Clicker Question
January 3, 2008
What drives the price of oil?
A) Total world oil supply
B) Demand by large economies
C) Short term production
D) New oil discoveries
E) Middle east stability
Reading Assignment
Chapter 4 is the focus this week. Reading ahead
Chapter 5.1-5.4 for Monday.
Homework Assignment
Applications Due Feb. 20th! Learn More:
http://www.colorado.edu/ses/prospectivestudents/degrees/certificates/renewable-and-sustainableenergy/undergraduate-rse-program
Undergraduate Certificate in Renewable and
Sustainable Energy
•
There is no Homework #4 due next week.
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18 Credit, Cross-Disciplinary Program open
to all majors
Core Courses (9 Credits)
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Note that Exam #1 in class is coming up on
Wednesday, February 10, 2016.
Details as discussed last lecture!
-- My office hours are Monday 1-2 pm,
Tuesday 11 am –12 pm
Also available by appointment – just email me.
-- The class Teaching Assistants will also be available in the Physics Help
Room (downstairs on the Duane 2B level).
Prasanth Prahladna : Tuesdays 3-4 pm, Paul Quelet : Wednesdays 10-11 am,
Ivan Kurz: Wednesdays 11 am – 12 pm
Light mill…
–
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•
•
Benefits:
• Gain confidence in a complex, changing
landscape: understand the fundamental
challenges, key issues, and nuances of a
transition to energy sustainability.
• Build your professional network: work to
solve energy problems with real clients in
private, government, and nonprofit sectors.
• Expand your perspective: work across
disciplines with students in natural and
social sciences, engineering,
communications, and humanities to
address challenging problems with crossdisciplinary approaches.
Energy Science and Technology – ENVS/PHYS
3070
Energy Policy – ENVS 3621
Energy Project Seminar – ENST 4150
Electives (9 Credits): Any energy-relevant
undergraduate courses (more every year!)
Program developed in collaboration with
RASEI and the National Renewable Energy
Laboratory (NREL)
Stirling External Combustion Engine
Radiation pressure (?)
Bajoran Lightship
Star Trek
http://www.stirlingengine.com
Very simple mechanism.
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Faraday’s Law
Electric Bill
I buy electricity from the
“Power Company”
Here in Colorado
My bill charged me for approximately 1000 kiloWatt-hours.
Note that kiloWatt-hours is (Power [kWatt]) x (Time [hours])
and is thus a unit of energy.
Wire moving in a magnetic field
OR
Magnetic field changing through wire
Note that 1 kWatt-hour can be converted into Joules.
 1000 J 
 60 min   60 sec 
E  (1kW  hour )  
  (1hour )  


 sec ond 
 1hour   1 min 
E  3.6 MegaJoules
Xcel charges approximately $0.09 (9 cents) per
kWatt-hour.
Thus, since I used ~ 1000 kWatt-hours, my electric bill was
for approximately $90 for one month.
Do I really leave 10 lightbulbs on all the time? No.
However, I use the electric oven (~1000 Watts) and I also
use the dryer a lot (~3000-5000 Watts). The hot tub
definitely does not help 
So Xcel does not charge me for Power, they charge a certain
rate for my total electrical energy usage.
For example, they do not care if I used 1000 kWatts for one
hour or 100 kWatts for 10 hours, etc. They only care about
the total energy.
Does that energy usage make sense?
If I had ten 100 Watt lightbulbs on all the time for one
month, how much energy is that?
720hours 
E  10  [(100Watts )  1month]  

 month 
However, we want kWatt-hours, not Watt-months. So we
need to use the fact that there are 720 hours per month.
E  720 kiloWatts - hours
Close to my usage.
I am a “good guy” and I care about the environment
(“a green guy”).
Who are these people using 100 QBtu in the US each
year?
Note that this does not include heating my house and hot
water, since that is from natural gas (another 1000 kWatthours) and another ~ $100 per month in the winter !
Well, 100 QBtu is the total. So the average per person is
using 3 x 108 Btu/year or 3 x 1011 Joules per year.
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Am I one of those people?
Electric Usage:
1000 kWatt-hours per month = 12,000 kW-hr per year
Convert this to Joules  4 x 1010 Joules
Natural Gas Usage (Heating my house):
1000 kWatt-hours per month in the winter
Estimate 9000 kW-hr per year  3 x 1010 Joules
Food:
I eat about 3000 Calories/day  4 x 109 Joules/year.
Now that is the energy of the food I eat, not the energy
it required to grow the food and get it to me.
In fact, it is about 10 x more energy to produce the food.
 4 x 1010 Joules
Transportation (Car):
I drive about 10,000 miles each year. My CR-V gets ~
20 MPG in the city (not highway miles). That means I
consume 500 gallons of gasoline a year.
* 6 x 109 Joules/42 gallons (front flyleaf)
 7 x 1010 Joules/year
Transportation (Flying):
Fuel consumed per person per mile is roughly the same
for cars and plane ! I fly over 10,000 miles per year.
 7 x 1010 Joules/year
Goods:
This is hard to quantify, but very rough estimate
 1011 Joules/year
Clicker Question
Totals:
How easily could you estimate your energy consumption?
Electric:
Heating:
Food:
Car:
Planes:
Goods:
Total:
4 x 1010 Joules
3 x 1010 Joules
4 x 1010 Joules
7 x 1010 Joules
7 x 1010 Joules
10 x 1010 Joules
A) Within 10%
B) Within 25%
C) Within 50%
D) Within 100%
35 x 1010 Joules !
The average per person in the USA was ~ 30 x
1010
Joules !
E) Within 200% (i.e. a factor of 2) or more…
Caveats: My electric, heat, and car are actually split with my
four person family. On the other hand, I am not including any
energy usage at work (big factor).
What is a statistical breakdown on energy usage in the United
States?
85% of energy
supplied via
fossil fuels
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