ENERGY PATHS in the ECOSPHERE

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ENERGY PATHS in the ECOSPHERE

• TREN 1F90
• Sustainability, Environment and Tourism

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ENERGY

• What is it?

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ENERGY

• Defined as
• THE CAPACITY TO DO WORK

• What is it?
• BASIC DEFINITIONS AND LAWS

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ENERGY

• POTENTIAL ENERGY
• Stored energy in all its forms
• When released, it can do work
• Examples
• Coal, oil, gas
• Foodstuffs
• Rivers and streams above sea level

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ENERGY

• KINETIC ENERGY
• Energy in motion
• Energy possessed by moving objects
• Examples
• Falling leaf
• Diving kingfisher
• Waterfall

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ENERGY

• POTENTIAL ENERGY

• KINETIC ENERGY

? INTERCONVERTIBLE ?
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Laws of Thermodynamics

• All energy follows basic laws of thermodynamics,
  central to the understanding of ecological
  processes and environmental issues.

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Laws of Thermodynamics

• FIRST LAW
• Energy can be neither created nor destroyed it
  can only change form.

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Laws of Thermodynamics

• SECOND LAW
• During transformations, energy goes from a
  concentrated form to a less concentrated form.
• Less concentrated energy is dissipated in the
  form of heat.

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Laws of Thermodynamics

• HEATis the inevitable byproductof energy
  transformations

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Laws of Thermodynamics
COAL ? Burned to generate electricity ? Transmissi
on of electricity through wires ? Lighting of
bulb filament ? Light energy

• HEAT

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Laws of Thermodynamics

• May be defined as the kinetic energy associated
  with the random motion of atoms and molecules

• HEAT

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Laws of Thermodynamics

• Useful in concentrated form (e.g., internal
  combustion engine), but generally dissipated to
  the environment in a dilute form

• HEAT

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ENERGY CONCEPTS

• ENERGY QUALITY
• The ability of a given form of energy to perform
  useful work
• Also called energy density
• High quality energy sources are concentrated
  (large energy content per unit of measure)

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ENERGY CONCEPTS

• ENERGY QUALITY
• All energy sources are degraded in quality with
  use, to a less useful form (heat)
  

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ENERGY CONCEPTS

• ENERGY QUALITY
• All energy sources are degraded in quality with
  use, to a less useful form (heat)
  
• ?
• Wise energy use requires careful matching of
  energy source with needs

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ENERGY CONCEPTS

• Matching of energy source with needs
• Use low quality energy for low-grade needs
• E.g., passive solar radiation for heating living
  spaces
• Use high quality energy for high-grade needs
• E.g., electricity to weld steel in industrial
  arc-welding

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ENERGY DENSITY / QUALITY

• Electricity, nuclear fission
• Natural gas, gasoline, coal, concentrated
  sunlight
• Geothermal, biomass, tar sands, oil shale
• Wind, ambient heat

• VERY HIGH
• HIGH
• MODERATE
• LOW

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ENERGY EFFICIENCY

• The ratio of useful energy output to the total
  energy input.

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ENERGY EFFICIENCY

• Internal combustion engine in car
• Energy in 1 litre of gas 6500 kcal
• Energy output from engineconsuming 1 litre of
  gas 1300 kcal
• Energy efficiency 1300 0.20 20
• 6500

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ENERGY EFFICIENCY

• Incandescent light bulb
• Every light bulb consuming 100 w of
  electricity radiates 5 w of visible light energy
  and 95 w of heat
• ?
• Incandescent light bulbs are about 95
  efficient as heaters, but only 5 efficient as
  light sources!

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NET ENERGY

• Total energy available in a given source
• minus
• the energy used to find, concentrate, and deliver
  energy to the user

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NET ENERGY

• Tar sand oil extraction process
• Tar sands mined in open pits
• Hot water and steam used to liberate oil
• ?
• Energy costs of extraction may be up to
  80-90 of energy recovered
• ?
• Net value of extracted oil is only 10-20 of
  the oils true energy content

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NET ENERGY

• Food productionin industrial nations
• High yield agriculture requires large energy
  subsidy (fossil fuels for machinery and
  fertilizer production)
• ?
• Though total crop yields per hectare
  increased, the ratio of food energy produced to
  fuel energy used actually decreased through the
  mid- to late 20th century

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Ethanol fuel production

• Ethanol (a renewable alternative fuel) is
  currently produced primarily from corn
• Corn ethanol requires fossil fuel inputs for
  production (industrial agriculture)
• Net efficiency of ethanol was quite low prior to
  1990s
• -gt some research claims it takes more fossil
  energy to produce than it yields

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Ethanol fuel production

• Efficiency may have improved in recent years
• 1991 24
• 1998 36
• 2001 67
• Shapouri (2004) attributed to technological
  advances in farming and manufacturing
• Source Shapouri, Hosein. 2004. The 2001 net
  energy balance of corn-ethanol.
  www.usda.gov/oce/reports/energy/net_energy_balance
  .pdf

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Ethanol fuel production

• Results still disputed by some authorities

About 30 percent more fossil energy is
required to produce a gallon of ethanol than
you actually get out in ethanol
David Pimental, 2006, cited in Ratigan, Dylan
Ethanol as gas replacement Hope or hype?
MSNBC On The Money, 23 May 2006
(http//www.msnbc.msn.com/id/12934470/ )