Electricity Production from Renewables Energies

1.3. Renewable energy sources

In our time scale, renewable energies are those continuously provided by nature. They come from solar radiation, the core of the Earth and from the gravitational forces of the Moon and the Sun with oceans. We can distinguish several types of renewable energies: wind power, solar power, biomass, hydraulics and geothermics [MUL 04, RSS].

1.3.1. Wind energy

The available wind resources are evaluated on a global scale at 57,000 TWh/year. The contribution of offshore wind power (at sea) is estimated at 25,000 to 30,000 TWh/year, if we limit ourselves to sites, whose depth does not exceed 50 m. The global production of electricity in 2008 was about 20,000 TWh (which corresponds to a primary consumed energy of about 50,000 TWh, related to the low efficiency of the thermo-mechanical cycles, often ranging between 30 and 40%). In theory, wind energy could satisfy the global electricity demand. However, the main disadvantage of this energy source is its instability. There is often not much or no wind during very cold or very hot periods; and yet there is an increased energy demand during these periods. This is why we could envisage an important development of wind power, all the while associating it with other renewable energy sources, which would be less random or complementary, or have thermal sources or electrical energy storage devices. However, if there are many ideas to store electrical power in large quantities (notably pumped storage power stations), ...