Simulation and Optimization of a Hybrid Renewable Energy System for application on a Cuban farm

Abstract: This paper presents an analysis of the feasibility of utilizing a hybrid renewable energy system to supply the energy demand of a milk and meat farm in Cuba. The study performs simulation and optimization to obtain a system design of a hybrid renewable energy system for application on the farm Desembarco del Granma in the Villa Clara province in the central part of Cuba, for three different cases of biomass availability. The energy resources considered are solar PV, biogas, and wind. A field study is carried out to evaluate the energy load and the biomass resource available for biogas production of the farm Desembarco del Granma, and the feasibility of biogas electrification is evaluated for the three different scenarios of biomass availability. The field study methodology includes semi structured interviews and participant observation for information collection. The farm Desembrero del Granma is estimated to have a scaled annual average electrical load of 264 kWh/day with peak load 26.34 kW, while the scaled annual average deferrable load of the farm was estimated to be 76 kWh/day with a peak load 16 kW. The thermal load was find to consist primarily of energy for water heating and cooking. The thermal demand for cooking was estimate to be 4.5 kWh per day, while the thermal load for water heating was not estimated. The thermal energy need for water heating is assumed to be provided for by solar thermal energy, and is not included in the energy system models of this study. For the modeling, the thermal demand for cooking is assumed to be provided by combustion of biogas. System simulation and optimization in regard to energy efficiency, economic viability and environmental impact is carried out by applying the Hybrid Optimization Model for Electric Renewables (HOMER) simulation and optimization software tool. For two of the biomass scenarios, the optimized energy systems received in HOMER were identical; hence only two biomass scenarios were analyzed. The first one represents the current biomass collected and the biogas production capacity of the farm (including the one not yet utilized), and the second one represents the amount of biomass available if the animals would be gathered in the same place all of the time. A PV-wind hybrid energy system with 100 kW PV installed capacity, 30 kW wind power installed capacity consisting of 10 wind turbines of the size 3 kW, a battery bank of 100 batteries (83.4 Ah/24 V), and a 100 kW inverter is considered the most feasible solution for the current biomass scenario. For the increased biomass scenario, a PV-biogas hybrid energy system configuration of 5 kW PV installed capacity, a 60 kW biogas generator, and an inverter of the size 10 kW is considered the most feasible option. Biogas electrification is shown to not be economically feasible for the current biomass scenario during the conditions modeled in this study, but for the increased biomass scenario biogas electrification was shown to be a feasible option. If the farm would build more biodigestors, biogas electrification could thereby be effective from a financial point of view.