I agree with Martyn, that the subject of energy efficiencies and conservation is an absolute minefield.
Whilst most attention is being given to electricity supplies, the issue must also encompass considerations of other fuels and usages.
In my opinion we will need to rely on a range of power sources, which might include nuclear, wind farms, tidal power, biomass etc, and fossil fuels such as coal oil and gas, as no one single technology is going to provide all our needs.
Local conditions will dictate what mix of power sources will be most appropriate; clearly the needs of desert dwellers will be different to those of the arctic.
Simply looking for alternative fuel and power sources will not be enough. As most of our energy goes into making heat, there is a lot that can be done to stop that heat being wasted. The centre for alternative technology in Wales has a very efficient house that uses practical amounts of insulation to reduce heat loss.
We can also look to find what is the best form or energy to use for a particular job. In my opinion we use electricity for too many jobs that can be done as effectively and certainly more efficiently by other fuels. It is important to bear in mind that the big power generators are at best only about 40% efficient. So for every 1kW you use the generator is throwing away 1.5kW up the cooling towers. Smaller generators are even less efficient. - But if the power plant is close to homes or businesses, the waste heat can be used for district heating or process heating. (Combined Heat & Power or CHP) here the potential efficiency can rise to 85%
On of the biggest problems with the environmentally produced renewables, is the unreliability of the source, and often the production period does not directly correspond with the high demand periods, so the storage of power is also a significant challenge. The obvious thought would be batteries, but these are not very efficient storage systems. Better is the large Denorwig (sorry about the spelling) scheme in Wales where water is pumped up into a high level reservoir so it can be released and used to generate power when demand is high. We probably do not have enough viable sites to implement this scheme elsewhere in the UK.
There are other energy storage strategies, but whichever system you look at there are losses in the process. The trick is to choose the process that best suits.
Perhaps we should look at the way energy is used. Could we use low-grade energy to do part of a job and then only rely on the high quality (and high expense stuff) to finish the job? Consider Central heating. Whilst in the UK there are very few Solar powered central heating systems, because we do not have enough solar energy, but if it could be used to raise the water temperature by only a few degrees, then the gas or oil has to do just a bit less work to get it up to the desired temperature. This could make 2 or 3% fuel saving.
There are heat pumps, which can take some heat from a low temperature source and by adding some mechanical energy produce a higher temperature (a refrigerator is an example) so for some people geothermal energy could have a future.
Careful design could make better use of sunlight through windows to warm houses.
I believe we have national opportunities to make at least 10 to15% energy savings with current technology. It really needs the government to make the idea of energy conservation attractive and accessible. Even with savings now, we will still need to look to alternative sustainable energy sources for the future.
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