The shaft that connects the
turbine and generator
The giant generators at Hoover Dam
produce more than 2,000 megawatts
Niagara Falls, Canada
(Canadian Falls)
Horseshoe Falls (Canadian Falls)
drop= 167 ft.
Water flow= 600,000 gallons/sec
American Falls (N.Y)
Drop= 176 ft.- water only falls 70 ft. because of the
rocks at the base
flow= 150,000 gallons/sec
American Falls (N.Y.)
Canadian Falls (Canada)
Niagara River (downstream from the falls)
Rapids along the Niagara River
(downstream from the falls)
Niagara River under the Rainbow Bridge that crosses into
Canada
Canadian Hydropower station along the Niagara
River (6 miles downstream from the falls)
The Niagara River makes a 99 meter (325 ft.)drop from the
Lake Erie to Lake Ontario
How Hydroelectricity is generated
Water is channeled to the power plant through two 9 K (5.6 mi.) long
tunnels built under the City of Niagara Falls
Water gate upstream of the Canadian Falls.
Opens between midnight and 8 a.m. to divert
water to the hydroelectric plant.
Sir Adam Beck Power Generating Station
Generating capacity= 1,499 MegaWatts
Generators inside the Sir Adam Beck Generating
Station #2
How Solar Cells Work
Photovoltaic Cells
convert sunlight directly into electricity
The cells are made from silicon, a very
common chemical element found in sand.
When sunlight shines on a solar cell, the
energy it carries blasts electrons out of the
silicon. These can be forced to flow around
an electric circuit and power anything that
runs on electricity.
A solar cell is a sandwich of two different layers of silicon that have been
specially treated or doped so they will let electricity flow them in a
particular way. The lower layer is doped with boron so it has slightly too
few electrons. It's called p-type or positive-type silicon (because
electrons are negatively charged and this layer has too few of them). The
upper layer is doped (with phosphorus) the opposite way to give it
slightly too many electrons. It's called n-type or negative-type silicon.
When we place a layer of n-type silicon on a layer of p-type silicon, a
barrier is created at the junction of the two materials. No electrons can
cross the barrier so, even if we connect this silicon sandwich to a
flashlight, no current will flow: the bulb will not light up. But if we shine
light onto the sandwich, something remarkable happens. We can think
of the light as a stream of energetic "light particles" called photons. As
photons enter our sandwich, they give up their energy to the atoms in
the silicon. The incoming energy knocks electrons out of the lower, ptype layer so they jump across the barrier to the n-type layer above and
flow out around the circuit. The more light that shines, the more
electrons jump up and the more current flows.
How solar cells turn light into
electricity
A solar cell is a sandwich of ntype silicon (blue) and p-type
silicon (red).
1.When sunlight shines on the
cell, photons (light particles)
bombard the upper surface.
2.The photons (yellow blobs)
carry their energy down through
the cell.
3.The photons give up their
energy to electrons (green blobs)
in the lower, p-type layer.
4.The electrons use this energy
to jump across the barrier into
the upper, n-type layer and
escape out into the circuit.
5.Flowing around the circuit, the
electrons make the lamp light up.
How Solar Cells
Work
Concentrating Solar Power
What’s New….
New Jersey Institute of Technology developed
solar cells made of carbon nanotubules and
buckyballs that are painted on (8/07)
Until a few years ago, there were two
known forms of pure carbon, graphite and
diamond. Then an improbable-seeming
third form of carbon was discovered: a
hollow cluster of 60 carbon atoms shaped
like a soccer ball. Buckminsterfullerene or
"buckyballs"--named for the American
architect R. Buckminster Fuller, whose
geodesic domes had a similar structure--is
the roundest, most symmetrical large
molecule known. It is exceedingly rugged
and very stable, capable of surviving the
temperature extremes of outer space
These roof shingles are coated with PV
cells made of amorphous silicon. When
installation is complete, the PV shingles
look much like ordinary roofing shingles,
but they generate electricity.
Researchers at German's Fraunhofer
Institute are working on a solar powered cell
phone by using device-integrated, highefficiency solar cells that offers a module
efficiency rate of 20%. This allows the cell
phone to remain continuously powered up as
long as it receives sufficient sunlight (about 2
hours per day), otherwise it can charged
using conventional means (6/06)
Clothes with solar cells
in them to power your
IPod.
Solar cells made by a company named
Nanosolar using nanoparticle ink and
roll-printing technology- sold for
$0.99/Watt- December 2007