Intermittency – in one word, the main problem facing many (not all) forms of renewable energy; in the UK, principally wind and solar, and now tidal (Hinkley Point C got the go-ahead despite its cost. So why not Swansea Bay? 27 June). So far, electricity from these renewable sources has been in modest amounts, and intermittency has been dealt with (I simplify, but only slightly) by backing-off gas-fired combined cycle (CCGT) plant which, together with nuclear, forms the backbone of the UK electricity generating system. When the wind is not blowing or the sun is not shining, CCGT plant is there to take the strain.

But this simple strategy fails if wind, solar, and now tidal presume to take over this backbone role. Smart metering (affecting consumers’ usage patterns) and international power exchanges can help, but the main action has to come from energy storage and regeneration plant, involving a new infrastructure to supplement hugely the existing pumped storage capability. This is bound to have serious cost implications, and until this is openly acknowledged, direct comparison of projected MWh costs from any intermittent renewable source with corresponding MWh costs from non-intermittent new nuclear generation is fundamentally invalid, and likely to be badly misleading.

Jim Waterton

Glasgow

• In my long experience of work as a public law specialist solicitor (now retired) Gideon Amos’s letter (28 June) is the first time I have seen a government inspector openly critical about the minister’s decision on the inspector’s report. If, as others are also saying, the ministers made their decision in reliance on a Treasury economist’s analysis which contained a “major mistake”, the decision can and should be challenged by an application to the high court for a judicial review. Or, better still and quicker, the ministers should voluntarily go back and make a fresh decision that takes account of all the evidence, including the experience of similar projects in France which have already been completed.

Robert Hinton

Brighton

• Domestic solar generation seized the imagination of UK consumers and, with government support through the feed-in tariff, around a million people spent their own money on installations (Report, 28 June). Treasury-led policy changes virtually killed this progress, severely denting consumer confidence and costing over 20,000 jobs. A more controlled reaction would have allowed the industry to continue to deliver efficiencies and drive down costs. The microgeneration certification scheme, the only government-approved standards body in the renewables sector, urges ministers to rethink assisting the sector which supports them in meeting their carbon-reduction targets. Given that the removal of the subsidy has had a much greater impact than expected, it should be urgently reviewed.

Dr Tim Lunel

Chair, MCSSCo, London

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