THE objections raised by Richard Philips (Letters, March 28) and Bruce Postlethwaite (Letters, March 29) regarding our renewable hydrogen proposals a stated in Neil Mackay's article ("The key to health and wealth? Bottled sunshine and wind", The Herald, March 26) would doubtless be agreed by many. However, recent advances in technology change considerably the outlook for self-sufficiency in green energy and the viability of our "Greenprint".

First, is the emergence of solid-state ammonia synthesis to produce ammonia directly from air, water and renewable energy that is rapidly decreasing in cost. The second is a recent breakthrough to break out hydrogen from ammonia for low cost. Details of these technologies are provided in our Hydrogen Scotland paper at

While ammonia produced and transported under such conditions could be economically viable our proposal is not to transport it (as Australia is gearing up to do on a massive scale to Japan and South Korea) but to use it as a battery. By this we mean producing and storing ammonia on disused oil and gas rigs servicing offshore wind farms for conversion to hydrogen then using fuel cells to provide electricity during periods of low winds.

Further, as we envisage a vast array of floating wind farms (the first now operating in Scotland) each serviced by a disused rig it should be possible to optimise the process of harnessing wind energy across the array to ensure a stable supply to meet a great deal of the needs of what we refer to as a European Supergrid. Also proposed is the prospect for the use of graphene as a superconductor to reduce to near zero electricity transmission losses throughout the grid.

It is our view that the proposed outlays of several hundred billion dollars in prolonging the life of North Sea oil and gas would yield a much lesser return on investment than our proposal, even by ignoring the vastly greater range of skilled, safer jobs that would be created and avoidance of the ever more critical damage costs of continuing to use carbon-based fuels.

We are not against the use of natural gas. Our proposals, contained in our Overview paper make a case for fracking where large-enough onshore deposits are located and making carbon-neutral use in situ of the natural gas extracted. An emerging process for doing this involves extraction of carbon as graphite (for electric car batteries) and hydrogen. Further, processing of the graphite to graphene (for use as a superconductor) is under development with carbon negative targets for both processes.

Donald MacRae,

46 Beauna Vista Drive, Rye, Victoria, Australia.

I WRITE, not to challenge the undeniable catastrophe of global warming, although I do harbour the notion that at least in part, this phenomenon is influenced by cyclical conditions such as the wobble of our axis, variations to our orbital journey and such like, all of which have effects on the Jet Stream and tidal programmes, such as the Gulf Stream and so on.

However, I write here seeking an answer to what is possibly to some, a very simple question, but which, when put to acquaintances with higher IQs and more advanced education than mine, tend to reply “I simply don’t know”; nor does Google provide a concise solution.

Perhaps I did not pay sufficient attention to the lectures of our Hyndland Secondary School’s principle science master Mr Willkie, but my understanding is that water expands when frozen, therefore taking account of Archimedes and the cause of his apparent triumphant yell of “Eureka”, water, in the form of ice, should displace more volume than it adds in its previous molten state.

Why then, when the ice of the polar caps melts, is it believed that they will cause ocean levels to rise? This performance, at least to my simple engineering mind, seems to be somewhat contradictory.

Can someone therefore, with a greater knowledge of physics or geology, please provide an understandable explanation, or perhaps we may hear from others, who are equally confused by this quandary?

Ian Cooper,

Flat 3/3, 1 Jackson Place, Glasgow.