Production factor of renewable energies
Newspapers and the Net are full of reports about the installation of wind and solar farms, all over the world. Good news! The electricity produced will be “clean”, with no CO2 emission, and no consumption of precious fossil fuel.
Unfortunately, there are limitations to the extension of these sources of energy. One major factor is energy density. Let’s see some figures to illustrate this.
Because of fluctuating electricity generation, the “production factor” of wind mills and solar panels is in average around 25% and 15% respectively. This means that the yearly energy production of a 1 MW generator is equal to (1MW x 365 days x 24h x 0.25) = 2200 MWh for a wind mill, and equal to (1MW x 365 days x 24h x 0.15) = 1300MWh for a solar farm.
As a comparison, a thermal power plant, using coal, gas or nuclear fuel, has a production factor generally higher than 85%. This means that the yearly energy production of a 1000MW power plant is equal to (1000MW x 365 days x 24h x 0.85) = 7500000 MWh = 7500GWh.
The limits of renewable ernergies
Consequently, in terms of produced energy, a 1000MW power plant (which is a typical power for a conventional power plant) is generating the same quantity of energy as 3400 (1MW) wind mills or 5700 (1MW) solar farms.
If the wind mills are erected 100 meters apart, this represents a line of 340 km.If we consider a solar panel efficiency of 150W/m², the area of the solar panels would be equal to 38km² (6.2km x 6.2km).
This shows the difficulty to increase significantly the part of renewable energy generators such as wind mills and solar panels.