Generation and Conservation

The generation elements of a sustainable economy attract more attention than the things that use energy.  A couple of acquaintances have installed rooftop PV and this has been the subject of discussion amongst the neighbours with questions like "how much electricity to the generate", "how much money do you make" etc.  In contrast, my four LED light bulbs and newly acquired Raspberry Pi attract little or no interest.  I am old enough to realise that "do you want to see my LED" is not the best way to start a conversation.  In a more general sense, wind farms and solar parks get more column inches in the media than boiler controls and politicians are careful in the choice of language they use to talk about energy consumption.

With a little creativity its possible to determine the perception of any project.  My view is that wind and solar sources are complimentary.  Wind produces most energy during the winter and solar can be a cheap source of electricity in summer, but both are discontinuous sources and without low cost storage, require an equivalent fossil fuel backup, which means wind and solar capacity has to be matched with a flexible and responsive technology such as gas turbines.

This is an attempt to make the case for focusing on conservation.  There are many ways of looking at the numbers, hopefully this one is simple, albeit with some gross over simplifications.  Let's start with the assumption that one house in a hundred as rooftop PV and that the installation costs £5,000 and produces 2,500 kwh/year.  The owner of the PV panels recovers his/her/its costs from a feed-in tariff.  The panels produce most of their output a few hours either side of solar noon during the summer months, not much during the winter and none at night.

Peak demand for electricity is in early evening during the winter months and this can't be met directly by solar generation, at a guess, the peaks are largely met by gas fueled generators.

As the result of some policy as yet undefined, instead of one household investing £5,000, one hundred households each invest £50 in conservation technologies, in some respects this is more of a challenge than installing rooftop PV,  For my household selectively replacing four 20 watt CFl's with 5 watt LED has resulted in reducing consumption by about 50 kwh/year .  Extrapolating this to 100 households results in savings of 5,000 kwh.  More to the point, these savings take place at the time of peak demand, thus reducing the need for fossil fuel capacity.

The more overall demand is reduced, the easier it is to integrate sustainable sources into the energy economy.