Energy sources fall into two main segments: raw materials and natural phenomena. Generally speaking, the former supply so-called fossil energies while the second supply so-called renewable energies.

Summary:

1. Primary and secondary sources of electricity
   1. What are the primary and secondary sources and those that are renewable or polluting ?

What are the primary and secondary sources of electricity production?

What are the primary sources of energy?

By definition, a primary source of energy comes from nature before being transformed. In case of non-use of the primary source in its initial state, it is exploited to transform it into a usable and transportable secondary energy source. The list of primary energy sources:

• Uranium
• Coal
• hydrocarbons
• Stream and waterfalls
• Force of the sea
• Sun radiation
• Wind force
• Oil
• Natural gas
• geothermal
• Waste and biomass

What are renewable or polluting sources?

Primary and secondary sources of renewable and polluting electricity Renewable sources or not? Primary sources Secondary sources Non-renewable Uranium Nuclear power plant Hydrocarbons Thermal power station (fossil) Coal Oil Natural gas Renewable Water power (hydraulic or marine) Hydropower plant Wind Wind power Solar radiation Photovoltaic solar energy Geothermal power Geothermal power Waste and biomass Cogeneration Concentrated solar thermal energy

What is fossil energy?

Fossil fuels come from the combustion of raw materials such as coal, oil or natural gas. These fuels are the result of a process of fossilization that took several million years, so they are called "fossil fuels" producing " fossil fuel ". Reserves of raw materials are abundant, but unfortunately not renewable.

Fossil energies are therefore polluting and their reserves are not infinite. Natural gas is today the least polluting fossil fuel because of its reduced CO2 emissions. This source of energy is presented today as a good complement to renewable energies, whose production is intermittent, because of its flexibility.

Nuclear energy also comes from a raw material that is uranium , so it is a fossil fuel. However, it is considered as an alternative to other fossil fuels because it is not emitting CO ₂ even if it causes problems of safety and storage of radioactive waste.

If it has offered energy independence to France for half a century, the cost of maintenance of the French nuclear fleet is now increasing , because of the longer life of the plants and the strengthening of standards safety. As for the new generation of reactors, the cost of the Flamanville EPR is very high.

Renewable energies, as their name suggests, are not dry . Also called " green energies " or " clean energies " because coming from natural phenomena (wind, solar radiation, force of the marine currents), they do not cause any direct pollution - but sometimes indirect because of the extraction of minerals (lithium, coltan , copper …) allowing the creation of wind turbines and solar panels in particular.

Their exploitation is booming: they are not yet able to replace other sources of energy but offer the possibility of significantly reducing the use of fossil fuels. The energy transition is also one of the biggest challenges of the 21st century. Many electricity providers promote sustainable development and offer green electricity offers. Some 100% ecological alternative suppliers have appeared such as Planet Yes, Enercoop, Plum Energy, ilek, Mint Energy, eKwateur and Elecocity.

Hydraulic power plants convert the strength of streams, waterfalls and even tides or swells into an inexhaustible source of energy that does not emit CO ₂ . This green electricity generation system is the oldest of the renewable energies. Like water mills since antiquity, hydro power plants capture the force of water supplying the rotating turbines to produce electricity through an electric generator. However, the consequences for the aquatic environment or the environment in general can be significant, especially if the construction of a dam leads to the flooding of large areas of land (eg the Three Gorges Dam in China).

In 2017, hydropower represents 10.1% of the energy mix in France.

This green energy is promised a bright future given its inexhaustible nature. In theory, capturing one-thousandth of the available wind energy on Earth would meet all of the world's electricity needs. Technological advances over the past decade have made wind turbines both more efficient and much less expensive to produce.

However, it has the major disadvantage of having intermittent production . To ensure the stability of the electricity transmission system, electricity production must always be about equal to consumption by businesses and households, or the time at which the wind blows is not controlled.

Battery storage systems, which must overcome this problem, must become more efficient over the coming decades: it is on this condition that green energies can become the world's leading source of energy.

The installation of terrestrial wind turbines sometimes arouses the hostility of local residents because their presence alters the landscape, generates noise and can present a danger for the local fauna. In France, the state now favors marine (offshore) and coastal wind turbines, where nuisances are reduced, and where the yield is often much higher.

The sun's luminous energy is collected thanks to sensors on solar panels and is converted into electrical energy (solar photovoltaic) or thermal (solar thermal, as for solar water heaters). The installation of photovoltaic panels can allow individuals to meet more than half of their heating needs (water and housing).

Like wind energy, photovoltaic solar energy has intermittent production depending on the elements . In the context of an energy transition towards green energies, states will therefore have to continue to rely on complementary sources of energy.

The principle is to exploit the natural geothermal flux on the surface of the globe . In general, this flow is quite weak and requires important devices (drilling …) to be captured. This type of energy does not depend on atmospheric conditions and therefore has the advantage of being almost continuous .

The techniques are sophisticated in geothermal heat pumps, which absorb the heat of the ground via a network of horizontal or vertical sensors, then transmit it to heat networks that return it inside the housing.

Biomass energy is produced by burning biological materials such as wood, by conversion to biofuels, or by extracting biomethane from organic waste in biogas plants.

Even though combustion produces greenhouse gases, biomass remains a renewable energy source: tree growth absorbs as much CO ₂ as its combustion releases into the atmosphere.

What is the primary energy mix in France?

To have a global vision of a country's dependence on different sources of energy, we consider the primary energy mix that integrates not only the origin of electricity production, but also the energy used for automotive fuel , fuel oil, gas or wood used for heating. In the graph below, some of the gas, coal and oil are used for electricity generation.

France has chosen to build a nuclear power plant, which accounts for nearly three quarters of the country's electricity production. Since most of the plants were built in the 1960s and 1980s, the investments have been depreciated for a long time in EDF's accounts and the marginal costs of production are low.

As a result, electricity prices in France are among the lowest in Europe. Nevertheless, this cost is growing as power plants age and safety and environmental standards increase.

Hydropower comes second, and its potential is now almost fully exploited. Alternative renewable energies such as wind and photovoltaics make up a small percentage of the country's total output, although it is increasing year by year - unlike other energy sources.

The challenge of the environment: the energy transition

The energy transition defines the change of the modes of production also of consumption of the energy. The challenge of the energy transition whose ecological transition will be to significantly increase the share of renewable energy (32% minimum in 2030) in the energy mix without exploding the consumer's electricity bill.

The energy transition law passed in 2015 sets a goal of doubling the production of renewable sources to increase nuclear production to 50% of the French energy mix by 2025 and become autonomous by 2030 in France. However, the development of renewable energy (RE) can only be achieved with increasing public financial support.