PROFESSOR Paul Younger’s input to the fracking debate (“Fracking expert: Sturgeon playing into hands of Putin”, The Herald, May 11) is most welcome, as much of the anti-fracking discussion is not based on the scientific or engineering evidence. While there are issues with fracking which need to be resolved, it would not be sensible to cut ourselves off from this resource. Public opinion is very often not well informed and can be based on prejudice or an often misplaced Green agenda. It is the duty of government to ensure that all the evidence is gathered and to base judgments on information not on gut feeling or political expediency.

While there is a need to introduce more renewable energy into the mix for electricity generation the variability of wind energy cannot meet the daily variation in demand. It is instructive to look at the web site www.gridwatch.templar.co.uk which shows how the UK demand for electricity is supplied by the different sources. For the last few months when the output from coal-fired stations has been quite low the steady demand has been met mainly by the nuclear stations and the variation in demand by combined cycle gas turbine plant which is more efficient than coal and produces less CO2 per Megawatt-hour. Some variation has also been supplied by pumped storage hydro stations. On many days the total wind output for the UK has been less than the generating capacity lost by the closure of Longannet. This happens quite frequently at the height of winter when the UK weather is dominated by an area of low pressure and demand is much higher than it is now.

In addition to production of electricity, the use of gas for domestic and industrial uses needs to be considered as has been very well explained in Gary Smith’s letter (May 12). If the supply of gas from the North Sea is to continue to fall and coal stations made to close to meet requirements for reduction of greenhouse gases where are we to get the gas to fulfil our needs? Those who close their minds to the possibility of gas from fracking do need to answer this question.

Louie Macari,

42 Imlach Place, Motherwell.

MORE than one million wells have been fracked in North America and Professor Andrew Watterson (Letters, May 12) couldn’t point to one significant environmental incident. No doubt there will be lots of work for his department, filling in the research gaps he identified, but what about the Scottish workers who rely on both affordable and dependable energy for our livelihoods?

If only Scotland could package and export its professional environmental lobby, no need then for a greasy manufacturing industry. Unfortunately, only the Scottish Government is gullible enough to consume their output, having left the post of Chief Scientific Adviser vacant for two years.

Had Prof Watterson's "precautionary approach” been applied to mobile phones, and we all remember the Green hysterics over the masts, Scots would still be calling using curly cords. He is pontificating at the expense of meaningful experimentation and knowledge: drilling and testing wells here in Scotland is the only way to evaluate fracking and redeem our faith in the scientific method.

Calum Miller,

24 Polwarth Terrace, Prestonpans, East Lothian.

THE excellent letter from Gary Smith of GMB Scotland was marred by the fact he has underestimated the cost of replacing gas for central heating by electricity by a large margin.

Currently the average energy user on a dual fuel tariff uses 3,500 units of electricity and 21,500 units of gas a year. Hence based on a unit price of electricity of 12p and that of gas at 3p (if his assumption of gas being four times cheaper is correct) gives a total annual bill of £945. However, 25,000 units of electricity a year at 12p a unit gives an annual bill of £ 30,000 a year. Mr Smith had forgotten that dual fuel consumers use seven times more gas than electricity.

Incidentally, I note that no politician has replied to my query that if the SNP review identifies fracking as an unsafe operation, then will Holyrood ban the imports of shale gas to Grangemouth from the United States?

I Moir,

79 Queen Street, Castle Douglas.

PROFESSOR Paul Younger avers that the contamination of ground water due to fracking is a “red herring” with regard to any future Scottish activity. But it is difficult to see how such a claim can be justified. For the densely populated central belt of Scotland very large numbers of residents will be located cheek by jowl with at least some of the many wells. They are likely to be exposed to contaminated ground water for many years, so even if the immediate levels of contamination are small long-term effects cannot be known.

In the United States, extensive testing near shale gas extraction wells has discovered that ground water pollution has occurred within a one-mile radius of the well head for nearly all wells tested. Furthermore, a new study from the Johns Hopkins Bloomberg School of Public Health has linked hydraulic fracturing to premature births and high-risk pregnancies. Pre-term births were 40 per cent higher among women who lived in areas of intense drilling and fracking operations, and the pregnancies of these women were 30 per cent more likely to be considered “high-risk,” according to the study. These are worrying statistics.

However, it is not just ground water contamination which is of concern. The dangers of fracking are compounded by the detection, by satellite, of abnormal methane leakage into the atmosphere, from the vicinity of the majority of the scanned fracking installations. Methane is a powerful greenhouse gas which traps 86 times as much heat as carbon dioxide over a 20 year period. So even small leaks could have a large climate impact.

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 of well activity. The residents of northern England are well aware of the earth tremors which accompanied fracking tests near Blackpool. Such reports will make them increasingly wary of fracking in their neighbourhoods, and so they, and Scottish residents sitting on shale, should be.

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

Alan J Sangster,

37 Craigmount Terrace,

Edinburgh.

NOWHERE in your account of the attack by Professor Paul Younger on the Scottish Government’s stance on fracking is there mention of the cost per fracked barrel.

In 2014 it was reckoned at between $ 20 and $ 50 while the Brent Crude price was north of $ 100.

This was when Ineos made its key investment decisions for Grangemouth. Brent has since fallen to $ 42, and the earlier surge of investment into light oil, shale gas, and so on looks imperilled: posing in fact a severe threat to the US economy. They have to sell the stuff. Hence Ineos's Dragon Class tankers. In happier years we could have built them.

So has Prof Younger's rhetoric much relevance? Though his ideas on geothermal technology look useful, please forget fracking in Scotland. Too many people (unlike Wyoming), old collieries, shale wasteheaps – too much legal expense. You'll save more carbon by raising road tax to wipe out our gas-guzzling 4x4s.

Professor Christopher Harvie,

West Avenel, 50 High Cross Avenue, Melrose.

NOT without a slight amazement have I read in the Herald about a “fracking expert” claiming that “the only real winner of this [non-fracking in Scotland] is Vladimir Putin”.

If the integrity of this expert’s scientific research matches the quality and objectivity of his foreign policy analysis, I would think twice before taking his arguments for granted in any judgment.

Andrey A Pritsepov,

Consul General of the Russian Federation in Scotland,

58 Melville Street, Edinburgh.