Energy
The ultimate addiction of civilisation
Energy consumption
 90% of energy consumed in developed
countries is from fossil fuels
 10% are from hydropower, nuclear, solar,
wind
 Renewable sources are alternative
sources
Energy efficiency: 1st law
 First law efficiency – amount of E without
consideration of its quality. Expressed as a %.
 It is a ratio of the actual amount of energy
delivered where it is needed to the amount of
energy supplied to meet that need
 A fluorescent bulb converts 1/5 of electrical
energy into light. Thus its 1st law efficiency is
20%
Energy efficiency: 2nd law
 Second law efficiency: the ratio of
minimum available work needed to
perform a particular task to the actual
work needed to perform that task
 A car has a 1st law efficiency of 20%.
80% is unusable energy.
 Out of that 20% 1st law efficiency, 10% is
2nd law efficiency
Energy efficiency
 1st law efficiency may be misleading. A high
efficiency may mean no more energy saving
improvements may be done.
 2nd law efficiency takes note of work. That is
energy applied.
 A car has a low 2nd law efficiency since high
quality gasoline wastes much heat that
otherwise may used to do additional work.
 The solution is to use a fuel that doesn’t waste
much heat and do more useful work.
REGULAR COMBUSTION
ENGINE
A lot of the energy is wasted in the heat
of the exhaust as well as in the radiator.
Pollution (NOx , SOx VOC and other)
Has a very low efficiency, about
20-25% .*
* Physics Today. April 2002
What is energy
conservation?
 This refers simply to getting by with more
work with less demand for energy
 This means improving 2nd law efficiency
 Cogeneration: using waste heat to do
supplementary work
 Example: Have you heard of the guy who
barbecues while driving his V8 engine car?
Fossil fuels
 95% of Philippine energy needs
 Relatively cheap as of now.
 Petroleum is also made into plastics and other
synthetic materials including fertilizers
 Only a few countries have enough supplies.
E.g. Saudi Arabia, Iraq
 Some of the countries have political problems
Where is the oil?
Why is the price of oil
going up?
 Economic development
 China, India and Southeast Asian
countries have a rising middle class who
want cars
 Political troubles: Iraq, Saudi Arabia
 USA- preference for SUVs
 New oilfields require more investments
Top 5 consumers of oil
1.
2.
3.
4.
United States
China
Russia
Japan
5. United States’ Automobiles
Two major choices
 Change your car for cars with new
propulsion technologies (hybrids, fuel
cells or electric)
 Change from gasoline or diesel to new
fuels but these new fuels can run your
car without engine modification
(biodiesel).
Easier to Change the Car
Than to Change the Person!!
 Sport Utility Vehicles are a Status Symbol
 Only 10-30% of people who own SUVs actually use
them for off-road activities
 38% of the cars on the road are SUVs
 With Hybrid technology, people can keep their
“big” cars while using less fuel.
 Ford Escape, 2004
 Dodge Durango SUV, uncertain release date
How Hybrids Work
 Electric portion of the motor gets power
from nickel-metal hydride battery (next to
fuel tank)
 NO PLUGGING IN NEEDED! (battery
maintained by regenerative brakingkinetic energy captured by forward
momentum)
 Gasoline engine made from plastic
materials
Other car technologies
 Electric cars
 Hybrid cars- gas and electric
 Fuel cell cars
Why go alternative?
 Mileage- a hybrid car can go 20 km or
more to a liter
 More environment friendly
 Celebrity appeal: Leo DiCaprio drives 4
hybrid cars. Russel Crowe drives one.
How It Works
 Two or more sources of power combined
 Ex:





Mo-ped
Trains
Buses
Mining trucks
Submarines
A BATTERY-POWERED
CAR
Battery efficiency: ~90%
Motor efficiency ~80%
TOTAL: 72%
No Pollution ???
Remember that the power had to be
generated somewhere else, most likely a
conventional coal plant! ~40%.*
Real Efficiency ~29%
* Berinstein, Paula. Alternative Energy: Facts, Statistics, and Issues. Westport, CT, Oryxpress 2001
Comparing the Battery and
Fuel Cell in automobile
Fuel cell slightly more efficient and
without the conventional pollution
Fuel cell design offers convenient
“recharge” at a gas station
Fuel cell automobiles are still much more
expensive ($80,000
80mpg/52mpg (Toyota Prius-hybrid)
~0
~0
~0
~6-7,000
~300
Can perform similar analysis for a large scale power generation
Components






Gas engine
Fuel tank
Electric motor
Generator
Batteries
Transmission
Electric Motor
Components
 Armature or rotor
 Thin wire coiled around two or more poles
 Commutator
 Plate pair attached to axle
 Brushes
 Provides “flipping” action with the commutator
 Axle
 Field magnet
 DC power supply
Poles
 Car motors usually have 3 poles…
 Better dynamics in the car (magnet cannot
get “stuck” b/w the poles)
 Avoids wasting energy and wasting the
battery
Generator
 Similar to electric motor, but only
produces electrical power
 Used in series hybrids
 Electric motor acts like a generator when
it slows car down to charge the batteries
Batteries




Higher voltages serial
Higher currents parallel
Energy storage device for electric motor
Electric motor: puts energy into batteries
and draws from them
 Gives that extra “help”
The upper arrangement is called a parallel arrangement. If you assume that each
cell produces 1.5 volts, then four batteries in parallel will also produce 1.5 volts,
but the current supplied will be four times that of a single cell. The lower
arrangement is called a serial arrangement. The four voltages add together to
produce 6 volts.
Types of Hybrids
 Parallel hybrid
 Fuel tank provides gasoline to engine
 Batteries supply power to electric motor
 Engine and electric motor work together to
turn transmission simultaneously
 Transmission turns the wheels
Parallel Hybrid
 Fuel tank and gas engine connect to
transmission
 Batteries and electric motor connect to
transmission independently
 Thus, electric motor and gas engine
propel auto
Civic Hybrid Stats
 48 mpg city/47 mpg highway (ULEV)
 Actual: 43 mpg city / 52 mpg highway
 City fuel efficiency decreases in winter when temps
are below freezing; closer to 35 mpg in city; highway
stays the same
 47 mpg city/48 mpg highway (SULEV)
 1/03: SULEV marketed in California
 650 miles per tank of gasoline
 IMA technology; 1.3 L VTEC 4-cylinder engine
 10 year battery life
Toyota Prius
 Parallel hybrid
 Electric motor starts the car
 Power Split Device
 Series hybrid
 Only Available in a Continuously Variable
Transmission (CVT)
How to make the most of
your hybrid




Don’t speed
Keep speed constant
Don’t stop abruptly
Manual transmissions: let the
regenerative braking work before putting
in the clutch
WHAT IS A FUEL CELL
 Reversed Electrolysis
Device
 Pt coated electrodes
 Use air as a source of
O2
How Does it Work
 Electrolyte- protonexchange-membrane
(PEM), Phosphoric Acid
 Combines Fuel and
Oxygen
 Produces H20 (l), heat,
CO2
www.howstuffworks.com
Still a little fuzzy? DOE’s website:
http://fossil.energy.gov/coal_power/fuelcells/fuelcells_howitworks.shtml
ADVANTAGES OF FUEL
CELLS
 EFFICIENCY
 Fuel cells can convert as much as 80% of the
energy stored in the fuel *
 QUIET
 NO MOVING PARTS
 EXTRA HEAT CAN BE USED
Graph Courtesy of Mercedes-Benz
* Berinstein, Paula. Alternative Energy: Facts, Statistics, and Issues. Westport, CT, Oryxpress 2001
MORE ADVANTAGES
Low Pollution- Fuel cells produce only
water and CO2 depending upon the fuel
used
Low Maintenance/Operating cost
Can use conventional fuels - gasoline,
methane, propane
Small or large scale uses
DISADVANTAGES
Still produce CO2 although with more
usable energy.
Expensive: (Pt) It costs about $40,000 to
make a fuel cell system for a car.*
 (Power plant estimated costs 1999: $800-1200/kWh (The first one in
Austin cost about $4000/kW)**)
 Hydrogen/Reformer Problem
 Clean Fuel
* Berinstein, Paula. Alternative Energy: Facts, Statistics, and Issues. Westport, CT, Oryxpress 2001
** Daily Texan 17.7. 2002
FUEL CELL IN
AUTOMOBILES
 Fuel Cell efficiency~40% (depends on fuel)recall reformer, up to 80% if heat
regenerated
 Motor efficiency ~80%
 Can be combined with recharging while
braking
Overall Efficiency: ~32%
What about other
alternatives?
 Solar energy- perfect for heating but has
low 1st law efficiency (electricity)
 Biofuels –low efficiency: renewable
 Nuclear – efficient but has waste disposal
problem
 Garbage – low efficiency
The major disadvantage of
alternatives
 EXPENSIVE!!! A hybrid car is double or
triple the price of a standard car
 That’s why only the likes of Russel
Crowe and Leo Dicaprio can afford one!
 However some alternatives are cheap.
 A pair of walking shoes is much cheaper
than an SUV.
 And so is a bicycle!
How can we conserve
energy?
 Increase your 2nd law efficiency: walk (walking
is good for the heart!)
 Properly maintain your car
 Take public transport. This increases 2nd law
efficiency
 Turn off the lights when not in use. Use natural
lighting
 Use airconditioning when absolutely needed.
What kind of energy
efficiency are you improving?
 I jog to my next class in Palma Hall.
 I car pool
 Instead of taking Ikot or Toki, I bike to my
next class
 I use low wattage fluorescent bulbs
 I use a solar powered calculator
More on alternative
energy sources
 Alternative energy
 Biodiesel