Saturday, March 13, 2010

How much land do you drink?

Say you drink 35 liters a year of alcohol. 14 liters is the rather high amount the average Irish person does. There is a podcast here where Saul Griffith describes how due to carbon rationing in the future you will have to decide between a shower and a glass of wine each day. So the question of how much effort goes into each brew is important for the future where the amount of land and energy we consume may be heavily taxed and rationed.

What area of land do you need of a crop of apples, barley, wheat, potatoes, grapes or sugar to keep someone in booze for a year? There is a table here of the yield in terms of (kcal/sq m/year) each crop produces

Cane sugar 3500
Beet sugar 1990
Potatoes 1600
Apples 1500
Wheat, cereal 810
Corn 250
Milk 420
Beef 130

So in terms of calories per square meter Cane sugar seems to win. You do have to calculate how efficiently the calories in the crop get into alcohol in the booze you drink.

This guy tries get the alcohol out of sugar beat. "so the theoretical yield of ethanol produced is around 50%alc per weight of sugar"

Each square meter is 2000 kcal according to the earlier table. A kilo of sugar is 4000 kcal. So for 14 liters of alcohol is 28 kilos of sugar. 14 liters is what the Irish person drinks annually. So that is 56 square meters of sugar beat to keep you in (bad) booze for the year.

Now for cider.Say scrumpy is 6.5% abv then one liter of scrumpy is 65 ml of alcohol. So 14 liters is 215 liters of cider. Is that right? Does the average Irish person really drink the equivalant of a pint of scrumpy every day?

Anyway I want about 200 liters of cider which is about 400 kilos of apples. How much area of orchard do I need to get that many apples?

cider and apple juice are both about 400 calories per liter . Growing apples is 1500 kcal per square meter. I estimate 1/2 of that makes it into the juice which is 750kcal. Each liter is 400kcal so 200 liters is 80000 kcal. If a meter is 750 kcal after pressing etc then that is 106 meters squared to keep you in good alcohol for the year.

So back of the envelope it would take about 100 square meters of orchard to keep you in booze for the year.

4.5% Beer seems about 400 kcal per liter. And all grain is to be generous 75% efficient at getting out the sugars from grain. So each liter requires 533 kcal of grain very roughly. Wheat, cereal 810 kcal per square meter per year that is 2/3 of a meter square per liter of beer.
So how many liters of 4.5% beer is 14 liters of alcohol? It is about 310 liters of beer (which is a huge amount!) or back of the envelope 250 square meters of land to keep you in beer if you include malting loses.

Now wine. Each square meter grows about a kilo of grapes. As 1 acre grows about 5 tonnes according to here.

So 112 liters of wine is about 14 liters of alcohol.
3 kilos of grapes produce about 2 liters of wine from looking at various recipes. So 112 liters is about 170 kilos of grapes. So 112 liters is about 170 sq meters of vineyard. So you need about 170 square meters of grapes to keep you in booze for the year.

So in Ireland you could keep you in booze for a year of square meters you would need 56 sugar beat, 100 orchard, 250 barley and in france 170 grapes, roughly.


Ange said...

Interesting, but you definitely need to add some graphs IMO.

red dave said...

Good point Ange. I worked this out a while ago. Went to do the graphs lost interest and never posted it. It does need graphs though.