Renewable energy is energy generated from constantly and naturally replenished resources such as sunlight, wind, geothermal heat, rides, rain and various forms of biomass. This energy cannot be exhausted on a human timescale, because it is practically unlimited. All those renewable energy resources combined are accounted for the production of more than 15% of world’s energy consumed and this share is growing rapidly in recent years. It is believed that technologies producing energy from sunlight alone will be capable to fulfill world’s energy demand for the next 1 billion years.
Currently the world relies heavily on non-renewable resources like coal, oil and natural gas. Fossil fuels are non-renewable energy resources, they are finite on our planet and the cost for retrieving them is growing, while causing too much environment damage at the same time. In contrast, the renewable sources of energy are much more environment-friendly and will never run out.
Most of them are directly or indirectly related with the sun. The solar energy can be captured by solar panels and then used for generating electricity, heating water, solar cooling, heating and lighting buildings and a variety of industrial uses. Wind is generated from sun’s heat and its energy is captured by wind turbines.
Water evaporation is also a result of sun’s heat, it turns into rain and comes back into rivers where the energy can be captured by hydroelectric power plants. Both sunlight and rain cause the biomass (organic matter) in plants to grow. The plants can be used to produce electricity, fuels or chemicals – so-called bio-energy.
Not all renewable energy comes from the sun. Geothermal energy is the energy generated from Earth’s internal heat. It can used for power production, heating and cooling of buildings. The gravitational pull between the Earth and the moon cause ocean’s tides – another source of energy. There’s also the waves energy, which is driven by both tides and winds. In addition to that, sun warms water’s surface creating temperature differences. All these sources can be used to produce electricity. There is also the hydrogen – the most abundant element on Earth. Although it is not found naturally as a gas, it can be found combined with oxygen in water and in many other organic compounds. Once separated, hydrogen can be burned as fuel or used for energy production.
It is theoretically possible to generate electricity by harnessing the kinetic energy from earthquakes, although it will be real challenge in practice. Big earthquakes release a lot of energy. The 9.0 earthquake in Japan (March 2011) unleashed energy, equivalent of more than 15,000 nuclear bombs. For now the question how to harness the tectonic energy is still open and the proper technology is not there yet.
Renewable energy is important because it is unlimited, it comes from clean sources of energy and have low environmental impact than traditional energy technologies.