Biomass energyThere have been no surveys of biomass energy resources in the Cook Islands since the 1980s. Approximately 65% of the land probably has light to dense tree cover with biomass energy potential. It is unlikely; however, that any of this will be, or should be, used for energy purposes, other than meeting existing demand for fuel-wood. Virtually all economically reasonable biomass-based energy generation in the Pacific utilises waste products of concentrated agricultural or wood processing industries. Neither is likely to be developed. There are about 43,000 coconut trees, considered by households as useful nut producers, with over 97% of production used for household purposes. In some Pacific island cities, there is considerable potential for coconut oil from copra as a fuel. In the Cook Islands, copra no longer has economic importance and market prices are far too high for serious consideration of such an option.Biogas Pigs and chickens, as well as other domestic livestock, represent a significant resource for biogas production through anaerobic digestion of their wastes.Solar energySolar energy is an excellent resource in the Cook Islands, particularly for atolls. The Pacific Islands Forum Secretariat collected two years (1995-1996) of horizontal, global solar radiation data through the Southern Pacific Wind and Solar Monitoring Project, which showed that insolation, corrected for a tilted collector, averaged over 5.5 kWh/m2 per day. Satellite data indicates that solar radiation in the northern group is higher than in Rarotonga, but there are no surface measurements to confirm this. The island of Pukapuka in the northern group has a photovoltaic system which provides 95% of the island's power needs, including street lighting and household requirements. Solar water heaters are well established and are found in nearly all the new housing and commercial buildings. Various solar photovoltaic installations for lighting, radio, water pumping, fish freezing and refrigeration on the outer islands but not have suffered from the lack of funds for post-installation support. On the other hand, Telecom has installed many PV generators, ranging from 600-7,800 peak watts with excellent performance and high reliability due to the quality of installations and good maintenance, using well-trained staff.Wind energyThe Forum Secretariat’s wind and solar monitoring project is the main long term data source for Rarotonga wind energy, and is used to estimate the wind regimes of other islands. At Ngatangila Point, wind data recovery was 100% during two years of monitoring. The annual average wind speed was 5.5 m/s. The highest hourly and daily averages were 17.7 m/s and 14.0 m/s respectively. A Danish feasibility study in 1997 estimated annual average wind speeds in the range of 6.1–7.5 m/s (at 30 m), which is thoroughly suitable for economic power generation. Various wind power installation have been installed in the Cook Islands and have suffered from both inappropriate technical design and the lack of expertise for post installation support.HydropowerThe Ministry of Works has monitored water flows at a number of sites on Rarotonga. There were estimates in 1990 of hydropower potential at several sites of possibly several hundred kilowatts, but development costs were too high. In 1987, a Norwegian/SOPAC regional wave energy resource assessment program included the Cook Islands. The southern islands were found to have the highest wave energy resource of all countries included in the study (23–28 kW/m). In the northern Cooks, the resource was also high for such low latitude. Close to the coast of Rarotonga, the buoy measured a long-term average of 24.5 kW/m. There is a large potential resource but installed wave energy systems globally are experimental, and cannot be considered for commercial use.