For once, ministers have put their money where their mouth is – into taking another stab at nuclear power. This week the business secretary, Greg Clark, announced plans to pump £5bn into a new nuclear power station at Wylfa in north Wales. It was a reversal of a longstanding Conservative policy not to underwrite nuclear construction. So why the sudden enthusiasm? And what does Clark know that the rest of the world does not?

For almost everywhere else, governments and corporations are pulling the plug on nuclear. Even in a world fearful of climate change, in which nations have promised to wean themselves off fossil fuels by the mid-century, almost no one wants to touch nuclear.

Germany will be nuclear-free by 2022. France – once Europe’s great nuclear advocates – is backtracking. President Macron is committed to cutting nuclear’s contribution to grid power from the 75% to 50%. Seven years after the Fukushima accident, all but a handful of Japan’s 54 nuclear power plants remain closed.

US utilities are shutting reactors fast too, even those with years of their operating licences yet to run. In America’s deregulated energy markets, nuclear cannot compete. Last week President Trump called for the utilities to suspend closures, citing national energy security. He may resort to the law to get his way, but even Trump is not demanding new reactors.

Meanwhile, the state-sponsored nuclear enthusiasm of China, recently the world’s premier builder, has dimmed. Beijing has issued no new construction approvals for over two years. Only Russia keeps up the momentum – which puts Britain in an embarrassing club.

Britain hasn’t completed a new nuclear power station for 23 years. The government’s professed reason for its newfound enthusiasm is fighting climate change, and in particular the need to find replacements on the grid for the remaining coal-fired power plants that it has pledged to shut by 2025. But while the cause is correct, the solution is increasingly at odds with the rest of the world.

Yes, nuclear is a proven large-scale source of low-carbon electricity. But renewable sources like solar and wind are both now cheaper, and are becoming cheaper still, while nuclear costs only rise.

Some who call themselves “eco-modernists” argue that nuclear and renewables would make a great mix: nuclear could fill in when the sun goes down and the winds drop. But there is a problem. Any effective stand-in for fickle renewables needs to be available at the flick of a switch. Hydropower or natural gas can do the job, but not nuclear. Its forte is to deliver constant baseload power.

The wind turbines of Burbo Bank offshore wind farm in the Irish Sea, near Wallasey, England. Photograph: Christopher Furlong/Getty Images

If nuclear ticked enough other boxes, it might still have a role to play in keeping the lights on. But it has always been a bad neighbour and troublesome citizen. Some of our fears about radiation may be exaggerated, but they are real fears nonetheless. And nuclear power’s links to nuclear weapons are not just about shared technology – at least not while Britain remains home to the world’s largest stockpile of plutonium.

We are sitting on 130 tonnes of a human-made element that lies at the heart of most nuclear weapons. The stockpile is at a warehouse at Sellafield in Cumbria, in defiance of warnings from scientists at the Royal Society a decade ago that in its present form it poses a major security risk, whether diverted for weapons or breached by terrorists.

The plutonium was manufactured over decades from used power-station reactor fuel. Britain wanted to be at the forefront of a new global industry using plutonium to fuel new designs of reactors. But production continues even though there is no sign of a world market for plutonium. And neither the new Hinkley Point reactor under construction in Somerset, nor the proposed plant at Wylfa, will burn the stuff.

The government seems determined to pursue a nuclear dream, even though it has palpably failed to come to terms with the toxic legacy of the country’s nuclear past.

Next to the site of the planned Wylfa plant sits the shell of an old nuclear power station. It was shut in 2015, but is not scheduled for demolition for almost another century, in 2105. It is one of 11 former plants that sit abandoned around our coastlines, from Dungeness in Kent to Trawsfynydd in Snowdonia, and Sizewell in Suffolk to Hunterston in south-west Scotland.

They are currently being put into what the industry terms “care and maintenance” – mothballed while their radioactivity decays, and until the government’s Nuclear Decommissioning Authority can find somewhere to put their remains.

On present form, that day may never come. Britain is today no nearer agreeing a final resting place for its most dangerous and long-lasting radioactive wastes than it was back in 1976, when the royal commission on environmental pollution said we should build no more nuclear power plants until that problem was resolved. Absurdly, the most recent plan has been to bury the waste in tunnels to be dug beneath the Lake District national park.

Nuclear power today is a largely friendless industry: uneconomic without heavy government support, uninsurable, stuck with a military heritage from hell, overtaken by cleaner competitors, beset by waste problems that no one has resolved, and always vulnerable to public panic after the Chernobyl or Fukushima accidents.

Some believe it may have a future when the waste problems are resolved and if radical new reactor designs emerge. That may be so. But the truth is that in the 60 years since the bomb-makers first promised us “atoms for peace”, nuclear power has gone from a sunrise to a sunset industry. Only the British government seems not to realise it.

• Fred Pearce is the author of Fallout: A Journey Through the Nuclear Age, From the Atom Bomb to Radioactive Waste