By Alex Kirby
BBC News Online environment correspondent
If all goes to plan, the UK in 2020 will look and feel a very different place from today.
Coal is in its twilight years in the UK
Round the coast will be wave, tidal and wind farms, generating huge amounts of renewable energy.
Buildings will use solar power for heating and ventilation, with perhaps enough left over to sell to the grid.
And there will be few pitheads or nuclear power stations dotting the distant horizon.
That is the future outlined in the government's Energy White Paper - a low carbon future which will rely increasingly on renewable sources and energy efficiency to cut emissions of greenhouse gases.
The UK has come a long way in a short time to dream up its clean, green future. It has written off a lot of its past on the way.
On the slide
Twenty years ago, a UK without coal as the main muscle of its economy would have been unthinkable.
Then the miners took on Margaret Thatcher and her government, and lost.
But the writing had been on the wall for coal for decades before that. Oil was simpler to use, and cleaner and safer as well.
Solar-generated power could provide 10,000 times more energy than the world currently uses
Nobody, except a few scientists, was talking about climate change, or had even heard of it.
If Mrs Thatcher deposed the miners from their place at the apex of Britain's industrial aristocracy, coal itself was already on the way out.
There was another rival as well - nuclear power, sold to Britons with the promise that it would provide "electricity too cheap to meter".
They are still waiting, though more in hope than expectation. They are waiting too for the nuclear industry to find a safe way to dispose of its wastes, and to sever the link to the military thinking which spawned it.
So now the way to the sunlit uplands of a non-polluting, well-heated UK lies through greater energy efficiency and increased reliance on renewable sources.
Blessed by Nature
Both make good sense. The cost of the energy wasted in the UK annually is estimated at a prodigious £5bn.
There are real savings in mundane actions multiplied millions of times - insulating buildings properly, not leaving TV sets on standby or overfilling kettles, using low-energy lightbulbs.
Nuclear power has not delivered
There is massive scope for exploiting the British geography, scoured by the North Atlantic's gales and tides, to generate electricity. And the technology is coming along to store it until it is needed.
The UK company Solar Century says it is even possible to use the Sun in the notoriously cloudy UK - because the latest devices rely on light of any sort, not specifically sunlight.
Size does matter
It says: "Solar-generated power could provide 10,000 times more energy than the world currently uses.
"If we covered a small fraction of the Sahara desert with photo-voltaic cells, we could generate all the world's electricity requirements."
The answers are there. Using them would also destroy any argument for securing access to foreign energy supplies, whether Gulf oil or North African gas.
All that is needed is governments prepared to think small and to help individuals to make incremental changes. Perhaps it will happen.