Possible topics for last 2 weeks(votes on first day of class)

(1 point for first, 2 for second etc.)

• Hydrogen economy (128)

• Nuclear Power (fission/fusion) (137)

• Fuel Cells (154); I’ll include this in with Hydrogen economy discussion.

• Unconventional Fossil (189) Won’t cover this.

• Other suggestions now??

Electric Circuit basics• V= I*R

• R is measured in OHMS () 1= 1V/1A

• R = l/A– : resistivity

• (e.g. Cu 1.69x10-8 m; Al 2.75x10-8 m)

– l length of the wire– A cross-sectional area of the wire

• P= I*V

Series and Parallel Circuits

Series circuit: Current is the same in all elements (voltages add)

Parallel circuit: Voltage is the same in all elements (Currents add)

The other side of the circuit

• Need a source of EMF to “lift” the electrons up the potential energy hill in the power source:– Batteries, Fuel Cells (chemical)– Generators (electro-magnetic)– Solar (photo-electric effect)

Batteries

All batteries have the same basic principle, but the chemical reactions and The materials used for the electrodes and electrolytes) differ. This givesDifferent voltages, internal resistances, masses, operating temps, etc.

H&K p 327

Batteries: Energy Density

http://www.hardingenergy.com/pdfs/ComparisonofApplication.pdf(as of Jan. 2004, note on this scale, gasoline is 12000 Wh/kg and 9500 Wh/l)Compare these numbers to table 10.1 in the text.

Faraday’s Law• “A coil of wire experiences an electro-

motive force that is proportional to the rate of change of the magnetic flux passing through the loop.”

• Magnetic flux is the product of the magnetic field strength times the area it passes through projected onto the field direction (just like solar flux on a panel).

Aperp

B

Basic AC Electric Generator

North American Power Plants

http://en.wikipedia.org/wiki/Electric_power_transmission

Another interesting site: http://carma.org/ will give you more info on thesePlants (and indeed 50,0000 others worldwide!).

US Electrical power Generation (2006)

http://www.eia.doe.gov/fuelelectric.html

Look at the text, whichShows an interestingDistinction betweenUtility producers and Non-utility producersIn terms of this mix.(p 319)

http://www.eia.doe.gov/cneaf/electricity/epa/epat4p1.html see for Information on actual energy consumed by fuel type.

US Electrical Power Generation

1978 Pub. Util. Reg. Policy Act opened up competition and led to the introdution of smaller producers (non-utility produces). Note the different mix of fuel sources!

Load (or capacity) factors

http://www.eia.doe.gov/cneaf/electricity/epa/epa_sum.html

Nuclear and Coal have very large “load factors” (these plants tend to run most of the time, and provide “base load” capacity. Other types of plants, like Natural gas, can be “fired up” more quickly and tend to be used to accommodate peak loads (sometimes called “peaking plants”).

U. Cincy Cogeneration Plants

http://www.uc.edu/facmgmt/utility.asp

Two generating stations: 47MW combined.

Annually produces:

245M kWh

Heat to 9Msq.ft of bldg space

Various fuel options can be used.

Typical generating station

http://www.wvic.com/how-gen-works.htm

Web site also has a good schematic of a generator in action

Typical Steam generator

http://en.wikipedia.org/wiki/Fossil_fuel_power_plant

Typical Gas generator(combined cycle plants)

http://en.wikipedia.org/wiki/Fossil_fuel_power_plant

http://en.wikipedia.org/wiki/Combined_cycle

Combined Cycle plants

http://www.cogeneration.net/Combined_Cycle_Cogeneration.htm

Combined cycle/Carbon sequestration plant

http://alt-e.blogspot.com/

Electrical distribution/transmission

You want to transmit at high voltage (to keep currents, and therefore losses low), but you have to deliver at small voltages (to keep customers safe). AC power, with the use of transformers, makes this possible.

Transformers

http://www.directindustry.com/cat/electricity/power-transformers-C-363.html

Transmission/distribution lines

http://www.osha.gov/SLTC/etools/electric_power/illustrated_glossary/transmission_lines.html

Some High Voltage transmissionlines are DC not AC (see right), but they look pretty much the same.

Examples.

• H&K 11-Prob. 2* A small transformer used for a doorbell steps down the voltage from 120V and 0.5A to 12V. What is the flow of current to the door bell, and what is the turns ratio of the transformer?

Wind Energy

http://www.windpower.org/en/tour/wres/euromap.htm An extensive site for WindInformation!!

Wind Energy

http://cenlamar.files.wordpress.com/2008/07/plan_3tiermap.jpg

The text gives (on page 407 in slightly different units) the formula:

P = 0.3*D2 V3 (W.s3/m5)

D-turbine diameter

V- wind velocitySo a 9m/s wind provides 27 times the power that a 3m/s wind provides!!

Examples.

• Estimate the size of a wind turbine designed to produce 3MW in a 15 m/s wind.

http://en.wikipedia.org/wiki/2003_North_America_blackout

2003 Blackout before andafter

Altamont Pass (CA)

http://www.ilr.tu-berlin.de/WKA/windfarm/altcal.html 6000 turbines, built 1980’s

San Gorgonio Pass (CA)

http://www.ilr.tu-berlin.de/WKA/windfarm/sgpcal.html 3500 turbines, built 1980’s

Wind Turbines

http://www.afm.dtu.dk/wind/turbines/img0003.jpg

Basics of a Wind Turbine

http://www.nrel.gov/wind/animation.html

Variable pitch allows the blades to be “feathered” when the wind gets too strong. Yaw drive allows the turbine to be directed toward the wind.

http://www.gepower.com/businesses/ge_wind_energy/en/image_gallery/index.htm

Web site for movie on wind turbine construction

Three Gorges Dam (China)

http://images.google.com/images?um=1&hl=en&client=firefox-a&rls=org.mozilla:en-US:official&q=three+gorges+dam&&sa=N&start=20&ndsp=20

ITAIPU (Brazil/Paraguay)

http://www.solar.coppe.ufrj.br/itaipu.html

ITAIPU (Brazil/Paraguay)

http://www.solar.coppe.ufrj.br/itaipu.html