JENNY Hogan's article on the role of renewables contains some half-truths and misleading inferences ("Time truth was told about the vital role of renewables in our wellbeing", Herald Agenda, April 22).
It is not true that fossil fuel generators are paid when they are "constrained off" the grid - in fact they pay National Grid for the fuel that they do not need to use. Only wind generators are paid, not for the electricity they do not generate, but for the consumer-paid subsidy they would otherwise collect.
The UK National Grid was never designed to take large amounts of intermittently-available electricity from the north of Scotland to consumers in the south of England. However, to upgrade the grid, and to provide backup and standby generation to deal with wind and possibly even more variable tidal power (zero to maximum twice a day) will more than double the cost to the consumer of subsidising renewables.
Many of those employed in the renewables industry are simply involved in the preparation of proposals. Others are in short-term construction jobs. There is essentially no continuing employment after wind farms have been built.
And what of the "huge potential" of our seas? Wave and tidal power are a long way from commercialisation. The likely practical potential of the former, if and when it can be developed, is actually rather modest, about 1.2GW, comparable to one small to medium-sized power station.
Offshore wind is a well-understood technology in the conditions of the Baltic and southern North Sea, but no developer has yet committed to construction, as opposed to plans, for the harsher environment of Scotland's northern waters.
It is not at all clear that renewables are working for Scotland, as opposed to working for French, German and Spanish energy companies, Danish, Spanish and German turbine manufacturers, and the makers of Chinese solar panels.
Jack W Ponton, FREng,
Scientific Alliance Scotland,
7-9 North St David Street, Edinburgh.