Renewable energy refers to any form of energy that can be replenished, meaning generated from natural sources like sunlight, tides, rain, geothermal heat and wind. Renewables, as these energy sources are commonly known, play significant roles in the generation of electricity. Their importance lies in the fact that these sources of energy are virtually inexhaustible.
There are five main forms or sources of renewable energy namely solar energy, hydropower, wind power, geothermal energy and biofuel–divided into three sub-forms: biogas, solid biomass and liquid biofuel. These various forms are said to be mostly derived from the sun or the heat generated within the earth. The energy from the sun is dissipated throughout the globe and is converted to different forms, hence the existence of the different forms of renewable energy.
Renewable energy is harnessed in different ways. While most projects involving this kind of energy source are large-scale, there are also renewable technologies applicable to small off-grid purposes like in remote or rural areas. This is important since not all places can be reached by conventional means. Renewable energy is everywhere so its potential use is very widespread.
Renewable Energy – Solar
Solar energy, the biggest source of renewable energy, refers to energy collected from the sun. This form of energy can be harnessed in many ways, the most common being by means of photovoltaic solar cells. Solar cells can directly transform energy from the sun into electricity through the photovoltaic effect. This, however, is usually small scale and uses a lot of solar cells for large applications. Another way of harnessing solar energy is by concentrating solar power (CSP). This method involves concentrating light by means of mirrors and lenses, therefore creating a high energy beam. The beam is then used as a heat source for power plants or is concentrated onto surfaces designed to make use of the photovoltaic effect.
Renewable Energy – Wind
Wind is used as a source of renewable energy by means of wind turbines, rotating machines which convert kinetic energy into mechanical energy. The mechanical energy is then converted into electricity, in which case the machines are called wind generators. The energy in water can be used in many ways. The most common use of hydropower is in the generation of electricity, using turbines which use the same principles as that of the wind turbines. Since water is denser than air, even a little water motion can produce considerable amounts of energy.
Renewable Energy – Geothermal
Geothermal energy refers to the energy obtained by harnessing the earth’s heat itself, either from shallow geothermal heat pumps or from kilometers deep into the crust. Geothermal power plants are very expensive to build but have low operating costs since the plants are basically self-sufficient when completed. These low costs also translate to cheaper energy prices.
Renewable Energy – Biofuel
Biofuel is a form of renewable energy that makes use of plants, as its name suggests. This energy source is specifically called biomass. Biomass is produced through the photosynthesis in plants. Biofuel is typically burned to release the chemical energy stored in it. The heat produced is then used to power generators and other machines which convert raw energy into usable energy.
