Chapter 21: New renewable
Energy Alternatives
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Renewable Energy
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sun
wind
geothermal
oceans
hydrogen
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Solar Energy
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conversion of hydrogen (H) to helium (He)
each m2 of area receives about one kilowatt
of solar energy= seventeen 60 watt light
bulbs
therefore each house has enough roof area
to generate all it needs using solar panels
passive and active solar energy collection
Passive Solar Energy Collection
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design of buildings
construction materials are chosen to:
maximize direct absorption of sunlight during winter
keep the interior cool in summer by:
south facing windows
planting vegetation for shade during summer
overhangs to block sun in summer
heat-absorbing construction materials
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straw, brick or concrete for example
Passive Solar Energy Collection
Active Solar Energy
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solar panels
solar cookers
photovoltaic cells
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Active Solar Energy
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solar panels
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few on the roof of a house or building
collection of mirrors
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power tower with molten salt creating steam that moves
the generator
tubes with oil which creates steam that move turbines
Active Solar Energy
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photovoltaic cells
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collect sun's energy converting it to electrical
energy using semiconductors.
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Benefits of PV cell
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quiet
safe
require little or no maintenance
no moving parts
no turbine or generator required
each unit lasts 20-30 years
Active Solar Energy
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allows families to cook without having to
gather fuel wood
lessens daily workload
helps reduce deforestation
helps relieve social and environmental stress
Benefits of Solar Power
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inexhaustible as energy source
enough energy to power earth as long as
technology develops
allows decentralized control over power
producing many new jobs
does not pollute
Drawbacks of Solar Power
localization
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Drawbacks of Solar Power
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costs
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Wind Energy
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wind turbines
windmills have been used for more than 800
years in Europe
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drain wetlands
irrigate crops
grind grain into flour
Wind
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first wind turbine was created in the late 1800s
rural electrification act 1935 killed its development
promoting dams and coal plants
not until the oil embargo of 1973 that the idea was
brought back and funding for research was given
low costs
kinetic energy converted into electric energy
different turbines are designed to work at different
wind speeds
faster the wind the more energy it generates
Wind: fast growing energy sector
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Offshore Wind Turbines
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more expensive
more productive
shallow areas
maintenance
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Benefits of Using Wind Power
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cleaner
under optimal conditions it is much more effective
than any other conventional energy source
small to large scale usage
farmland can lease a small area and still be
productive
once built, the costs are only for maintenance
as efficiency increases the cost of electricity
decreases
Downsides of Wind Power
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wind is intermittent and unpredictable
good resourses are mostly away from
populations
grid has to be built and that costs money
conspicuous
people object to farms due to aesthetics
not-in-my-backyard syndrome
threat to birds and bats
Geothermal Energy
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generated deep within Earth
from an area of volcanic activity along two tectonic plates
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Benefits and Limitations
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Benefits
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reduces emissions relative to fossil fuels
other pollutants it produces are in very small quantities
filters help control pollutants
Limitations
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can produce other pollutants like CO2, CH4, NH3
sources may not be truly sustainable
limited to area where tectonic plates meet
water used for energy corrodes equipment shortening
lifetime of the plant
chemicals in the water may pollute the air
Ocean Energy Sources
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tides
waves
currents
Tides
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rising and fallen of the ocean level
twice each day
erecting dams across the outlets of the tidal
basins
outgoing tide will pass through the turbines
generating electricity
no pollution
high impact on the ecology of estuaries
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Hydroelectricity from Tidal Waves
La Rance- France
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Wave Energy
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converting mechanical energy to electricity
harness the motion of wind-driven waves at
the ocean surface
greater energy is found in deeper ocean sites
NY
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Wave Energy Generator
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Currents
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marine kinetic energy
essentially like underwater wind turbines
are now been tested in Europe
Hydrogen
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Benefits
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storage of energy generated by sustainable energy is a
problem, hydrogen fuels cells are promising
Hydrogen is the fuel and it is abundant
clan, bonds H2 and O2 making water as final product
Drawback
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to make the fuel (H2) energy is required and carbon based
pollutants are produced
possible risk of depleting ozone from stratosphere if H2
leaks
Bloombox or Bloomenergy
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stack of silica plates covered with patented solutions on both sides
it converts oxygen into energy with a minute use of energy (gas,
electric, biodisel, etc)
one "box" is required for every European home, 2 for every American
home
no need of the grid
several companies are already using it in California
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EBay
Google
FedEx
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CBS 60 minutes 2/21/2010
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The End
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