How much oil is needed to get a gallon of milk in the retail store?

Question

OK, milk comes from cows but oil is needed at every step of the way. The feed, the barn, the truck, the equipment all use oil.

Answer 1

Your question doesn't sound correct.  All my life I was told that milk comes from cows.  And gasoline comes from oil....So when does a person get milk from oil?

Answer 2

I came up with .021 gallons of gas per gallon of milk. This is only a very rough estimate since there are a lot of variariables. I won't bother with the math (easy in Excel) but here are my assumptions:

10 gallons of gas and diesel used per acre per year to grow corn (#1)

150 bushels of corn per acre per year (#2)

56 pounds of corn per bushel(#3)

75 pounds of feed per cow per day (#4)

8,000 kg of milk per year (#5)

100 miles traveled by milk to market (#6)

6 mpg for a semi(#7)

50, 000 pounds per truckload (#8)

50 miles traveled by feed to dairy (guess)

The estimate is composed of three parts, .0157 gal gas/ gal milk to produce corn to feed cows, .00220 to transport feed, and .00283 to transport milk.

The distances are particularly poor assumptions; if you double them the result goes up to .026 total. The feed production component is probably actually lower since I assume here that cows only eat corn, while in actuality part of their diet is grasses, and these take less fuel to produce. On the other hand, if you're interested in greenhouse gas production, you'd have to include natural gas used to make fertilizer, and electricity used for many things. I suspect these would far outweigh the amount of gas and diesel used. You could also include the gas used by the consumer to get to the store, but how much would you allocate to the milk vs. other things you buy...?

In any case, the number will vary depending on the market, and at least this gets you started in case you want to spend more time improving the estimate by finding better assumptions.