Going nuclear over rising power costs EDF, the French state-owned power company, can point to one big advantage of the nuclear power station it wants to build at Hinkley Point in southwest England. Once the reactor is turned on, it will churn out electricity at a steady price, unmoved by gyrations in wholesale gas costs. There may be a case for including nuclear generation in the UK's energy mix. However, predictability comes at a price. To make sure the plant is built, the government is having to guarantee an index-linked price of £92.50 per megawatt hour, roughly twice the current market rate. Few would bet on wholesale electricity costs holding steady at double their present level for 35 years - indeed, some experts expect prices to fall. Yet that is the wager the government has made on the country's behalf. It is a gamble that has seemed attractive before. Work on Sizewell B, the last nuclear power station to be built in Britain, began in 1987 shortly after a spike in gas prices. Like the reactor now planned at Hinkley Point, it was intended to be the first of a fleet of plants that would eventually meet a substantial portion of the UK's energy needs. The cost of the power generated by Sizewell B has been estimated at £85 per megawatt hour in today's prices. In part, that reflects the cost of customising an American reactor design to meet UK regulatory requirements, some of them imposed during a 340-day public inquiry that was the country's longest at the time. Subsequent plants, had they been built, would have been constructed more cheaply to the same design. But politicians lost their enthusiasm when gas prices fell and private operators proved unwilling to assume the risks of nuclear generation. For all the talk of a British nuclear renaissance, Hinkley Point may yet prove to be one of a kind. For years, the industry argued that new technology meant that reactors could now be built more cheaply. In 2006 Areva, the French nuclear technology company, quoted a price of £24 per megawatt hour. That has been exposed as fantasy. The deal announced by the government this week shows that the cost of nuclear generation has continued to rise. Politicians insist that the current estimates are realistic. But there are signs that hope may have triumphed over experience. The plant that EDF is building in Flamanville in France is now expected to cost two and a half times as much as originally thought. A full £2bn has been added to the cost of Hinkley Point even before any concrete has been poured. The government says that EDF and its partners will bear responsibility for any cost overruns. Its determination may be tested. Some of the debt issued to pay for construction will receive a public guarantee. That politicians are pressing ahead despite rising costs, at a moment when electricity prices have become politically charged, reflects the constraints they face. The UK's existing nuclear power stations are reaching the end of their lives, and its dirtiest coal plants are being shuttered to comply with EU rules. New capacity is therefore needed. The government refuses to allow coal-powered stations to be built unless they are fitted with equipment to prevent carbon dioxide from reaching the atmosphere - technology that has yet to be invented. Replacing coal with gas would reduce carbon dioxide emissions but probably not by enough to meet the government's stringent targets. Yet if new nuclear plants are needed to keep the lights on, that is because the UK has ruled out other options by adopting targets for emissions reduction that are among the toughest in the world. If policy makers believe these commitments are defensible even now that their cost has been laid bare, they should make their case. If not, they should reverse course. That this would be embarrassing is no excuse for saddling Britain with costs it cannot afford. The idea of legally binding "carbon budgets" may have made an attractive addition to Tony Blair's legacy when he proposed the idea in the dying days of his premiership. He was not the first politician to make incautious promises during a time of plenty. Nor was he the last; the coalition government seemed indifferent to cost when it committed to halve greenhouse gas emissions from 1990 levels as part of an effort to be the greenest government ever. However, the country should now ask whether it can afford to race ahead with emissions reduction while others drag their feet. The UK has decorated itself for an environmental record it has yet to earn. If these medals have become millstones, they should be cast off.