Renewable energies (solar, hydro, wind, geothermal, and Biomass) are developing intensely all over the world, driven by the need to fight against global warming by reducing greenhouse gas emissions.

Renewable energy definition: how is renewable energy defined?

Energy is said to be renewable when produced by a source that nature constantly renews, unlike energy dependent on sources running out. Renewable energies are diverse, but they all come from two main natural sources:

The Sun: it emits transformable radiations into electricity or heat, it generates zones of unequal temperatures and pressure at the origin of the winds, it generates the water cycle, it allows the growth of plants and the generation of the Biomass.

The Earth: in which the internal heat can recover the surface.

The renewable nature of these energies, their low emission of waste, polluting emissions, and greenhouse gases are advantages. But their relatively scattered energy power is much lower than that of highly concentrated non-renewable energies. They can be in the case of solar and wind power "intermittent" and difficult to store because they are instantly transformed into electricity, requiring the occasional supply of other energies. Their implementation also requires heavy investments, even if, over time, they become more and more competitive with fossil fuels.

2. Renewable energy definition; the history of renewable energies?

During prehistoric times, humans only used Biomass generated by fire. He later learned about animal traction when he domesticated them; he continued to advance thanks to the invention of the sailing navy for travel and trade; the watermills and windmills then appeared. Humanity used natural renewable energies, then came steam engines, diesel engines, electricity, and geothermal energy in the 19th century. At the beginning of the 20th century, the first solar water heaters were put into operation in California. Wind turbines followed them and took on a large scale around the 1990s. At the start of the 21st century, renewable thermal and photovoltaic energies were more and more omnipresent. Nowadays, the main objective is to use more and more renewable energies to eradicate fossil fuels. Biomass, hydropower, solar, marine energy, wind, and geothermal energy are the main sources of renewable energy.

3. Renewable energy definition; renewable energy types

3.1 Hydraulic energy

The Sun dries up the water, and this causes water vapor to fall back. We are then in the water cycle. When the latter returns to the oceans through rivers, the hydroelectric dams providing electricity capture the energy. The movement of waves and the tides form hydraulic energy; it exists thanks to underwater currents and is then called tidal energy. When it is thermal energy of the seas, it's production is due to temperature differences. There is still the osmotic energy that is created by mixing fresh water with sea water.

3.2 Solar energy

This type of renewable energy comes directly from the capture of solar radiation. Specific sensors absorb the energy of the Sun's rays and redistribute it in two main operating modes:

Solar photovoltaic (photovoltaic solar panels): solar energy is captured for the production of electricity.

Solar thermal (solar water heater, heating, thermal solar panels): the heat from the Sun's rays is captured and redistributed, and more rarely is used to produce electricity.

3.3 Wind power

In the case of wind power, the kinetic energy of the wind drives a generator that produces electricity. There are several types of renewable wind energy: onshore wind turbines, off-shore wind turbines, floating wind turbines… But the principle remains broadly the same for all these types of renewable energies.

3.4 The Biomass

Biomass (mass of plants) includes wood, straw, corn cobs, biogas, and biofuels. Wood from forest or wood industry waste is burnt to produce heat. It represents 14% of global energy consumption. Biogas comes from the fermentation of organic waste. Its combustion produces heat, but also electricity by cogeneration. Biofuels come from cultivated plants (sunflower, beet, rapeseed, etc.): the most common are biodiesel (or methyl ester of vegetable oil, VME), ethanol, and its derivative, ethyl-tertio-butyl-ether, or ETBE.

3.5 Geothermal

Energy comes from heat emitted by the Earth and stored in the basement. Depending on the resource and the technology used, the calories are directly exploited or converted into electricity.

Related: Environmental engineering, definition, tasks, and importance

4. Renewable energy definition; What are renewable energies used for?

Solar energy can produce electricity (thanks to photovoltaic panels) and heat (thanks to solar thermal panels). These signs are often visible on the roofs of houses, sheds, and even some stores.

- Wind turbines are useful to generate electricity. We can install wind turbines at sea and on land.

- Geothermal energy uses heat stored below the Earth's surface. This heat is useful to heat buildings or generates electricity.

- Marine energies include tidal energy (movement of the tides), wave energy (movement of waves), tidal energy (force of sea currents), thermal energy (temperature difference between the seabed and the surface of the sea). Most of the time, these energies are useful to generate electricity.

- Hydropower harnesses the power of water through dams or small power plants on rivers. The force of the water activates a turbine which drives an alternator and produces electricity.

- Biomass can be useful for heating (wood, heat from waste incineration plants), to produce biogas (anaerobic digestion), which will be in fire to produce heat and/or electricity, to produce biofuels, to make chemistry.

5. Renewable energy definition; Advantages of renewable energy

Generally, renewable energies are cleaner than the fossil and fissile energies currently in exploitation around the world. They are greener, widely available, and are "free" once production facilities pay for themselves.

To be more precise, one should look at the advantages and disadvantages of each renewable energy source. Here are a few examples:

- Wind power is the quintessential clean energy. Without rejection or waste of any kind, it ensures good energy independence with a good coefficient of performance. On land or off-shore, wind turbines prove excellent production capacities and are a feasible alternative for the most remote areas where access to electricity is difficult.

- Biomass energy: wood in logs or pellets Biomass energy joins the combustion of wood. Wood is a very common fuel, especially in France, where it is widely in use. Although this energy still emits greenhouse gases, the emissions are less compared to the amount of CO2 that a tree will have absorbed in its lifetime. A well-managed and renewed forest means that wood reserves are not exhausted. Therefore, Biomass is an energy that contributes to local development while being very cheap (logs and wood pellets are the cheapest fuels on the market).

- Solar energy is commonly acclaimed in the energy sector and is developing at high speed. Electricity production thanks to photovoltaics and heating thanks to thermal solar panels, solar can be in exploitation on a large scale in parks planned for this effect or on a small scale in individuals even if solar panels have a better performance in very sunny areas.

Originally published on Live Positively.