Milk production at a diary farm was low so the farmer
wrote to the local university asking for help from academia.
A multidisciplinary team of professors was assembled and
two weeks of intensive on-site investigation took place.
The scholars then returned to the university, notebooks
crammed with data, where the task of writing the report
began. Shortly thereafter the farmer received the write-up,
and opened it to read on the first line:
“Consider a spherical cow …”
Pie
of the
Day
US Energy Consumption
4%
farms
other
US Energy Consumption
17%
There are
2 million
farms in US
food system
other
What percent of our (US) meals
are eaten in the car?
A.
B.
C.
D.
1%
2%
5%
20%
Trivia from “The Omnivores Dilemma” by Michael Pollan
US Energy Consumption
4%
For feedlot beef,
the ratio is 35:1
farms
other
Farm Energy Consumption
(% of on farm consumption)
2.2
2.4
What does this energy
consumption buy us in
terms of food energy?
1.1
4.2
0.7
machinery + fuel
fertilizer
pesticides
3 calories of fossil energy
buys us
1 calorie of food
1970
52.7
36.3
irrigation
transportation
seeds
drying
Recycling Ratio
monoculture
Sun
Outputs
Inputs
Machinery + Fuel
Tractors
Trailers
Trucks
Diesel
Gasoline
Fertilizer
Anhydrous ammonia (N)
Potash (K)
Phosphate (P)
Pesticides
Water
Seeds
Transportation Equipment + Fuel
Electricity (drying)
Farm
Ecosystem
Grain
Residue
Near Environment
Recycling Ratio = 0
Factory Farm
Recycling Ratio
Horses, compost, seeds
Grain, residue
Rain
Sun
Outputs
Inputs
Farm
Ecosystem
Grain
Near Environment
Recycling Ratio = 1
Sustainable Farm
US Energy Consumption
17%
food system
other
Food System Energy Consumption
(% of total US consumption)
3.00
5.00
farm
food processing
packaging
2.01
fuel for processing
transportation
wholesale/retail
1.33
2.60
1991
0.98
1.58
refrigeration/preparing
Colorado is 66,700,000 acres.
Field Crops in the US
Corn = 79,400,000 acres (11,100,000,000 bushels)
Cotton = 15,300,000 acres
Rice = 2,840,000 acres
Sorghum = 6,280,000 acres
Of the 2 million farms,
6.7% account for 75% of
farm sales (2002, USDA)
Soybeans = 74,900,000 acres (3,090,000,000 bushels)
Wheat = 57,300,000 acres (1,810,000,000 bushels)
Field Crops in US, 2006
Land Use
24%
corn
34%
cotton
rice
sorghum
6%
32%
1%
3%
soybeans
wheat
How do we get these high yields?
Better living through chemistry
Fertilizers and Pesticides
Better living through biology
Fertilizer Facts from
The Fertilizer Institute
• Three main ingredients: nitrogen, phosphorus,
potassium.
• China is the largest producer and consumer of
chemical fertilizer.
– US is #2.
• The fertilizer industry is $10 billion/yr business.
• Modern fertilizer accounts for ~1/3 of all crop
yield.
– Some say that modern fertilizer has allowed the
earth’s population to expand by 30-40% over the
carrying capacity.
Haber-Bosch Process
1st industrial chemical reaction process to use high pressure
Fritz Haber, 1918 Nobel
O2 + N2 + CH4
P = 200 – 400 atm
T = 400 – 650 °C
Carl Bosch, 1931 Nobel
Fe Catalyst
CO2 + NH4+
nitrogen fertilizer
Where does all this corn go?
3 of every 5 corn kernels in the US goes to feed animals
Conversion efficiency:
(kg of grain:kg of meat)
Chicken, 2:1
Pork, 4:1
Beef, 7:1
What about meat?
Grain yields ~ 30 kJ of metabolizable energy/hectare
Beef yields ~ 1 kJ of metabolizable energy/hectare
When was high fructose corn
syrup created?
A.
B.
C.
D.
1920
1940
1960
1980
Trivia from “The Omnivores Dilemma” by Michael Pollan
Dupont CEO’s, Chad Holliday, Sept 2005
Biorenewable resources
• organic materials made of recent biological origin
• are by definition sustainable
• this is what we did until 150 yrs ago
Bioenergy
• conversion of the chemical energy in the molecule to heat
Biobased products
• transportation fuels
• chemicals and natural fibers
Why is a return to bio-based
energy and products attractive?
•
•
•
•
Environmental quality
National security
Excess agricultural production
Rural development
Challenges
• Handling of a solid fuel
• Low density, so volume dictates
transportation limits, not mass
• High moisture content
• Lower heating value than fossil fuels
• Contain high oxygen content
References
Food and Energy Resources, Edited by D. Pimentel, C. Hall, Academic Press Inc., 1984
Energy, 2nd Edition, by G. Albrecht, Prentice Hall, 1995