From Daily Mail Online
Strike a light: Britain's energy use is equivalent to everyone having 125 lightbulbs on all the time
How 125 light bulbs can end the energy crisis
By David MacKay
The public debate about our energy crisis will be a waste of time - unless we start using numbers we all understand.
To survive, we need to know how much energy we use, decide how much energy we would like to use in the future and learn how much energy each future source could supply. Then we can have a constructive conversation about our realistic options.
But we have to have a universal way of measuring these things - and that's where the humble light bulb comes to our rescue.
One 40-watt light bulb, left on 24 hours a day, uses energy at a rate of about one kilowatt-hour per day and would cost about 10p. So how many 'light bulbs' of energy do you need?
Transport and heating are two of our biggest forms of energy consumption. Transport (of humans, food, freight and rubbish) consumes the power equivalent to every person having 40 light bulbs on all the time. Heating has a similar average power consumption of 40 light bulbs per person.
The total energy consumption of Britain is equivalent to every person having 125 light bulbs switched on all the time. At present, almost all of this power comes from fossil fuels.
Of our future supply options, wind power is the renewable with the biggest potential: if we covered ten per cent of Britain with windfarms, they would supply about 20 light bulbs of power per person. Offshore windfarms the size of Wales could deliver 30.
Wave power could give us four each, if all our coastline were filled with wave machines.
Hydroelectricity could supply 1.5 light bulbs per person if we dammed every valley.
Solar panels making hot water on all south-facing roofs would supply 13 light bulbs for each of us.
If a renewable source is going to make a big contribution, it needs a lot of land. If a renewable facility is not intrusive, it's probably useless. To deliver 20 light bulbs of power per person from wind, for example, we'd need a hundredfold increase in wind power in Britain.
So how can we make a plan that adds up? Well, we could reduce our consumption - drive less and turn down the thermostat. Energy-saving technology changes could help. Another good idea is to replace petrol and diesel-powered vehicles with electric vehicles.
In addition to using our own renewables, Britain could obtain energy from other sources such as nuclear power. Further ideas - such as 'clean coal with carbon capture and storage', which involves grabbing the carbon dioxide created when you burn coal and shoving it down a hole - are still unproven.
Let's imagine that technology and lifestyle changes manage to halve British energy consumption. Here is the rough scale of building that is required if we wanted to get one third of this from wind, one third from nuclear, and one third solar facilities: we would have to build wind farms with an area equal to the area of Wales; we would have to build 50 Sizewells of nuclear power; and we would need solar power stations in deserts covering an area twice the size of Greater London.
I'm not recommending this particular mix of options, just trying to convey the scale of the challenge of making a plan. We need to get building.
David MacKay is Professor of Physics at Cambridge University. His book Sustainable Energy - Without The Hot Air, is published by UIT and is available in electronic form for free from www.withouthotair.com.