Mechanical energy: Its application in renewable energies

Energy is everywhere in the universe and on Earth. It occurs in various forms. Mechanical energy is probably one of the easiest energies to understand.

Generated naturally by any body in motion, mechanical energy has always been used by humans. Over time, its uses have developed thanks to a better understanding of physical phenomena.

Mechanical energy plays an essential role in renewable energies today. Converted into electrical energy, it contributes to the production of green electricity and to reducingcarbon footprint of the man. What are the different forms and sources of energy? What exactly is mechanical energy and how is it used in renewable energies to produce electricity?

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What are the different forms of energy?

Energy takes on multiple forms, exploitable directly by humans, or indirectly following a transformation. Each scientific advance marked a major advance in the development of human societies.

Mechanical energy

Mechanical energy refers toenergy generated by moving objects. It is the sum of two types of energy: kinetic energy (linked to the movement) and potential energy (linked to the position).

In an isolated system, mechanical energy remains constant, under the law of conservation of energy. On the other hand, any obstacle, shock or friction causes energy losses.

Thermal energy

Thermal energy is produced by the agitation of atoms and particles within a body or substance, under the effect of the increase in its temperature, following a physical, chemical, mechanical or nuclear reaction. The thermal energy can then be transformed into electricity, as in a Thermal power plant.

By transferring from a hot body to a cold body, thermal energy produces heat. Heat exchanges are the basis for the functioning of heat pumps and any heating system by convection, conduction or radiation.

Electric power

Omnipresent in our daily lives, electrical energy is generated by the displacement of electrons along a conductor. The movement is caused by a difference in electrical potential (or voltage). Electrons create electrical current by moving from a high voltage point to a low voltage point.

Nuclear energy

Nuclear energy Is the energy released by atoms during a nuclear reaction Such as the fission or fusion.

Nuclear power plants use the heat released by fission to generate water vapor. It activates a turbine connected to an alternator to produce electricity.

Radiative or light energy

Radiative or light energy is the energy carried by electromagnetic waves. The light of Soleil is the most powerful form of radiant energy.

Radiative energy is used on a daily basis by humans, for example to heat food in the microwave or turn on the television using an infrared remote control. It is also contained in ultraviolet, X-ray, or gamma rays.

Chemical energy

Chemical energy is released by the transformation of the bonds between atoms and molecules, during a chemical reaction. For example, it is the source of the heat produced by the combustion of wood, biomass or fossil fuels (oil, gas, coal).

It is also chemical energy that allows the storage of electricity in electrochemical cells and batteries, or the transformation of electricity into hydrogen in the hydrogen fuel cell.

How do you define mechanical energy?

In physics, the source of mechanical energy is movement. More precisely, mechanical energy is the sum of the potential energy and the kinetic energy of a body or system. It is calculated using the following formula: Em = Ec + Ep.

Kinetic energy (Ec): definition

Kinetic energy isenergy generated by moving objects. It is related to the speed and mass of the object. The heavier and faster the latter is, the more the kinetic energy increases. Thus, the kinetic energy of an airplane in flight is higher than that of a car on the highway.

Les rotational or translational movements accentuate kinetic energy. These physical properties are used by athletes to give more strength to a ball.

Potential energy (Ep): definition

Potential energy measures theenergy stored in an object due to its position. It can be:

• Gravitational : the gravitational potential energy of an object is linked to its position at height. The higher it is placed, the more energy it produces in its fall.
• Elastic : elastic potential energy is produced by the deformation of an object. For example, a compressed spring stores elastic potential energy. She is released when he is released.
• Electrostatic : electrostatic potential energy is created by interactions between positive and negative electrical charges. Opposite charges store or release energy when they repel or approach each other.

How is mechanical energy used in renewable energies?

Renewable energy technologies take advantage of the mechanical energy of natural resources. They transform their kinetic and potential energy into a new form of energy that can be directly exploited: electrical energy.

Hydraulic power

Hydraulic power is the second largest source of electricity production in France. Hydroelectric power plants capture mechanical energy from moving water to generate electricity. They combine thenatural kinetic energy of currents With thegravitational potential energy generated by waterfalls.

Under water pressure, the hydraulic turbines engage and drive the alternator. It is he who, at the end of the chain, carries out the transformation of mechanical energy into electrical energy.

Hydraulic dams increase the potential energy of water. Retained upstream of the power plant, the water, released on demand via a system of valves, flows at full speed into the forced pipes and activates the turbines.

The final quantity of electricity produced is proportional to the power of the water and therefore to the difference in height between the upstream and the downstream of the hydroelectric power plant.

Tidal energy

Tidal energy works on the same principle as hydraulic power. The difference? Elle Harnesses the mechanical energy of the tides.

Thanks to a system of dams, gates and storage basins upstream and downstream, tidal power plants play with the alternation of tides.

Depending on the high tides and the low tides, the water is transferred from one basin to another, activating the turbines and the alternator as it passes. The difference in height between the pools maximizes the gravitational effect and the mechanical energy of the sea.

Tidal energy is still confidential. France has a unique tidal power plant on the Rance site in Brittany. Each year, it produces around 500 GWh, covering the annual electricity consumption of 225,000 inhabitants.

Wind energy

Wind turbines use the kinetic energy of the wind to generate electricity. The force of the wind makes the blades turn. These activate the generator which transforms mechanical energy into electrical energy. The production capacity of wind turbines increases with the force of the wind and the speed of rotation of the blades.

The power generation potential of Wind energy On land and at sea is significant. It is estimated at 200,000 TWh and 420,000 TWh per year respectively by the World Energy Association (WWA) and the International Energy Agency (IEA).

Tidal energy

Located off the coast, tidal turbines exploit the kinetic energy of marine currents to produce electricity. The turbines rotate according to the tides, driving the alternator that converts mechanical energy into electrical energy.

Linked to tides and the speed of currents, tidal energy is a renewable energy intermittent, but reliable and predictable. While the technology is mature, it is still in the experimental phase in France, with several pilot farms under development.

Wave energy

Wave energy — or wave energy — is a promising renewable energy. Emerging technologies exploit the kinetic movements of waves and waves to generate mechanical energy. This is transformed into electricity by a wave energy converter (WEC).

With 1 watt/m²/year, the kinetic energy of waves is low compared to that of other renewable energies, especially solar energy. But, given the surface of the oceans, the potential of wave energy is considerable.

The theoretical annual global production is estimated between 8,000 and 80,000 TWh of electricity by the International Energy Agency.

In the experimental phase, oscillating water columns, surge systems, float systems or even underwater oscillators have not yet reached commercial maturity.

Mechanical energy is pervasive in renewable energies. Derived from natural sources and transformed into green electricity, mechanical energy contributes to building a more sustainable energy future.

While the mechanical energy of sources such as wind and waterways is now well known and exploited, the kinetic potential of the sea is still poorly valued.

However, the electricity production capacity of marine energies is estimated between 20,000 and 90,000 TWh per year by the International Energy Agency. The second largest tidal reservoir in Europe, France could seal the fate of mechanical energy at sea in its future energy and climate programming law (LPEC).