Energy Efficiency

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Energy Efficiency

• The Rocky Mountain Institute was planned and
  built by energy experts - passive heating, super
  insulation and partly earth sheltered. It makes
  use of the following
• super insulation
• temperature monitors operate shutters, etc.
• solar cells
• The renewable energy revolution begins!

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CHAPTER 20

• ENERGY EFFICIENCY AND RENEWABLE ENERGY

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The importance of improving energy efficiency

• 81 of all commercial energy used in the U.S. is
  wasted we waste as much energy as 2/3 of the
  world consumes
• Amory Lovings says we should stop driving
  Petropigs and stop living in energy sieves
• Energy efficiency is percentage of total energy
  input that does useful work in an energy
  conversion system

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The importance of improving energy efficiency -2

• Energy-efficient systems may be more expensive
  initially, but have lower life-cycle cost
  initial cost lifetime operating costs (includes
  extraction, transporting, processing, etc.of
  fuels)
• Compare cost of electricity to solar energy
• Dont use high quality energy when lower quality
  of energy can do the job.

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The importance of improving energy efficiency -3

• Three least efficient energy-using devices are
• incandescent light bulbs - 95 waste
• internal combustion vehicles - 90 waste
• nuclear power plants - waste of fuel waste of
  energy to dispose of dangerous wastes

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Ways to improve energy efficiency

• Use of waste heat which cannot be recycled so
  rate of flow to environment is slowed
• In Industry use
• Co-generation - combined heat and power systems -
  waste heat used for another purpose
• Replace energy-wasting electric motors with
  motors with adjustable speed drives

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Ways to improve energy efficiency

• In Industry- Other energy-saving measures
• High efficiency lighting
• Recycle, reuse and repair
• Change regulation of electric utility companies

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Saving Energy in Transportation

• Increase fuel efficiency in vehicles
• opposition by automakers since 1985
• small, fuel-efficient prototypes made, but not
  mass-produced - higher cost
• inflation adjustments --gt low gasoline prices
• what about Lovins freebates
• Move more people and freight by trains and boats
  or better designed trucks

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Electric Cars

• No pollution from the cars
• Electricity to recharge batteries --gt pollution
  elsewhere unless solar or wind is source of
  power
• limited range and expensive batteries

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Hybrid and Fuel Cell Cars

• Ecocars or Supercars use
• small hybrid electric-internal combustion engine
  using fuel and
• small battery (recharged by engine) for
  acceleration
• Fuel cell cars - two electrodes in electrolyte
• hydrogen oxygen reaction --gt 50-60 efficient

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Saving Energy in Buildings

• Compare World Trade Center to Ga. Power Company
  building in Atlanta- features
• largest surface faces south
• each floor blocks hot sun from lower floors
• lighted desks, not lighted rooms
• In general - reduce energy and CO2 emissions, and
  save money
• Better insulation - even bales of straw

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Energy Efficient Building

• Besides super insulation
• Passive solar heating
• High efficiency natural gas furnace
• Heat pumps in warm climates
• Least efficient is coal or nuclear fired
  electricity
• Plug up leaks and energy-saving windows
• even covering water heater and ducts

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Energy Efficient Building-3

• Set higher energy-efficient standards for new
  buildings
• Buy energy efficient lights and appliances
• Energy waste results from
• underpriced fossil fuels
• government subsidies and tax breaks
• not using life cycle cost analysis

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Direct use of solar energy for heat and
electricity

• If current subsidies for fossil fuels and nuclear
  energy are phased out, renewable energy sources
  will account for 50 of energy production - from
• improvements in energy efficiency
• mix of renewable energy from several sources

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Direct use of solar energy for heat and
electricity -2

• Benefits of this change
• save money
• create jobs
• decrease oil imports
• decrease pollution and environmental degradation
• increase military, economic and environmental
  security

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Solar energy to heat homes and water

• Passive solar energy captures sunlight directly
  within structure - slow storage and release of
  energy
• Active solar heating system uses collectors and
  fans/pumps for distribution

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Cooling houses naturally

• Trees, overhangs, awnings, insulating foil and
  windows
• Earth tubes - soil temperature is cooler

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Solar energy for high temperature heat and
electricity

• Solar thermal systems - power tower is central
  solar receiver heliostats - mirrors that track
  the sun - govt. subsidized project in California
• Solar thermal plant - distributed receiver
  system- oil in pipes is heated and distributed
• Parabolic dish collectors

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Solar energy for high temperature heat and
electricity -2

• Non-imaging optical solar concentrator -
  intensifies solar energy
• Solar cookers - for developing countries -
  decrease fuel wood use

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Solar energy to make electricity

• Photovoltaic (solar) cells - sunlight strikes
  silicon atoms - electrons released--gt electric
  current many cells together
• Used in roof shingles, in solar-electric window
• What is green design? Oberlin College
  Environmental Studies Center
• BP Amoco to use solar panels on service stations

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Solar for the future

• New kinds of solar cells are in the works
• Ideal technology for developing countries where
  commitment has not been made to fossil or nuclear
  fuel energy generation
• Need aggressive programs to encourage utilities
  etc. to utilize solar energy

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Electricity from moving water

• Large-scale hydropower projects - reservoir
  water flows to turbines at controlled rates
• Small-scale hydropower projects - no reservoir
  output varies with stream flow
• Pumped storage hydropower systems - at surplus
  energy times - energy pumps water to higher
  reservoir for later release

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Electricity from moving water

• Problems due to environmental and social
  consequences of large dams
• wildlife is threatened
• river flow is disrupted
• wetlands are destroyed

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Tides and Wave electricity

• High and low tides - flow into and out of bay --gt
  spin turbines
• Functions in limited areas - 2 in operation
• Wave generation of electricity might be possible
  in some coastal areas

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Heat stored in water --gt electricity

• Ocean thermal energy conversion- based on
  temperature differences - research and
  development stage

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Saline Solar ponds

• Makes use of differences in density of water at
  different depths facility at Dead Sea had high
  operating costs

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Freshwater solar ponds

• Black plastic bags filled with water - covered by
  fiberglass insulation panels
• Requires no energy storage and backup systems no
  pollution, small energy yield

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Electricity from Wind

• Worlds fastest growing energy resource
• But only 1 in U.S many good potential areas -
  Saudi Arabia of wind
• Wind farms
• Other countries - China is wind superstar
• Should be one of cheapest energy sources in next
  decade - could be used to make hydrogen gas from
  water --gt fuel cells

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Energy from biomass

• Burning of wood and manure
• Can be used to turn turbines --gt electricity
• Use of fast growing plants (biomass)
• Bagassse - residue from sugar cane harvest - used
  in Hawaii and Brazil
• Must be used where produced for
• Manure better used for fertilizer?
• Burning trash in incinerators - using heat?

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Biomass to gaseous and liquid fuels?

• Biogas - methane and CO2
• liquid ethanol
• liquid methanol
• biogas digester - anaerobic bacteria convert
  plant and animal waste to methane for heating and
  cooking
• gasohal - gasoline mixed with ethanol

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Solar-Hydrogen Revolution

• Hydrogen gas combine with oxygen --gt water - no
  pollution
• Water can be split into hydrogen oxygen
• But it takes energy to release the hydrogen from
  natural gas or steam
• A better possibility is solar energy to make
  hydrogen - photovoltaic-photoelectrochemical cell

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