thomas l acker chelsea atwater and dean howard smith
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Energy Efficiency in Industrial Agriculture: You Are What You Eat

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Thomas L. Acker Chelsea Atwater and, Dean Howard Smith. Energy Efficiency in Industrial Agriculture: You Are What You Eat. Research issue. Modern industrial farming technologies for growing fruits and vegetables have changed substantially in recent decades.

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research issue
Research issue
  • Modern industrial farming technologies for growing fruits and vegetables have changed substantially in recent decades.
  • In many locations such as Arizona, these industries are highly energy and water intensive operations.
  • As such, the sustainability of these operations is called into question.
  • The economic, social and climate implications of energy use in agriculture are worth further discussion.
the subterranean forest
The Subterranean Forest
  • Hypothesis: the social-metabolic regime of a society is limited by the conversion of energy to allow for the harvest of more energy.
  • Each human must expend a certain amount of energy harvesting food, in whatever form, to allow for continued life to allow for more food harvesting and so on.
  • If an individual’s energy budget is such that more energy is expended capturing energy than is captured, then, obviously, the individual will die.
budgeting
Budgeting
  • The metabolic rate of the human body is such that perhaps 20% of the energy consumed can be directly applied to capturing more energy through hunting, gathering or working in the fields.
  • Thus, the individual must harvest at least 5 units of energy for each unit of energy spent in the process of harvesting in order to survive.
  • Any deficit below the 1:5 ratio will be unsurvivable.
  • Any surplus above the ratio will allow for additional work unrelated to energy harvesting such as singing and dancing. Other authors estimate smaller and greater estimates.
efficiency
Efficiency
  • A megafauna hunting society estimates an output of 40-60 megajoules (MJ) per hour of labor.
  • Reduced to a productivity of 4-6 MJ of output per hour for small game hunting.
  • With the advent of agriculture the typical output of a worker increased to 12-20 MJ per hour of labor.
social changes
Social Changes
  • The socio-economic basis of the agrarian civilizations lies in the tributary appropriation of surplus. This means that the producers (peasants) have to regularly contribute a part of their harvest as rent, tribute or tax of which a “ruling class” with its retinue of specialists and servants are supported and provided for. The result is a fortifying vertical social differentiation, normally in the following categories:
  • peasants, landlords (aristocracy), warriors, priests (scholars), the court (rulers, bureaucrats), craftsmen, merchants. In addition there is usually a lower class that can include up to 10% of the population earning their livelihood as wage laborers, barterers, beggars or thieves. (Sieferle, 2001, page 25)
consequences
Consequences
  • The social organizational changes, due to the metabolic change in society, eventually led to the need for yet a new energy regime as the populations grew and a solar based energy regime was no longer sustainable. Thus fossil fuels entered the energy budget and eventually the food stream.
photosynthesis
Photosynthesis
  • Twidwell and Weir estimate that the maximum efficiency of photosynthesis is 5%. They further estimate that the photosynthesis of cassava and cereal is 2% and 3% respectively.
can it be
Can it Be?
  • A solar based energy regime must convert one unit of human energy into, grossly, between 100 and 250 units of harvested solar energy to be merely survivable.
the energy regime reached the capacity so
The energy regime reached the capacity, so…
  • In a solar based energy regime, the amount of energy embodied in food production must always exceed the value of the energy necessary to produce and harvest that food. Industrial agriculture, reliant on fossil fuels and non-gravity fed irrigation, has completely turned the energy budget of growing food upside down.
calculations
Calculations
  • Average weight= total weight/sample size
  • Weight/unit = average weight*16
  • Useable/unit=weight/unit *(1- refuse%)
  • Serving/unit= (useable/unit)/ serving size
efficiency1
Efficiency
  • Kcal of production energy/Kcal of food energy
  • Gallons of water/Kcal of food energy
  • 8 ounce glasses
day as a vegetarian
DAY AS A VEGETARIAN
  • BREAKFAST: 4 eggs = 320 calories
  • 320*28= 8,960
  • ____________________
  • 8960 input to 320 output
  • SNACK: 1 oz. peanuts = 170 calories
  • 170 * 1.4 = 238
  • LUNCH: Sushi! = 450
  • ¼ cup dry rice = 160
  • ¼ cup salmon = 90
  • 1 in pod = 200
  • ____________________
  • 448 + 720 + 830 + 9198 = 11196
  • 450 + 490 = 940
  • 10781 input to 840 output
  • DINNER = 350
  • 3 oz Spinach = 30 cal
  • 1 med tomato = 35 cal
  • 1 ear corn = 83 cal
  • ½ c. cowpeas a.k.a. black eyed peas= 110

oz. broccoli = 44 cal

  •  11196 + 6.9 +21 +207.5 +710.6 +805.64= 12946.64
  • 840 + 302= 1142
  • 12946.64 inputs for 1142 output
  •  Dessert: 100
  • coffee with 1 oz sugar = 110 cal
  • __________________________
  • 12141 + 398.2 = 12539.2
  • 1098 + 100 = 1198
  • 12539.2 input for 1198 output

10.5:1 Inefficiency

day as a meat eater
DAY AS A MEAT EATER
  • BREAKFAST: 406
  • 4 slices = 240 calories
  • 8 oz milk = 86 calories
  • 86*19 = 1634
  • 1 orange = 80 calories
  • 18090 input to 406 output
  • LUNCH: 265
  • 3 slices beef = 135 calories
  • 2 slices whole wheat bread = 110 cal
  • 1 oz Spinach = 10 cal
  • 2 slices tomato = 10
  • 18090 + 4725 + 242 + 2.3 + 6 = 23065.3
  • 406 + 135 + 110 + 10 + 10 = 761
  • 23065.3 input to 761 output
  • SNACK: 1 oz. peanuts = 170 calories
  • DINNER = 520
  • 4 oz chicken = 240 cal
  • 1 cup = 60 cal
  • baked potato w/ skin= 220 cal
  • ______________________________
  • 23303.3 + 3840 + 41.4 +270.6 = 27455.3
  • 931 + 520 = 1451
  • 27455.3 input to 1451 output calories

18.9:1 Inefficiency

alternative menu
ALTERNATIVE MENU
  • BREAKFAST: 335
  • 1 c cooked oats = 145 cals
  • 1 oz sugar = 110 cal
  • 1 orange = 80 calories
  • 1273.7 input to 335 output
  • LUNCH
  • 4 oz Shrimp = 70 cals
  • 3 oz Spinach = 30 cal
  • 1.1 oz. broccoli = 44 cal
  • 1273.7 + 4865 +6.9 +805.64= 6949

6949 input to 479 output

14.5:1 inefficiency

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