By Richard Black
Environment Correspondent, BBC News website
How should Britain generate its electricity in the coming decades?
It is a question that the government is wrestling with, as are the private sector companies that actually make and deliver power to homes and businesses around the country.
Now you can have your say.
The BBC News website's electricity calculator lets you choose your ideal generation mix to power the country in 2020.
Are you wowed by waves and wind? Are you a freak for fission or fossil fuels?
Open the calculator, have a play, make your choices.
But be aware that what you think is an ideal option may turn out to have a sting in the tail, in terms of price or climate change.
Time of change
Academics have been saying for almost a decade that Britain has an energy crisis coming if big decisions are not taken; now the wolf appears to be at the door.
Over the next decade or so, we will lose as much as 20% of our existing capacity.
Almost all of Britain's remaining nuclear reactors are to close as they reach the end of their working lives.
About a third of its coal-fired power stations will also close under the terms of a European pollution directive.
Meanwhile, demand for energy in all its forms rises inexorably.
Do nothing, and the lights will at some stage go out.
Currently most of our electricity comes from fossil fuels, principally natural gas and coal. Nuclear reactors provide about one-fifth, and the remaining few percent are split between renewables, mainly wind turbines and hydro, and imports.
Use more coal and gas, and Britain's greenhouse gas emissions will soar; boost renewables heavily and there is a price premium.
Nuclear reactors come with concerns over safety and waste, while raising imports would increase Britain's exposure to the vagaries of international energy markets.
Another approach would be to reduce demand through energy efficiency measures. But there is a limit to how much can be done this way; and it is not necessarily free.
Energy efficiency and insulation can only do so much
The calculator is not an exact tool; many of its projections rely on things we cannot know for sure, such as fluctuations in natural gas prices and the cost of building new nuclear reactors.
But we have made it as precise as we can. A substantial amount of solid research time has gone into identifying and analysing reports, data and projections.
You may have questions about where the data has come from and how we have used it, and we have given some answers in our FAQ pages.
Now it is over to you. We will collect the choices you make - anonymously - and publish them at some stage as a snapshot of opinion from our readers. Enjoy!