Japanese telephone company Nippon Telegraph and Telephone Corp (NTT) has together with Sanki Engineering Co developed software to maximise the mix of renewable and non-renewable energy resources. The software, designed for use at NTT's hybrid power generation facility on the island of Kume in Okinawa, analyses seasonal and climatic variables to determine the island's energy needs and ensure a constant supply of power to the island's homes, hotels and businesses. The software factors in the season, time of day and climate to monitor power consumption levels. It then generates graphs showing the extent to which clean energy can be used to meet that demand. The Kume facility, which began operating in April, is the nation's largest hybrid power plant, consisting of a Micon 225 kW wind turbine and a 20 kW solar power system. NTT's local repeater station is powered by the station, and excess energy is sold to Okinawa Electric Power Co. NTT plans to modify the software so it can be marketed for use in other regions.