Energy: Definitions

1

• Energy Definitions
• and Units

2
Energy Definitions 1

• Energy The ability to do work.
• Power The rate of energy usage.
• An energetic person is not necessarily powerful
  or forceful, why?

3
Energy Measures Units

• 1 Btu
• 777.9 ft-lbs
• 1055 joules1055 watt-sec
• 252 calories
• 0.000293 kilowatt-hour

4
Power Measures Units

• 1 hp
• 2545 Btu/hr
• 550 ft-lbs/sec
• 178.2 cal/sec
• 745.7 watts

5
Energy Definitions 2

• Usually measure power, then integrate to get
  energy generated or used using a microcontroller.
• Mechanically, power equals force times velocity,
  or torque times rotational speed,
• Electrically, power equals voltage x current,

6

• Energy Generation
• and Usage

7

• Fuel (Calorific Content) kWh/Kg
• Brown Coal (Lignite) 2.8
• Coking (Black) Coal 8.3
• Oil 12.5
• Natural Gas (North Sea) 10.8
• Liquefied Petroleum Gas (LPG)
• is a mixture of Propane and Butane 13.8
• Propane 13.9
• Butane 13.7
• Kerosene (Paraffin Oil) 13.0
• Petrol (Gasoline) 13.0 (132 MJ/US gal, 36.6
  kWh/US gal)
• Diesel 12.9
• Bio diesel 10.9
• Ethanol 8.3
• Methanol 6.4
• Dry Wood 4.4
• Green Wood 2.5
• Agricultural Crop Residues 2.5 - 5.0

8
Earths Energy Balance

• Yearly energy resources (TWh)
• Solar energy absorbed by atmosphere, oceans,
  Earth1 751,296,000.0
• Wind energy (technical potential) 2
  221,000.0
• Yearly energy consumption (TWh)
• Electricity (2005) 3 -45.2 Primary
  energy use, non-electric (2005) 4 -369.7
• From Wikipedia, 2008-11-20
• 1. Smil (2006), p. 12
• 2. Archer, Cristina. "Evaluation of Global Wind
  Power". Stanford. Retrieved on 2008-06-03. (72 TW
  at 0.35 capacity factor)
• 3. "World Total Net Electricity Consumption,
  1980-2005". Energy Information Administration.
  Retrieved on 2008-05-25.
• 4. "World Consumption of Primary Energy by
  Energy Type and Selected Country Groups,
  1980-2004". Energy Information Administration.
  Retrieved on 2008-05-17.

9
Energy Generation Solar

• The total solar energy absorbed by Earth's
  atmosphere, oceans and land masses is
  approximately 3,850 zettajoules (zJ) per year.
• In 2002, this was more energy in one hour than
  the world used in one year.
• Photosynthesis captures approximately 3 zJ per
  year in biomass.
• The amount of solar energy reaching the surface
  of the planet is so vast that in one year it is
  about twice as much as will ever be obtained from
  all of the Earth's non-renewable resources of
  coal, oil, natural gas, and mined uranium
  combined. From Wikipedia, 2008-11-20,
  http//en.wikipedia.org/wiki/Solar_power

10
Energy Information Administration,
http//www.eia.doe.gov/emeu/aer/pecss_diagram.html
, 2008-11-20
11
A Sankey Diagram
12
Whats a Quad ? A quad is a unit of energy equal
to 1015 (a short-scale quadrillion) BTU,1 or
1.055 1018 joules (1.055 exajoules or EJ) in
SI units. The unit is used by the U.S.
Department of Energy in discussing world and
national energy budgets. The global primary
energy production in 2004 was 446 quad,
equivalent to 471 EJ. 2 Some common types of
an energy carrier approximately equal 1 quad
are 8,007,000,000 Gallons (US) of gasoline
293,071,000,000 Kilowatt-hours (kWh) 36,000,000
Tonnes of coal 970,434,000,000 Cubic feet of
natural gas 5,996,000,000 UK gallons of diesel
oil 25,200,000 Tonnes of oil http//en.wikipedi
a.org/wiki/Quad_(unit)
13
World Power Capability versus Time
Wikipedia, 2008-11-20, http//upload.wikimedia.org
/wikipedia/commons/a/a0/World_Energy_consumption.p
ng
14
Power Demands per Country per GDP
Wikipedia, 2008-11-20, http//upload.wikimedia.org
/wikipedia/commons/0/0b/Energy_consumption_versus_
GDP.png
15

• Household
• Energy Usage

16
Remember Power Units

• 1 hp
• 2545 Btu/hr
• 550 ft-lbs/sec
• 178.2 cal/sec
• 745.7 watts

17
Household Energy Usage
18
(No Transcript)
19
U.S. Household Energy Consumption The amount of
carbon dioxide (CO²) emitted from a power plant
generating enough electricity for the average
American home for one year is nearly twice the
amount of CO² generated by the average family car
in a year. Annual household lighting use 2,100
kilowatt-hours (kwh) Annual household
electricity use 10,660 kwh / household Emissions
factor 1.58 pounds CO2 / kwh Annual
household emissions 22,880 pounds CO2 /
year Car emissions factor 11,500 pounds CO2 /
car / year Number of U.S. households 109,902,09
0 Total Annual U.S. household energy use 1200
billion kwh / year Power output of one power
plant 4 billion kwh / year Sources Census
Bureau, Energy Information Administration,
Environmental Protection Agency
20

• Humans as Energy Sources

21
http//www.windstreampower.com/Human_Power_Generat
or_Series.php
22
How do I convert Watts to Calories burned? First
keep in mind that Watts and Calories are two
different units of measurement that can't be
directly converted back and forth. However if
you use Watt-Hours instead of just "Watts" you
then have a way to convert to calories. Here are
the steps Convert Watt-Hours to Watt-Seconds
(Joules), then convert Joules to Calories, then
adjust Calories with human body efficiency
factor. So for this example let's assume that you
provide pedal power to a 100 Watt television for
one hour. Since one Joule is equal to one Watts
X Seconds you perform dimensional analysis and
get 100Watt-hours X (3600 seconds / 1 Hour)
360,000 J Now use the conversion factor 1 cal
4.184 J to convert Joules to Calories 360,000 J
/ 4.184 86,042 Calories When you look at the
label of Oreo cookies or other food items at the
store, the term "Calories" is really
(kilo-Calories). So you divide by 1000 to get 86
Calories. Assuming that your body is about 25
efficient when cycling you divide by 0.25
Calories burned running a 100 Watt Television
for 1 hour 86 / 0.25 344 which is about
equivalent to one piece of PIZZA! http//sciences
hareware.com/bicycle-generator-faq.htmcalories
23

• Human energy consumption How dim is your
  lightbulb?
• An adult body needs, on average, 12 kilocalories
  per pound to maintain it's weight. My "ideal
  weight" for my height according to most charts
  I've looked at is 195 pounds. So, my body needs
  12 x 195 lbs 2,340 kilocalories to maintain
  it's weight. Now lets convert that to
  watts.2,340 kilocalories per day / 24 hours
  97.5 kilocalories per hour / 3600 seconds per
  hour 0.0271 kilocalories per second x 4,184
  joules / kilocalorie 113.32 joules/second or
  113.32 watts. So I'm roughly equal to the power
  consumption of a slightly bright light bulb (100
  watts is a little above average).If I draw
  113.32 watts for an entire hour, that's .113
  kilowatt hours. Over a 24 hour span, that's 2.712
  kilowatt hours per day. Over an entire year,
  that's 989.88 kilowatt hours. At an average price
  of say, 0.11 per kilowatt hour for electricity -
  that means my body would consume 108.89 of
  electricity per year if I could somehow plug
  myself into the wall.Interestingly, the brain
  is on average 2 of the body's mass but consumes
  20 of the body's energy. In my case, my brain
  should weigh 3.9 lbs and uses 197.97 kilowatts of
  energy per year.A horse is supposedly about 8
  times more powerful than a human. That's why 1
  horsepower is equal to 745.7 watts. Consider how
  incredibly powerful your car is my car has 173
  horsepower at peak at the crank. To the wheels,
  on average, it probably puts down something like
  65 horsepower or 48,740 watts of power. In other
  words, I would have to work 487 seconds (8
  minutes) to equal the power output of 1 second on
  average from my car.
• http//heartsofthegods.blogspot.com/2007/03/human-
  energy-consumption-how-dim-is.html

24
Humans as energy sources
2008-11-20, http//www.recumbents.com/mars/tetz/E-
Assist.htm, John Tetz
25
How Much Power Can a Human Supply Producing 1800
watts for a few seconds should be within the
range of the best power lifters and perhaps for
up to a minute. Remember 1 watt means applying a
force of 1 newton through a distance of 1 meter
in 1 second. So if you lifted 1 kg, that's 9.8
newtons of force, about 10 newtons, for 1 meter
in 1 second, that would be 10 watts. So lifting
180 kg, 1 meter high in 1 second would be 1800
watts. The best power lifters can do squats of
several times their body weight for 1 rep. Let's
say the power lifter weighed 100 kg, about 220
lbs.  He might be able to do 3 times his weight
for a single rep. That would be 300 kg. But
remember he's actually raising his own weight as
well. So he's actually lifting 4 times his
weight, 400 kg for this one rep. For a male of
average height, he might be raising this over a
distance of 1 meter (4000W). So doing 1800
watts of power for one minute would be like
giving this power lifter a weight of only 60 kg
(for a total weight of 180 kg) and doing squats
with this light weight for the high number of
reps of 1 per second over one minute. This would
be possible for a weight so much lighter than
their usual 1 rep maximum weight.
http//groups.google.com/group/alt.sport.weightl
ifting/browse_thread/thread/29aeae8ba0ac69c3 Paul
Cassel ltpcasselremo..._at_comremovecast.netgt
26
Available Muscle Power
The average "in-shape" cyclist can produce about
3 watts/kg for more than an hour (e.g., around
200 watts for a 70 kg rider), with top amateurs
producing 5 watts/kg and elite athletes achieving
6 watts/kg for similar lengths of time. Elite
track sprint cyclists are able to attain an
instantaneous maximum output of around 2,000
watts, or in excess of 25 watts/kg elite road
cyclists may produce 1,600 to 1,700 watts as an
instantaneous maximum in their burst to the
finish line at the end of a five-hour long road
race. 2008-11-20, http//en.wikipedia.org/wiki/Hu
man-powered_transport
27
Two Types of Muscle Fibers
Every muscle is made up of two types of fibers.
Fast-twitch fibers move 2 to 3 times faster than
slow-twitch fibers, but they tire more easily.
Fast-twitch fibers, logically, are used for
sprinting and quick ascents. Inversely,
slow-twitch fibers are used for long rides of
moderate intensity. Most people have half
slow-twitch and half fast-twitch fibers in their
muscles. However, genetics again plays a role.
Some long-distance runners have as much as 80
percent slow twitch fibers, while sprinters tend
to have more fast-twitch fibers.
http//www.exploratorium.edu/cycling/humanpower1.
html
28
How Far Do You Want to Go?
It takes less energy to bicycle one mile than it
takes to walk a mile. In fact, a bicycle can be
up to 5 times more efficient than walking. If we
compare the amount of calories burned in
bicycling to the number of calories an automobile
burns, the difference is astounding. One hundred
calories can power a cyclist for three miles, but
it would only power an average car 280 feet (85
meters)! http//www.exploratorium.edu/cycling/huma
npower1.html
29
At rest we inhale about 550ml of air, of which
115ml is oxygen. When we exhale between 3 and 5
percent of that breath - about a quarter of the
oxygen - becomes carbon dioxide, about 27ml of
this pernicious greenhouse gas. This means that -
assuming CO2 weighs 2g/litre - the average
resting human produces 170,000 litres, or 340kg
of carbon dioxide per year. With a moderate level
of activity, we can increase this to a
conservative 500kg of carbon dioxide per
year. In Europe, the average automobile emits
about 170 grams of CO2 for every kilometre. In
the USA and Canada this is considerably higher,
but lets take the European average as a starting
point. If I were to travel 20km from A to B by
car then my vehicle would emit approximately
3.4kg of carbon dioxide. If I travelled at an
average of 100kph (about 60mph), then the journey
would take 12 minutes, during which time I would
not exert myself, and thus personally emit only 8
grams of CO2. The total for the journey would
thus be 3.4kg 0.008kg of carbon dioxide. If,
instead, I travelled by bicycle, then I would
have to exert myself. There is no way I could
cycle at 100kph, but can easily reach 20kph,
making my journey last 1 hour.  When I cycle I
breathe at between 20 and 30 breaths per minute,
so lets assume 30bpm, with no increase in oxygen
intake per breath. Over that hour of cycling, a
person would therefore emit only 100 grams of
carbon dioxide, or just 3.4 of the carbon
emitted by the combined car and human. If you
want to reduce your carbon dioxide emissions then
travel slower. http//earth-blog.bravejournal.com/
entry/22233
30
Energy Usage and Speeds
2008-11-20, http//www.exploratorium.edu/cycling/h
umanpower1.html
31
Electric bicycles are even more efficient than
human powered bicycles. This is because humans
need to eat, and our US food supply chain is
highly inefficient. This chart shows that the
(food supply)-to- (human mechanical output) is
only about 2.5 efficient. Notice that humans
are only about 25 efficient in converting food
to mechanical output.
32

• According to one of the above sources, in 1975
  humans consumed 2.51 1020 Joules of energy
  through fossil fuels. Compared to the 1.34
  1019 Joules of energy consumed through food,
  humans ironically use roughly nineteen times more
  energy than they eat. If we limit the amount of
  energy we consume via fossil fuels to the amount
  of energy we consume through food, would we be
  able to scratch the energy issue off our
  chalkboard?
• Vickie Wu -- 2009
• http//hypertextbook.com/facts/2009/VickieWu.shtml

33

• Some other
• pedal powered possibilities

34
http//www.windstreampower.com/Human_Power_Generat
or_Series.php
35
Pedal Powered Blender
36
Pedal Powered Cell Phones
37
Pedal Powered Boat
http//www.humanpoweredboats.com/Photos/HydrofoilH
PBs/WetWing.jpg
38
Pedal Powered Washer
http//web.mit.edu/teresab/www/Bicilavadora/index.
html
39
Pedal Powered Water Pump
http//ecoworldly.com/2008/06/12/bicycle-powered-w
ater-pumps-and-filtration-systems/
40

• The ASME 2009 Human Powered Vehicle Challenge
  East and West competitions have been confirmed!
• HPVC East will be hosted by Drexel University in
  Philadelphia, PA from April 17-19, 2009.HPVC
  West will be hosted by Portland State University
  in Portland, OR from May 1-3, 2009.
• Click here to view revised rules for the 2009
  Human Powered Vehicle Challenge! For further
  details on the 2009 competitions, please continue
  to check this website or visit the HPV Peerlink
  site.
• Results are in for the 2008 HPVC Latin America,
  which took place September 2-4, 2008 in
  Maracaibo, Venezuela!
• Visit the HPVC Results page for complete details
  on all three HPVC 2008 competitions. Email us at
  hpv_at_asme.org.
• Human Powered Vehicles are aerodynamic, highly
  engineered vehicles that may be for use on land,
  in the water or the air. Some land-based HPV's
  have achieved speeds of over 60 mph. ASME
  sponsors the Human Powered Vehicle Competition in
  hopes of finding a design that can be used for
  everyday activities ranging from commuting to and
  from work to going to the grocery store. Senior
  engineering students can use this competition for
  their capstone project and with their efforts
  design and construct a fast, sleek, and safe
  vehicle capable of road use.
• The point of the competition is the elegance and
  ingenuity of the design, including presentation,
  practicality and safety. All areas of engineering
  problem-solving are addressed - it's not as
  simple as it appears to design and build these
  vehicles. And the competition itself is great fun
  for the team.
• The vehicles are judged on design, safety and
  performance. The first stage of the competition
  is the preparation of a comprehensive design
  report. The second part of the competition
  includes design presentation and performance
  events, held over a weekend where the vehicles
  race against one another in time trials and an
  endurance event.
• There are three different vehicle classes
• Single Rider - operated and powered by a single
  individual
• Multi-rider - operated and powered by two or more
  individuals
• Utility - vehicle designed for every-day
  transportation for such activities as commuting
  to work or school, shopping trips, and general
  transportation
• The rider (or riders) can be in upright, prone or
  recumbent positions. The single and tandem
  vehicles compete in sprint and endurance events.
  The practical vehicle emphasizes the usefulness
  of the vehicle for daily activities such as
  shopping, transportation or recreation. The
  practical vehicles must negotiate a slalom course
  with the challenge of carrying packages, going
  over bumps, potholes or other obstacles while
  stopping at signs and obeying the rules of the
  road.

41

• Energy
• Future?

42
Energy Information Administration,
http//www.eia.doe.gov/emeu/aer/pecss_diagram.html
, 2008-11-20
43
Energy Generation Choices

• The total solar energy absorbed by Earth's
  atmosphere, oceans and land masses is
  approximately 3,850 zettajoules (ZJ) per year.
• In 2002, this was more energy in one hour than
  the world used in one year !?!
• The amount of solar energy reaching the surface
  of the planet is so vast that in one year it is
  about twice as much as will ever be obtained from
  all of the Earth's non-renewable resources of
  coal, oil, natural gas, and mined uranium
  combined. From Wikipedia, 2008-11-20,
  http//en.wikipedia.org/wiki/Solar_power

44

• Fundamental Theorems
• Of Electromagnetic Energy Generation

45
Amperes Law

• Charge in motion, I(t) ,
• creates a magnetic flux, .
• Flux always comes out of the north pole,
  according to the right-hand rule.

I(t)
46
Amperes Law states that an electric current
produces a magnetic field. The magnetic field
curls around the current using the
right-hand-rule, that is, with your right thumb
pointing in the direction of the current, your
fingers point in the direction of the magnetic
field.
f
f
f
I
f
47
Faradays Law

• A changing magnetic field
• creates a voltage (or current).

48
Lenz Law

• Current is induced so as to oppose a changing
  magnetic field.

49
Lenz Law states that current is induced so as to
oppose a changing magnetic field.
Faradays Law states that a changing magnetic
field produces a voltage. For a coil with
N-turns, the magnitude of the voltage is equal to
the number of turns multiplied by the rate of
increase or decrease of the magnetic flux
inside the coil, V -N(df/dt).
50
Lorentz Force Equation

• Explains forces acting on charged particles in
  electric and magnetic fields.
• A charged particle moving in a magnetic field
  will be deflected. If the velocity of the
  particle is perpendicular to the magnetic field,
  the particle will deflect perpendicularly to the
  plane of the velocity and the magnetic field.

51
A Simple AC Generator
iron
iron
52
Electrical Energy Generation

Turbine, drives generator
N
S
Working fluid (water, steam)
-
53
Permanent Magnet DC-Motors

• Permanent magnet DC-motors can also act as DC
  generators. They rectify the output voltage
  using a mechanical commutator. Often the coil
  rotates in a magnetic field.

IDC by Lorentz force eqn
54

• A diode is needed to prevent stored energy in the
  battery from driving the motor backward.
• (We will use this overall arrangement for the
  experiment.)

IDC
55

• Energy Storage

56
Electrical Energy Storage

• Two different metals and an electrolyte-
  separator are required for an electrochemical
  cell.
• According to Benjamin Franklin, a collection of
  individual cells is called a battery.
• Cell voltages depend on the metals involved.

57
An Electrochemical Cell Discharging
No load voltage
ions diffusing
58
Cell Voltages

• Non-rechargeable or primary cells
• Dry cell 1.5V per cell
• Rechargeable or secondary cells
• Lead-acid cell 2V per cell
• NiCad 1.2V per cell
• NiMH 1.2V per cell
• Li-ion 3.7V per cell

59
Comparison of Various Chemistries
From wikipedia, rechargeable batteries,
2008-24-2008
60
Battery Management

• Some newer chemistries require great effort for
  battery management systems (BMS) to prevent cell
  damage due to overcharge, overdischarge,
  overcurrent, overtemperature, while maintaining
  charge balance among the cells.
• Older chemistries, such as lead-acid, allow some
  overcharge, which works to balance the cells. We
  will use lead-acid cells.

61

• Source to Load Matching

62
Component Matching 1

• All humans have a maximum power-out point, with
  an individualized torque and speed.
• This maximum power point is easily matched to a
  load by having gears on a bicycle. Using gears,
  the human can continue to operate at the maximum
  power-out point for any load.

63
Component Matching 2

• A DC generator is chosen to be attached to the
  bicycle wheel so that it will be able to provide
  as much power as the human can generate, assuming
  about 80 efficiency in the generator.
• From the human power vs time plot, a 300W
  generator should be adequate for most people.

64
DC generator power curves
2008-11-20, http//www.windstreampower.com/443902_
PMDCG.php
65
Component Matching 3

• The storage battery nominal voltage should be
  chosen in conjunction with the DC generator
  voltage output.
• If the DC generator can produce 15V out, then a
  single deep-cycle 12V lead-acid battery will
  work. The size of the battery, and thus the
  weight, depends on how much charge and energy you
  want to store.

66
http//www.windstreampower.com/Human_Power_Generat
or_Series.php
67
Inverters

• Inverters are power-electronic devices that
  convert DC to AC. Many families presently have
  these in their automobiles. These devices
  convert 12V DC to 120 Vrms AC.
• The power rating of the device determines its
  size and cost.

68
Component Matching 4

• The inverter should be chosen so that its input
  voltage matches that of the storage battery.
• Fortunately, most inverters are designed to
  operate at about 12V in order to function with
  standard lead-acid batteries.

69
Matching Battery to Inverter to Load

• When attaching devices to the 120V AC inverter
  output, it is important that the power rating of
  the inverter not be exceeded.
• Many inverters have some overcurrent (overpower)
  protection, but users should do a power
  calculation before attaching the AC loads.

70

• The Lab

71
http//www.windstreampower.com/Human_Power_Generat
or_Series.php
72
http//www.windstreampower.com/Human_Power_Generat
or_Series.php