Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, biomass tides, and geothermal heat, which are renewable (naturally replenished).
About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from hydroelectricity. New renewables (small hydro, modern biomass, wind, solar, geothermal, and biofuels) accounted for another 2.8% and are growing very rapidly. The share of renewables in electricity generation is around 19%, with 16% of global electricity coming from hydroelectricity and 3% from new renewables.
Energy in water can be harnessed and used. Since water is about 800 times denser than air, even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy.
There are many forms of water energy
Wind power is power generated by the wind. Airflows can be used to run wind turbines. Modern wind turbines range from around 600 kW to 5 MW of rated power, although turbines with rated output of 1.5–3 MW have become the most common for commercial use; the power output of a turbine is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically. Areas where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms. Typical capacity factors are 20-40%, with values at the upper end of the range in particularly favourable sites.
Solar energy is the energy derived from the sun through the form of solar radiation. Solar powered electrical generation relies on photovoltaics and heat engines. A partial list of other solar applications includes space heating and cooling through solar architecture, daylighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes.
Biomass (plant material) is a renewable energy source because the energy it contains comes from the sun. Through the process of photosynthesis, plants capture sun’s energy. When the plants are burnt, they release sun’s energy contained in them. In this way, biomass functions as a sort of natural battery for storing solar energy.
Sri Lanka is blessed with the renewable energy sources which can be utilized to fulfill energy requirements of the country. Ceylon Electricity Board as a power utility of the country has promoted generation of electricity using Renewable Energy Resources since early nineties by giving the required assistance to the private sector, which includes training & capacity building, pre-feasibility studies and resource assessments. The procedure for electricity purchases from small renewable energy producers (SPPs) by the CEB was regularized beginning 1997 with the publication of a standardized power purchase agreement (SPPA) which included a scheme for calculating the purchase price based on the avoided cost principle. This was offered to all sources of power plants of capacity less than 10 MW.
Moreover, the government has identified the development of Renewable Energy Projects, as a matter of policy to diversify the electricity sector from high cost thermal power generation. Therefore, required incentives and assistance was provided for the renewable energy resource development (Mini Hydro, Bio Mass, Wind, etc.,). Further, National Energy Policy 2006 has identified fuel diversify and energy security in electricity generation as a strategic objective and development of renewable energy projects was identified as a part of this strategy. Action has been taken to introduce a cost based, technology specific, three-tier tariff instead of avoided cost based tariff with effect from year 2007. For more details on renewable energy development in Sri Lanka: Latest Status of Non-Conventional Renewable Energy Sector.