Transcript Exponential Growth/Decay

AVG. 85.6 = 74.4%
P110/120 Exam 2
Frequency
12
10
8
6
Frequency
4
2
0
55
70
85
Bin
100
More
Revisions to course Schedule
Tuesday Nov 11
Chpt. 10
Electricity Basics
Thursday Nov 13
Chpt. 11
Electromagnetism
Electrical
Generation
Tuesday Nov 18
Thursday Nov 20
Chpt. 12
Solar electricity
Tuesday Nov 25
Kinetic sources
Thursday Nov 27
Thanksgiving
Tuesday Dec. 2
????
HW7
The Future
HW8( replaces
Art. sum 3)
Thursday Dec. 4
????
The Future
Tuesday Dec 9
????
The Future
Thursday Dec 11
????
The Future
Term paper
FINAL EXAM
7:15 PM
Tuesday, Dec 16
2008
Sediments and sedimentary
Rocks could account for another
6x107 Petagrams!
(www.physicalgeography.net/9r.html)
http://www.whrc.org/carbon/
(Woods Hole Research Center)
H&K Fig.
9.6:
Feedback
(positive
and
Negative)
“Butterfly effect” in
complex systems
Green House gases
• Contributions to green house effect
depend on IR absorption, concentration
and lifetime in the atmosphere.
GAS
Sources
GW
P
Lifetime 2003 conc.
(yr)
ppm
CO2
(5500 MT/y)
Burning organics/
deforestration
1
100
373
CH4
(600 MT/y)
Rice fields, landfills,
animals
21
10
1.7
NOx
(16 MT/y)
Fetilizer/deforestration, vehicles
310
170
0.31
CFC’s
(1MT/y)
Aerosol sprays,
refrigerators, ACs’
130012000
70-100
0.003
NF3
(<2-3kT/y)
Plasma cleaning FP
displays etc.
17000
550-750
0.00045
GWP: “Global Warming Potential”: the ability of the gas to trap IR light (heat).
Carbon Sequestration
(“Clean coal” as of ~ 2000)
Research and Creative Activity, Oct 2008, IU OVPR publication
Note that “clean coal” is a term that has been around for a long time, but it
has only recently morphed into this incarnation. Originally it referred simply to
using low-sulfur coal, then to including emission control measures, and finally
to include limits on CO2 emissions. It’s true meaning in the mind of the user
is therefore to be taken with some appropriate degree of skepticism!
Kyoto Protocol (1997-99)
Green: Signed and ratified
Yellow: Signed with ratification pending
Red: Signed and declined to ratify
Grey: No position
Built on Rio Summit of 1992, been
“in force” since Oct. 2005. Goal is
to reduce developed nations CO2
emissions by 5% from 1990 levels
http://en.wikipedia.org/wiki/Kyoto_Protocol
10 ppm ozone at ~ 50 km compared to
40 ppb ozone in the troposphere!
http://www.mardiros.net/atmosphere/atmosphere_structure.html
Ozone levels at
Halley Bay station
(Antarctica)
http://www.atm.ch.cam.ac.uk/tour/part2.html
TOMS Satellite movie
(Total Ozone Mapping Spectrometer)
http://www.atm.ch.cam.ac.uk/tour/anim_toms.html
TOMS Satellite movie
(Total Ozone Mapping Spectrometer)
http://www.atm.ch.cam.ac.uk/tour/part2.html
http://en.wikipedia.org/wiki/Montreal_Protocol
Sept. 2006
Montreal Protocol (1987-9)
An agreement to limit the
emission (and eventually
eliminate the use) of CFC’s that
contribute to Ozone depletion. In
force as of 1989, modified several
times (most recently Beijing
1999).
Has been hailed as one of the
UN’s most successful
international agreements.
http://en.wikipedia.org/wiki/Montreal_Protocol
Thermal Pollution
• Remember, all energy production
eventually leads to thermal energy being
dumped into the environment.
• To carry the waste heat away from a
1000MWe power plant requires about 104
gallons/second (for an 8K temp. rise).
• In an increasing number of (local)
applications, some of this waste heat is
used to heat local buildings (“cogeneration”)
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.
http://www.uc.edu/facmgmt/utility.asp
Impact of Thermal Pollution
• Reduced oxygen content in lakes/rivers/ponds
the heat is released to.
• Changes in reproduction, growth and behaviour
throughout the food chain; e.g. algae plumes
• Chemical reaction rates increase.
• Changes in local temperature gradients
(especially vertical gradients) can upset the
natural exchange of nutrients between surface
and deep water
Thermal Pollution:
Local water sources
Cooling towers
Term paper (see website)
ASSIGNMENT: You are to research some
technology related to energy (production,
conservation, mitigation of side effects, etc.) that
has been implemented recently or has been
proposed for use at some point in the future. The
paper should describe the technology in
sufficient detail for an intelligent but uninformed
reader can understand its function, and it should
state (and support) your own argument for why
this technology should or should not be
implemented in the market place.
• See the link on the web site for more details.
Possible topics
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Fuel cells
Wind farms.
Passive/active solar heating
Geothermal climate control
High-efficiency appliances
Next generation nuclear plants.
Solar Cells, what promise exists in recent materials advances?
Personal transportation options.
Alternative organic fuels
Options for storing radioactive waste from power plants.
Nuclear Fusion
Methane clathrate
Control measures for any pollutant of your choice (including carbon).
Advanced oil recovery methods
Biomass fuels
Cogeneration technologies
Hydrogen economy (this has lots of possible subtopics, storage,
generation, use, hazards etc.)
Future automobile design (again lots of subtopics exist)
The electrical power grid
Real time pricing of electricity
Others of your own choice.
Basics of electricity
• There is a force other than gravity that
acts “at a distance” (and is stronger).
• This force can be attractive or repulsive
• “Static Electricity” comes in two flavours;
we call these positive and negative (like
charges repel, unlike charges attract).
• At least some of the charges in metals are
very mobile.
• The force is stronger if charges are closer.
• We can define a potential energy
associated with the relative location of
charges (this is a conservative force).
Basics of electricity (cont.)
• The basics on the previous slide form the basis for
all of our electrical technology!
• We measure charge in Coulombs (6.24x1018
elementary charges)
• In electrical circuits, you have an “electromotive
force” that provides the “push” (V: VOLTAGE,
measured in VOLTS, a potential energy difference
per unit charge 1 V = 1J/1 Coulomb) DEMO.
• Moving charges carry the energy (I: current,
measured in AMPS 1 A =1Coul/sec).
• Power = I*V (1 watt = 1volt*1 Amp)
• The ratio of voltage to current is called the
resistance of the circuit
– OHM’s Law:
V=IR (R measured in OHMS, W)
Resistance
• Electrical resistance is much like thermal
resistance, it depends on the length and
cross section of the wire, and on the
material the wire is made of.
• R = r l/A
 r : resistivity
• (e.g. Cu 1.69x10-8 Wm; Al 2.75x10-8 Wm)
– l length of the wire
– A cross-sectional area of the wire
• Wires designed to carry a lot of current must
have a large cross sectional area.
Ohm’s Law
• The ratio of voltage to current in a circuit
(or circuit element) is equal to the
resistance of that circuit (or element)
R=V/I
V=IR
I = V/R
• R is measured in OHMS (W) 1W= 1V/1A.
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)
Examples
• Consider a 1200W North American
toaster. What current does it draw? If it is
used to toast two slices of bread in 1
minute, how much does toasting each
slice cost (take $0.08/kWh for the cost of
electricity).
• A 50 W resistor is connected across a
voltage of 120V. What is the power
dissipated in the resistor?
Batteries
H&K p 327
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.
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.
North American Power Plants
http://en.wikipedia.org/wiki/Electric_power_transmission
US Electrical power
Look at the text, which
Shows an interesting
Distinction between
Utility producers and
Non-utility producers
In terms of this mix.
(p 319)
http://www.eia.doe.gov/fuelelectric.html
US Electrical Power Generation
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.
http://www.uc.edu/facmgmt/utility.asp
US Electrical power
http://www.eia.doe.gov/cneaf/electricity/epa/epa.pdf#page=15