The study investigates alternative energy scenarios for Bozcaada island, Turkey. The island has good wind and solar energy potentials while connecting to the grid. So, it is considered a grid connected and standalone system in the study. The system consists of a photovoltaic (PV) array, a wind turbine, an electrolyzer, hydrogen storage, a fuel cell (FC) and a converter as the main equipment. Six scenarios, grid, grid/wind, grid/PV, grid/wind/PV, wind/FC, and wind/PV/FC, are simulated using the hybrid optimization model for electric renewables (HOMER) tool to define the optimum systems. The HOMER examines the systems according to their net present costs (NPC) and cost of energy (COE). The results show that the most suitable grid connected system is the grid/wind as $0.103/kWh although the electricity price of the grid is $0.17/kWh. The optimum system in the standalone scenarios is the wind/PV/FC with a cost of $0.836/kWh. Also, the effects of some parameters, such as wind speed, solar radiation and cost of the equipment, on the system type and COE are examined by using sensitivity analyses. Finally, these systems are investigated from environmental point of view considering CO2 production.