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8.21 The Physics of Energy
Fall 2009
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The Energy Problem
Course Mechanics
Physics of Energy
8.21 Lecture 1
The Physics of Energy:
Introduction to Course
September 9, 2009
8.21 Lecture 1: Course Introduction
1 / 11
The Energy Problem
Course Mechanics
Physics of Energy
1. The Energy Problem
Energy issues seem to be everywhere
Economics
Volatile oil prices
Corn-based ethanol & rising food prices
Cape wind & property values
Politics
Iraq and Middle East politics
Russian Gazprom cuts natural gas to Ukraine
Offshore drilling
Environment
Global warming from CO2
→Pressure on many ecosystems, species
→Sea level rise
→Floods, hurricanes, drought
Mercury from coal plants
8.21 Lecture 1: Course Introduction
2 / 11
The Energy Problem
Course Mechanics
Physics of Energy
We use more and more energy
70
50
500
40
30
400
20
10
0
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
Energy use/person
×
=
World energy use (EJ)
Per capita energy (GJ)
60
300
200
100
8
0
1965 1970 1975 1980 1985 1990 1995 2000 2005
Population (billions)
7
Year
6
5
Global energy use
4
3
[data from BP]
2
1
0
1965 1970 1975 1980 1985 1990 1995 2000 2005
Year
But resources are limited
World Population
[Data from U.S. Census bureau]
8.21 Lecture 1: Course Introduction
3 / 11
The Energy Problem
Course Mechanics
Physics of Energy
[image: EIA]
Energy flow from sources to uses is COMPLEX
8.21 Lecture 1: Course Introduction
4 / 11
The Energy Problem
Course Mechanics
Physics of Energy
In this class, we’ll use physics to understand Energy:
2001 U.S. Energy Use By Sector
Total 102 EJ
Transport
28 EJ (27.28%)
Residential
21 EJ (20.87%)
Commercial
18 EJ (17.79%)
∼28%
transport
(mechanics)
∼40%
∼3%
heating/AC
lighting
(thermodynamics)
(EM)
Industry
35 EJ (34.06%)
[data: EIA]
U.S. energy use
Physical requirements: ?How much energy do we need to use?
Physical limitations: ?How much energy is available for use?
?How efficiently can we use energy?
Physical consequences: ?Can we limit side effects?
8.21 Lecture 1: Course Introduction
5 / 11
The Energy Problem
Course Mechanics
Physics of Energy
Energy Sources
Currently about 85% of U.S. energy from fossil fuels
Photo courtesy of Rennett Stowe on Flickr.
Coal (23%)
Photo courtesy of craig1black on Flickr.
Petroleum (40%)
Many issues:
Political: Foreign sources
Economic: Increased global demand, limited resource
Environmental: CO2 � warming, NOx � smog
8. 21 L ecture 1: C ourse I ntroducti on
6 / 11
The Energy Problem
Course Mechanics
Physics of Energy
Alternative Energy Sources
Solar
Nuclear
Other
renewables
solar thermal
[thermo]
Ultimate source of most E
PV [quantum]
Issues: efficiency, scaling,
distribution
fission, fusion
[quantum]
wind, waves, hydro,
tides, [fluid mech]
ocean, geothermal
[thermo]
Vast potential
Vast potential
Issues: safety, waste,
security, technology
Clean energy sources
Substantial potential
in wind, geothermal;
others more limited
Study physics of each
8.21 Lecture 1: Course Introduction
7 / 11
The Energy Problem
Course Mechanics
Physics of Energy
Some course objectives
Overview of natural and human earth energy systems
–Underlying physical processes
–Order of magnitude quantities + efficiencies
–Example: energy flow from sun → this slide → space
New physics relevant for energy
–Thermodynamics
–Quantum mechanics
–Fluid mechanics
Abstract theoretical principles → concrete energy applications
–Principles → order of magnitude estimates
–Learn to estimate or look up details
8.21 Lecture 1: Course Introduction
9 / 11
The Energy Problem
Course Mechanics
Physics of Energy
8.21: Not just a class
It’s an Adventure!
We are teaching
this course
for the second time,
learning as we go
We will cover
more material
than you can absorb
Focus on core,
rest is optional.
You are invited to
participate
in optimizing the course.
We want your Feedback!
Ask questions!
Give us comments!
What works,
what doesn’t?
Find errors in notes, and
other material
–There will be prizes!–
8.21 Lecture 1: Course Introduction
10 / 11
The Energy Problem
Course Mechanics
Physics of Energy
3. Physics of Energy
Now over to BOB
8.21 Lecture 1: Course Introduction
11 / 11
The Energy Problem
Course Mechanics
The Physics of Energy
The Big Picture
• Uses
(12 lectures)
• Sources (19 lectures)
• Environmental physics and systems (7 lectures)
Review of GIR level physics
Novel: stat. mech, quantum, fluid dynamics
Physics/energy systems
8.21 Lecture 1: Course Introduction
The Energy Problem
Course Mechanics
The Physics of Energy
What’s the physics?
•
•
•
•
Mechanics
Electricity and magnetism
Heat
Energy in chemical processes
• Statistical physics
Thermodynamics, entropy, efficiency, cycles, phase
changes, thermal radiation
• Quantum physics
States, probabilities, wave functions, eigenenergies
and eigenstates, tunneling, radiation
• Fundamental physics
Particles and forces, the Standard Model, origins
and flow of energy in the Universe
8.21 Lecture 1: Course Introduction
The Energy Problem
Course Mechanics
The Physics of Energy
• Nuclear physics
Nuclear structure, nuclear binding, stability and decays,
radiation
• Condensed matter physics
Electrons in matter, bands and gaps, semiconductors,
radiation absorption
• Fluid dynamics
•
•
•
•
•
•
•
Fluid flow, pressure, viscosity, Bernoulli’s law, drag, lift
Nuclear fission reactor design, dynamics, stability, and safety
Solar voltaic energy flow, thermodynamics, and efficiency
Wind power potential, aerodynamics, design
Atmospheric energy flow and climate change
Environmental radiation
Energy storage
Conservation
Ambitious!!
8.21 Lecture 1: Course Introduction
The Energy Problem
Course Mechanics
The Physics of Energy
Matter collapsing
under gravity
Nuclear fusion
in stars
G RAVITY
E LECTROMAGNETISM
S TRONG I NTERACTIONS
W EAK I NTERACTIONS
Sunlight
SOLAR FUSION CYCLE
THERMAL
RADIATION
Nucleosynthesis
SEMICONDUCTOR
PHYSICS
Fossil
fuels
Solar voltaic
energy
Solar thermal
energy
Hydro
power
Wind
Fissionable
isotopes
Fusion
fuels
FLUID
DYNAMICS
Tidal
energy
NUCLEAR STABILITY
NUCLEAR DECAYS
QUANTUM TUNNELING
Nuclear
fission power
Fusion
power
8.21 Lecture 1: Course Introduction
Radioactive
isotopes
Geothermal
energy
The Energy Problem
Course Mechanics
The Physics of Energy
To whet your appetite
• Why a rare isotope of lithium is a key player in
the future of nuclear fusion power.
It’s the fundamental fuel because tritium is made from it.
d + t → 4 He + n
n + 6 Li → 4 He + t
And tritium is the fuel for fusion energy for the foreseeable future.
• Why is coastal Massachusetts prime wind
power real estate.
http://rredc.nrel.gov/wind/pubs/atlas/
Wind power class 6 near population centers is a
winning combination.
f(v, k, λ)
f(v, k, λ)
1.4
k = 1.3, λ = 1
1.2
k = 2.5, λ = 1
1.0
k = 3.1, λ = 1
0.8
k = 1.9, λ = 1
k = 1.8, λ = 1
0.6
k = 1.8, λ = 2
k = 3.7, λ = 1
k = 1.8, λ = 3
0.8
k = 1.8, λ = 4
0.4
0.6
k = 1.8, λ = 5
0.4
0.2
0.2
v
v
0.5
1.0
1.5
2.0
2
4
6
8
10
8.21 Lecture 1: Course Introduction
The Energy Problem
Course Mechanics
The Physics of Energy
To whet your appetite (II)
• Why is geothermal energy a form of nuclear energy?
What does it have to do with refrigeration?
• Because the ultimate heat source is radioactive decay of
potassium, thorium and uranium in the earth’s interior.
• Perhaps the most promising exploitation of geothermal energy
is through the use of heat pumps, which are basically
refrigerators run backwards.
• Is the role of hydrogen more similar to ??
• a flywheel?
• methane?
• Answer: a flywheel! Methane (Natural gas) is a naturally occurring energy source that can be
used as a fuel. Hydrogen would also be fuel if it occurred as molecular hydrogen (H2 ) in
nature. Instead it is always found tightly bound to other elements. It always takes more
energy to liberate they hydrogen than it will generate when it is used (2nd law of
thermodynamics), so hydrogen is an energy storage device like a flywheel (and not, at
present, a very efficient one).
8.21 Lecture 1: Course Introduction
The Energy Problem
Course Mechanics
The Physics of Energy
To whet your appetite (III)
• What is a fission poison and why is it important for
power grid operation?
• It is a fission product that continues to be created after a reactor
is turned off. A fission poison absorbs neutrons and prevents
the reactor being restarted for several days.
• What is the difference between solar thermal energy and
solar voltaic energy, and what are the roles of each in our
energy future?
• The differences are huge:
– Solar Thermal: thermal fluid power technology resembling fossil
fuel and nuclear plants, relatively mature technology, few exotic
materials, promising storage options, significant economies of
scale suggest commodity applications.
– Solar Voltaic: solid state electrodynamics unlike other energy
sources, rapidly developing technology, rare and exotic materials,
storage issues, relatively efficient at small scales suggesting end
user implementation.
I wish I knew!
8.21 Lecture 1: Course Introduction
The Energy Problem
Course Mechanics
The Physics of Energy
What we do not cover in 8.21
• A lot!
• All of the crucial economic, political, and policy issues.
• Chemistry and biology of energy
– Coal! Carbon capture and sequestration, coal gasification.
– Biofuels. . . cellulosic ethanol, advanced biofuels
– “Artificial” photosynthesis
– Fuel cells
• And, of course, everything at an advanced level!
8.21 Lecture 1: Course Introduction