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Left Hand of Dorkness
11-21-2005, 10:38 AM
Simple question. I want to heat up water for tea (or for French Press coffee). Am I using less energy by running electricity through metal coils to heat them up and then transfer the heat to my water (i.e., running water through a drip coffeemaker), or by using electricity to create magical zappy rays that heat up water (i.e., putting a mug of water in the microwave)?

Daniel

raindog
11-21-2005, 11:48 AM
I would guess the microwave uses more energy.

But the nameplates may tell you---the microwave probably is listed in Watts; the coffee maker may or may not have this info on the name plate. (Or it may list volts & amps; V x A = W)

More watts used= more energy used.

lissener
11-21-2005, 12:05 PM
IANAEE, but I've heard that the microwave is the most energy inefficient appliance in the kitchen.

vetbridge
11-21-2005, 12:22 PM
This doesn't answer your OP, but the drip coffee maker is not going to get the water to the temperature I would want it to be at for the French Press (or for tea IMHO).

Quercus
11-21-2005, 02:22 PM
More watts used= more energy used.
No. More watts used = more energy used per second

You also need to know how long it takes to heat up the water. Multiply that times the watts, and you'll know which one used more energy. Except that the wattage listed is probably more of a maximum average, and how much the appliance really uses might vary a lot.

Left Hand of Dorkness
11-21-2005, 03:13 PM
This doesn't answer your OP, but the drip coffee maker is not going to get the water to the temperature I would want it to be at for the French Press (or for tea IMHO).
This is an excellent point. When making my french press coffee, I've been nuking a mugful of water until it boils, then taking it out and, about twenty seconds later, pouring it over the grounds. The coffee comes out splendidly, both delicious and caffeinerriffic. The drip coffeemaker's water came out cool enough that when I made tea today, I could drink the water immediately from the mug. I'm no tea connoisseur, though, so the weakness of the resulting tea isn't something I'm qualified to judge.

I'm surprised that microwaves are so energy-inefficient: for some reason, I thought they were far more efficient than stoves and other coil-heaters.

Daniel

scm1001
11-22-2005, 04:06 AM
I doubt whether it is possible to be more efficient than heating a large volume of water with a coil - it should be almost 100%. A small volume of water may not be so good as much of the energy is used to heat the coil.

A microwave has lots of losses
"A microwave oven does not convert all electrical energy into microwaves. A typical consumer microwave oven could consume 1100 W, and deliver 700 W of microwave power. The remaining 400 W are dissipated as heat by components of the oven. The main source of energy loss is the magnetron tube which is much less than 100% efficient at generating microwave output from the power source. Lesser amounts of power are consumed by the oven lamp, AC power transformer losses, magnetron cooling fan, food turntable motor and control circuits. This waste heat does not end up in the food but is mostly expelled from the cooling vents on the oven and heats the air in the kitchen. "
from http://en.wikipedia.org/wiki/Microwave_oven

kanicbird
11-22-2005, 07:49 AM
Microwaves are 'the most efficient' because they just heat the food and little else. Much like the most efficient way to heat a person (w/o using 'slave labor) is an electric blanket.

Also when you heat water in the microwave you typically heat just what you need, while stove heating you usually heat more then you need and let the rest cool.

As pointed out above coil in water is going to be just about as good as it gets, just as long as you avoid he inefficencies of being human

Left Hand of Dorkness
11-23-2005, 11:21 AM
Very interesting! Of course, I thought of another waste of energy: the water pot tends to stay on with the water in it, keeping it hot until someone uses it.

Perhaps the most efficient would be for me to:
1) Heat the water in a pot.
2) Immediately turn off the coil, transfer the water to my mug, and microwave it until it's actually hot enough to brew tea.

Not that I'm likely to go through all these steps, though....thanks for the answers!

Daniel

vetbridge
11-23-2005, 11:38 AM
My favorite (current) way to make hot water for coffee/tea/cocoa:
http://www.toastess.com/product_details.asp?product=39

The base plugs into the wall outlet, while the kettle can be removed, hence it is termed "cordless".

VegaBean
11-23-2005, 07:08 PM
I just got a machine that will tell you this exactly.
It' s called a Kill-a-Watt and is available lots of places on line.
You plug it into a wall then plug your coffee maker into it and it records the kw-hrs used.
Repeat with the microwave. I would do it for you, but I don't use coffee.
http://www.thinkgeek.com/gadgets/electronic/7657/

raindog
11-24-2005, 08:25 PM
No. More watts used = more energy used per second

You also need to know how long it takes to heat up the water. Multiply that times the watts, and you'll know which one used more energy. Except that the wattage listed is probably more of a maximum average, and how much the appliance really uses might vary a lot.
Oh, No.
As long as we're nitpicking......

It is not energy used per second, as much as energy used for all seconds ; total KWs used. Which as you noted, includes the element of [I]time.

I assumed that "more watts used" assumed the element of time. That seems fairly obvious. A microwave may use more watts per second, but if it heats the water in one fifth the time it may, or may not, use more total energy. You pay for Kilowatt Hours---

robby
11-24-2005, 09:42 PM
Oh, No.
As long as we're nitpicking......

It is not energy used per second, as much as energy used for all seconds ; total KWs used. Which as you noted, includes the element of [I]time.

I assumed that "more watts used" assumed the element of time. That seems fairly obvious. A microwave may use more watts per second, but if it heats the water in one fifth the time it may, or may not, use more total energy. You pay for Kilowatt Hours---
Watts (and kilowatts) are units of power, which is energy per time.

Kilowatt-hours, BTUs, and joules are units of energy.

Or in short, you mean "total kW-hours used" in your second paragraph above.

TellMeI'mNotCrazy
11-25-2005, 12:20 PM
My favorite (current) way to make hot water for coffee/tea/cocoa:
http://www.toastess.com/product_details.asp?product=39

The base plugs into the wall outlet, while the kettle can be removed, hence it is termed "cordless".
Electric kettles are as common as toasters here in South Africa. I'm starting to wonder how I ever lived without one - they heat the water to boiling very quickly, and they're just so easy, and absolutely perfect for french press coffee.