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 gives Different voltages, internal resistances, masses, operating temps, etc. H&K p 327

Batteries: Energy Density (as of Jan. 2004, note on this scale, gasoline is 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). A perp B

Basic AC Electric Generator

North American Power Plants Another interesting site: will give you more info on thesehttp://carma.org/ Plants (and indeed 50,0000 others worldwide!).

US Electrical power Generation (2006) Look at the text, which Shows an interesting Distinction between Utility producers and Non-utility producers In terms of this mix. (p 319) 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 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 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 Web site also has a good schematic of a generator in action

Typical Steam generator

Typical Gas generator (combined cycle plants)

Combined Cycle plants

Combined cycle/Carbon sequestration plant

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

Transmission/distribution lines Some High Voltage transmission lines 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 An extensive site for Wind Information!!

Wind Energy The text gives (on page 407 in slightly different units) the formula: P = 0.3*D 2 V 3 (W.s 3 /m 5 ) D-turbine diameter V- wind velocity So 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.

Blackout before and after

Altamont Pass (CA) turbines, built 1980’s

San Gorgonio Pass (CA) turbines, built 1980’s

Wind Turbines

Basics of a Wind Turbine 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.

Web site for movie on wind turbine construction

Three Gorges Dam (China)

ITAIPU (Brazil/Paraguay)

ITAIPU (Brazil/Paraguay)