Spectacular Waste of Electrical Energy
Almost three quarters of the 13 billion tons of oil equivalent of primary energy produced every year are actually transformed (© OECD/IEA, Explore 2014). The transformation of oil into various products (gasoline, plastics, pesticides, etc.) generates around 16% of wasted energy. The transformation to electricity generates around 60% of losses and is the major source of wasted primary energy resources. As a whole, around 30% of primary energy is wasted. A full 80% of that waste comes from electricity generation. Electricity production is thus extremely wasteful (Fig. 5.11).
Traditional thermal power plants have an efficiency of around 30-40%. This means that three units of primary energy are required to produce one unit of transportable electricity. Conventional electricity production is therefore incredibly inefficient. To produce electricity, an alternator transforms the rotating energy of a turbine into electricity through an electromagnetic reaction. Mechanical energy is therefore required to produce electricity. Most of the time, this energy comes from gas under pressure which, as it expands through the turbine, forces the rotating movement of the turbine. This gas can be obtained from any coolant. It can be steam or gas. In combined cycle plants, there are even two generators: one supplied with natural gas, the other with vapor generated from water heated up by the exhaust of the gas from the first generator. In any case, the gas needs to be heated up to expand and therefore create mechanical pressure on the turbine. It is this heating process (burning of oil, gas, coal or nuclear fission), in a boiler, followed by a double transformation into mechanical and then electrical energy which leads, by its natural inefficiency, to yields around 30-40%.
Fig. 5.11 Transformation and losses of primary energy (© OECD/IEA, Explore 2014)