h a l f b a k e r yQuis custodiet the custard?
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In this country, flammable hydrocarbons are often plumbed directly into one's kitchen. The cost per unit of heat of mains gas compared to electricity is understood to be cheap. According to the back of my envelope, the cost-per-kilowatt-hour of gas is 37 times cheaper than lecky.
Embracing the British
way of life, I often drink more than ten cups of tea per day. In this household, the electric kettle is by far the biggest consumer of power. Given the number above, it would make remarkable economic sense to boil water on the gas stove. Even if only 10% of the heat ended up in the water, it would still work out cheaper. And yet, we continue to use the electric kettle. Because: Convenience. Love of efficiency. Hatred of whistles.
An Automatic Gas Kettle would turn the situation around. The Automatic Gas Kettle would have the following features.
* A dedicated base, plumbed into the mains gas and electricity supplies. The main kettle is of course cordless.
* An insulated tank for reduced heat loss.
* A piezo-ignition system for the self-contained burner, so that pressing the switch immediately starts delivering heat to the water.
* A bimetalic strip (or thermocouple) to automatically cut the gas when the water has boiled.
These features would give the kettle the same user experience as its electric counterpart.
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//the cost-per-kilowatt-hour of gas is 37 times cheaper than lecky. // |
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What what what?? I mean, what?? If that's true, then a compact gas-driven generator with an efficiency of only 10% would still save you 2/3rds of your electricity bill. |
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OK, so in the UK, apparently, 1 Therm of natural gas (why do they use such weird units?) costs around 35p, and is equivalent to just under 30kWh. |
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So, if you had a generator with an efficiency of 33% (which seems reasonable), then you'd get 10kWh for 35p, or about 3.5p/kWh. The remaining 67% of your energy would presumably end up as waste heat, which could itself be used to heat the house directly. |
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Given that domestic electricity prices in the UK are about 12p/kWh, why doesn't everybody just have a gas-powered generator?? A quick Google suggests that £3000 will buy you a 10kW natural gas generator. |
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It does seem a bit extreme doesn't it! Let me check that envelope again. |
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The correct ratio is 3.25 times cheaper. The reason for my mistake is that the unit cost is not per-square-metre, as measured on the meter, but per-kilowatt-hour, so the conversion to kilowatt-hours was done twice. |
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Ah, we annotated at the same time. Hmm. |
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// 3.5p/kWh // 12p/kWh // £3000 will buy you a 10kW natural gas generator // |
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(Admittedly unreliable) Envelope again: an 8.5p saving per unit, so the investment would break even in just over 35MWh's time. Google reports the average home uses 5.5MWh per year, so that's about six years before it starts saving you money. That is actually a better return than solar panels. |
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Such devices have existed since your 19th century. Numerous versions can be seen in museums. |
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Essentially, the kettle only fits on the ring on one orientation. The spout lines up with a sealed copper bulb. A lever is pressed to start the gas flow, which then latches. When the kettle boils, the steam heats the bulb, and the air expands, causing a small metal bellows to expand and pressing on a sear, which releases the gas valve catch. |
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The whole thing only has about six moving parts. |
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There's a specimen in one of the reconstructed shops in the Black Country Living Museum. |
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