Human Energy Needs

1
Human Energy Needs
2
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

3
1850s Fuel Usage

• Primarily Wood Used

4
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

5
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

6
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

7
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..

8
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

9
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
10
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

34
35
11
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?

12
So, when was the last time you used your natural
gas powered stereo?
13
High Quality Energy

• High quality energy is energy like electricity.
  Electrons running through wires at the speed of
  light constitute very high quality energy.

14
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)

15
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!)

16
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.

17
Energy Conservation

• Well discuss this as we go through all the
  energy types but lets list some ways here..

18
Design appliances and machines with energy
conservation in mind
Refrigerators Yesterday Today Which was really
more efficient?
compressor
compressor
19
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