My coffeemaker, a 1995-vintage Hamilton-Beach automatic drip filter machine, takes roughly eight minutes to make four cups of coffee. The appliance is rated at 1000 watts (one kilowatt), which means that in those eight minutes it uses roughly 0.133 kilowatt-hours. Of course, I don’t turn off the power as soon as the coffee is ready: I keep it on to keep the coffee hot until I, and any coffee-drinking female guest with the fortitude to endure my company, finish it off. So the machine therefore typically stays on for half an hour, and therefore uses about half a kilowatt-hour of electricity.
This morning my coffeemaker was on for the typical half-hour and used the typical half-kWh. While I drank my coffee, I read an article in the Ottawa Citizen by Mark Winfield, a York University professor and serial anti-nuke, on what he feels is the folly of continuing to rely on nuclear power in Ontario. It occurred to me that the printing presses that printed Winfield’s Citizen piece, and the internet servers that host the Citizen’s growing online presence, were powered mostly with the nuclear energy he opposes.
Moreover, the revenues that Ontario’s nuclear plants generate through the sale of low-cost electricity to provincial ratepayers helped to pay Winfield’s $109,636.32 salary. That revenue is taxed in a variety of ways, from taxes on profits, to income taxes on the salaries of employees at the nuclear plants, as well as the good old HST applied to every kWh of nuclear power, of which nuclear raises more than all other power sources combined because it makes more kWhs than all other sources combined. And, the profits of the provincially owned nuclear utility, OPG, go into the general coffers of the province. So, instead of criticizing Ontario’s most important energy source, Winfield should thank OPG and Bruce Power for helping to fund his ivory-tower lifestyle.
But to my point: I had my coffee, and read Winfield’s Citizen piece, at five-fifteen a.m. At the time I was enjoying my coffee and morning reading, Ontario electricity carbon intensity per kWh (CIPK) was 40.9 grams. That means that I, through my use of an electric-powered coffeemaker, was personally responsible for 20.45 grams of CO2.
Had Ontario listened to Winfield years ago and replaced its nuclear fleet with the fuel he would rather see used, i.e. natural gas, Ontario’s CIPK at five a.m. this morning would have been 388.7 grams. Which means that instead of being personally on the hook for 20.45 grams by virtue of my consumption of half a kWh to make coffee, I would have had 194.35 grams—over nine and a half times as much—on my conscience.
(You can do this counterfactual calculation yourself: simply multiply the kWh usage from any appliance you use by the current CIPK given in Table 1, then do the same calculation using the counterfactual CIPK given in Item 1 up on the right. That will give you your actual and counterfactual carbon footprint from the use of that appliance in Ontario. The counterfactual CIPK assumes Ontario’s nuclear plants have been replaced by gas plants, which emit 550 grams for every kWh generated.)
It’s easy for people making 109 grand a year to advocate expensive, carbon-heavy electricity. But the good news is, nobody has to listen to them. Sri Lankans, who live on less than $7,000 per year and who are currently protesting electricity price hikes, might, if they could, offer Ontario some good advice on who to listen to.
Re: “It occurred to me that the printing presses that printed Winfield’s Citizen piece, and the internet servers that host the Citizen’s growing online presence, were powered mostly with the nuclear energy he opposes.”
You know, if a Toronto subway rider looked up from their seat and saw an ad that stated this train is powered by nuclear energy, Winfield’s cud would go down the tubes. Always missing obvious opportunities!
More and more the reasons for anti-nukers to be anti-nuke is not health/safety because the long near nil mortality/damage record stands that nuclear plants just haven’t been the delivers of Doomsday even on its very worst days as anti-nukers have long wished, but rather are anti-nuke on implacable philosophical beefs — like wanting to banish the atom for the some especially evil thing it did at Hiroshima or dormantly mutated poisoned humans springing from the population like mushrooms or such. But you know, a crucial step in public nuclear education is swiftly and directly bopping like a gopher head such unchallenged anti-nuke articles and features as Winfield’s — never let one go unanswered in print or broadcast! But unfortunately, media organs like the Kos and the Times are culling letters to the editor and feedback from us pro-nuke peons, and who require some kick butt rebuttals from nuclear pros with credentials and respected organizations behind their back. But the irony of Sri Lanka is being a nation that often ignored the science education and nuclear energy investment recommendations of one of its star citizens and one of the most forward thinking people of the age residing there — Arthur C. Clarke.
I appreciate the thread of your comment on electricity use however you have overestimated the energy consumption by your appliance. The label rating is the maximum power demand by the appliance — in this case heater plus indicator. The heater in such devices is normally controlled with a simple thermostat or equivalent. While boiling the water to make the coffee the demand would be 100%. Once finished there is usually an audible “clink” as the heater cycles on and off.
It might be better to estimate the energy use by estimating the heat required to raise the mass of the water to 100°C. This should be more than that required to keep it hot for the balance of the time (depending on how long and neglecting evaporation).
4 cups ~ 1 L or 1 kg water. Temperature rise from 10°C to 100°C requires (1 kg) x (1 kcal/kg-K) x (4.2 kJ/kcal) x (90 K) = 378 kilojoules.
1 kWh = ( 1000 J/s ) * 3600 s = 3.6 MJ
378 kJ / (3.6 MJ/kWh) = 378/3600 kWh or 0.105 kWh
If your coffee maker does this in 8 minutes,
1 kW * (8 minutes)*(60 s / minute) = 480 kJ — we might infer that it is ~ 378/480 = 78% efficient — the losses heating up the air in the room.
If we use 480-378 = 102 kJ over 8 minutes to estimate the keep hot function then the average power for this feature is
(102 kJ/8 minutes) x (1 minute / 60 s) = 0.2 kW
So, adding 0.2 kW for the 30 minutes provides an additional 0.1 kWh for a total of 0.2 kWh — not the 0.5 kWh you estimated.
I think this is almost beaten to death except that the utility bills include an ~ 10% inflation of the energy consumption to account for distribution losses.
Bryan, good calcs! Your initial suggestion to just base it all on the calories to raise a kilogram of water to 100 °C reminds me of my 12/12/12 post.
I was just getting around to writing a clarification based on my trusty Kill-a-Watt, which measures usage in real time. My coffeemaker yesterday used 1061 W (roughly a kilowatt) for about four minutes to brew two cups, then went through this weird cycle of 1061 to roughly 450 W then down to 0.3 W — about four times — before settling down to 0.3 W which I guess was to keep the plate warm.
Think I’ll write up my dehumidifier — it runs continuously at what appears to be the same rate. That’s probably a better indicator.
And then — as James Greenidge suggests, I’ll just do it for the TO subway. That’s where the GHGs are saved.
There’s a kWh readout on the kill-a-watt. You can use that to get the total energy usage…
I think the 0.3 W may be the power indicator. That power won’t keep very much warm.
I can’t find useful specifications on the Kill-a-Watt as to how it measures power consumed. The coffee maker is a resistive load so power factor isn’t an issue.
The power level variation you observed may be the thermostat function operating within the averaging time of the meter giving an apparent average of ~450 W. The resistive heating element operates at only one power level without power controls that are uncommon in such appliances. (The common stovetop element operates with an on/off duty cycle control that uses a heated bimetallic strip switch where the knob adjusts the power to the wee strip heater.)
Your dehumidifier is another matter. The compressor and fan motors will have significant power factors. The website for this instrument describes power factor measurement in what seems to me to be an obtuse manner. Real power factor measurements are not trivial to do well.
So, you’re saying it’s good we have nuclear power, so you can waste it in a 20 year old crappy appliance?
And so ends the world.
Try a model with a thermos. Not because they use less power, but because they don’t burn the coffee. I’ve pulled cups from my $40 model after as many as 4 hours and it’s perfectly drinkable. The craptastic model it replaced made the coffee turn into sludge in less than an hour.
It’s not a crappy appliance, it’s excellent — -that’s why I’ve hung on to it for this long.
It’s excellent precisely because it keeps the joe hot but not too hot. Plus, coffee never sits in it for more than three-quarters of an hour.
0.11 kWh in 38 minutes, according to my kill a watt.
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