Our Daily Bleg: How Much Does Ice-Making Contribute to Global Warming?

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A reader who works as a research scientist but wishes his name to be kept anonymous — “to avoid any hate mail coming my way” — writes in with a fervent couple of questions.

Being from Europe I have always wondered why Americans drink so much soda. Given the associated health risks, which has been discussed on your website and many others, it just seems ludicrous. Besides this obvious question and the associated health care costs, I was wondering how much energy is actually being wasted each year by making all the ice being added to the sodas. Could you estimate how many metric tons of carbon dioxide are being senselessly generated for making the ice which is added to the beverages which are eroding public health and public funds?

Anyone out there who can tell our curious, timid scientist a) why Americans drink so much soda; and b) how environmentally-unfriendly all that ice is? Back-of-the-envelope calculations welcome.

Mary S.

No energy is being "wasted" because ice-cold soda is delicious.

Scott W

Here's my quick calculation that does not include commercial ice making:

Assuming an ice maker or ice maker portion of a freezer takes 150W
Assuming it runs 12 hours/day = 1800 Wh/day = 1.8 kWh/day
75.11 million housing units in the US (2009 data via Wolfram Alpha)
Assuming 60% have ice makers in some form = 45 million household ice makers

45 million households * 1.8kWh/day/household = 81000000 kWh/day

81000000 kWh/day * 0.0005883 metric tons of CO2/kWh (carbonfund.org) = 47652 metric tons CO2/day

As to why Americans drink so much soda, it may be to make up for all the smoking we're not doing anymore (which Europeans don't seem to mind as much).


a) If soda and wine were the same price (as is often the case for table wine in Europe), I would kick my diet coke habit and pick up a Merlot habit. Duh.


Just to give a very rough estimate:
per capita soda consumption in the US: 789*8oz (http://www.cspnet.com/ME2/Audiences/Segments/Publications/Print.asp?Module=Publications::Article&id=5506D87134B44810A3E2B2ADDBF6C73C) = 6312oz
Total Soda consumption: 300m*6312=1.9 trillion ounces
Figure about 15% of total cup's volume is ice (http://www.sugarstacks.com/beverages.htm) (e.g. ice=.15/.85=.176 of soda volume) this is probably low for restaurants, but compensates somewhat for less ice if drinking from bottles/cans, and assuming ice is same density as soda: .176*1.9t oz= 330 billion ounces of ice
assuming 1 liquid ounce of water = 1 ounce of mass (it doesn't, but it's close), 330 billion oz = 9.4 billion kg
Energy to produce ice (in Denmark) = .064 kWh/kg (http://www.lcafood.dk/processes/industry/iceproduction.htm): 9.4 billion kg*.064 kWh/kg = 600 million kWh
US average: 1.297 lbs CO2/kWh: 600m*1.297 (http://www.carbonfund.org/site/pages/carbon_calculators/category/Assumptions) = ****780 million pounds of CO2**** (about 350,000 metric tons)


Travis T.

Average American drinks 150 quarts of soda a year, so let's say that's 400 12 oz servings

Rough, rough estimation of ice per drink, let's say 5 oz, roughly 150 mL, so 60 liters of ice per year per American

300 million Americans: 18 billion liters of ice per year

Assuming that since 1 calorie (~4.2 joules) is the amount of energy it takes to increase the temperature of 1 mL of water 1 degree, it takes the same amount of energy to decrease the temperature by 1 degree, the amount of energy required to freeze 18 billion liters of water from 22 degrees to 0 degrees is roughly 400 trillion calories (~ 1.7 x 10^12 joules) or about 470,000 kWh

give it a boost by an order of magnitude for inefficiency of energy and call it 5,000 MWh, using Scott's CO2/kWh conversion, I get about 3,000 metric tons of CO2/year

googling "3000 metric tons of CO2", the second hit says that this is the amount of CO2 that could be saved by having shopping malls stop playing muzak: http://www.grist.org/article/2011-02-03-how-malls-can-save-both-the-earth-and-your-ears

source for soda consumption: http://fooddemocracy.wordpress.com/2007/11/09/chew-on-this-us-soda-consumption/



As a recent convert from soda-drinking American to water-drinking American, I think I can answer part of your first question.

I grew up with soda as did many of the people my age. Since I wasn't used to the taste of water growing up, it was hard for me to adapt to its relatively bland taste today. Many Americans aren't willing to make that switch.
Also, soda cans are convenient for travel and easily available almost anywhere you go.

Bottled water is convenient and available too but I don't see you complaining about bottled water. How much waste is involved in manufacturing the bottles and transporting those bottles to their end users? Water from the tap is imminently cheaper per gallon. Given that Europeans drink a lot more carbonated water than Americans do, can't we turn the question around to you?

Besides, now that I'm a water a drinker, I happen to be an ice water drinker. Your initial complaint about making ice for sodas applies to me as well!



I thought that Superfreakonomics showed that global warming from carbon emissions was a total non-issue (if we really cared, we'd eat kangaroos instead of cows which output no methane) and that even if it was an issue we could quickly, effectively, and inexpensively counteract it with the "garden hose to the sky" idea. Maybe I drew incomplete conclusions from the global cooling chapter.


I don't have back-of-the-envelope calculations but I have anecdotal evidence.

For myself and a lot of my friends, it's a norm at this point. A lot of them drink soda all the time and I often get soda when I'm out to eat. Around the house I drink a lot of fruit juice (which is just as sugary as soda) but I know I'm exceptional that way. When you go out to restaurants here it seems like you're offered a plethora of soda choices and only a handful of other non-alcoholic options (water, coffee, tea, sometimes milk and juice).

I've also asked my friends why they always put ice in their drinks (even in winter) and the answer is usually along the lines of they just prefer it that way. I think if their norm was to not have ice in their drinks then they wouldn't seek out ice from the bin in the freezer. The question for me is where the norm started. Is it from the same one-upping mindset that led to larger portion sizes in restaurants?



I don't understand hotel ice machines, and I'm American. I can't imagine it would be cheaper to install those things on every floor and run them 24/7 than to have room service just bring buckets of ice to guests upon request. (They're also noisy and usually ugly.) Most rooms have minibars nowadays—why not just add an ice tray in there?


Americans drink a lot of soda because it's cheap and tasty. If we drew a handy quadrant graphic with cheapness and tastiness, we'd had four quadrants:

1. Cheap and bad tasting
2. Cheap and tasty
3. Expensive and bad tasting
4. Expensive and tasty

In general, we're going to gravitate to the "tasty" quadrants. "Cheap and tasty" is where cost conscious people will go. "Expensive and tasty" is where a smaller, more affluent group will go (if we're talking about beverages, Jessica's comment vis-a-vis wine prices is applicable). I guess people might buy into the other two quadrants, but those would be a very small minority of consumers.

So that's why Americans drink soda. (Yes, this is the long way of saying, "Because it tastes good and doesn't cost much.")

There are a lot of interesting economic underpinnings and implications here. For example, why is soda in the "cheap and tasty" quadrant? Well, most of soda is sugar (typically high-fructose corn syrup - HFCS). HFCS is made from corn and some chemicals, and it's really, really cheap because of US corn subsidies. So we can add another layer:

- Why do Americans drink so much soda? It's cheap and tasty.
- Why is soda so tasty? Because it's full of delicious sweetness (typically provided by lots of HFCS).
- Why is soda so cheap? Because corn is so cheap.
- Why is corn so cheap? Because the government says so.

So why do Americans drink so much soda? Because the government has made corn so cheap.

Of course, the great irony is that some governments (mostly local, but it's been discussed at the federal level) would also like to put a "sin tax" on soda, ostensibly to make it more expensive, therefore discouraging consumption and reducing obesity and its related ailments. An easier way to make soda more expensive is to stop subsidizing corn, but for some reason it's more politically palatable to tax soda consumption than to remove corn subsidies.



A follow-up question: Which uses more energy, the ice or the soda? Are we saving energy by putting all that ice in? I don’t have time to do the calculations right now, but I would guess the syrup has more embodied energy (and carbon) than the energy needed to freeze the ice. Growing the corn for the corn syrup, processing it and shipping it takes a bit of energy and given how much more the soda costs (the restaurant) than the ice I would think the ice is “greener.”
Of course it would be even better not to drink as much at all.


Ok, I did some math:
From Rob’s estimation above, 1oz of ice has about a 1gCO2 footprint.
According to eiolca.net and their Economic Life-Cycle tool, http://www.eiolca.net/ “Flavoring syrup and concentrate manufacturing” totals 395 Metric Tons per $1 million dollars of activity. That’s 395g/$
I seem to remember, though I can’t find the source right now, that a fast food chain spends roughly $0.13 per 22oz drink (assuming 5oz of Ice gives $0.13/17oz = $0.0076/oz) multiply that by 395g/$ gives about 3gCO2/oz

Ice: 1gCO2/oz
Soda: 3gCO2/oz

If you want to save the planet, don’t skimp on the ice!


As an American who takes my beverages (be they sodas, water, or beer) out of the fridge and drinks them without ice, I suppose this doesn't really apply to me (except to the extent that I'm paying to refrigerate extra items).

However, for the times when one wants a hot beverage, I wonder what it costs to boil water for a cup of tea/coffee/hot chocolate (or to purify water in countries where tapwater is non-potable). So if we wanted the most energy-efficient form of caffeine boost, would it cost more to add ice to your soda or to brew a cup of coffee?

Zach Brannan

Isn't the per capita soda consumption greatest in Scandinavia and particularly Iceland? I can also say that in Europe soda is more expensive and alcoholic beverages are cheaper than in America.


Surprisingly, most of the energy used by ice making machines is for heating elements to release the ice from the mold. http://www.nist.gov/el/building_environment/ice-041211.cfm

Personally, I rarely choose soda, and when I do, I ask for it with no ice. I hate the watered-down taste at the end. If I'm going to spend my money on sugar water with a ridiculous markup, I sure don't want it to be diluted with ice, which is often half the glass.

Tom in Raleigh

I have to cast my lot with the folks who noted that "wasted" is not the right term. If one is deriving some utility from one's drink being cold (I know I sure do!), then there's value in the ice or in refrigeration. The waste would come from using more energy and water than necessary to make ice. This is clearly an efficiency criterion.

I love the comment about "waste" and bottled water in Europe. I love European fizzy water--it's really good. But it's bottled in heavy glass bottles that must be shipped by modes that probably emit a fair bit of greenhouse gas (diesel?), so there's that.

[Disclaimer--I'm a political scientist, not an economist. Although I love econ too.]


"...I was wondering how much energy is actually being wasted each year by making all the ice being added to the sodas"

Answer: None. It doesn't taste good warm. Since I make full use of the ice that is produced, no energy is wasted.


I think the question in many ways can be reversed, as in: "Why don't Europeans drink as much soda as Americans?"

Some of the answer is certainly cultural. Here in Atlanta, Coca-Cola is in some ways the dominant religion, like pizza in Naples. Soda companies and the goods they sell are a part of our social history; alcohol is much more culturally ingrained in Europe. Also, the drinking age is three years higher in America than most of western Europe, and I wonder how much soda American minors consume while their French peers consume wine.

Soda is especially unique among beverages as being really nasty when it's warm. Europeans are much more likely to drink warm beverages, and might therefore have an aversion to soda.

I am one data point, and therefore not entirely representative. But most of the soda I drink was chilled not with ice, but with a residential refrigerator. Because the refrigerator was running anyways to keep my milk cold, the marginal environmental impact of my soda chilling is zero.



I can't answer the question, but it's something I've often wondered about myself (and I'm an American). Not the ice, but the attraction of soda. Most of it is horrible-tasting stuff - far too sweet and fizzy - and worst of all, it doesn't do much to quench my thirst.

I would suspect, though, that in a full analysis the ice-making energy is really minor compared to the energy costs of excess sugar. Energy goes into growing & refining it, adding it to the drinks & distributing them. Then the excess calories promote obesity, which causes more energy to be burned hauling around overweight bodies. In the long term, obesity has serious health consequences, which lead to more ambulance rides, ER & doctor visits, digging larger holes for the oversized coffins...


Like Tom, I am a political scientist, not an economist, but I have to say that Josh has the most compelling argument. It's all politics and profit. The subsidy of corn to create cheap corn syrup (or ethanol) when corn can be a detrimental crop to the land and leads to a product which has a detrimental effect on those who consume it (whether that be many domesticated animals or soda consumers), which in turn has sparked outrage at the unseemly obesity of Americans and created calls for an additional sin tax, which will pay for the subsidy, is not unlike the agricultural subsidies for tobacco growers who produced products which had deleterious effects on health, which then created action against the use of said products through advertising, education and sin taxes. Also, it is super tasty and our Puritanistic roots have resulted in a society where beverages of an alcoholic nature are discouraged, generally by government.


John Goforth

A theory: To the older generations out there, Coca-cola was a little bit of a luxury good. In 1930 at 5 cents a bottle there was quite a bit of trade off to be considered when purchasing a coke. A matinee at the local movie theater went for the same price. 5 cents could get you a 2 oz Hershey's bar. Cigarettes, another luxury of the time, were around 15 cents a pack. If you consider a matinee now goes for about $5-10, 2 oz hershey's bar runs at least $1.00, and a pack of cigarettes runs around $3-10, a comparable can of coke going for $.33 (in a 12 pack) is one of the few luxury items that has gotten cheaper when inflation is taken into consideration. If a person still considers these things to have an equal amount of utils, then it could almost be compared to putting .33 cents into a slot machine and getting $1-10 dollars back guaranteed on the first pull and each additional pull decreasing the reward in accordance with diminishing marginal utility.

A few other thoughts:

Advertising: When you consider prohibition, Coca-cola probably has one of the longest continuous advertisements in America for any beverage. Off hand, I can not think of another type of advertising memorabilia that people collect to the extent that they collect Coca-cola memorabilia. When people pay good money to collect your old advertisements, its probably a good sign that your campaign/product was a home run. Combine that with repetition from all types of media, it's a winning equation.

The Up-sell: Next think of how many burgers we consume each year. The natural product for an up-sell is something to drink and fries, and behold, the combo meal is born. As we're also the worlds largest consumers of french-fries, being the worlds largest consumers of carbonated beverages makes sense.

Culture: Again, we had prohibition for that to happen there had to be a considerable amount of teetotalers. From a hospitality standpoint, offering an alcoholic beverage to a guest might be offensive, and offering water would be declasse. The only people that don't drink Cokes out of principle are Mormons (because of the caffeine) . So for the purpose of being hospitable, offering a coke is usually an surefire bet. Also, we have a relatively high drinking age as compared to other countries so we have a larger market of people that can not consume any other beverage with addictive properties.

As to the global warming aspect, I'm not sure that is a relevant. Every engineer I've ever met is fueled by caffeine. They are the reason Jolt Cola exist. If there is a solution to global warming it will probably be discovered with the aid of a mind boggling amount of ice cold caffeinated beverages.



"...2 oz hershey’s bar runs at least $1.00..."

At my usual supermarket, I can buy decent 65-70% cacao chocolate, in bulk, for less than $5/lb.