The Barriers to 100% Renewable Isolated Minigrids: Why Combustion Generators Still Dominate?
Abstract
Isolated minigrids in the Brazilian Amazon, which currently rely heavily on diesel generation, face significant challenges related to fuel logistics, environmental impact, and cost volatility. This study explores the potential of hybrid renewable energy systems (HRES), combining photovoltaic generation (PV), battery storage (BESS), and diesel gensets, to support the region’s energy transition. Using real load and meteorological data from three contrasting communities (Fernando de Noronha, Tefé, and Iauretê), we simulate various renewable fraction (RF) scenarios, from 90% to 100%, using HOMER Pro®. Results reveal that while achieving a 90% RF is technically feasible with moderate increases in photovoltaic and battery storage capacity, the push toward 100% RF requires exponentially greater infrastructure, averaging an 83% increase in PV and a 237% increase in storage. This \"last-mile\" effect is consistent across all sites regardless of community size or solar resource, highlighting BESS as the primary technical and economic constraint. Additionally, per capita energy infrastructure requirements escalate sharply at higher RF targets, posing challenges for scalability and environmental licensing. The findings suggest that while minigrids with high shares of renewables are a promising solution for decarbonization and improving energy access, full autonomy from diesel remains economically prohibitive under current conditions. A phased energy transition strategy aiming for 80–90% RF, combined with complementary technologies such as biofuels or long-duration storage, is recommended. These insights can guide infrastructure planning, investment, and policy decisions for sustainable minigrid deployment in remote and environmentally sensitive regions.
Keywords
Minigrid, Photovoltaic Generation, Battey Storage, Energy Transition