Do proposed HVDC supergrids overcome all the problems of intermittency?

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Many sectors of the renewable energy industry are seeing unprecedented growth in deployment of existing proven technologies (solar PV, offshore wind) or major increases in research and development activity (biomass, biofuels, CSP). But advances in electricity storage seem to be proceeding at a much slower pace, perhaps because there is a belief that the creation of supergrids, possibly based on HVDC, will get around the problems by elegantly facilitating the balance of demand and supply over the wide area.

But such plans will take a very long time to come to fruition in Europe – a free trade area that spent decades attempting to standardise domestic electrical plugs and sockets, only to give up. And there is an enormous amount of effort required to establish the appropriate pan-European financial systems to support such an approach.

Traditional demand-side management and peak-levelling techniques that have been developed in the past, including large-scale projects such as pumped hydro schemes, are unlikely to be sufficient to deal with the variations created when dozens of GW of wind-powered or solar generating capacity is brought on stream in various European countries – and the prospect of using CCGT power plants on spinning reserve is unlikely to be viewed with delight by generating companies.

The multiple national and bi-lateral proposals to increase the reach of power grids – perhaps using HVDC transmission –should go some way towards levelling load and better matching generation with demand. But are bigger grids the only answer, and if not, does energy storage technology R&D, in areas such as flow batteries, molten salt towers, flywheels, compressed air and so on deserve greater support? It is also a great deal easier to store heat than to store electricity, so more effort might be made to consider combinations of generation and storage technologies that take into account end uses. This would make a big difference to the viability of, say, biogas fuel cells or combined heat and power installations. It would be a mistake if storage became the forgotten branch of the vigorous renewables technology industry.