. . . back to part 2 . . .
How much is inside hot water? - part 3
Let's look at these numbers:
|
gas method
| kettle method |
|
0.3 kWh of chemical energy
|
0.11 kWh of electrical energy
and
0.06 kWh of chemical energy
|
Total: 0.3 kWh of energy
|
Total: 0.17 kWh of energy
|
In terms of energy used in the home,
the kettle method uses least.
|
|
|
However, this is not the full story.
In Britain, and almost all countries,
extra electricity demand is met by turning up
a fossil fuel power station.
|
|
But, in my house, I buy my electricity from Good Energy,
which means that it all comes from windmills, right?
I don't think so. Even if I stick Good Energy stickers
all over my kettle, the truth is that whenever I switch
the kettle on, a fossil fuel power station somewhere has to turn
up a little.
And in Britain, power stations convert chemical energy
to electricity with an efficiency of roughly 40%; then 8% of
the electrical energy is lost in the electricity network.
(That's an overall efficiency of 37%.)
So every 1 kWh of electricity that I use
entails the consumption of
1 kWh/0.92/0.4 = 2.7kWh of chemical energy at the power station.
So the energy balance sheet looks like this:
|
gas method
| kettle method |
|
0.3 kWh of chemical energy
|
0.11 kWh of electrical energy, which involves the use of
0.3 kWh of chemical energy (at the power station)
and loses
0.19 kWh of heat (mainly in the cooling tower and a little the electricity network)
and
0.06 kWh of chemical energy (gas at home)
|
Total: 0.3 kWh of energy
|
Total: 0.36 kWh of energy
|
So when we take into account the way power stations work today,
the two methods actually use roughly equal amounts of
energy. The gas method uses slightly less.
|
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Continue reading part 4 of How much is inside hot water...
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