The challenge of providing electricity supply to the nearly 750 million people worldwide who still lack it requires solutions that do not compromise global climate objectives. Although hybrid renewable energy systems are put forward as the ideal alternative to fossil fuels, their life-cycle-associated emissions —material extraction, manufacturing and construction— tend to be overlooked at the planning stages.
To address this technical gap, a new international study led by researchers from the Chair of Urban Energy Transition (CATENERG) at UPV, in collaboration with Delft University of Technology, proposes a pioneering methodological framework. This model applies an ex-ante life-cycle assessment to evaluate and mitigate environmental impacts from the earliest stages of project design.
📘 «Decarbonising hybrid renewable energy systems for electricity access from the project»
👥 Authors: Lucas Martínez-Rodríguez, Tomás Gómez-Navarro, Ivan Ligardo-Herrera, David Ribó-Pérez.
📍 Journal: Sustainable Energy Technologies and Assessments (SETA).
🔗 DOI: https://doi.org/10.1016/j.seta.2026.104954
X-raying emissions: the hidden weight of manufacturing and concrete
The methodological framework has been practically validated in a pilot project for the isolated rural community of El Santuario (Honduras). The reference system, designed to reliably supply around 500 inhabitants for 20 years, combines 57 kWp of photovoltaic panels, a 50 kW inverter, a 30 kW biomass gasifier as backup and 175 kWh of battery storage, in addition to a local distribution network.
The baseline case analysis determined total life-cycle emissions of 256,443 kg of CO2 equivalent (256.4 tonnes), yielding an emission factor of 0.18 kgCO2e/kWh. When breaking down the data, the study reveals that impacts are not evenly distributed, but are critically concentrated at very specific points:
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Manufacturing dominance (66%): Component production accounts for the bulk of the impact, led notably by the manufacturing of photovoltaic panels, which represents 64% of the emissions in this phase.
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The impact of civil works (21%): The assembly and installation phase constitutes the second major source of emissions, due almost entirely to the use of concrete for site preparation and paving, which accounts for 77% of the assembly impacts.
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Underestimated gases: The study warns that assessments accounting only for direct CO2 underestimate the real impact by 15%, since gases such as methane (CH4) and nitrous oxide (N2O) represent a very significant fraction of the total gas inventory.
12 Strategies to cut environmental impact by 31%
The main advantage of integrating life-cycle assessment into the planning phase is the ability to apply corrective measures before investments are made. The research team designed and quantitatively evaluated a catalogue of 12 strategies aimed at avoiding, reducing and replacing high-carbon-intensity materials:
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Foundation optimisation: Replacing the full paving of the plot with concrete poured only at the support points of the fixed structures, drastically reducing cement use (representing a 11% reduction in the project’s total emissions).
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Use of existing rooftops: Installing part of the photovoltaic capacity (14 kWp) on the roof of the system’s control shed, avoiding additional ground foundations (-4%).
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High-efficiency photovoltaic modules: Upgrading the design to panels with 23% efficiency, which reduces the total collection area required and the volume of the support structure needed (-3%).
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Logistics and local travel: Optimising the travel schedule of international specialist staff and prioritising the hiring of local technicians for civil and electrical works (-4%).
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Replacement of network materials: Using local timber poles instead of concrete for the secondary distribution network, and replacing copper conductors with aluminium on the main lines (-2%).
The combined application of these measures reduces the project’s overall inventory to 177 tonnes of CO2 equivalent, achieving an optimised emission factor of 0.12 kgCO2e/kWh.
Comparative analysis against other energy alternatives
The study compares the optimised HRES against conventional electrification methods in remote areas, demonstrating its clear environmental superiority:
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Compared to a standalone diesel generator: Pure fossil-fuel combustion systems reach emission factors of 1.14 kgCO2e/kWh. The proposed model reduces this impact almost tenfold.
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Compared to conventional grid extension: Connecting the community to Honduras’s national electricity grid (whose average emission factor sits between 0.35 and 0.61 kgCO2e/kWh) generates a much higher net impact once the construction footprint of the 12 kilometres of high-voltage line required and the transmission losses are added.
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Compared to an HRES with fossil-fuel backup: Replacing the biomass gasifier with a diesel generator to cover the same 10% backup would increase the project’s total inventory by 257 tonnes of CO2 equivalent.
A strategic tool for real-world decision-making
For international development professionals, technology companies and public planners, the conclusions of the study backed by the Chair are clear: the sustainability of clean infrastructure cannot be assumed by default — it must be designed.
This methodological framework provides a replicable tool for selecting suppliers with decarbonised value chains, replacing high-impact materials in local networks and correcting civil works designs in time. Incorporating life-cycle indicators at the early design stage is the most effective way to avoid unnecessary environmental impacts and ensure that rural electrification rigorously meets the criteria of a just energy transition.
