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The thing that stands out to me is how inefficient kettles are in terms of power usage. Is it a simple case of more power equals shorter time to boil? Is there

The thing that stands out to me is how inefficient kettles are in terms of power usage. Is it a simple case of more power equals shorter time to boil? Is there a more efficient way to turn electricity to heat?

solox3 14y ago
Kettles are pretty efficient. Good kettles have tungsten heating elements. Even so, it takes so much energy to heat water because of its ridiculous specific heat capacity (http://en.wikipedia.org/wiki/Heat_capacity#Metrology.2C_the_measurement_of_heat_capacity http://en.wikipedia.org/wiki/Heat_capacity#Metrology.2C_the_...).
- kaliblack 14y ago
  Thanks for the information. I guess it's that I can't comprehend the scale required to make that much of an impact. It's easier (for me) to think at the single unit.
batiudrami 14y ago
Of all the types of energy, it's easiest to turn other types of energy (such as electricity) into heat. That's why, when converting amongst other kinds of energy (such as light, or motion), a side effect is often heat (and things getting hot which don't need to be is a sign of an inefficient process). Essentially the kettle just converts electricity to heat (very efficient) which heats the element inside the kettle which is transferred to the water surrounding it via conduction (also very efficient). There's almost no wasted energy, and you know that because the area around the kettle does not get hot. Kettles do use a lot of energy because water requires a lot of energy to heat up - in fact it's among the highest of all substances (the measure of this is called the heat capacity or specific heat - the amount of energy to raise an amount of a substance by one degree Celcius/1 Kelvin. If you want to be more energy efficient at boiling water, put only the amount of water you need in the kettle, rather than boiling extra, but obviously this is not a solution when scaling electricity infrastructure. edit: I should note that Kettles are not completely efficient - there is still some energy loss (for instance, through resistance in the wiring in the kettle, and heat conducted to the kettle itself or radiated to the surrounding air).
- lmm 14y ago
  Could one make a heat pump kettle that would be "more than 100% efficient", by moving head from the surrounding air into the water rather than just resistive heating? I remember seeing that approach recommended for heating houses.
- eru 14y ago
  Kettles with heat pumps could go beyond 100% efficency.
Dylan16807 14y ago
There's no such thing as an inefficient way to turn electricity into heat. A light bulb, a television, a fan, a refrigerator, a speaker, a kettle are all going to turn all of their power into heat.
- alexkus 14y ago
  And given the climate in the UK for most of the year the excess heat means your heating needs to do a little bit less[1]. 1. But probably net less efficient in that the majority of houses in the UK use gas for their heating and gas is cheaper than electricy kWh for kWh in the UK.

solox3 14y ago

Kettles are pretty efficient. Good kettles have tungsten heating elements. Even so, it takes so much energy to heat water because of its ridiculous specific heat capacity (http://en.wikipedia.org/wiki/Heat_capacity#Metrology.2C_the_measurement_of_heat_capacity http://en.wikipedia.org/wiki/Heat_capacity#Metrology.2C_the_...).

kaliblack 14y ago
Thanks for the information. I guess it's that I can't comprehend the scale required to make that much of an impact. It's easier (for me) to think at the single unit.

batiudrami 14y ago

Of all the types of energy, it's easiest to turn other types of energy (such as electricity) into heat. That's why, when converting amongst other kinds of energy (such as light, or motion), a side effect is often heat (and things getting hot which don't need to be is a sign of an inefficient process). Essentially the kettle just converts electricity to heat (very efficient) which heats the element inside the kettle which is transferred to the water surrounding it via conduction (also very efficient). There's almost no wasted energy, and you know that because the area around the kettle does not get hot. Kettles do use a lot of energy because water requires a lot of energy to heat up - in fact it's among the highest of all substances (the measure of this is called the heat capacity or specific heat - the amount of energy to raise an amount of a substance by one degree Celcius/1 Kelvin. If you want to be more energy efficient at boiling water, put only the amount of water you need in the kettle, rather than boiling extra, but obviously this is not a solution when scaling electricity infrastructure. edit: I should note that Kettles are not completely efficient - there is still some energy loss (for instance, through resistance in the wiring in the kettle, and heat conducted to the kettle itself or radiated to the surrounding air).

lmm 14y ago
Could one make a heat pump kettle that would be "more than 100% efficient", by moving head from the surrounding air into the water rather than just resistive heating? I remember seeing that approach recommended for heating houses.
eru 14y ago
Kettles with heat pumps could go beyond 100% efficency.

Dylan16807 14y ago

There's no such thing as an inefficient way to turn electricity into heat. A light bulb, a television, a fan, a refrigerator, a speaker, a kettle are all going to turn all of their power into heat.

alexkus 14y ago
And given the climate in the UK for most of the year the excess heat means your heating needs to do a little bit less[1]. 1. But probably net less efficient in that the majority of houses in the UK use gas for their heating and gas is cheaper than electricy kWh for kWh in the UK.