Transcript Energyx - Berkeley Cosmology Group

Julio Contreras, Julian Contreras, Ilian
Meza and Kevin Pascua
An electric generator is a device
that converts mechanical energy
to electrical energy.
•A generator forces electrons in
the windings to flow through the
external electrical circuit.
•The source of mechanical
energy may be a turbine steam
engine, water falling through a
turbine or, a wind turbine,
compressed air or any other
source of mechanical energy.
http://science.howstuffworks.com/electricity2.htm
• Rotor: The rotating part of an
electrical machine
• Stator: The stationary part of
an electrical machine
• Water stores potential energy
http://ga.water.usgs.gov/edu/hyhowworks.
html
Hydroelectric power now supplies about 715,000
megawatts or 19% of world electricity.
dams produce electrical power through the use of
gravitational force of falling or flowing water.
energy source is normally applied to peak load
demand, because it is readily stopped and started
The world's largest Dam
is the Three Gorges Dam
on the third longest river
in the world, the Yangtze
River.
http://www.top-alternativeenergysources.com/hydroelectricpower.html
http://en.wikipedia.org/wiki/Three
m
Pumped storage is a
method of keeping water in
reserve for peak period
power demands
Water that has already
pumped flowed down, gets
pumped back up to a
storage pool next to dam
This process is done too
provide enough energy
when customer demand for
energy is high, such as
during the middle of the
day.
This process is usually
done at night when energy
demand is relatively low
PROS
• Directly stores water
•
• In case of a drought, the
dam will still have a
relatively constant
•
supply of water
• Controls flooding &
provides recreational
•
activities such as boating
fishing and swimming, if
the lake is not being
used for drinking water
Simple design makes for
inexpensive repairs and
maintenance costs
Produce inexpensive
(after completion) and
clean power
If needed, can be shut
down instantly, where
thermal plants take
hours, and nuclear plants
can take days
CONS
• Requires flooding of entire valleys and scenic areas
• Disrupts natural seasonal changes in he river, and
ecosystems can be destroyed
• plant decay caused downstream of major dams
produces as many greenhouse gasses as more
conventional methods of producing electricity
• Expensive to build
http://www.ussdams.org/
A wind energy system transforms the kinetic energy of the wind
into mechanical or electrical energy that can be harnessed for
practical use. Wind electric turbines generate electricity for homes
and businesses and for sale to utilities.
www.awea.org/faq/wwt_basics.htm
http://www.e-marineinc.com/products/images/wind
Pros
Cons
• One of the cheapest forms of
energy available today
•Doesn’t release any harmful
pollutants or gases as
byproducts
•Safer and cleaner source of
energy than natural gas, coal or
oil
•Efficient renewable energy
• A never ending resource,
therefore power cuts and power
failures are almost non-existent
in areas that rely upon wind
power to generate electricity
•Wind turbines can get
damaged or completely
destroyed when hit by a heavy
storm or a severe lightning
•Helps to solve the electricity
problems up to a large extent,
but it does not eliminate it
completely
•Doesn’t necessarily flow in
the same speed all the time.
http://www.awea.org/faq/wwt_basics.html
Solar Energy
Uses of Solar Energy
• Production [of electricity] and heating of water
through photovoltaic cells and directly for drying
clothes
• Also used to heat swimming pools, power cars,
attic fans, calculators and other small appliances
• produces lighting for indoors or outdoors
• cook food
• About 30% of our total energy consumption is
used to heat water
Solar Energy Forms
Photovoltaic (PV) solar cells
• directly convert sunlight into electricity
• are combined into modules called arrays, and
the number of arrays used determines the
amount of electricity produced
• simplest cells are used to operate
wristwatches and calculators; more
complicated systems are used to light houses
Pros
&
• No pollution
•
• Able to harness electricity in
remote locations that are not
linked to a national grid Ex. in
space, satellites are powered by •
high efficiency solar cells
• The installation of solar panels in
remote locations is usually much •
more cost effective than laying the
required high voltage wires
•
• Can be very efficient in a large area
of the globe, and new technologies
allow for a more efficient energy
production on overcast/dull days
• Solar panels can be installed on top
of many rooftops, eliminating the
problem of finding the required
space for solar panel placement
• Once installed, they provide a free
source of electricity, which will pay
off over the coming years
Cons
the initial cost of solar cells can be
above $1000, and some
households may need more than
one
for around half of each day, solar
panels are not producing energy
for your home
weather can affect the efficiency of
solar cells
pollution levels can affect a solar
cells efficiency, this would be a
major con for businesses or
industry wishing to install solar
panels in heavily polluted areas,
such as cities
http://www.clean-energy-ideas.com/articles/pros_and_cons_of_solar_energy.html
Geothermal Energy
What is it?
• Geothermal energy is contained in
underground reservoirs of steam, hot
water, and hot dry rocks
• Originates from radioactive decay of
minerals, and from solar energy
absorbed at the surface
Energy Efficiency
• The thermal efficiency of geothermal plants is
low.
• Energy around 10-23% because geothermal
fluids do not reach the high temperatures of
steam from boilers
• Created using Rankine cycle
Uses
• For bathing since
Paleolithic times
• Space heating since
ancient Roman times
•Now more
commonly used
for electricity
Geothermal Map of the U.S
www.wikipedia.org
Geothermal Hotspots
www.wikipedia.org
Pros and Cons
Pros
Cons
-Clean
-Less reliance on electricity and gas
-No emissions
-Capital cost
-Amount of land needed
Comparing
Energy
Source
Operational
Efficiency
Energy Density
(Bay Area)
Cost
(US$ / kWh )
Operation
Pollution (green
house gas)
Coal
31%
24
0.055
High
Combustion
15%
45
0.116
High
Natural Gas
25.3%
33.4 – 82.7
0.045
Low
Uranium
(Nuclear)
33-35%
5.7x105182
2555
Low
Energy Source
Operational
Efficiency
Energy Density
(Bay Area)
Cost
(US$ / kWh )
Operation
Pollution
(green house
gas)
Hydro
70-85%
103 kW/m3
0.04
None
Wind
25%
400W/m2
0.070
None
1.353 kW/m2
3/peak watt
None
0.767
Low
Solar
10%
Geo-thermal
10-23%