Optimization Analysis of Regional Energy Chains by 100% Renewable Energy

This study proposes an optimal design for a 100% renewable, off-grid electrical system for Namie Town, Fukushima, a region promoting local energy independence after the 2011 disaster. The town has rich solar, wind, and biomass potential and hydrogen infrastructure, but a quantitative analysis of an isolated system integrating these four elements—renewables, biomass power, hydrogen storage, and an off-grid configuration—has not been fully conducted. We developed an energy optimization model using linear programming with 8760-hour time-series data to minimize the total annual cost. The model compares a photovoltaic (PV) and wind system (PW case) with a system that also includes biomass (PWB case). Results show that adding biomass reduces the electricity cost by 2.20JPY/kWh (from 19.08 to 16.88JPY/kWh) by lowering the required capacity of PV, batteries, and hydrogen storage. The energy curtailment rate dropped from 19.2% to 8.7%, and overall system efficiency improved from 63.3% to 77.1%. This indicates biomass can function as a key dispatchable power source, improving stability and cost-effectiveness for an isolated renewable electrical system.