These above mentioned energy sources can be replenished naturally. In comparison to fossil fuels that are commonly utilized for energy generation, these sources are eco-friendly. Another major advantage is that they generate clean electricity without the emission of hazardous greenhouse gases. With the rising need for electricity, and issues regarding the energy crisis, renewable energy resources are the future hope to meet the demand of the worldwide population. It is estimated that about 50 percent of the energy generated from the renewable sources is used to produce electricity.
It refers to any organic material derived from plants and animals. Humans have been using biomass for generating energy since long time. For example, wood biomass has been used to provide heat in many regions. It is still practiced in remote areas as the major source for cooking and heating. Apart from releasing heat, biomass can also be converted into electricity, biodiesel, ethanol, and methane gas. Generation of electricity from this source is commonly implemented in various industries, in which the leftover biomass like wood waste or paper waste is burnt to produce steam, which is then used for producing the electrical energy.
It is used less commonly as compared to other renewable sources. It refers to the energy present inside the Earth's crust. In order to generate electricity from this source, deep wells are dug and water with high temperature or steam is pumped into the Earth's surface. Naturally occurring hot water areas and heated groundwater aquifers are called geothermal reservoirs. Geothermal power plants are built near such reservoirs. Presently, on the Earth's surface, this type of energy occurs mainly nearby hot springs and volcanoes. It is also used for heating purposes.
It is the most commonly used renewable resource. Electricity generation by using it was discovered in the 1880s. The principle behind the working of hydroelectric power plants, is to use mechanical energy of moving water (swiftly falling or descending water) to rotate the blades of a turbine, which in turn produces electricity. As the source is moving water, it is obvious that the power plants are located near the water bodies (natural waterfalls or man-made dams). The higher the amount and speed of flowing water, greater is the electricity production.
It is commonly used to generate electricity and heat energy. For electricity generation, there are two methods, direct and indirect techniques. In the former case, solar energy is converted directly into electricity by using solar cells or photovoltaic devices. In case of the latter one, solar heat that is harvested through the solar thermal collectors is used to heat fluid and produce steam. This steam produces electricity by using generators. The disadvantage of solar energy is the variance in intensity depending upon the climatic conditions and location.
The speed and velocity of wind is used to rotate blades of a windmill, which then generates electricity with the help of a generator. Wind turbines or windmills are installed, especially at the higher elevated areas, and in a particular orientation so as to harvest maximum wind energy. A series of wind farms installed for supplying electricity in a mass scale is called a wind power plant. Nowadays, many private companies have started the business of installing such plants to produce and sell electricity to large industries.
As per statistics, the use of renewable energy resources has tremendously increased in recent times. However, one of the major drawbacks of such sources is the high cost that is involved. More sophisticated techniques need to be introduced in order to combat this problem, and make these sources available to the general public.