The problem with most discussions about ways to save energy is that they're based on incorrect information and it's time to have a serious look at what can and can't be done, writes David MacKay.
The public discussion of energy options tends to be intensely emotional, polarised, mistrustful and destructive. Every option is strongly opposed: the public seem to be anti-wind, anti-coal, anti-waste-to-energy, anti-tidal-barrages, anti-carbon-tax and anti-nuclear.
It can shed light on the scale of the energy problem if all forms of energy are discussed in simple personal units. In the book: Sustainable Energy - without the hot air, the author expresses everything in kilowatt-hours. One kilowatt-hour (kWh) is the electrical energy used by leaving a 40-watt bulb on for 24 hours. The chemical energy in the food eaten to stay alive amounts to about 3 kWh per day. Taking one hot bath uses about 5 kWh of heat. Driving an average European car 50km uses 40 kWh of fuel. With a few of these numbers in mind, evaluation of some of the recommendations that people make about energy can be made.
In total, the European lifestyle uses 125 kWh per day per person for transport, heating, manufacturing, and electricity. That's equivalent to every person having 125 lightbulbs switched on all the time. Most of this energy today comes from fossil fuels. What are our post-fossil-fuel options?
Among the energy-saving options, two promising technology switches are the electrification of transport (electric vehicles can be about four times as energy-efficient as standard fossil-fuel vehicles) and the delivery of winter heating and hot water by electric-powered heat pumps (which can be four times as energy-efficient as standard heaters).
Among all the energy-supply technologies, the three with the biggest potential today are wind power, nuclear power, and solar power – especially solar power in sunnier countries, which Britain could buy via a European electrical super-grid (yet to be built).
What about tidal power? What about wave power? What about geothermal energy, biofuels, or hydroelectricity? The sober message about wind and solar applies to all renewables: all renewables, deliver only a small power per unit area, so if renewable facilities are to supply power on a scale comparable to our consumption, those facilities, whether centralised or decentralised, must be big.
