This suggests that it is more economical to have it on only some of the time. HOWEVER this doesn't take any account of my gas consumption (the more I use the gas fire, the more the electric heater will switch off). So I really ought to read my gas meter as well.
How complicated.
What this is all leading to is my wondering whether the best solution to being a bit greener about my energy would be to install a wind turbine, rahter than have some gas central heating. Because basically it takes quite a lot of energy to heat the place, and whether that's electricity or gas it is using precious resources and giving off greenhouse gases unless I can find a way to secure some renewable energy to feed it. I've got a pile of logs in the garden, but the gas fire occupies the place where I'd burn logs so that's not an option right now.
8 comments:
It appears that domestic wind turbines are a bit of an eco-con.
Wind farms are also not as wonderful as most people think. At low wind speeds they actually consume more power than they produce, and in fast wind speeds, have to be shut down for safety reasons.
This website explains it quite well:
www.timhunkin.com/a125_arch-windpower.htm
That's very interesting, though it does sound as though a well-designed turbine in a good windy spot could be moderately effective.
It seems to me that wind turbines need to be combined with a simple physical energy storage system so that they don't suffer from that ridiculous fluctuation in production described on the web site you mentioned. I mean, if instead of feeding power straight into the electricity grid, you use it instead to do a mechanical job (drive a heavy weight up a shaft), then you can get a constant flow of power from weights being allowed to fall down the shaft against a resistance, and that will yield a constant flow of power. Then there need be no problem of too much power in high winds and none at all when the wind drops.
Please someone invent a simple domestic version of this for me and I will be very happy.
Instead of weights and pulleys,a more elegant and reliable system might be a pumped storage arrangement (as used on a large scale at Trawsfynnydd in Wales). Use your wind rotor to pump water from a low-level source to a higher reservoir or tank; then the outflow from the reservoir can drive a water turbine linked to a generator. It has the added advantage that the reservoir can also be fed by diverting the stream from a river.
Well, that's all very well, but if (as in my case) you do not have ready access to a stream on your property, nor to the space to install a hydro-electric plant, which, as I recell generally requires a considerable discrepancy in height between the upper pool and the lower one, this is not really quite so practical as my simple and elegant idea of some weights in shafts, which is just the old grandfather clock system of storage of energy, in effect.
"It seems to me that wind turbines need to be combined with a simple physical energy storage system so that they don't suffer from that ridiculous fluctuation in production described on the web site you mentioned."
That's an interesting idea. Certainly fine for a giant turbine, but probably not feasible for a domestic model. The amount of torque required to lift the weight would be substantial, even with gearing. You could use small weights with a longer shaft, or use some sort of spring... The problem would be having enough weight/height to get a dynamo going.
The shaft would need to be at least the height of a skyscraper to make it worthwhile.
Another option would be to store the energy as chemical energy, in the form of a battery. Only a small current is needed to charge a lead-acid battery. You would, of course, have to convert your appliances to run off DC, or use an inverter. There are, however, obvious environmental issues involved in the production and disposal of battery cells.
Which leaves us with the national grid... Inefficient, yes, but with enough wind turbines connected throughout the country and offshore, there should certainly be enough redundancy for when some places are windy and others aren't.
Yes, you can power a grandfather clock with a 10 pound weight for a few days, but this is only possible because the amount of energy needed is tiny. Though why even bother with that? There are more efficient ways of telling the time...http://en.wikipedia.org/wiki/Sundial
OK, in Norwich you might have difficulty constructing a high-level reservoir, since (as Noël Coward famously observed, Norfolk is "very flat" – until you start cycling around the county!) But you will need some vertical space to construct a shaft for your weights to rise and fall, either concealed within your property (a chimney might be able to be converted) or in a freestanding structure alongside.
While the wind is raising your weights (through fairly high-ratio gearing) they can't be falling to drive the generator – unlike different portions of the water circulating in a constant-flow system. So the basic idea may be simple, but its practical application is far less so. There would have to be some sort of control device (I imagine something like derailleur cycle gears?) for switching between at least two independent weight/pulley mechanisms, so that one could be driving the generator while the other was being rewound by the wind power. And that would have to be subtly responsive to the continuous fluctations in wind speed and to the varying electrical load.
But the real rub is that modern electrical devices need much more energy than the escapement of your old grandfather clock. Let's do some rough calculations. The potential energy stored by a falling weight system is the product of the mass raised, the height rise and the acceleration due to gravity, about 9.81 ms^-2. So 100kg (roughly 2 cwt) of weights in a tower the height of your house (say 20 metres) will store about 19620 joules. That will light a 1-watt torch bulb for 5½ hours, or power a typical desktop computer (Pentium 200MHz running Linux with 15" CRT monitor, consuming 130 watts) for all of 2½ minutes. Perhaps not really very useful.
Back to the drawing board, I fear!
What's really striking is what an incredibly efficient generator the human body is (we eat a few ounces of renewable organic matter and despite having to do some work on it to digest it, still manage to extract enough energy to drive a machine like a bicycle or walk or run in ways it would be impossible to get a machine to do on the basis of so little fuel). So presumably what we really need is a treadmill to generate heat or light for our houses. This would keep us fit and slim as well as providing the heat and light we need without having to burn fossol fuels. And pumping/winding/treading the generator woudl make us warm anyway, so less heating would be needed anyway. Can I patent this machine please (as well as the storage system proposed in the previous comment)?
Individual (domestic) wind turbines in urban areas produce very small amounts of power in an unreliable way. Their manufacture and installation would use quite a lot of energy, disproportionate to their output.
As all the infrastructure is in place to distribute electric power and deliver it to every house in the UK, it makes sense to use big, efficient, wind turbines in exposed, windy, places, connected to large pumped-storage resevoirs like the one in Wales.
This also means that the decision to use renewable energy is taken centrally, by the power generators (encouraged by government or EU measures), and gets used by everybody whether they can be bothered to be 'green' or not.
The concept of individual wind generators really started in the USA, where lots of people wanting to live 'green' lifestyles go off to a plot of land in remote Montana or wherever and become 'self-sufficient' (except for relying on fossil-fuelled industry to manufacture their generator, of course...).
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