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Human Energy Needs. Primitive – 2000 Hunter-gatherer – 5000 Early agriculture – 12,000 Later agriculture – 20,000. Early industrial – 60,000 Modern industrial – 125,000 Current U.S. – 250,000. Energy needs (kcal/person/day) have mirrored societal evolution. 1850s Fuel Usage.

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energy needs kcal person day have mirrored societal evolution
Primitive – 2000

Hunter-gatherer – 5000

Early agriculture – 12,000

Later agriculture – 20,000

Early industrial – 60,000

Modern industrial – 125,000

Current U.S. – 250,000

Energy needs (kcal/person/day) have mirrored societal evolution
1850s fuel usage
1850s Fuel Usage
  • Primarily Wood Used
1900s fuel usage
1900s Fuel Usage
  • Wood and Coal Use about equal
  • Easy transition to make because both are solid fuel
  • Oil = liquid need to change furnace technology
1950s fuel usage
1950s Fuel Usage
  • Big switch to fossil fuels is complete
  • More use of liquid and gaseous fuels
  • Very little use of renewable fuels or nuclear
1990s fuel usage
1990s Fuel Usage
  • Oil is now the dominant fuel type followed by natural gas and coal.
  • More use of alternative fuels and nuclear
  • Wood primarily used in third world nations
amount of fossil fuels being used
Amount of Fossil Fuels being Used
  • The U.S. tops the charts in terms of total usage and in terms of per capita use
  • And this amount is astronomical……..
u s energy use
U.S. Energy Use
  • In 1991, the U.S. consumed 81.5 quads
  • Estimated use for 2000 was 96.2 – 100 quads
  • How much is a quad?
    • 1 quad = 1,000,000,000,000,000 BTUs
    • 1 BTU = energy required to warm 1 lb water 1 oF
how much is a quad
How much is a Quad?

472,000 Barrels of Oil/Day for 365 Days

or 172,280,000 Barrels of Oil

75 Supertankers

500,000 Railroad

Cars of Coal

Annual Production of 20

Three Mile Island Nuclear Plants

what is this energy being used for
What is this energy being used for?
  • Liquid Fuel is for vehicle use
  • Heating less than 100 oC is space-heating
  • Other heating is for industrial purposes
  • Electricity generation is only 8%



need to match energy quality with quality of task
Need to match energy quality with quality of task
  • Amory Lovins – physicist, states that high quality energy is currently being wasted doing low quality tasks.
  • What do we mean by high quality and low quality?
high quality energy
High Quality Energy
  • High quality energy is energy like electricity. Electrons running through wires at the speed of light constitute very high quality energy.
low quality energy
Low Quality Energy
  • Energy with lots of waste heat is low quality energy.
  • Energy that is widely dispersed and not “focused” is also low quality
  • Examples include burning fossil fuels (lots of waste heat) and solar (widely dispersed)
task quality
Task “Quality”
  • High quality tasks are those that require high quality energy – electricity is needed to run “electronics”
  • Low quality task can be accomplished with less focused energy – space heating. Remember how much energy is devoted to the task of space heating (35%!)
so what should we do
So, what should we do?
  • Conversion of space heating tasks to solar energy is a good match of energy and task quality.
  • On average sun puts 1 cal/cm2/minute on all earth surfaces. This is plenty to heat spaces under that cm2.
energy conservation
Energy Conservation
  • We’ll discuss this as we go through all the energy “types” but let’s list some ways here……..
design appliances and machines with energy conservation in mind
Design appliances and machines with energy conservation in mind

Refrigerators: Yesterday & Today

Which was really more efficient?



resource conservation energy conservation
Resource Conservation = Energy Conservation
  • Energy needed to extract resource
  • Energy needed to change resource into usable product, e.g. water
  • Energy needed to dispose of waste resource following use, e.g solid waste