The difficulty is in the laws of science. Fossil fuels developed in the earth over millions of years, but we consume energy in one year what took 10,000 years to concentrate. Renewable energy means that we must consume no more in one year than we create in that time.

There is plenty of available energy in the environment, for the solar budget is 15,000 times as much as we need, nearly all of which is re-radiated into space. In renewable energy, we have to delay that re-radiation long enough to use. The technical problem is that in its immediately available form, solar energy is so diffuse.

One litre of solid or liquid fossil fuel contains tens of thousands of times the energy of one litre of wind-turbine air moving at 20 knots, the speed needed for viable large wind turbines.

A 2000mw steam station using compacted fossil fuel can be housed in a single building.

Large turbines in suitable wind can generate about 10mw per sq km of land, so it needs 200 sq km to replace that coal station if wind blew continuously, but more to compensate for periods when some turbines are becalmed.

Waves one metre high have an extractable power of one mw/km of wave front. That coal station is equivalent to a 200km line of waves, which would just about stretch round the coast of Scotland. Again, the waves are not always high enough.

Biomass is a method of time-condensing energy in plant tissue. Solar energy at best is about 1.3kw/sq m, but only about 4% is converted to tissue. Biomass is carbohydrate, a poor fuel for vehicles because of its low calorific value. Hydrocarbon fuels have several times the energy of the same weight of carbohydrate, which gives longer range for vehicles, but the real limiting factor is the lack of land available for growing biomass.

The above large magnitudes should be borne in mind. Solar energy cannot be harvested in small structures, so they will always be highly visible. In the US, there has been serious consideration of solar panels in the sunshine states of Texas, Arizona and California.

The necessary land area is more than 200,000 sq km, which will be of low environmental impact, for the earmarked land is desert.