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(pulling random data points from around the internet) It takes approximately 255 liters of water to make 250ml of milk. So 1020 liters per liter of milk. There

(pulling random data points from around the internet) It takes approximately 255 liters of water to make 250ml of milk. So 1020 liters per liter of milk. There's 3.78542 liters per gallon. So that makes about 1930 liters per half gallon milk. 510 gallons of water for 0.5 gallons of milk. It takes between 2500 and 5000 joules of energy per liter of tap water depending on the water source (2000 times that for bottled water). So up to 9,650,000 joules of energy per half gallon of milk for the water(about 2680 Wh). 1.25 to 1.44 kg of feed to produce a liter of milk (0.2645 gallons). To produce 1kg of wheat requires between 500 and 4,000 liters of water. But then you need to transport the feed to where the cows are... Then you have to transport the milk. How far is it, and what sort of fuel is used? What sort of bottle is used? If it's come across the country via truck in a plastic bottle, that doesn't get recycled, that could be a lot of fuel. How long was the milk refrigerated before it reaches a home fridge? There's 4 million joules to make a PET 1 liter plastic bottle. So about 7.5 million joules for a half gallon one(2 kilo watt hours). Often the transportation uses more than that for the bottle, but varies greatly. One amount mentioned is 4 million joules per liter. That's 4 kilo watt hours just for the bottle. There's lots more to it, but I guess 1-2 days of solar power production from a 5kW solar system for a half gallon of milk.

groby_b 8y ago
That data (1000 gallons for a gallon of milk) comes from Natural News, which is... not a very precise source. A cow consumes, worst case (2000 lbs, lactating, it's hot) ~80 gallons per day. That same cow produces 3-4 gallons of milk a day. On top of that, most of that water is excreted again - otherwise, your cow would gain 640lbs a day. Or, with the 1000 gallons/gallon of milk scenario, some 12,000 lbs/day Assuming that that water is tap water is also... well, a most pessimistic assumption. If you wish a quick sanity check of your numbers, US milk production is ~25 bln gallons/year. Roughly ~70 mln gallon/day. Assuming it took one day at 10kW for a gallon of milk, that'd be 700GW continuous energy consumption for our annual milk production. This is a substantial part of the total US energy production. Second check: Assuming really cheap energy ($0.09/kWh, 10kW, 24h), that gives us a milk energy price of ~$21.00/gallon. Just the energy. This does not quite match, either. $14/gallon if you go exclusively with wind energy, which is IIRC the cheapest right now.
- throwaway12iii 8y ago
  Milk costs about $3.50 per gallon in the USA. If approximately 73% of the milk price is subsidized, that is about $12.96. Also, oil is heavily subsidized, which is the main cost of plastic bottled milk dispatched by oil using trucks.
  - quickthrower2 8y ago
    Wow, in Australia it’s about 1 AUD or 70c USD per litre. So about the same price, but no subsidies as far as I know. That said we recently had to fund raise for farmers due to too dry weather and supermarkets increased the price a little bit explicitly to help them out.
    - niij 8y ago
      > supermarkets increased the price a little bit explicitly to help them out How is this different from normal supply and demand?
      - sjwright 8y ago
        Because the supermarkets are a oligopsony. This distorts the market.
        benj111 8y ago
        I thought you'd spelled oligopoly incorrectly, then I googled. I've done a business studies degree so surprised I hadn't come across the term. TIL. https://en.m.wikipedia.org/wiki/Oligopsony https://en.m.wikipedia.org/wiki/Oligopsony
      - quickthrower2 8y ago
        Actually I looked more closely today and they sell two supermarket branded milk cartons: one with the donation of 10% added to the price and the regular milk. Same stuff inside I presume!
    - 8y ago
lucideer 8y ago
> 1020 liters per liter of milk > 1.25 to 1.44 kg of feed to produce a liter of milk ... 1kg of wheat requires between 500 and 4,000 liters of water Not sure which specific sources of random data-points you've picked from around the internet, but generally to arrive at the figure of x litres of water per y litres of milk, a full life-cycle analysis is done which would typically account for feed production and feed transport. So there's going to be a lot of overlap in your figures. Secondly, the energy requirements for getting fully treated drinkable water to residential taps is going to be significantly different than that required to supply agricultural water for irrigation, etc.—at least a portion of that should be untreated/reclaimed waste water.
war1025 8y ago
I don't know how much milk a breast-feeding mother makes, but I'd guess it's on the order of a quart a day. I can guarantee my wife does not drink 1000L of water a day. Which I guess is a way of saying that these numbers factor in a lot of externalities that don't get factored in to other parts of the discussion. So the value judgment ends up skewed much more than it should be.
jdietrich 8y ago
A more credible source (The International Journal of Life Cycle Analysis) puts the figure at about 3.9MJ per litre, which equates to 4.1KWh per US gallon. That figure includes fodder production, processing, Tetra-Pak type cardboard packaging and transport to retail. It's based on the Norwegian dairy industry, but the US dairy industry should be in the same ballpark - the transport inputs are probably greater, but the inputs in production are probably lower due to lower welfare and biosafety standards. https://sci-hub.tw/10.1007/BF02978855 https://sci-hub.tw/10.1007/BF02978855
B1FF_PSUVM 8y ago
> It takes approximately 255 liters of water to make 250ml of milk. We must be close to running out of water on Earth, if it's vanishing away so quickly. No cream in the coffee, people. Coffee is made without water, right?
- deleted 8y ago
  [deleted]
ninguem2 8y ago
Milk that normally lasts three weeks (as reported in the OP) is pasteurized. That requires boiling it, at a minimum. Need to add that to your energy calculations.

groby_b 8y ago

That data (1000 gallons for a gallon of milk) comes from Natural News, which is... not a very precise source. A cow consumes, worst case (2000 lbs, lactating, it's hot) ~80 gallons per day. That same cow produces 3-4 gallons of milk a day. On top of that, most of that water is excreted again - otherwise, your cow would gain 640lbs a day. Or, with the 1000 gallons/gallon of milk scenario, some 12,000 lbs/day Assuming that that water is tap water is also... well, a most pessimistic assumption. If you wish a quick sanity check of your numbers, US milk production is ~25 bln gallons/year. Roughly ~70 mln gallon/day. Assuming it took one day at 10kW for a gallon of milk, that'd be 700GW continuous energy consumption for our annual milk production. This is a substantial part of the total US energy production. Second check: Assuming really cheap energy ($0.09/kWh, 10kW, 24h), that gives us a milk energy price of ~$21.00/gallon. Just the energy. This does not quite match, either. $14/gallon if you go exclusively with wind energy, which is IIRC the cheapest right now.

throwaway12iii 8y ago
Milk costs about $3.50 per gallon in the USA. If approximately 73% of the milk price is subsidized, that is about $12.96. Also, oil is heavily subsidized, which is the main cost of plastic bottled milk dispatched by oil using trucks.
- quickthrower2 8y ago
  Wow, in Australia it’s about 1 AUD or 70c USD per litre. So about the same price, but no subsidies as far as I know. That said we recently had to fund raise for farmers due to too dry weather and supermarkets increased the price a little bit explicitly to help them out.
  - niij 8y ago
    > supermarkets increased the price a little bit explicitly to help them out How is this different from normal supply and demand?
    - sjwright 8y ago
      Because the supermarkets are a oligopsony. This distorts the market.
      - benj111 8y ago
        I thought you'd spelled oligopoly incorrectly, then I googled. I've done a business studies degree so surprised I hadn't come across the term. TIL. https://en.m.wikipedia.org/wiki/Oligopsony https://en.m.wikipedia.org/wiki/Oligopsony
    - quickthrower2 8y ago
      Actually I looked more closely today and they sell two supermarket branded milk cartons: one with the donation of 10% added to the price and the regular milk. Same stuff inside I presume!
  - 8y ago

lucideer 8y ago

> 1020 liters per liter of milk > 1.25 to 1.44 kg of feed to produce a liter of milk ... 1kg of wheat requires between 500 and 4,000 liters of water Not sure which specific sources of random data-points you've picked from around the internet, but generally to arrive at the figure of x litres of water per y litres of milk, a full life-cycle analysis is done which would typically account for feed production and feed transport. So there's going to be a lot of overlap in your figures. Secondly, the energy requirements for getting fully treated drinkable water to residential taps is going to be significantly different than that required to supply agricultural water for irrigation, etc.—at least a portion of that should be untreated/reclaimed waste water.

war1025 8y ago

I don't know how much milk a breast-feeding mother makes, but I'd guess it's on the order of a quart a day. I can guarantee my wife does not drink 1000L of water a day. Which I guess is a way of saying that these numbers factor in a lot of externalities that don't get factored in to other parts of the discussion. So the value judgment ends up skewed much more than it should be.

jdietrich 8y ago

A more credible source (The International Journal of Life Cycle Analysis) puts the figure at about 3.9MJ per litre, which equates to 4.1KWh per US gallon. That figure includes fodder production, processing, Tetra-Pak type cardboard packaging and transport to retail. It's based on the Norwegian dairy industry, but the US dairy industry should be in the same ballpark - the transport inputs are probably greater, but the inputs in production are probably lower due to lower welfare and biosafety standards. https://sci-hub.tw/10.1007/BF02978855 https://sci-hub.tw/10.1007/BF02978855

B1FF_PSUVM 8y ago

> It takes approximately 255 liters of water to make 250ml of milk. We must be close to running out of water on Earth, if it's vanishing away so quickly. No cream in the coffee, people. Coffee is made without water, right?

deleted 8y ago
[deleted]

ninguem2 8y ago

Milk that normally lasts three weeks (as reported in the OP) is pasteurized. That requires boiling it, at a minimum. Need to add that to your energy calculations.