Since global warming became a public issue, interest in clean renewable energy has grown. In short, clean energy is energy that is produced without giving off byproducts that harm the earth, such as the carbon dioxide emitted by oil and coal refineries. Renewable energy is energy that comes from natural resources that are infinite in supply, such as water, geothermal heat and sunlight. Clean renewable energy fits both criteria.
The three most common types of clean renewable energy are wind power, solar power and water power. Wind power is typically harnessed through wind turbines, which use spinning blades to capture and convert the wind’s kinetic energy into mechanical energy. On a smaller scale, windmills can be used to power grinders and other simple machines.
Solar power is collected via solar panels, or silicon cells, which are angled toward the sun to collect energy from its rays using a process that is called photovoltaics. When the sunlight hits each cell, it absorbs it and sends it to a semiconductor. This semiconductor works to collect the energy from the light and convert it into usable energy by drawing the current into a generator.
A very simple solar cell is present on solar powered calculators. Parabolic dishes are also used to collect solar power, or more specifically to collect heat rather than light energy. As an example, this is how a solar-powered stove operates.
Water power comes in several forms. Two forms used today are hydroelectric energy and ocean energy. Hydroelectric energy usually uses dammed water, flowing through the dam and downward, to power a turbine and generator. Since the water is unnaturally contained and is meant to flow downstream, it has a huge gravitational pull downward, which results in a great amount of available kinetic energy.
Ocean energy is produced via the action of tides. This energy can be harnessed much in the same way as hydroelectric energy. The changes in movement due to rotation of the earth, including the actions of high tide and low tide, make it more difficult to collect. The sheer amount of ocean covering the Earth makes it a potentially great source of energy in the future.
Other forms of clean renewable energy that are being studied or put into practice on a smaller scale are hydrogen power, geothermal power and that obtained from the use of ethanol and other biofuels. Biofuels are typically produced from organic material, such as corn. Biomass, which is usually derived from decaying plant and animal matter, is another form of clean renewable energy.
As the supply of petroleum, coal and other non-renewable forms of energy decreases, scientists continue to study clean renewable energy to ensure people's needs can be met while protecting the planet. These studies also test scientific theories about energy, investigate environmental issues and forward technological progress. Since interest in the use of non-renewables is growing rapidly, clean renewable energy may one day be the only type of energy available.