This is a case study of Wang-An Island's energy demands and potential renewable energy sources (RESs). Optimal integration of RESs was simulated using the EnergyPLAN model. The RES evaluation indicated an annual production potential of 458.1 GWh, which substantially surpassed local energy requirements of 22.3 GWh. The potential of yearly electricity generation from RESs of 299.7 GWh apparently outnumbers local electricity demand of 6.4 GWh as well, indicating that 100% renewable electricity would be achievable if surplus electricity can be stored and then reused during an electricity deficit. Electricity production from fully exploited RESs is able to supply only 5.8 GWh of electricity mainly caused by mismatches in times of electricity demand and production. The integrated optimization can supply 3.7 GWh of electricity. A deficit of 2.68 GWh can be compensated for through electricity storage or biomass energy. Although the total amount of generated renewable electricity during the whole year cannot yet satisfy the total amount of yearly demand, electricity storage can help to satisfy most of the electricity needs for the year. © 2015 Elsevier Ltd. All rights reserved.