Types of renewable energy

Renewable energy is the type of energy that gets naturally replenished and comes from natural resources such as sunlight, wind, geothermal heat, rain, and tides. During the last few years the concept of renewable energy has gained significant notoriety, due mainly to environmental concerns about climate change and high oil prices. It is an established fact that the biosphere cannot sustain in the long term the increasing level of carbon dioxide emissions that come from the utilization of fossil fuel. This is why renewable energy is such an important topic, and we will discuss the main types of such energy that are currently being used to alleviate this energy crisis.

- Hydropower: this type of power is derived and obtained from the energy of falling water. Hydropower has been used for centuries for the operation of devices like watermills and sawmills, but in modern history that term is almost exclusively associated with the generation of electricity (hydro-electric power).

- Solar energy: this is the energy that is derived from the sun in the form of solar radiation. Solar energy technologies can be separated into two broad categories: passive or active. This categorization is based on the way they obtain, transform and distribute solar energy. The active solar technology rely on the use of photovoltaic panels and solar thermal collectors to capture the energy. Passive technologies include orienting buildings toward the Sun, utilizing building materials with favorable thermal mass, and implement spaces that allow for a natural circulation of air.

- Biofuels: these include a wide variety of fuels that come from biomass, such as bioethanol and biodiesel. Bioethanol is a type of alcohol that is obtained from sugar and starch crops, and is currently being used as automobile fuel. Biodiesel can also be used as fuel for cars; this type of biofuel is derived from vegetable oils, animal fats, or recycled greases.

- Geothermal energy: this energy is derived from the heat of the Earth's inner core. The heat and subsequent steam is used to drive turbines and spin generators, transforming this renewable energy into electrical power.