A colleague poses a hypothetical question, a good one. Suppose that an SNP administration keeps its nerve and Scotland, unlike England, rejects proposals for more nuclear power stations. Suppose, further, that we wake up in the 2020s to discover that ambitious targets for renewable energy, like most ambitious targets, have not been met. Do we then import English electricity?

That would be logical, but embarrassing, not to say expensive. If the country happened to be politically independent, it would also place us in a position of energy dependence, the very antithesis of self-determination. It might also make us seem a bit silly.

Such, though, is the problem with the anti-nuclear argument in a carbon-averse age. It is the problem that faces all those who say, often quite reasonably, that giant wind farms are a monstrous blight on a precious landscape. Where is the power to come from?

Alex Salmond has set his face against a new generation of nuclear stations to replace Torness and Hunterston: "no chance", he said at the weekend. His pair of Green allies at Holyrood naturally agree. In contrast, Alistair Darling, the Westminster Trade and Industry Minister, will today publish a white paper that is expected to nominate nuclear as an essential "option".

Politically, this is combustible stuff. It will produce a great deal of background heat, but not much light. It will suit the Scottish government's rhetorical purposes, for a while. But it does not answer the question: if not nuclear, what? If - a big if - Hunterston shuts in 2011, as scheduled, and if Torness follows in 2023, how do you replace fully 40% of our electricity needs?

You could rely on Vladimir Putin's gas, if that's your taste, the commodity that an authoritarian regime is deploying even now to bully and blackmail Europe's former Soviet states. You could pin your hopes for a while longer on diminishing oil reserves and the shrinking hopes of stability in the Middle East: just forget all pious talk of a carbon-neutral world and "energy security".

Meanwhile, you could, in theory, return to coal for base-load power to supplement renewables and compensate for their natural vagaries. Scotland still has plenty of seams to be worked, though the geology is challenging. Open-cast mining is more problematic, obviously, for environmentalists, but the SNP is perfectly correct to claim that coal could again be burned to generate power. New carbon-capture technologies promise minimal risk to the environment. At the moment, however, that's all they do: promise, at an unquantifiable cost.

Salmond would like to see a million domestic wind turbines as part of the energy mix. The idea - power from the people, to the people - is probably one whose time is coming. But when? How? At what price? It is one thing for David Cameron to stick up a vanity windmill in central London to improve his green credentials and power a couple of light bulbs, quite another to rewire all of Scotland. Whoever pays, and putting aside consumer resistance, that's a long-term, multi-billion pound project.

Such is the energy conundrum, however. There are no quick, perfect answers. There is no single clean, cheap, flawless resource capable of commanding universal support. Press a committed environmentalist on choices and brisk dismissals follow: no nuclear, minimal carbon on sufferance and nothing of any other variety capable of making a malign "impact". What's left?

The authentic environmental case turns, always, on the need to reduce energy use at every turn. Only then do renewables become viable. Wind power, wave power, biomass and the rest will not replace 40% of our electricity, even if an environmentalist could be persuaded to countenance a return to coal-mining as an alternative to clean-but-dirty nuclear. Green arguments depend on reduced consumption, almost as a moral imperative.

You might wonder, though, why the N word arouses such loathing. Friends of the Earth Scotland has been pleased to discover that a majority of MSPs agree with the campaigners in opposing new nuclear stations. But why should the planet's guardians detest an energy source that bears no guilt for global warming, that produces no CO2 to speak of, and that may even offer a solution to climate change? What's so bad about nuclear?

Three answers spring to mind. One is that nuclear accidents tend to be definitive. They do not resemble any other sort of industrial calamity. The promoters of nuclear say that a Chernobyl or a Three Mile Island is impossible these days. The public responds: they would say that, wouldn't they? The nuclear industry tells us that modern generators cannot lead to catastrophe, but the industry was free with such claims long before catastrophes struck. Hence the second answer. Rightly or wrongly, like it or not, nuclear is not trusted. You could say, accurately, that Torness and Hunterston have hummed away quietly for decades with few real problems. People think instead of Dounreay and Sellafield: different technologies for a different job, perhaps, but symbolic of reckless pollution, "mishap" after mishap, and a culture of dishonesty.

Not cheap, either. In the 1950s, famously, we were promised electricity from "atomic energy" so cheap it would hardly be worth metering. Instead, construction proved vastly expensive and the cost of decommissioning - never mentioned at the outset - turned out to be mind-boggling. That was before waste become an enormously costly and emotionally-charged conundrum.

Hence the final answer. For many, nuclear waste is the sticking point. They have good reason. They may have grown up in an industrial Scotland littered with slag heaps, where miners died young in their tens of thousands, where coal-tainted air blighted bodies and lives, but nuclear residue is different. It is different because the nuclear industry has no real solution for effluent that remains toxic for millenniums, beyond sticking the stuff in a very deep hole and hoping - I simplify the science somewhat - for the best.

Deal with these three factors and nuclear power becomes as advertised, the wonder of the age. Fail to deal with them and you offer, at best, a possible least-worst alternative. As is well-known, that has been good enough for the French. Lacking real mineral wealth, and disinclined again to be held hostage entirely by Opec, France chooses to rely on nuclear for 70% of its electricity. You can dispute the wisdom, but you can at least say this: good or bad, it amounts to a coherent energy policy.

That's our real problem, in Scotland and in Britain. Too many governments have ducked the challenge for too long. We wrecked coal, we dashed for gas, we embraced then rejected nuclear. Meanwhile, we spent an oil bounty on everything save preparations for a post-oil era. Then, ever alert, we discovered energy insecurity and global warming. If Scotland's new government appears short on perfect solutions that may be because it has arrived very late in this game. And because there are, actually, no perfect solutions.

Convince me of the viability, sooner rather than later, of coal and carbon capture and I will pick up where I left off, years ago, among those protesting against the construction of Torness. I'll even think about my own little windmill. I have a strange feeling, however, that the anti-nuclear argument is being overtaken, and overtaken fast, by the unfolding climate crisis.