Design of Eco - Friendly Hybrid Electricity Options for Centeral Rift Valley Climatie Condtions, Ethiopia
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Date
2024-10
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Addis Ababa University
Abstract
Energy poverty in Sub-Saharan Africa necessitates innovative and sustainable solutions. This dissertation addresses this challenge by investigating low-carbon hybrid microgrid systems (MiGs) for electrifying a typical 250-household remote community in the Ethiopian Central Rift Valley (E.C.R.V.). The study focuses on integrating renewable energy sources (wind, solar, floating photovoltaics - FPV) with diverse storage technologies (lithium-ion batteries, pumped hydro storage - PHS). To assess the region's renewable energy potential, wind speeds were measured at various heights throughout a year and analyzed alongside solar radiation data from existing databases (PVGIS 5.2, NASA Power). This comprehensive evaluation revealed significant potential for both wind and solar energy generation, informing the design of sustainable MiGs. Additionally, the potential for pumped hydro storage (PHS) was assessed using LiDAR-based digital elevation models (DEM) with a resolution of 12.5 meters, identifying Tedecha Island, with its unique volcanic crater pond, as a prime location for a small-scale PHS system. Leveraging this natural feature, a novel MiG design incorporating the Energy-Water-Food Nexus (E-W-F-N) was proposed, aiming to optimize excess energy for water management and agricultural productivity.
Extensive simulations and optimization using HOMER Pro, PVsyst, and MATLAB identified optimal hybrid systems tailored to the specific needs of mainland and island communities. For the mainland, a 35.8 KW solar PV system, 20.4 KW wind turbines, and 72 KWh lithium-ion batteries proved the most cost-effective, with a levelized cost of electricity (LCOE) of $0.190/KWh. For the island community, the lowest-cost option was a 41 KW solar PV coupled with a 254 KWh PHS system (LCOE: $0.061/KWh), highlighting the potential for locally available resources to reduce costs. An alternative 32.2 KWp (FPV-PHS) configuration was also identified, showcasing a 7% higher energy yield and significant water savings (2.19 m3/m2/year) compared to land-mounted PV, at a reasonable LCOE of $0.140/KWh. Sensitivity analysis of the land-based PV-PHS system revealed its robustness under varying conditions, achieving an LCOE of $0.0882/KWh while maintaining 75% of PHS capacity, thereby yielding a surplus of 750 m3 of water annually for EW-F-N applications. This demonstrates the system's potential to simultaneously address energy and water scarcity challenges. Furthermore, this dissertation addresses critical gaps in the literature by proposing a novel microgrid design paradigm that incorporates the Energy-Water-Food Nexus (E-W-F-N) and developing a comprehensive methodological framework for designing and evaluating FPV-based systems, particularly small-scale (20-50 KWp) configurations. This research confirms the technical and economic feasibility of hybrid MiGs within the Ethiopian context, offering a pathway to expand electricity access and foster sustainable development in the E.C.R.V. and similar regions. The study's focus on small-scale FPV-PHS systems and E-W-F-N integration provides valuable insights for the widespread adoption of sustainable energy solutions in underserved communities. Future research directions include exploring the integration of bioenergy, assessing the long-term performance of mainland systems, conducting a detailed geological assessment for the PHS reservoir, and investigating the use of locally-sourced materials
for FPV platforms to further enhance sustainability and cost-effectiveness.
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Keywords
Ethiopia, Central Rift Valley, Hybrid Microgrid, Renewable Energy, Energy Storage, Pumped Hydro Storage, Floating Pv, Energy-Water-Food Nexus, Off-Grid Electrification