I agree with Andrew McKie's assessment of "the current batch of egomaniacs" and their disinterest in our national power supplies but to describe the 1970-80 decade as candle-lit is a bit much ("Shale gas is the answer to our ever-growing energy demands", The Herald, July 1).

The candlelight resulted from Ted Heath's Conservative Government's decision to introduce the three-day week. The primary cause was the price hike in oil supplies by the OPEC countries during the 1973 oil crisis.

The reduction in the working week was to reduce oil imports and enable the build up of coal stocks. Electricity supplies were cut off to all parts of the UK for three hours at a time on a rota system. The exceptions were hospitals, emergency services and the energy providers. This included British Gas HQ in London where I and many others often worked a six-day week, producing the pipeline maps from St Fergus to all places south as quickly as possible. This was to convey the natural gas lurking beneath Scottish waters to the people of the benighted south.

After a change of government in the mid-1970s, there was a return to the five-day working week and electricity was available whenever it was needed.

As Andrew McKie rightly states, there is a carbon cost to all potential forms of energy. There is also a carbon cost to living. The seven billion people on this planet exhale a lot of CO2. Their natural waste yields a great deal more and the effort expended in producing food for the world's population probably generates as much CO2 as the people exhale.

Carbon dioxide is not a pollutant; it is part of the natural process of life. In a bygone age the carbon cycle was a deal between the exhalers of CO2 and its absorbers as the trees and other vegetation produced oxygen for humans and animals.

Under the soils of Yorkshire and Lancashire lie billions of tons of coal, enough to continue rates of extraction similar to the 1940s (250-300 megatons) for 300 years. By all means get the shale gas if we must but put some miners back to work while some of the skills are available. Modern mining methods will not lead to ground subsidence at the surface, unlike fracking.

As for bings, James Young of Bathgate, who patented the process of producing oil from shale in 1850, generated a large one on his way to fame and fortune. These days such waste material would be feedstock for road building, plugging holes in sea wall defences and building airport runways.

Additionally, the pyrolysis of shale produced not only a fuel gas but oils and other by-products. In the years up to and during the First World War, Scottish shale oil production was in excess of 2,000,000 tons per annum. Production continues in many countries, including China, Russia, Estonia, Germany, Brazil and most recently the US.

Whatever carbon cost has to be met because of the exploitation of such fossil fuels the answer lies in planting more trees since they are the real experts in carbon capture.

Philip Blanshard,

The Old Schoolhouse,

Berriedale, Caithness.

Andrew McKie is much too complacent about the dangers of the dubious method of shale gas extraction, termed fracking. In relation to the earth tremors which accompanied fracking tests near Blackpool, he observes that since coal mining can also be equated to minor seismological events we need not be concerned.

The science tells a different story. Recent research reported in a geological sciences journal points to direct links between fracking in the US and a magnitude 5.7 earthquake in the near vicinity. This is not insignificant.

Furthermore, extensive testing near shale gas extraction wells, again in the US, has discovered that ground water pollution has occurred within a one-mile radius of the well head for nearly all wells tested. This is further compounded by the detection, by satellite, of serious methane leakage into the atmosphere from the vicinity of the majority of fracking installations.

In the US some of these disadvantages of fracking can be tolerated because they exist in the vast expanses of meagerly populated terrain. Nevertheless, recent reports suggest that even the gung-ho Americans are beginning to question this technology. In crowded Britain the technology has little chance of securing public acceptance.

Finally, fossil fuels range in energy content from 30-45 megajoules/kilogram, with coal at the lower level and gas at the top. For a given amount of energy consumed it makes essentially little difference what form of fossil fuel we use, the pollution of the atmosphere with carbon is much the same.

So gas is not cleaner than the alternatives, as Andrew McKie suggests. It most certainly is not cleaner if it is consumed in addition to the oil or coal it may replace. On current global growth pressures, it seems highly unlikely the unused coal or oil would be allowed to remain safely below ground.

Alan J Sangster,

37 Craigmount Terrace,

Edinburgh.