Objectives I. Human Use of Sun’s Energy for Food Relevant Ecological Concepts Challenges + Approaches to Feed 7-10 billion Consequences of Moving Down Food Chain Comparison of Diets across Earth II. Human II. Human Use of Sun’s Energy for Fuel Relevant Ecological Concepts Past formation of Fossil Fuels Present-day Use of Non-renewable Fossil Fuels Present-day Need for Renewable Fuels

Humans + Food Energy - Relates to: A. Population size + carrying capacity “ need (‘demand’ for animal food B. Primary and secondary productivity C. Trophic level of consumption D. Ecological efficiency E. Land use + landscape/conservation ecology

Global variation in estimated NPP - Humans consume 40% of global NPP!!

Challenges for future: Less water for irrigation Increasing temperatures -> drought Loss of land to non-farm uses Increased fuel costs Increased fertilizer costs Fewer new technologies on horizon Plan B Lester D. Brown Earth Policy Institute

How to feed 7-10 billion well! 1. Improve land (plant) productivity A. Increase multi-cropping B. Improve water-use efficiency + plant less water-demanding crops C. Move down food chain - less water to produce animal feed D. Raise cost of water E. Put local people in charge to manage resources

2. Produce animal protein more efficiently. A. 38% of grain used as animal feed in world B. variation in efficiency in convert grain to protein beef = low aquaculture herb. fish = high C. variation among countries in type of meat eaten China = # 1 = pork; 2nd in world = chickens; fish on rise, too D. most soybeans used as grain for animal food; has improved efficiency greatly

3.New animal protein production systems A. Milk in India: feed animals with roughage B. Use crop residues (straw/corn stalk) for cows C. China aquaculture: 4 fish at different trophic levels

Why does human population size depend on our trophic level? Figure 2

4. Move down food chain A. How many people can earth support - depends upon our trophic level Country kg grain/person /yr billions supported USA Italy India (almost all to humans) B. Of our 800 kg grain, ? eaten as grain; ? to feed animals C. Complete table below:

Cultural Evolution of Diet A. Diets include carbos + protein B. Must have amino acid complementarity -> can get all required AAs from plants e.g. L.A.: Beans + rice (corn) Asia: Soybeans + rice Middle East: Chickpeas + wheat/millet What do all three have in common to get a lot of N?

Government Policies Under Debate A. Plant corn for food or fuel? B. Farm bill with farm subsidies

The Hungry Planet Peter Menzel ItemRange $ spent on food Calories in diet Sugar used Obsesity level Meat consumption

Calculate your daily required calories A. Height (in) B. Activity level C. BMI (body mass index) 18.5 (small boned) (large boned) = overweight >30 = obese (60% of US = overweight or obese) D. Weight (lb) E. Calories if 30 yr (add 7 female or 10 male for each year below 30) F. Calories for my age __________

I.Human Use of Energy for Fuel: relevant ecolgoical concepts: Sun: origin of (almost) all energy that humans use Ecosystem = energy-transforming machine Photosynthesis: sun energy transferred to chemical bond energy Respiration: release (and transfer) of chemical bond energy; generation of ATP + heat Aerobic Anaerobic: less release of energy Incomplete decomposition: accumulate biomass and energy

PAST SCENARIO: Accumulation of chemical bond energy from past photosynthesis A. Production > Decomposition B. Death, then into decomposer food web C. Bury by sediments; anaerobic --> decomposition slowed and incomplete D. Organic matter (biomass) transformed to fossil fuels Chemical Fossil Fuels from Geologic Composting!

Physical Transformation of Organic Matter When? Carboniferous ,000,000 yrs ago Where? Ocean: Algae (diatoms) Sedimentation Pressure/heat (Crude) oil + natural gas (hydrocarbons)

Where? Land Woody plants in swamps Biogas via anaerobic respiration by bacteria Incomplete decomposition; much energy remains Peat (a fuel) Sedimentation; weight squeezed out water Pressure + heat transformed wood fragments --> thermogenic natural gas leaves + wood --> oil + coal If anaerobic -- S in coal Trapped by overlying sediments Retrieval by drilling/strip mining

coal Major coal deposits in USA - red = high in S

Chemical transformation of organic plant matter Lipids, proteins, carbos, lignin, cellulose Kerogens (complex heavy hydrocarbons) Heat --> Lighter hydrocarbons by breaking bonds of kerogens

PRESENT: break fossilized chemical bonds Uses: Drive ‘machines’ Heat Electricity Which fuels used for which use? Relation of oil to gasoline Relation to electricity Sources Relative cleanliness

What’s in a barrel of oil?

How is electricity made and used?

Speed of Depletion of Non-renewable Energy Sources How old are the sources? When were they discovered + put to use? What % have we used? What is projected time of depletion?

"There are currently 98 oil producing countries in the world, of which 64 are thought to have passed their geologically- imposed production peak, and of those 60 are in terminal production decline."

Renewable alternative fuels - relate to sun’s energy Solar Wind Biofuels (see PPT on 203 website) Seed (e.g. corn) -> ethanol Vegetable oil (from seed) -> biodiesel Crop residues (e.g corn stalks) + Non-crop cellulose (e.g. switch grass + Miscanthus) -> ethanol

EBI: Energy Biosciences Institute UI + U Cal-Berkeley