The most energy-efficient way to boil water

hot drinks 002

This time of year I seem to put the kettle on a half dozen times a day. After inhaling two or three cups of coffee in the morning I pass through the kitchen again and again: black tea with lunch, green tea with my snack, hot cider in the afternoon when the fireplace is flagging (ooh, that was good – I think I’ll have another), and cocoa after dinner as a sort of “dessert.”

Recently, I got to wondering: is firing up a burner on the electric range really the best way to heat that water? I use a good, tight kettle, I put it on a burner it fits, and I generally only heat as much water as I’m going to use. But maybe I should be using the microwave? Or maybe I should invest in one of those snazzy electric kettles the Brits swear by? Help me, Google!

Well, I consulted the great oracle and here’s the upshot: It’s no biggie. Really. The Christian Science Monitor, in an article on this very topic, quoted Michael Bluejay of the energy use website michaelbluejay.com: “You’d save more energy over the year by replacing one light bulb with a CFL [compact fluorescent light bulb] or turning off the air conditioner for an hour . . . at some point over the whole year.” (For the record, the microwave is a teeny bit more efficient at heating that cuppa than the stove, and quite a bit better for reheating small amounts of food.) At the end of their article, the Christian Science Monitor adds another bit of advice from the energy guru:

“However, Mr. Bluejay reiterates that most of us won’t put a dent in our overall energy use just by choosing one appliance over another. “Focusing on cooking methods is not the way to save electricity [at home],” he says. “You should look at heating, cooling, lighting, and laundry instead.”

Still gotta know? I don’t blame you. Even though, as the Christian Science Monitor article says, even the most hardcore tea drinker will hardly even save a dollar a year by fiddling with boiling methods, you may still be curious or need to know the environmental impact. Stanford Magazine rated the methods thus, from most to least efficient:

  1. An electric kettle or induction cooktop powered by renewable energy (solar panels on the roof)
  2. An electric stove powered by renewable energy (solar panels on the roof)
  3. A gas stove
  4. An electric kettle with grid electricity
  5. An electric stove with grid electricity
  6. A microwave

Keep in mind that the wattage rating of your microwave, the age of your stove, and the efficiency of your electric kettle all play into this. (And if you’re approaching it from a purely environmental angle, the source of your electricity does, too. Is it hydroelectric? Coal burning? LP? Wind? Solar?)

Another ranking, done by Pablo Päster of TreeHugger, gives an entirely different order to the list because Mr. Päster tested his own (and we can assume, given where he works, very efficient) appliances.(Electric kettle followed by microwave followed by stove. Interestingly, he also had a much higher estimate of possible yearly money savings, as high as $5.00.)

In the end, this is the only way you can really know: personal testing. If you still have the manuals for your appliances they should list the wattage. Wattage x time to boil 8 oz of water = energy usage. If you don’t have a clue what the wattage is (or you want to be really really sure) your local library or public utility district probably has Kill A Watt® meters that you can rent. Plug your appliance into the Kill A Watt®, plug the Kill A Watt® into the outlet, and go to town. (On a side note I have always wanted to rent of these but I am afraid that I would go bonkers and test every single electrical item in the whole house and take a whole notebook worth of notes and spiral out of control. I can get pretty obsessive about science.)

In conclusion I would like to reiterate my original point: it’s not that big a deal. As interesting as this is, if you want to save money or lessen your environmental impact, focus elsewhere. Think bigger.

— Amanda

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