Transcript Renewable Energy - Downtown Magnets High School

Renewable Energy:
Solar Energy
Types of Renewable Energy
•
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Solar
Water
Wind
Biomass
–burning
–conversion to liquid fuels
• Geothermal
• Solar-Hydrogen
Current Sources of Energy
Direct Solar Energy
• Used to
– Heat houses and buildings
– Heat water
– Create high temperature heat
– Create electricity
Indirect Solar Energy
• Methods of creating electricity
– Biomass Energy
– Wind Energy
– Hydropower
– OTEC
– Waves & Tides
Passive Solar Heating
• Uses special materials, design
orientation and space to utilize
solar energy.
• Considers exposure direction,
windows, building materials,
eaves
• Requires NO input of energy
• East Coast
Trombe Wall
• Passive
heating system
where a
massive wall is
built behind a
window
exposed to the
sun that will
retain and reemit solar heat.
Extended Eaves
• Passive heating that blocks the
summer sun
Water Heating
• Flat box with glass on top, black on the
bottom, water tubes in middle
–Hot water coming
out of tubes is
placed in top of
water tank
–Cooler water from
bottom returned
to collector
Passive Solar Heating
• Solar
Cookers
–metal lined
box and
mirrors
focus solar
energy to
cook food
Fresh Water Solar Ponds
• Passive: Holes are
dug and lined with
black plastic.
–Water heats up,
but heat is
prevented from
escaping with
insulating panels.
• Doesn’t require
expensive storage
Active Solar Heating
• Input of
energy to gain
full benefits
from solar
heating.
• Ex: using
pumps or fans
to utilize sun
energy
PV Cells: Active Heating
• Photovoltaic cells
• When photons from
sun hit a thin wafer of
metal, a small elec.
current is produced
• Many cells must be
linked to prod usable
energy
• Used in remote areas,
calculators, watches
Solar Cell Backpack Anyone?
It will charge
your iPod
PV Solar Cells
• Pros: used in remote
areas, no greenhouse
gas emissions emitted,
noiseless
• Cons: initial cost, much
land is needed, many
must be used to be
efficient, wears down
over time, breaks
easily, materials aren’t
recyclable.
Grid vs Stand Alone PV Cells
• Grid: PV Cells
linked together; can
send power back to
city’s lines. Can get
$$
• Stand Alone: PV cell
by itself (not
connected to city’s
power). Needs a
battery to store
energy when sun
not available. (Hg)
Active Heating
• Solar Towers
–many mirrors are used to focus
solar energy  heats oil 
turbine
Solar-Hydrogen Energy- Theory
• H gas used for energy in 2 ways:
–burned directly - since no carbon, it
burns cleanly
–combined with oxygen gas to
produce water (fuel cells)
• Problems:
–H2 gas is costly to make through
chemical rxns
Fuel Cell
Device that takes H and O to make
electricity. Byproduct = water &
heat.
Fuel Cell Car
Fuel Cells
•
Pros:
1.
2.
3.
No CO2 emitted
H can be produced from water
High efficiency
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Cons:
1.
2.
3.
H is very flammable
H not found alone in nature
Energy is needed to produce fuel (from
water)
No distribution system in place.
4.