In alignment with the European Union’s "Fit for 55" package and the Spanish National Energy and Climate Plan (NECP), the Spanish power sector is undergoing a decarbonisation process. While existing research has extensively characterised the transition through specific metrics, a holistic understanding of the environmental trade-offs remains limited. Shifting toward renewable-heavy systems often mitigates climate impacts but may inadvertently increase other environmental burdens. This study aims to provide a comprehensive environmental profile of the seven key technologies in the Spanish electricity mix by applying the European Commission’s Environmental Footprint (EF 3.1) methodology.
To this end, a "cradle-to-grave" Life Cycle Assessment (LCA) was conducted for (onshore) wind power, hydropower (reservoir), solar thermal (CSP), solar photovoltaic (PV), hard coal plants, combined cycle gas turbine (CCGT), and nuclear power. To carry out the simulations, the study used the SimaPro software with the Ecoinvent v3.10 database, adapting some of the processes with data from the current Spanish context. This research evaluates all 16 impact categories defined by the EF 3.1 framework, including acidification, freshwater ecotoxicity, eutrophication (marine, freshwater and terrestrial), human toxicity (cancer and non-cancer), ionising radiation, land use, ozone depletion, or mineral and metal resource use. The functional unit is defined as 1 kWh of electricity produced at the plant busbar.
Results reveal significant hidden trade-offs. While wind and nuclear power consistently show the lowest scores in Climate Change overall category (0.0124 and 0.00636 kg CO₂ eq/kWh, respectively), they exhibit distinct pressures in other areas. Nuclear power represents the main contributor to Ionising Radiation (0.72 kBq U-235 eq/kWh) and Fossil Resource Use (13.2 MJ/kW) due to uranium mining. Conversely, coal power remains the most damaging technology across most categories, notably in Acidification (0.0137 mol H+ eq/kWh), Particulate Matter (1.57E-8 disease inc./kWh), and Marine Eutrophication (0.0018 kg N eq/kWh).
The analysis highlights that Photovoltaic (PV) technology, while carbon-efficient, presents a high intensity in Resource Use of Minerals and Metals (2.26E-7 kg Sb eq/kWh) and Land Use (6 Pt), primarily driven by the manufacturing stage of multi-Si panels and mounting structures. Solar thermal energy shows a non-negligible impact in Freshwater Ecotoxicity (0.677 CTUe) due to the use of synthetic oils and nitric acid in nitrate salts used for storage. Hydropower exhibits the highest impact in the Water Use category (2.27 m³ depriv./kWh), reaffirming its critical role in water-stressed regions like Spain. Additionally, Combined Cycle (CCGT) technology, reveals a significant drawback in Ozone Depletion (5.14E-8 kg CFC11 eq/kWh), the highest among all technologies evaluated, primarily due to upstream supply chain emissions.
The study demonstrates that a decarbonisation strategy based solely on GWP reduction provides an incomplete picture of environmental sustainability. The transition to a renewable-based mix in Spain involves shifting burdens from emissions to resource consumption and localised toxicity. By identifying these "burden-shifting" processes, this research provides insights for policymakers to refine the NECP 2030-2050 objectives. It is concluded that integrating the Environmental Footprint framework into national energy planning is vital to ensure that climate neutrality does not come at the cost of mineral exhaustion or increased toxicity to humans.
