Contribution in technical problem-solving using Life Cycle Analysis and Multi-criteria Decision-Making Models : applications to the energy sector

Σαγάνη, Αγγελική; Sagani, Angeliki

Συμβολή στην ανάπτυξη τεχνικών λύσεων χρησιμοποιώντας Ανάλυση Κύκλου Ζωής και Πολυκριτηριακά Μοντέλα Λήψης Αποφάσεων : εφαρμογές στον ενεργειακό τομέα

Doctoral Thesis

Author

Σαγάνη, Αγγελική

Sagani, Angeliki

Date

2025-12

Abstract

The transition towards low-carbon and cost-effective energy systems is a strategic priority of Greece, a country endowed with abundant renewable energy potential. Solar energy conversion units and wind power systems constitute key pillars for the decarbonization of the electricity sector under a circular economy framework. Despite their potential, significant knowledge gaps and practical limitations remain. Most of life cycle environmental performance evaluation studies focus primarily on the operational phase of renewable energy technologies, often neglecting Greenhouse Gas (GHG) emissions and non-renewable energy use associated with the stages of manufacturing, transportation, installation, and end-of-life management. Region-specific data are scarce, emerging technologies, including third-generation solar Photovoltaics (PVs), offshore wind turbines, and hybrid systems, have been poorly evaluated, and recycling and reuse infrastructures remain insufficient. The absence of comprehensive policy frameworks further constrains the implementation of circular economy principles, alongside the widespread deployment of renewable energy technologies. The current Ph.D. dissertation addresses these shortcomings by developing a holistic, multi -dimensional methodological framework for the assessment and optimization of both conventional and renewable energy systems. The framework developed integrates energy system design and modelling, economic analysis, Life Cycle Assessment (LCA), and Multi-Criteria Decision Making (MCDM). The energy modelling component captures system configurations and technology interactions, as well as operational behaviour under realistic meteorological data and grid constraints, encompassing load-following dispatch strategies. The economic analysis evaluates the economic viability of systems, employing key performance indicators, such as the Levelized Cost of Energy (LCOE), Net Present Value (NPV), Internal Rate of Return (IRR), and Cost-Benefit Ratio (CBR). From an environmental perspective, the LCA assesses the adverse impacts across all life cycle stages, i.e., from manufacturing and operation to end-of-life treatment, quantifying climate change impact, fossil and nuclear energy use, resource consumption, and other environmental pressures. Finally, the MCDM approach evaluates competing objectives and stakeholder priorities, aiming at supporting sustainable decision-making regarding technology selection, system configurations, and end-of-life strategies. This integrated framework constitutes a flexible, scalable, and future-ready tool, able to facility both project-level analysis and long-term strategic energy planning. Application of the framework at multiple scales yielded important insights. At the building level, grid-connected solar PV systems with capacities of 5-10 kWp were found to be economically viable, and achieved significant life cycle reductions in GHG emissions and non-renewable energy use. However, systems below 5 kWp were cost-ineffective, due to high upfront costs and low electricity prices, highlighting the need for cost reductions in module manufacturing and balance-of-system components, alongside supportive policies such as investment incentives, feed-in tariffs, and credit trading mechanisms. Fully autonomous hybrid systems, integrating solar PV arrays, energy (battery) storage, diesel generators, and biomass-based heating, were identified as the most suitable solutions for decentralized energy supply in remote households, offering both technical reliability and improved sustainability. Sensitivity analysis emphasized the influence of load management and fuel prices on economic feasibility, underscoring the importance of both operational optimization and policy support. At the community level, hybrid electricity supply systems combining wind, solar, battery storage, and diesel generators provide robust, cost-effective, and sustainable solutions for isolated Aegean Islands. In Lesvos, Karpathos, and Astypalaia, renewable generation supplies over 90% of electricity, with diesel generator as a backup, while batteries align fluctuating generation with demand and stabilize the grid. A significant surplus of electricity, exceeding 40% in all three Islands, highlights the opportunities for additional storage or flexible use. From an economic perspective, these hybrid systems achieve competitive LCOE (0.12–0.15 €/kWh) compared to the current diesel-based systems on the islands, despite higher up-front investments. From an economic point of view, the substitution of diesel generators can decrease GHG emissions by over 92%, to below 71 gCO₂eq/kWh, providing a circular economy-driven solution towards the deep decarbonization of non-interconnected islands. At the grid scale, thermal power plants remain the major contributor to environmental impacts, especially in terms of global warming potential and non-renewable energy use. In contrast, large hydro and renewable energies, including wind, solar, small hydro, and biomass systems, provide a modest but significant mitigation potential. Future scenarios with higher renewable energy penetration suggest substantial reductions in climate change impact, emphasizing the importance of systemic planning and life cycle-informed strategies for decarbonization. Transmission infrastructure, including lines and substations, as well as grid power losses, also represent a notable share of life cycle environmental impacts; however, their contribution is small compared to the adverse impacts from the electricity generation sector. Critically, achieving sustainable energy transitions requires attention to the end-of-life phase of renewable technologies. The disposal, recycling, or repurposing of components, such as wind turbine blades, significantly affects both environmental and economic performance. Combined LCA and MCDM analyses demonstrated that mechanical recycling of wind turbine concrete foundations and repurposing of composite materials were the most effective end-of-life strategies, reducing global warming potential, non-renewable energy use, land occupation, and waste costs. Energy-intensive chemical or thermal recycling, particularly when involving long-distance transport, proved less efficient. Integrating remanufacturing, and design-for-recycling, along with waste prevention strategies, support a circular economy, while financial incentives can further enhance adoption of renewable technologies. In summary, the achievement of sustainable energy transitions requires more than just deploying renewable energy technologies; it strongly depends on the combination of technological optimization, circular economy integration, storage management, policy incentives, and life cycle-informed decision-making. This Ph.D. thesis specifically contributes by assessing and optimizing across multiple scales, providing valuable insights for cost-effective, reliable, and sustainable decarbonization from buildings and communities to island microgrids and national grids.

Department

Σχολή Ναυτιλίας και Βιομηχανίας. Tμήμα Βιομηχανικής Διοίκησης και Tεχνολογίας

Number of pages

209

Language

English

URI

https://dione.lib.unipi.gr/xmlui/handle/unipi/19132

Collections

Τμήμα Βιομηχανικής Διοίκησης και Τεχνολογίας

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Αναφορά Δημιουργού-Μη Εμπορική Χρήση-Όχι Παράγωγα Έργα 3.0 Ελλάδα