In 2003, the nuclear industry was very nearly killed off in Britain. In 2009, it is so resurgent that captains of the energy industry are arguing it is renewables that should be killed off, or at least kept on a starvation diet.

Today, the Confederation of British Industry has thrown its weight behind the nuclear industry's calls for the government to scale back "overambitious" wind power targets in favour of atomic energy. Two foreign-owned energy giants, E.ON and EDF, have recently told the government it must essentially choose between new nuclear and major renewables developments. With global warming, energy security and fuel poverty all rendering energy policy a matter of life and death today, in their own ways, this new polarisation in the nuclear debate is a desperately dangerous development.

In 2003, just before the government completed its first energy white paper, nuclear power was kept alive only because a few mandarins insisted language be inserted about a review in five years. Five years of half-hearted government efforts to mobilise renewables and efficiency ensued. Looking back now, many of us in the renewables industries see the dead hand of a civil service Sir Humphrey in the slow-motion episodes of real-life Yes Minister that we lived through. The proportion of renewables in the UK energy mix was about 3% back in 2003. It is about 3% now. With the best renewable resources in Europe, the UK is third from bottom of a European league table topped by Sweden with 40% renewables in the energy mix.

Meanwhile, renewables industries globally have been, and are, growing faster than almost all other industries. 2008 was the first year in which more renewables capacity came onstream than fossil fuels and nuclear combined, in both Europe and America. Over the past five years, the solar photovoltaics industry (PV) has grown 600%. Wind has grown 250%. Hundreds of thousands of jobs have been created.

Renewables companies that didn't exist at the turn of the century ride high in stock exchanges. The German government has shown, in a national scaled experiment, that national economies can be run entirely on renewables, overcoming intermittency and covering "baseload" by mixing and matching different members of the renewables family. The renewables industries claim they can run the global economy entirely within 20-40 years.

Swimming against this optimistic tide, EDF and E.ON are now warning the UK government that efforts to get to 20% renewables in the energy mix – the official EU target – are not only unrealistic but damaging to nuclear plans. Additional carbon-generating plants will be needed because of intermittency, they say, ignoring the German experience. The EDF CEO, Vincent de Rivaz, says he is concerned that high levels of wind construction will require new British nuclear plants to be shut down when the wind output is high.

The truth is that there is only so much money available, and the nuclear advocates – scared by the growth rates of renewables – are scrabbling to ensure most of it goes to them. De Rivaz has yet to persuade his owners, the French government, that his plan to build four British reactors at well over £4bn each makes commercial sense. He has made it clear to Whitehall that he will need major subsidies.

And so the battle lines have been drawn for a new phase in the long-running fight to win hearts and minds. The backers of nuclear will argue that grown ups can't expect to get enough energy from renewables, that renewables are too expensive, that they can't cover baseload: arguments that increasingly struggle in the face of fast-emerging real renewables experience abroad. The renewables advocates will argue the reverse.

We will push our trump card hard: that our costs, on the whole, are falling, while nuclear's are rising. This means that most renewable electricity will soon be cheaper than nuclear electricity in most markets, and will inevitably fall yet further. This in turn means that the market-enablement mechanisms we need of government – feed-in tariffs, renewables obligations and the like – can be temporary, while the nuclear industry will need subsidies that extend essentially forever.

Whatever the logic of the arguments, though, one thing is clear to me, after all these years. This is a battle of cultures. In the big energy companies, and across much of the top of the civil service, many people with grey hair find great difficulty thinking that things can be done differently in energy policy, and/or want to hold on the centralised power that centralised power plants offer.

In the renewables industries, a lot of people (generally without grey hair) know that things can be done both differently and better. We know too that decentralised power democratises energy: it delivers power to the people both literally and metaphorically. This is an idea that makes many aged civil servants and energy bosses reach for the dirty tricks manual.

Meanwhile, behind the arcane language of the public debate, energy policy remains a matter of life and death.

• Social entrepreneur and author Jeremy Leggett is founder and chairman of Solarcentury, the UK's largest solar solutions company.