Imagine it is the winter of 2010 and Britain is struggling to generate enough electricity to cope with demand.
IF explores what would happen if a series of events led to a catastrophic power cut.
We want your thoughts and opinions on the issues raised by If...the lights go out.
This online forum is now closed.
I wonder how many days of darkness we would have to endure before the government realises that it is all well and good to talk about green electricity but the only way to produce large amounts of electricity without producing carbon dioxide is nuclear.
It is 25 years since anybody designed a nuclear reactor - we should be able to design something now that is a lot safer and more efficient than the current reactors.
I think a winter of power cuts coupled with food and water shortages, business layoffs, closed shops, and no Eastenders should be enough to change the minds of most of us.
Ray , Soton
Thank you BBC Two for the "IF" programme. I feel it brought the subject to a wider audience. It also reflected one of my private nightmares. A warm and well-lit home, yet I often ponder the likely problems facing me personally if the lights go out.
Within the 20 years that I have lived here, the lights have gone out so often that I lost count.
However, if that happens on the scale portrayed and the situation worsens as time passes (weeks or months) and winter follows winter, mass emigration could start to countries that would perhaps not be much warmer, but at least more civilised. Then it could be the turn of "us British" to queue at immigration controls and be sent back to the Isles.
The whole matter just screams out, "Wake up! you lot. Stop passing the buck and hiding behind old bits of paper. Get on now with the nuclear power plant programme".
Look across the Channel and see just how many stations are built and are being built in France.
S G Swan, Aldeburgh, Suffolk
The program on electricity pandered to the scare mongering rubbish that seems to be popular these days.
In the winter of 1990, major cities such as Nottingham were without power for several days following severe snow. After one day it lead to failure of the water supply. It was fairly unpleasant but there was no looting, no government crisis board, no ministers sacked and no people migrating to areas that still had power.
Why can't the BBC report serious issues like this using a balanced approach? It is this sort of reporting that leads to the panic buying we see in the US and increasingly in the UK.
Tom Booth, Reading
Why must the market be involved? Energy should be under national control and not economical control and what needs to be done to keep the energy infrastructure working is done, without question. Alternative energy sources need to be put in place, by force if need be.
It's that, or roll-on power shortages, and I bet we still won't learn from such a drastic lesson.
Sept 11th was inconceivable before it actually happened, so expect the events in last night's programme to happen soon.
Using nuclear power is not an option, we have no way to get rid of the waste, and no real knowledge of the long-term effects.
Why are we expecting the lights to come back on? Coal and oil are finite energy sources and will run out. We need to be planning for not having electricity at all.
I would like to thank you for provoking thought with your 'IF' programme. I hope the rest of the series is as good as the first. However, I think it is worth noting my worry that provoking these discussions might result in the government taking knee-jerk reactions.
Why do so many shops and businesses leave lights on overnight? Vandals or burglars will do what they want anyway. We could save a lot by being in the dark at nights.
On a different tack, even if there was no attack on our gas supply, how many decades of gas is there left? Can our governments stop thinking about just now and plan for the future?
Craig Thornton, Lincoln
I am shocked that people have taken this fictional programme as fact. As an employee in the energy industry it is very clear that this was a piece of sensationalist journalism.
Ronnie Smart, Bury St Edmunds
There seem to be many ways to produce electricity which are far cleaner than those presently used. Biomass, wave power, tidal power, and wind turbines for example. The biggest problem with these clean forms of production is finding ways of storing the electricity produced when it is not required. Far more research should be going into the development of hydrogen cells which would allow us to store the electricity.
Tidal power seems to be one area that is seriously underestimated as a source, surely it is one of the few things that is constant unlike the sun shining or wind.
Jenny Proudfoot, Edinburgh
I think this programme proves the point "think global, act local". If everyone turned off appliances that were on standby and reduced the waste of resources, our reserves will last longer. This would allow us to build more wind farms and more power stations, enabling us to become more self-sufficient.
This, and the other "IF" programmes shows that British society needs to look at its impacts now and plan to reduce them, rather than accepting the annual increases in demand of finite resources.
Joanne Thomas, Swansea, Wales
The programme put the majority of the blame on the government for the distribution of electricity in the UK. But it seems to me that the consumers also have a responsibility to prevent an electricity shortage in the future.
How many of us waste electricity by leaving lights on, videos and TV's on standby? We are unnecessarily draining an already overburdened supply. We need to learn to be more energy efficient, this needs to be promoted not only by the government but also the energy suppliers. Will it take a huge rise in electricity bills or a major powercut to make us realise just how wasteful we are?
The chaos could be avoided if the utilities were renationalised and under direct government control. Privatisation of utilities serves only fat cat bosses and shareholders, not the general public. Essential services are just that, and cannot be left to the whims of the marketplace.
Simon Egan, Exeter
The issues of how to reduce energy use by improving energy efficiency should be a key priority, this will reduce demand. A strategy which has produced significant results in Scandinavian countries.
Zaid Alwan, Newcastle
The answer is staring us in the face. It shines everyday. We need to ensure that legislation is brought forward to force all new builds to incorporate solar panels on roofs. Grants should be made available to existing households to install solar panels. This would be far cheaper than building a series of new nuclear power stations. It would also be far less damaging to the aesthetic quality of our environment caused by the massive wind turbine farms and their effect on the UK's bird life.
Jeff Clarke, Widnes
Maybe scaremongering? Power cuts in US/UK/Italy etc last year were down to shoddy maintenance, human error and bad communication strategies between companies/countries not lack of generation capacity. Undoubtedly the gap between supply and demand is decreasing and demand will eventually outstrip current levels of generation. Why not put more effort into lowering demand? Then renewables stand a chance of matching it.
Melody Stokes, Coventry
This programme was very powerful and hopefully the government will realise that we have to act now to save the UK from a total blackout. I personally am very worried and the government should be too.
Stephen Wallace-Clarke, Bognor Regis
I think the main point is that we have a huge number of technologies at the centre of our society that could fail in these occasions (all of which use electricity). Do we need to look at how we use technologies to prepare for the future?
Nuclear power is bad. Fuel rods don't last forever and have to be replaced, the spent rods are highly radioactive and have to be stored safely for decades. I don't see a private company wishing to take on this burden seriously. A decommissioned reactor also leaves behind nasty radioactive rubbish for decades.
Glan Thomas, Putney, London
Why did the programme make no reference to water-generated power? Hydro-electric is a considerable provider of energy in Scotland and some years ago there was great enthusiasm for harnessing tidal power. Unlike wind, which as IF pointed out can fail, tidal range will always be there as long as we have the moon's gravity: why aren't we exploiting it?
Mark Savage, Eastbourne
I find it difficult to believe that people are choosing to ignore what is clearly a significant risk to our day-to-day living. We must tackle this issue constructively by involving local communities, parliament and businesses that can help the situation. Nuclear power is a good option and more investment is needed. It is proven to be cheap reliable and safe.
Dale McAlpine, Workington, Cumbria
Anyone who says that programmes that explore issues like this are only scaremongering is simply burying their head in the sand. Ok - the scenarios are fiction, but are based on facts and current policies. Given the growing apathy towards politics, perhaps programmes like this are the ideal way to encourage people to participate more actively in political debate. How many people would have watched if it had been a straight documentary?
We should stop the de-commissioning of nuclear power stations and embark on a building program of replacement nuclear power stations to replace older stations.
Paul Humphrey, Luton
We have made the wrong decision in reducing nuclear capacity. France has a much lower chance of suffering what was described in the programme, they have more nuclear plants.
Doug Shuttleworth, Holmfirth
As other people have said here, the market is not suitable, appropriate or acceptable in providing something so vital; our energy. If nuclear and coal are too dirty and gas has dependency issues renewable seems like the only alternative. But why concentrate on windmills? We are an island surrounded by water that is pounding our coast with energy continuously, why not use that?
Mark Davies, Worcester
Too many years of the "I'm alright Jack" mentality has brought about a world where it's the here and now we think about, not the future. This programme SHOULD be a wake up call for all of us, not just those in power!
Debbie Clewes, Winsford, Cheshire
We need to start to focus more upon renewable energy sources, and not just reach the government's target of 10%. Surely a greater combination of wind, solar, hydro-electric and tidal power would be beneficial to the National Grid?
Tom Gilchrist, Ripon, North Yorkshire
Watching this program has highlighted several major issues. No one, from the government to the generating companies, is responsible for maintaining the electricity system. Surely the government should be responsible for generation of electricity, as this is a key requirement for the country?
The electricity generation networks should be renationalised to ensure that the capacity will always be there.
David Carroll, Billingham
I suggest that the BBC should let the terrorists do their job on their own and not suggest targets for them in all their programmes.
Evan Morgan, Hertford
Electricity, we consume it, love it, hate it... but without it? The question needs to be addressed.
Paul Neal, Worthing
What we need is a far better informed debate on subjects such as this. The role of science and technology in society has been largely hijacked by those with political agendas and by the media - to the extent that we no longer trust in science. One of the consequences is a disjointed energy policy and a premature closure of nuclear capacity for the wrong reason - to allay the fears of the public.
It seems incredible to me that we have reached this situation and, make no mistake, the issues in the programmes are all too real. If we are to get out of this hole, we need to frame our debates with the right level of scientific input - not be influenced by the popular press.
Steven Wood, London, UK
I hope after tonight's program it is clear to us all that the consequences of not using renewable energy are far uglier than any wind turbine.
This is an extreme, worse case scenario. It's just playing on the fears of people to make good television, shameful.
Ben Hall, Kent
I think it is inconceivable that the electricity supply industry should be privately run.
Mike Bruce, Rickmansworth
IF is just scary! It's scary to think that any of this could actually happen!
James, West Sussex
I'm off to make a cup of tea while l still can!
Watching the programme, I'm amazed at how close the commentators keep getting, before pulling back as if they've realised what an unfashionable, radical, apostate view they'd be airing if they told the simple truth: Power should never have been privatised.
G. C. Smith, Croydon, UK
I hope Mr Blair is watching this tonight and taking note.
First class programme! Communications and computers will be hit hard and planning for such an event NOW is very important. For example, the delivery of medical supplies such as insulin and power for dialyses machines will fail.
More programmes like this dealing with the things we can do now to be prepared please.
George Shaw, Belfast
Why don't we use solar energy in the summer and wind power in the winter?
Keep nuclear fuel. This is currently the only way to keep ourselves in a safe margin. Unfortunately no matter how many wind turbines, solar panels etc this is not a guaranteed supply as the wind can stop blowing and snow can cover solar panels.
With the moves away from fossil fuels, nuclear is the only guaranteed medium. Sure, it's a major pollutant, but we have mechanisms for dealing with it. It's a small price to pay.
This country is gone to pot. Firstly the rail network has to be upgraded with taxpayer's money and the health service is near enough laughable if it wasn't so serious.
Why would I not believe that the National Grid infrastructure is being looked after in the same shoddy way?
As someone who works in the industry, it is not a "what if" but a when.
Gary, West Midlands
As well as the imminent power shortages this programme is also reminding us of the continuing terrorist risk.
We need to educate people much more seriously about the environmental impact of energy wastage and we need more investment by the government and fuel and energy producers into new energy research.
Up until 30 years ago ALL of our gas came from the refining of coal! We have no need at all to import ANY of our energy resources. The government's policy should be making ourselves self sufficient and not having to import resources.
Dave, West Bromwich, West Midlands
Why doesn't the government require that all new residential buildings are built with solar panels linked into the national grid? This would reduce the power required from coal/gas/other power stations.
The government should make it more financially viable for everyone to convert or use renewable energy sources, like solar powered panels on their homes or in their gardens.
Also there should be more programmes like this one to increase awareness. People should be more energy conscious, turn off lights when not in use, turn off electrical equipment at the plug, don't leave equipment on standby and not having lights in towns over Christmas kept on all night.
There are many ways we can all save energy.
Diana Symes, Leigh, Lancashire
If we do not want to choke our atmosphere we have to go nuclear.
Much as I have my concerns over this technology the "alternative energy sources" are not developed highly enough to be efficient enough to provide viable solution.
Carl Garner, West Bromwich, West Midlands
I think that if we do not start to change our attitude about how we live our lives and how we use electricity, we will face serious problems.
Liam J Warren, Poole, Dorset
The trouble is people don't see this scenario as real.
Most people, when told about conserving energy, believe it's just "hippy stuff". We need to address this problem, but before we can do that, people need to see that this problem is frighteningly real.
Richard John, Bridgend, Wales
With no electricity, at least we could see the stars again!
Why are so many people against wind turbines? To me these are a more efficient source of electricity.
Shaun Fox, Bridport
The country has already left it too late.
Even without our long planning inquiries we could not get sufficient capacity in place by 2010 when the first generation of nuclear plants close down.
Do we really think that wind power is the answer if it will take about a thousand windmills to replace just one nuclear plant? Come on, get serious!
Steve Harris, Stroud
Surely any strategy for power generation must be matched by a strategy for a reduction in consumption.
Looking around I get the impression we are generally very wasteful of electricity. Most households now have dozens of lights purely for decoration, don't use low energy bulbs, and leave many items like TVs on standby all day.
More offices and homes need smarter intelligent heating and lighting that ensures less wastage by automatically switching off lights when no one is in the room, for example.
Equally there should be a drive to encourage manufacturers to reduce the power consumption of their products.
Wind turbines are not the answer. They cost more to build than the value of the electricity they produce in their lifetimes, they only produce electricity when the wind blows, they kill birds by the thousand and they ruin the view.
If we want to produce serious amounts of power, nuclear is the only answer.
Angus Palmer, Godalming
I think you need to make a clearer distinction between generation of electricity and distribution.
Yes, there are some challenges with generation, as coal and nuclear power is progressively phased out, but they are not insurmountable.
Most European countries have their electricity grid interconnected with neighbours, and no European country is fully self-sufficient.
Britain can do a lot more in this direction and also save much more electricity by being more efficient. But the real problem is probably distribution, making sure there is an up-to-date grid infrastructure.
Till Stenzel, London
During the course of my work I visit a lot of homes, and it never ceases to amaze me how HOT they are!
In the middle of winter people turn the heating right up and wear thin clothing - what's wrong with wearing a fleece or sweater about the house?
How about a tax on exterior Christmas lighting? All this one-upmanship over outside Christmas displays is an awful waste of electricity.
Lisa Baxter-Jones, Newport, S. Wales
This country seems to have lost the plot. From a strategic point of view the swing away from our own resources is so stupid as to be unbelievable. We should not be dependent on other (often unstable) countries for our energy, but should have adapted our own resources to protect our interests.
It's a shame you didn't coincide the date of the first programme with the 20th anniversary of the miners' strike.
How ironic that we can potentially get ourselves into a huge mess over fuel simply because we decided to close the pits.
I remember in 1980 there were predictions of zero growth in energy demand in the next 20 years. That prediction was seriously wrong. In the same way, I hope you are seriously wrong too!
John Airey, Peterborough
There won't be a long term problem with electricity generation. From the start of mains electricity to the 1980s, when Thatcher fought the miners, most of Britain's electricity came from coal.
The coal is still there, just waiting to be dug up. There's enough for several centuries.
True, if we go back to coal generation, our international carbon agreements will go out of the window, but we'll certainly survive long enough to find alternatives, like satellite solar power.
The problem with energy in the future is with oil, not electricity. What on Earth do you think the Iraq war was about?
Simon Richardson, London
Why are the media constantly trying to evoke fear in the public? Ok, so it sells but really aren't these people forgetting that we survived without any electricity once and people didn't stop functioning. Perhaps the media are more concerned that their money will dry up?
Katie, Telford, Shropshire
It's not scaremongering to point out the future dangers - however there is a danger of always looking to big technical solutions to the problems. So, power cuts mean we need more nuclear power. Water shortages mean we need more reservoirs, or we need to tow icebergs from the poles. It would be encouraging if for once we thought a bit more small scale.
Energy shortages mean we should use proven energy efficiency technologies and domestic scale renewables (solar panels, small wind turbines). Water shortages can be saved by low flush toilets. The problem is these solutions are not the great projects where politicians can cut ribbons and demonstrate they have saved the public form catastrophe, so they always come second to the obvious solution...
Are there not enough problems in the world without you imagining more? This is pure speculation on your part with only the barest of evidence to support it. You may well have a programme on "If... the BBC continues to broadcast this sort of drivel, will the license fee be discontinued?"
Tony Sudworth, Cardiff, Wales
I think there's one solution to both the power shortage and obesity problems - every household should have an exercise bike connected to a large rechargeable battery. You could burn off some calories and light your own house at the same time.
Nuclear power is the only viable means of the UK meeting the Kyoto target.
It is also the only source of power generation that ensures security of supply and the government should embark on a nuclear new-build policy in order to significantly increase the proportion of electricity that is generated by nuclear power stations.
Ian Currie, Sale, Cheshire
If the government persists in its present strategy of relying on wind power to provide 10% of our electricity by 2010 power cuts will be inevitable.
I suggest that no new house should be built without solar cells. We must look at more diverse ways of producing our energy by renewable sources instead of polluting our hillsides and ruining our beautiful countryside.
Jenny Keal, Builth Wells