Gas-hob kettle or electric kettle?

[adam2]

Since becoming energy aware we now avoid the more high powered kettle elements. Not that there is any energy saving in use, but because it would reduce the peak load on any off-grid electricity supply. (Actually we would use our hob kettle or the wood burner in that instance).

There is no saving by use of a lower powered kettle.
To boil a certain volume of water needs a certain amount of energy.
A lower powered element will simply run for for longer to achieve the desired result.

As you point out, a lower power kettle is useful if only a restricted electricity supply is available, such as from a modest sized generator or inverter, or from a lighting circuit. (not that I actually recomend connecting even a lower powered kettle to a lighting circuit)

[emordnilap]

Some years ago, the electric kettle at work failed; I asked on FreeCycle if anyone had one to spare.

I got five - one of them even delivered! All worked; one had a temperamental switch which is probably why it was given away but we now have a stock of kettles to keep us going for quite a while.

[Fire]

I have a Wesco whistling kettle that is very well made, has an ingenious spout mechanism and works very well on an induction hob. The problem with electric kettles is that they break.

Figures for induction & electric hobs come out somewhat worse than gas hob or electric kettle

From results elswhere, boiling 500ml water:

3kW Induction hob 2mins 38sec = 0.132 kWh = 1.538p & 71g CO2

1.2kW Electric hob 9mins = 0.180 kWh = 2.098p & 97g CO2


Its not the efficiency of the electronics (generally very high) but the losses in the heat transfer process & the internal resistance of heating elements (of whatever nature), why superconductivity works, it reduces that resistance to nil. Though some elements rely on that resistance to create heat.

[Catweazle]

A heating element needs electrical resistance or it won't work.

Power = Current squared x Resistance

[adam2]

A heating element needs electrical resistance or it won't work.

Power = Current squared x Resistance

Yes

[the_lyniezian]

Wouldn't both be a good idea, at least to hedge against things like power cuts? Surely a hob kettle would still be useful if you had to rely on a bottle-gas powered stove (like perhaps a camping stove, which I'm sure will form part of your emergency stash?) or pretty much any decent source of heat you can stick it on?

[Fire]

A heating element needs electrical resistance or it won't work.

Yes, as per my final point, however that same resistance causes losses.

A resistive load is ideal for DC voltages, but wer'e using AC therefore have instantanious phasing errors.

An inductive load can also have issues too if the load is not timed to the source, which is what the (often fake) energy saver units are about.

Not all heating elements are resistive, such as induction.

[adam2]

It could reasonably be argued that an induction hob still heats due to resistance.
The circuitry in the hob induces currents in the metal pan which becomes heated due to the resistance of the pan.

[Catweazle]

A heating element needs electrical resistance or it won't work.

Yes, as per my final point, however that same resistance causes losses.

The losses are in the form of heat, which is exactly what we want. No losses = no coffee .