No-one likes losing amenities, but the task of collecting alternative energy is formidable, and sacrifices are necessary.

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.

Chris Parton, Uddingston.

The decision by Scottish Ministers to give their consent to the proposals for a wind farm at Gordonbush is premature (The Herald, April 10).

Many issues remain unresolved and lessons have not been learned from other wind farms constructed on deep peat. It is a political decision rather than one based on best environmental practice. The site is completely inappropriate. Other industrial brown field sites are available and should be used before damaging pristine areas of wilderness beyond repair. How many more areas of Sutherland, both on- and off-shore, will be sacrificed in the pursuit of the fantasy wind energy as the answer to a politician's dream?

The current Scottish Government is pushing through plans to export surplus renewable energy to Norway without any form of consultation. To generate the surplus energy necessary, many areas similar to Gordonbush will be lost. There may be short-term gains but there will be long-term losses which cannot be measured in financial terms.

Allan Tubb, Golspie.

I write in full support of Messrs Mitchell and Lindsay (Wind farms despoil Scotland's wild places, April 11). I would particularly like to highlight three words used in relation to generating capacity: insignificant, uneconomic and unreliable. When will our politicians recognise that these monstrosities bring little or no benefits to anyone, other than the developers and the land owners? We, the consumers, have to pay inflated costs for the little electricity generated and put up with a destroyed landscape, for negligible gain.

They are factories comprising huge turbines, and are nothing other than industrial units, regrettably placed in the most conspicuous and, very often, the most attractive of places. If they are so wonderful, why doesn't our government start promoting Arthur's Seat in Edinburgh, as a potential site? It is certainly windy enough.

John A Douglas, Lochwinnoch.