Impact of Agricultural Waste Characterization in Biomass: Solar PV Hybrid Mini-grid Performance

There are presently 600 million of people in Africa without access to electricity. The electrification rates of most African countries are below 20%. The lack of access to electricity is a major drawback for the continent especially in rural areas of sub-Saharan Africa (SSA) where there is an untapped economic potential. Most rural areas have promising agrobusinesses that could generate a profit of one trillion dollars by 2030 if cost-effective energy facilities are implemented. For this reason, hybrid mini-grids using renewable energy (RE) sources such as solar photovoltaic (PV) and biomass technologies such as anaerobic digestion (AD) are recommended as the solutionist approach to eradicate the energy poverty in off-grid communities with high agricultural potential. From this perspective, this study sought to briefly review the functionality of a biomass and solar photovoltaic hybrid mini-grid (BSPVHM) coupled with diesel generators and a battery energy storage system (BESS) used as back-up. To predict the performance of the biogas power unit in a BSPVHM, waste characterization and biomethane potential (BMP) tests were conducted with four types of agricultural wastes: cow dung, poultry droppings, grass, and vegetables. Through X-ray fluorescence (XRF), the toxicity level of inhibitory elements in substrates was assessed and found to be within an acceptable range. Three BMP test sets were run for each co-digestion process under mesophilic conditions at 37 °C with (1) grass and cow dung, (2) food waste (fruits and vegetables) and cow dung, and (3) chicken droppings and cow dung. For each set, the highest volume of biomethane was considered and particularly assessed. The first set produced a biomethane volume of 1378.8 ml; meanwhile, the second and the third only produced 965 ml and 495 ml, respectively. This study aimed at establishing the correlation between substrates’ composition with biomethane yield and power contribution of the biogas power unit and the overall performance of the BSPVHM.