Solar energyThe country experiences sunshine for majority of the year. A recent study estimated the average daily solar radiation at 4.1-5.2 kWh/m2, which indicates significant potential for solar power. This data is in need of revision, as calculations were made from eight sites in 1996. The economic feasibility of photovoltaic (PV) electricity needs to be further explored.The current installed capacity of solar PV is about 25 kW, with 60–80 % being installed by the RCD Solar Company. It provides 120 W/4 kW solar systems for hospitals, schools, domestic and commercial use. Significant work has also been done by the Environmental Foundation for Africa (EFA).Wind energyData on wind speeds across the country is rare. The existing data indicates a countrywide average speed of 3–5 m/s. However, wind speeds of up to 12 m/s seem to be possible in some areas so wind power may offer very promising opportunities for Sierra Leone. The Ministry of Energy and Power (MEP) is encouraging studies of sites that may hold potential. With wind turbines capable of operating with low wind speeds now on the market, there is a strong potential for these systems in rural areas, especially in the north. There is currently no wind energy system in Sierra Leone.Biomass energyBiomass potential is high, from forest resources, and 656,400 tons of crop waste annually, amounting to a total generation potential of 2,706 GWh. Potential feedstocks include rice husks and straw. However, at the current deforestation rate, and with 65 % of the population living in rural areas, the harvesting of traditional fuels can lead to environmental, health and social impacts. In terms of biofuels, a recent initiative led by Addax Bioenergy, a Swiss group, with financing from a number of different international development organisations, is to construct a biomass-fueled power plant and sugarcane ethanol refinery in the country, at a total cost of €258 million. The refinery is expected to produce up to 90 million litres of ethanol annually, and will be powered entirely through the conjoined biomass station, which will also feed renewable power into the national grid system.Geothermal energyNo study has yet been conducted into the geothermal potential of Sierra Leone, and there are no current uses of the technology in the country.HydropowerThe estimated hydroelectric potential is 1,513 MW from roughly 27 different sites. Nearly all however, suffer from enormous flow variation between the wet and dry seasons. According to the Lahmeyer International report (1996), only two of the 27 sites studied in the Master Plan are deemed to provide hydropower at attractive costs and with annual flow regulation. Yiben II, Bekongor III, Kambatibo, Betmai III, and Yiben I are the most promising plants in terms of generation cost. Presently, Sierra Leone has two hydroelectric plants. These are the 2.4 MW Guma plant, installed in 1967 in the Western Area, which has been out of service since 1982 and the only operational 6 MW run-of-the-river type located in the Eastern Province. This plant is operated by the BKPS consortium, and is connected to a regional grid linking thermal power plants in Bo and Kenema. The Bumbuna Falls plant, after nearly two decades of successive governmental promises, was finally commissioned in 2009, and currently provides approximately 50 MW in the wet season, and 18 MW in the dry. The plant is linked to the Freetown electricity grid through a 161 kV connecting line.Many of the rivers investigated suffice for only small to medium hydro systems (i.e. 1–100 MW), but there is also a potential for pico to mini hydro systems (5 kW to 1 MW). Resources under 2 MW are expected to be an area of potential for Public Private Partnerships (PPP). Long-term plans in the hydropower sector include the further expansion of the Bumbuna facility by 275 MW, and further expansion of the Bekongor facility to 200 MW of total capacity.