It was some bitter irony the election of Donald Trump as US president came during climate change talks in Marrakech.

Just as we heard 2016 could be the hottest year on record, just as sentiment around the renewable energy sector was mounting new heights, a political hand grenade was thrown into the ring from mid-West America.

Trump has had only contemptuous words for global warming memorably insisting it was a Chinese hoax to undermine America.

On the campaign trail he vowed to scrap the Paris climate change agreement ratified by Barack Obama barely two months ago.

One of the former game show host’s first acts since he beat Hillary Clinton to the White House last week was to appoint another climate sceptic, Myron Ebell, to head up the Environmental Protection Agency.

Trump has promised to bring back coal and get America drilling for oil again at full speed while disdaining Clinton’s message to build the US into a world number one renewable powerhouse.

So is it all doom and gloom for clean tech in a world which also threatens to become increasingly protectionist too? Will Trump influence negatively impact already fragile green business confidence in post-Brexit Britain?

It would clearly be foolish to think that Trump’s accession can be positive, even if over the past week he has pedaled a slightly softer line on issues such as the Obamacare health programme and that infamous pledge to build a concrete wall with Mexico.

He may yet realize that threats to send cheap Chinese solar panels packing back to Shanghai might be counterproductive.

Even if he did try to unpick the Paris climate agreement it is expected to take years to complete. And he may have other priorities.

But the real reason why renewable power should not be devastated by governments run by Trump – or even Theresa May – is that it is on a roll. The price of clean power is falling all the time and even if politicians are unwilling to act on that, many businesses are taking matters into their own hands anyway.

New estimates from the Department for Business, Energy and Industrial Strategy released last week showed government expects the costs of large-scale solar PV built in Britain to fall to £67 per megawatt hour by 2020. That compares to the £92 figure used just three years ago and the £92.50 subsidy used for Hinkley Point C nuclear power station running for 35 years.

The solar figure for 2030 assessed by BEIS is £60, cheaper than onshore wind and combined cycle gas turbine plants.

That is exciting but also depressing. Why is it that government consistently underestimates renewables? Is it partly because the civil service takes too much advice from fossil fuel-based utilities and “consultants” closely linked with more traditional power sources?  

Meanwhile the May government has taken power in an atmosphere where the European Union has been disparaged, not least for supposedly loading the UK with unnecessary regulatory burdens. Could environmental ones be unwound, and with them all the European renewable targets?

They still could be even though Greg Clark, the new BEIS secretary of state, has tried hard to allay fears.

He is not allowing solar to compete on Contracts for Difference subsidies – which is a mistake – but he is at least pressing ahead with calls for evidence on the future of the UK’s energy system.

Look around however and one sees many commercial concerns, hospitals and local authorities signing their own low carbon deals direct with power producers. Its not just about global warming, it’s about security of supply, convenience and falling costs.

Trump can slow a green revolution but he cannot stop it.