Solar cells combined with geothermal or wind power systems reduces climate and environmental impact

Global evidence on climate change and rising greenhouse gas emissions underscores the need to decarbonize energy supply, including heating and cooling. Electricity and heat production contributed about 25% of global GHG emissions in 2010 and around 34% by 2019, highlighting the sector’s growing impact. Sustainability assessments must consider multiple pollutants beyond GHGs, including toxicity, ecotoxicity, and ozone depletion. In this context, integrating multiple renewable resources into unified power plants can improve reliability, efficiency, land use, and energy security. This study examines environmental impacts of three integrated renewable-based power plants combining geothermal, solar, and wind resources, with a focus on the rapidly advancing perovskite solar cell (PSC) technology. The research question is how combining renewable technologies—particularly incorporating PSCs—affects lifecycle environmental impacts, and how improvements in PSC efficiency and lifetime change these outcomes. The purpose is to inform optimal technology integration strategies for sustainable power generation.

Prior studies have conducted thermodynamic and economic analyses of standalone geothermal, solar, and wind power plants and LCAs of these individual technologies, including CSP, PV, PSCs, and wind. Some research examined technical integration of geothermal with solar or wind, and LCAs for standalone systems, but few studies have evaluated the environmental sustainability of combined renewable power cycles. The literature notes PSCs’ rapid efficiency gains but concerns about stability, lifetime, and materials (e.g., lead). This study fills a gap by applying LCA to systems integrating two renewable sources, including PSCs, to assess trade-offs and synergies that previous work on single technologies or renewable–fossil hybrids has not covered.

The study employs a comparative Life Cycle Assessment (LCA) using OpenLCA and the ReCiPe 2016 (H) midpoint method. Goal and scope: assess environmental impacts of three integrated renewable power plants—combined geothermal–wind (CGW, Case I), combined solar–geothermal (CSG, Case II), and combined solar–wind (CSW, Case III). System boundary: cradle-to-gate for all combined systems, aggregating raw material extraction with manufacturing. Functional unit: 1 kWh of net generated electricity. Lifetimes: geothermal 30 years, wind 25 years, PSC 3 years (base), with scenarios up to 15 years for PSC. Transportation and end-of-life phases are excluded due to data limitations. Technologies and capacities: geothermal binary plant (5 MW, average European case data), Vestas 3 MW onshore wind turbine, PSC unit 0.42 kW (reflecting modular, space-constrained applications). To avoid over-attributing impacts to PSC due to capacity differences, an allocation method based on power generation capacity is applied. Data inventory: compiled from literature and ecoinvent v3.9; inventories provided in Supplementary Data 1–3. Impact categories: full ReCiPe set computed; four dominant midpoints are analysed and reported in detail—Climate Change (CC), Freshwater Ecotoxicity (FE), Ozone Depletion (OD), Marine Ecotoxicity (ME). Scenarios: 17 total. Base: B1 (CGW), B2 (CSG, PSC 3 years, 17% efficiency), B3 (CSW, PSC 3 years, 17% efficiency). Lifetime-improvement scenarios (L1–L6) assume PSC life extension from 3 to 15 years. Efficiency-improvement scenarios (E1–E8) assume PSC efficiency increase from 17% to 35%. Sensitivity analysis: scenario analysis varying PSC lifetime and efficiency to assess robustness and influence of key parameters. Scoring approach: ranks environmental performance across cases and scenarios per impact category; higher scores indicate lower impact. Limitations acknowledged include data maturity gaps (especially PSCs), exclusion of end-of-life and transport, and uncertainties in large-scale PSC manufacturing and materials (e.g., lead).

• Among base scenarios, B3 (CSW) has the lowest Climate Change (CC) and Ozone Depletion (OD) impacts, while B1 (CGW) has the lowest Freshwater Ecotoxicity (FE) and Marine Ecotoxicity (ME) impacts. • Extending PSC lifetime from 3 to 15 years reduces GHG emissions by 28% for CSG and 56% for CSW; in CSW, a 7-year increase yields ~49% CC reduction. Across FE, OD, and ME, longer PSC lifetimes consistently reduce impacts; at 15 years, CSG FE becomes lower than CGW. • Increasing PSC efficiency from 17% to 35% reduces CC by 18% (CSG) and 37% (CSW). Lifetime improvement has a larger impact reduction than efficiency gains across categories. • CC contribution analysis (base cases):

• CGW (B1): O&M (geothermal) ~46% of CC; well drilling and wind construction also significant (steel, copper, concrete).
• CSG (B2): O&M 36%, geothermal well drilling 28%, PSC M&I 22%; aluminium and steel in M&I notable.
• CSW (B3): PSC manufacturing and wind construction each ~27% of CC; PSC encapsulation adhesives and ITO glass contribute; wind tower, foundation, nacelle are key construction drivers; wind O&M relatively small. • FE contribution analysis (base cases):
• CGW (B1): wind construction 42% (copper in generator/nacelle frame; steel in tower), geothermal well drilling 35% (steel, activated bentonite), wind O&M also notable.
• CSG (B2): PSC M&I ~50% (aluminium), PSC manufacturing ~36% (hole-transport layer deposition using chlorobenzene), geothermal well drilling ~13%; geothermal construction and O&M <1%.
• CSW (B3): PSC M&I 44% (aluminium, steel), PSC manufacturing 36% (chlorobenzene), wind construction next largest. • Scoring across scenarios:
• CC/OD: L6 is most sustainable; B2 is most pollutant.
• FE: L5 (CSG with PSC life 15 years) least pollutant; B1 (CGW) scores 8; B3 is most pollutant in FE.
• ME: CSG cases (L1, L3, L5) have lower ME than CSW; B1 scores 8 with low ME; other cases score lower due to higher impacts. • Overall, CSW exhibits the lowest CC among configurations; PSC lifetime improvements deliver the most significant environmental benefits; PSC-related stages (M&I and manufacturing) dominate toxicity-related impacts, especially FE, due to materials like aluminium and solvents (chlorobenzene).

The study demonstrates that integrating renewable sources can lower lifecycle environmental impacts compared to relying on single technologies, and that configuration choice matters: CSW minimizes CC and OD, while CGW performs best in FE and ME among base cases. Including PSCs in integrated systems can be environmentally favorable provided that lifetime and efficiency improve; lifetime extension exerts a stronger influence than efficiency gains. These findings support the research aim by showing how technology combinations and PSC advancements change impact profiles and identifying environmental hotspots (PSC M&I, PSC manufacturing solvents, wind construction materials, geothermal drilling) where improvements can yield large benefits. Practical challenges remain: intermittency of solar and wind, grid stability, storage needs, siting and transmission, and supply chain dependencies on critical materials for PSCs, wind turbines, and geothermal equipment. Addressing these through technological innovation, material substitution, circularity, and robust policy frameworks can help realize the environmental advantages of combined renewables. The scoring framework further clarifies trade-offs, highlighting scenarios (e.g., L6, L5) that balance impacts across categories and providing a decision aid for stakeholders.

Integrating renewable energy technologies—geothermal, solar, and wind—into combined power plants can reduce environmental impacts and enhance energy security and resilience. The combined solar–wind configuration yields the lowest carbon and ozone depletion footprints among base cases, while combined geothermal–wind performs best in freshwater and marine ecotoxicity. Key to maximizing sustainability is improving PSC lifetime (more impactful than efficiency gains), which substantially reduces impacts in integrated systems and enhances PSC competitiveness versus conventional solar. The study’s LCA and scoring identify environmental hotspots and promising scenarios for deployment. Future work should expand datasets for PSCs at scale, develop standardized end-of-life and recycling pathways (including safe lead handling), and explore broader social and regulatory factors to enable optimal technology integration. Advancements in technology, supply chains, and policy can support a transition to cleaner, more reliable, and sustainable power systems using exclusively renewable resources.

Data maturity differs markedly between established (geothermal, wind) and emerging (PSC) technologies, introducing uncertainty in inventories and impact results—especially for large-scale PSC production, durability, and end-of-life, including lead management. Transportation and end-of-life phases are excluded due to insufficient data. Allocation and modeling assumptions (e.g., capacity-based allocation, cradle-to-gate boundary) may affect comparability. Intermittency, supply chain constraints, and geographic variability also influence generalizability. While scenario analysis addresses sensitivity to PSC lifetime and efficiency, broader uncertainty quantification is limited.