Perfect Cup of Resource Efficiency
by on 02.19.05
This one cup brew-tool by Frabosk beats every other model or brand, hands down, for simplicity and overall resource efficiency. It has a permanent filter; works with any cup design..use your favorite travel mug or ordinary ceramic cup... and it's good anywhere you can get hot water. Get the best taste with loose tea or coffee, and bypass the cheap razor/expensive blade scam that the pod-coffee makers push. You could get five of these and spend far less money and cover less counter space than you would for just one of the plug-in "to go" brewers. Read on for more thoughts on peak energy efficiency on the fly, regardless of brew tool.
TreeHuggers want to know: what's the most efficient way to get a cup-'o hot water among these choices?
+ micro-wave a cup -- cold versus hot tapwater fill?
+ range-top kettle -- cold versus hot tapwater fill?
+ a plug-in water heating kettle-- filled with cold versus hot tapwater?
Efficiency very much depends on how your tap water is heated.
Absolute best way: if you have an undersink "on demand" hot water heater, fill up direct from the hot tap; microwave it a bit more if you want it even hotter.
Second best: if the dishwasher is already running or, if someone in the same hot water piping loop is showering, draw direct from the hot water tap and microwave in ceramic cup, as needed, to boost temp.
Third best: use a counter top, plug-in small water heating kettle (the heat is directly transferred to the water and, unlike a range-top tea kettle, little energy goes into heating up the device itself). Make sure its an auto-shut off model for safety and efficiency.
Tied-for third: microwave a ceramic cup that was filled with cold tap water. Issues with this distant third are: you frequently compete with other's use of the wave, it takes two or three more minutes more than the "absolute best" method, it can boil over, and the cup becomes unpleasantly hot on the handle.
Absolute worst: (and grossly wasteful of both water and energy) running the water for a length of time to bring it up to "hot", just for one cup of water, per choices two and three above.
NOTE: Hot water pipes vary in diameter and length so an exact calculation of wasted water and energy is not straightforward for the worst case. But you can get an idea from a hypothetical one. Assume that each meter of hot water supply pipe...that's the pipe that goes from your basement or closet-held hot water heater to your tap... holds aproximately 0.4 liters, and your tap is located 10 meters from the heater. Waiting for it to get hot means you have to waste 4 liters (about a gallon) of water before you even begin to feel the heat at the tap. You'll probably waste a similar additional amount before the pipe reaches thermal equilibrium with the hot water flowing through it, and reachs "hot to the touch" status at the tap: so that's 2 gallons wasted total. Then, you're going to fill up just one cup with that hot water, wasting also the heat in the gallon of hot water laying in the pipe. The only scenario that voids this waste is if you have set up the diswasher to run just as you leave home with a hot cup of coffee or tea. The most pathetically wasteful setting of all is when you live in a third floor flat, and the landlord has all hot water originating in the basement. That's at least a 20 meter (14 gallon + energy) shot at the climate changed future per caffeine buzz.
by: John Laumer
Hot tap water is much more likely to contain lead and other toxic metals from your pipes. It shouldn't be used for cooking or drinking.
Hot tap water is also more likely to contain bacteria as it rests in an imperfect warm dark chamber.
Cold tap water boiled in a tea kettle over a gas stove should be the most resource efficient. Microwaves and those electric one minute water heaters pull in 1-3kw to run. High demand electric appliances are the reason we need such excess power capacity as we have today. The 8am noon 5pm power spikes for cooking. 8-5 for offices. Do your laundry and dishes outside these hours.
In small villages in small countries they've connected high drain appliances over the internet to allow power queueing so they can maximize the output from the few power plants they do have. May have to wait 30 mins. to start the dishwasher, but all your town needs is a few wind mills then.
Addendum items. Rate of lead salt dissolution in hot water pipes is controlled by the age and material of plumbing (lead pipe, copper pipe, plastic pipe), the type of solder used and tidiness of joints, the "aggressiveness" of water in corroding metal (determined by pH, alkalinity, carbonate hardness), the presence of H2S generating iron bacteria if water is from a well, and to a lessor degree, temperature. No one factor or group of factors will typify lead exposure risk for every person.
Microwave energy is highly concentrated on the water within the cup. And that will be exactly the amount of water you need to drink a cup of hot water. When boiling water in a tea kettle, people tend to overfill to make sure they have enough, and all the heat applied to that extra water is wasted. Moreover, much of the applied energy is used to bring the actual kettle up to temperature, not just the water. IF its a whistling kettle, energy is lost to steam as well. All these represent wasted energy, whether from gas or electric power. Carbon dioxide is emitted regardless of whether gas is combusted on your stove or at the power company.
I don't know the exact figures but running a 2000kw microwave for a minute is probably going to burn ALOT more natural gas (or worse) at the power plant (loss in transmission, conversion) than using your stove top for 3 minutes. I recommend using a whistle kettle because you'll know exactly when it's done and the steam only pours out between the time you hear and turn off the fire. Also you'll never accidentally forget about your water and find yourself with a ruined pot 20 minutes later.
Am I allowed to ask a question?
For boiling a cup of water, which is most energy-efficient and/or environmentally friendly
a) an electric kettle, with concealed element, 3000watts
b) same brand and style electric kettle, 2000 watts
c) an old "whistling" kettle, used on a gas stove.
I do understand that different manufacturers will be using different bits inside their electric kettles, and that this will alter their efficiency, so I daresay you can't give a hard and fast answer. But I'll bet you could give a good guideline.
and I suppose I should additionally be interested to know, does the equation change once one is boiling say 2,3,4 or 5 cups of water - and if so, roughly where? (ie. taking into consideration the energy needed to heat the element, the speed the water boils at, the fact that when boiling several cups of water presumable heating the entire kettle on the hob is a benefit rather than a negative, etc. etc.)
Deciding bewteen a gas stove and an electric kettle is difficult. If all your electricity comes from wind or solar power, the choice is clear. But if you r electricity comes from the National Grid it could be argued that you should look at the national average fuel efficiency in electricity generation. Even this is difficult, as figures quoted usually do not include the high energy cost of transporting gas large distances. This means that the efficiency factor for electricity generation is probably not much more than 0.3. If you have a good kettle, you might get up to 0.8 for your local efficiency, giving 0.24 overall.
The kettle on a gas stove is probably similar. In winter the waste heat helps to warm your kitchen, so is not completely wasted. If you have air-conditioning you will be drawing additional power to get rid of the waste heat in summer.