Renewable Energy and Conservation

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Renewable Energy and Conservation

• Chapter 12

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HOW DO WE MAKE ENERGY???
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Passive Solar Energy
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Passive Solar Energy
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Active Solar Energy -uses a collecting device
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Active Solar Energy -uses a collecting device
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SOLAR ENERGY

• Light energy harnessed from the sun
• Photovoltaic Cells (solar panels) are very
  expensive to build and install but once youve
  got them, you have free energy! (Last time I
  checked, sunlight was free!)

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Solar Energy

• PROS
• Low pollution
• Low maintenance
• Good for rural areas
• Can be incorporated into roofing material.
• Sun is FREEEEEEE!!

• CONS
• Only 10-15 efficient
• New RD is proving to be closer to 33!! ?
• Large Scale Use needs lots of land (solar farms)
• High startup costs.
• Energy cant be stored long-term.

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Solar-Generated Hydrogen
FUEL CELLS
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Hydrogen Fuel Cell
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Hydrogen

• PROS
• No pollution
• no SOx or NOx or PM
• only water heat
• Can be stored transported (liquefied fuel)
• H is 2X as efficient as gasoline

• CONS
• Produces NOx (small amount)
• Only 8 efficiency
• Little/No infrastructure
• Vehicles not widely available

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Direct vs Indirect Solar Energy

• DIRECT SOLAR
• Solar panels
• Solar-generated hydrogen

• INDIREC T SOLAR
• Biomass
• Wind
• Hydropower

• 
  
• BUT THERE ARE OTHER SOURCES!
• Oceans (wave movt, thermal, tidal movt)
• Geothermal (earths heat)
• Pumped Storage Reservoirs (gravity)
• Cogeneration (get heat when you make electricity)
• Conservation Increased Efficiency

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Biomass
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Biomass

• Biomass energy, or "bioenergy
• Energy from plants and plant-derived materials,
  crop waste, or animal waste
• Burned for energy
• Most primitive energy source on earth

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Biomass

• Advantages
• Renewable if managed properly
• Can be found worldwide
• Lower landfill use by burning wastes
• Planting trees can provide a Carbon Sink
  (counteracts the CO2)

• Disadvantages
• Air pollution!!!
• crops take up a lot of land and water
• planting and harvesting take lots of energy
• crops are not available year round
• Biomass crops take up land that could be used for
  food increases food costs
• Increased soil erosion, desertification, and
  water supply degradation

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Biofuels
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Biofuels

• Biomass can be converted
• directly into liquid fuels, called
• "biofuels, to be used for
• transportation
• Ethanol is an alcohol created from biomass
  (usually corn)
• Biodiesel is made by combining alcohol (usually
  methanol) with vegetable oil, animal fat, or
  recycled cooking grease.
• Blended with gasoline, both increase vehicle
  performance and cut down carbon monoxide and
  other smog-causing emissions.
• ? Some types (biogas CH4 is quite clean)
• ? Heavy government subsidies
• ? 30-40 of the energy in starting material is
  lost in the alcohol conversion process

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WIND ENERGY

• Using wind to turn aerogenerators or wind
  turbines to generate electricity.
• Wind turns turbine
• Turbine spins a generator
• Generator makes electricity

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WIND ENERGY

• Coastlines/offshore
• Islands
• Tops of mountains
• In the plains

• Why is it Indirect Solar Energy???
• Sun ? Temp
• Temp ? Pressure
• Pressure ? Wind

• 
  

• PROS
• Widely used, cost efficient
• No air pollution
• Combined w/ agriculture double land-use!
• Potential for much offshore wind energy

• CONS
• Birds/Bats killed
• Loud
• Ugly
• Expensive initially

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HYDROELECTRIC ENERGY
? Expensive! ? Floods the area ? Changes natural
flow ? Affects fish migration ? Reservoir-Induced
Seismicity ? Water-borne diseases
(schistosomiasis)

• Running water in rivers turns turbines inside
  dams to generate electricity.

? Creates reservoir for recreation ? Prevents
flooding ?19 (world) 9 (USA) power ? Great
potential for LEDCs
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TIDAL WAVE ENERGY

• Tidal dams are built across bays
• High Tide water goes into a reservoir, pushing
  turbines.
• Low Tide water recedes, pushing turbines

• Wave Dams are built anywhere in the water
• As waves rise and fall, air is pushed into and
  out of a turbine tunnel

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TIDAL ENERGY WAVE ENERGY
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Ocean Thermal Energy Conversion

• Uses temperature differences in the ocean to run
  a turbine/generator.
• Requires another liquid with a low boiling point
• ammonia, propane, etc
• Its never burned it only changes physical state
  (liquid ? gas ? turns turbine ? back to liquid)

Video http//www.youtube.com/watch?vx59MptHscxY
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Ocean Thermal Energy Conversion
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Ocean Thermal Energy Conversion

• ? Great in the tropics!!! (Hawaii)
• ? No pollution
• ? Reusable liquid material (ammonia, etc)
• ? Unclear impact on marine organisms (?temp)
• ? Inefficient so far (3-4)
• ? Not on a large scale need more RD!
• ? Expensive due to inefficiency

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GEOTHERMAL ENERGY

• Hot water from deep underground creates steam
• The steam turns turbines which generate
  electricity
• How does digging the wells for this type of
  energy affect the environment?

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Pros Cons geothermal

• ? great in geologically active areas (volcanic
  Iceland, western USA, Japan, Philippines)
• ? inexpensive, efficient, reliable
• ? not land intensive
• ? minimal air pollution
• ? geothermal heat pumps can be used for homes
  (small scale)
• ? renewable or not?
• ? small amt of H2S gas
• ? can cause subidence

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Pumped Storage Reservoirs

• Pump water uphill at night (low electricity cost)
• Water flows downhill during day to generate power
• Just like in a normal hydroelectric dam

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Pumped Storage Reservoirs
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Cogeneration

• Aka Combined Heat Power
• Burn some fuel for electricity
• Heat is also used to make steam
• Steam turns a turbine for electricity
• Heat is also used to heat buildings other uses.
• Steam is condensed back to water for reuse.
• Get more for your money!
• Very efficient and cost-effective.
• Great for small scale (restaurants, hotels, etc)

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CAFÉ standards

• Corporate Average Fuel Economy
• Standards for average fuel economy
• Guidelines are set by EPA.