Tea drinkers:
Most people use water kettles, either stovetop or electric. Some of us use realtime hot water dispensors, which are sometimes a function of coffee machines but in some rare cases they are dedicated stand-alone units.
Pros and cons to each:
stovetop water kettle on ⌁electric stove:
— slow to boil and brew
— wasteful/lossy, esp. if not induction (fuel→heat energy→steam→turbine→AC power→grid transmission→conversion back to heat energy)
— no temp control (green tea drinkers must wait for water to drop to 80°C)
+ BifL: never breaks down and generally outlives you
stovetop water kettle on 🔥gas stove:
— slow to boil and brew
+ energy efficient (fuel→transmission→heat energy); more heat loss on the stove than with electric, but still much less loss than all the electric stages
— …but all city gas pipelines are inherently leaky and unburnt gas is 25× worse for climate than CO₂ (OTOH, this leakage happens wheter you consume gas or not)
— no temp control (green tea drinkers must wait for water to drop to 80°C)
+ BifL: never breaks down and generally outlives you
⌁electric water kettle:
+ fast to boil (1m 20s to boil 25cl in my kitchen)
— …but slow to brew (brewing cannot start until all water is boiled)
— wasteful/lossy (same chain of energy losses as stovetop electric but less waste between the wall and the water)
± /some/ kettles have temp ”control”, but you have to watch it. Some exceptional units can be set to shutoff at 80°C.
+ BifL: never breaks down?
hot water dispensor (⌁electric):
— slow to boil (1m 50s according to YT video X2VdGK2t5vo)
+ …but overall faster to brew because the infusion begins instantly, and this is what matters. So what if it takes 30s longer for hot water if brewing is 1m 20s ahead of the kettle method?
— wasteful/lossy (same chain of energy losses as stovetop electric but has the least energy waste between the wall and the water as the water passes through a small heated pipe; OTOH some energy is used on the pump)
+ all appliances have true temp control, so green tea can be instantly infused with 80°C water automatically and without excessive heat
— non-BifL; it breaks! The usual electro appliance shitshow: complex design; no service manuals; no wiring diagrams; undocumented commands; booby-trapped; spring-loaded… self-destructs when disassembled; spare parts cost more than a new unit [if you can find them] because they bundle several parts together instead of selling individual components… the market seems to have abandoned the dedicated (water only) hot water dispensors
My question: after boiling water in an electric water kettle, I poured it into a glass with a meat thermometer, which went up to ~88°C. Where did the other 12 degrees go? Is it normal for water to fall so rapidly in temp, or is my thermometer dodgy?
I highly doubt that gas stove is more efficient that anything other than a wood fire.
And the electric kettle is very obviously the most efficient way.
Edit: https://angrybearblog.com/2023/11/comparing-energy-efficiency-of-boiling-water-household-appliancesWhat do you mean you have to watch the temp control? Obviously they shut off at the temp you set
I highly doubt that gas stove is more efficient that anything other than a wood fire.
We’re talking from energy source to water, not wall to water. Sure, if you neglect everything that gets the energy to your wall, then electric is more efficient.
What do you mean you have to watch the temp control? Obviously they shut off at the temp you set
There are 3 varieties of electric kettles:
- on/off, no control
- temp guage (analog or digital), no setting
- configurable so you can set the temp which is then targetted
BTW, your link is unreachable to me. (Cloudflare strikes again)
Here: https://archive.is/bpbp6
Theoretical Energy for 1l is 100Wh, so the kettle is within margin of error of 100% efficiency in this study. 100/350≈0.29 so 29% efficiency for the gas stove
Yes this is from the wall.Losses in electricity transmission seem to be ~2-10% in the EU:
Now calculation the loss of the electricity generation of the energy mix sounds like a pain in the butt, so I’m just gonna take only gas power plants:
Gas power plants vary from 30-60%: https://www.pcienergysolutions.com/2023/04/17/power-plant-efficiency-coal-natural-gas-nuclear-and-more/
So I get a worst case for the electric kettle of 27%, assuming an old gas power plant at 30% and 10% transmission loss to your home.
And a best case of 59% with a new gas plant and 2% transmission loss.
But since the other power generation methods also lie on the lower end I’d take the worst caseGas loss (here called UFG) is 0.5% in the EU and 1.8% in the US. That gives us a worst case of 28% for the gas stove
I have to retract what I said initially, this seems a lot closer efficiency whise.
For the greenhouse gas emissions, the electric kettle should pull ahead in the future as renewables take overI appreciate the research and references.
For the greenhouse gas emissions, the electric kettle should pull ahead in the future as renewables take over
Perhaps in most regions outside of populist-rightwing-controlled regions, that will be the case. ATM I am not in the US but still they are tearing down the nuclear power plants and building 3 new natural gas fired plants. So progress is moving backwards where I am.
Centralised gas burning would be more efficient than burning it on a domestic stove, but hard to grasp that the difference would be enough to exceed conversion and transmission losses. Worth noting that there are a couple ways to get hot water from gas:
- simple pot on stovetop
- water runs through a coil of fire-heated pipe inside an insulated box – aka a tankless combi boiler
The 2nd option would not give boiling water, as I would not want boiling water to run through the domestic pipework, but I wonder how a small tankless gas-fired tea water appliance might do as far as increasing the gas efficiency, should it be invented.
In any case, if electric-fueled heat were generally efficient, I would expect the gas-fired combi boilers to be much less popular. Though note as well that economy is not closely tied to efficiency. Natural gas cost per kWh is much cheaper in my area than electric cost per kWh (by a factor of 2 I think).
I think those 12 degrees went to your writing skillpoints because I love your post.
Is it possible your meat thermometer - I’m assuming it is metallic - was cold and absorbed the missing degrees?
Possibly preheat the thermometer before the reading?
That and the glass too
My guess is that the glass absorbed some heat, lowering the temp before you could measure it
Gas has a conversion efficiency of 100% but not all of it every the kettle. That leads to efficiencies lower than the electric ones. With good induction it is also faster than every other method so that would be my choice if I had an induction cooker. Until then I use the next best and cheapest solution which is electric with a wall plug.
Keep in mind that the us - as usual- historically made strange political choices so their kettles are limited to half the speed as everywhere else.
Gas has a conversion efficiency of 100% but not all of it every the kettle. That leads to efficiencies lower than the electric ones.
Yes but you’re only talking wall to water. From energy source to water gas is the most efficient because it does not have the lossiness of generation and transmission that electric does.
With good induction it is also faster than every other method so that would be my choice if I had an induction cooker.
You’re purely talking boil times. But the end game is brewed tea, in which case it cannot be faster because after boiling the water you still need ~1—3 min to brew it. That’s why the inline heating elements in dispensors are interesting. It starts brewing immediately so the 1m50s it takes to boil all the water can be neglected.
