The Spectacular Growth of Electricity Production
Electricity production is at the heart of the energy transition. While it represents 38% of primary resources consumption, it accounts for only 20% of final energy consumption. This is due to the high level of energy losses incurred when transforming primary resources into electricity.
In electricity production, fossil fuels (oil, coal, natural gas) are combusted. The combustion heats up a coolant that then expands. Such expansion results in an increase in pressure that drives mechanically the rotation of a turbine. The mechanical rotation is transformed into electricity thanks to an alternator. From start to finish, calorific energy is transformed into electrical energy through a mechanical conversion. The multitude of the transformation at each of the various steps and the associated losses make electricity production an inefficient process. On average, 60% of the calorific energy is lost in the transformation.
Nuclear energy is produced in like manner. Instead of combustion as for fossil fuels, it is the nuclear fission reaction that creates massive emissions of heat. Most renewable energies operate under different principles. Hydro-electricity uses the potential energy of moving water. Once the water is released from a dam, it gains speed and is used to directly rotate turbines within the dam. Wind farms use the kinetic energy of the wind to rotate turbines. Photovoltaic energy uses solar radiation which produces electricity by actuating semiconducting materials. Finally, geothermal energy or concentrated solar plants operate in a more traditional way as they use heat to expand a fluid and create mechanical pressure. Geothermal energy harnesses the natural heat deep inside Earth, while concentrated solar uses the heat of the sun.
One of the main characteristics of electricity is that it cannot be stored. This means that production needs to balance out consumption at all times. Excluding losses in distribution, production always equals consumption.