Renewable energies are all those sources of natural resources that can be recovered after being used by humans to meet their needs. They are limited and polluting alternatives to burning non-renewable fossil fuels.
Renewable energies are found unlimitedly in nature or can be regenerated in a relatively short time. For example, when we use the Sun we are not wasting it or destroying it, we simply make use of its light radiation or its heat..
Renewable energies are sustainable, that is, we can use them without affecting their production and employment in the future. This assures us that the next generations will be able to supply themselves with these energy sources to be able to live.
There are different types of renewable energy depending on the resource from which it is obtained. Let's look at the most important examples.
Hydropower is electricity generated by the force of water. This is the most widely used renewable energy worldwide, with 60% by 2019.
The way to transform water energy into electrical energy is through hydroelectric power plants. These are facilities of great economic investment due to the type of constructions that must be carried out to ensure operation. The first hydroelectric plant was built in 1882 on the Fox River, in Wisconsin (USA)..
Although water is considered a renewable natural resource, the energy obtained from a hydroelectric plant may be limited due, among other things, to the deposit of materials in dams and droughts in the region.
On the other hand, the construction of the hydroelectric plants alters the ecological structure of the area, including the displacement of native species and human populations. For example, the construction of the "Three Gorges" dam on the Yangtze River in China displaced more than a million people..
From water we can obtain another type of energy in addition to electrical energy. Hydraulic energy refers to using water to produce the movement of a machine.
This is one of the longest running renewable energies. It involves using moving water to spin a wheel that is connected to other devices. For example, hydraulic power was used to grind grain; in this case, the water turned some rocks that, when moving, crushed the grains to produce flour.
The Sun is the source of renewable energy par excellence. When we use the sun's rays to heat something we are using solar thermal energy. Its heat can be used to heat spaces, such as in greenhouses, cook food using solar ovens and heat water.
An example of how we obtain solar thermal energy is through solar collectors. These are devices that have a water tank that circulates through tubes that concentrate the heat. They are usually installed on the roofs or terraces of buildings.
The source of photovoltaic energy is the Sun, which is free and present in all parts of the world. In order to obtain electricity from the Sun, systems are required that transform light energy into electrical energy..
Photovoltaic systems are built by a material that when receiving light, its electrons move and an electric current is produced. Silicon is the most widely used material for this purpose and is abundant on Earth.
The main drawback of relying on photovoltaic energy is that the Sun is not available at night and when the sky is cloudy. In this case, you must use another source of energy or store the energy in batteries..
Technological advances related to the solar industry have led to a reduction in the cost of equipment, which makes the transfer to the use of solar energy as an alternative to fossil fuels more attractive..
You may be interested in seeing the advantages and disadvantages of solar energy.
Wind energy is a clean alternative energy because it does not generate waste or polluting gases as happens with fossil fuels. Wind is an inexhaustible source of energy, when it is used in the generation of energy it is not used up. However, it is not available 24 hours a day, 365 days a year.
Wind turbines generate electricity by capturing energy in the wind. Thus, the higher the turbine, the stronger the wind and the higher the energy production. These structures are generally located in fields, but can also be installed offshore.
Wind energy is the fastest growing renewable energy in recent years. By 2019, countries such as Uruguay, Portugal, Ireland, Denmark and Lithuania obtained more than 25% of electrical energy from the wind.
You may be interested in seeing the advantages and disadvantages of wind energy
Biomass energy refers to the energy obtained from biological compounds, mainly wood, manure from farm animals, agricultural waste, among others. Biomass is a renewable form of energy that is derived from the photosynthesis process of plants.
Wood was used since ancient times to cook, illuminate and warm humans. Today it is mainly used in the construction of buildings and furniture.
Some crops or their residues, such as corn, are used to produce ethanol, which is used to replace gasoline in vehicles.
Municipal waste collection can extract energy; This is what is called "transforming garbage into energy". Biological matter in municipal waste can be broken down to generate methane, which is then used as fuel gas.
Geothermal energy is the energy that comes from the Earth. Heat accumulates inside the Earth that can be used to produce electricity..
However, not everyone has access to this type of energy. Only 0.3% of the world's electrical power comes from the geothermal source.
Energy can also be extracted from the oceans. These cover 70% of the Earth, which means that it is an unlimited energy source, since the generation of energy does not consume the material from the ocean..
Energy can be extracted from the ocean through waves or the movement of tides. The technologies for this are still in the experimental phase, but they promise enormous potential as an alternative to non-renewable energy..
Where does the energy of all the stars in the Universe come from? From hydrogen! Hydrogen is the most abundant element in the universe, it is found as part of water, biological molecules and hydrocarbons.
Electrical energy can be produced from a hydrogen fuel cell. In the battery, the hydrogen loses its electron to the electric current. Oxygen from the air enters the battery, which reacts with hydrogen, producing water. In this way, electricity, water and heat are produced.
The big drawback of hydrogen fuel cells is their high cost.
You may be interested in seeing:
DeGunther, R. (2009). Alternative Energy for Dummies. Wiley Publishing. New Jersey.
Dunlap, R.A. (2020) Renewable Energy. Combined edition. Morgan & Claypool Publishers.
Usher, B. (2019) Renewable Energy. Columbia University Press. New York.
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