% of the regional area), including 7,139 hectares of rooftop space. Critically, 48% of the suitable land is classified as agricultural land, highlighting potential land-use competition. Furthermore, the study extrapolates the material requirements to a global scale, estimating the percentage of global mineral reserves required for a comparable energy transition. The analysis yields an estimate of 0.75% for aluminum, 17.69% for copper, and 34.89% for silver. These findings provide crucial insights into the material and geographical constraints impacting the feasibility of urban energy transitions.