Making%20current%20cars%20more%20efficient

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Making current cars more efficient

• Minimize the force required
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• Make m small
• Make Cr small
• Make CD small
• Make Af small
• Make v small
• Or any combination of reducing these values

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Flex-Fuel Vehicles

• Internal combustion engines designed to run on
  more than one fuel
• Second fuel is usually ethanol or sometimes
  methanol
• Fuel blend is detected by sensors that adjust
  ignition and timing to match the mixture
• Most North American vehicles are optimized to run
  on mixtures up to E85.

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The first Flex Fuel Vehicle

• Any guesses?

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The first flex fuel vehicle was

• The Ford Model T!!!!
• Designed to run on petroleum, ethanol or kerosene
• Prohibition made ethanol unviable and decreasing
  costs of petroleum made it more attractive
• 1909-1927

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Alternatives to the internal combustion engine

• Flywheels
• Electric batteries
• Hybrids
• Alcohol
• Hydrogen

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Flywheels

• Energy storage device
• Flywheel is spun up and the energy is stored as
  rotational energy to be used at a later time
• Designed to resist losses of rotational energy
  due to friction, etc
• Energy stored is given by
• Ek I?2
• where I moment of inertial of the
  flywheel, and ? is the angular velocity.
• The moment of inertial is a function of the mass
  and the distance from the center of rotation
• So the structure of the flywheel and the
  rotational rate determine the amount of energy
  stored.
• Ultimate limit on the energy storage is the
  strength of the flywheel. Spin it too fast, and
  it will tear itself apart.

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Flywheel vehicles

• Could extract energy from braking-rather than
  waste the energy into frictional heating of
  brakepads, reverse the engine and spin up the
  flywheel.
• Need to be recharged on the power gird, saves
  gas, but drains electricity
• The big implementation problem is materials which
  can withstand the stress needed to spin the
  flywheel fast enough to make this a worthwhile
  alternative.
• Prototype mass transportation vehicles have been
  built (In Sweden and by Lockheed)
• Used in Formula 1 racing to recover energy lost
  in braking and along with a continuously variable
  transmission to improve Formula one car
  acceleration.
• Also used in the incredible hulk roller coaster
  at Universal Islands of Adventure in Orlando,
  Fl.
• Ride starts with an uphill acceleration, rather
  than a gravity drop.
• Flywheels are used to provide the initial energy
  impulse, otherwise the park would brown out the
  local energy grid everytime the ride began.

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Hybrids

• Still use gasoline powered engines, but combine
  them with (usually) batteries to achieve better
  fuel economy.
• Different from a flex-fuel vehicleFlexible fuel
  vehicles (FFVs) are designed to run on gasoline
  or a blend of up to 85 ethanol (E85).
• no loss in performance when operating on E85.
• FFVs typically get about 25-30 fewer miles per
  gallon when fueled with E85.
• Idea is to use as small as possible a gasoline
  engine, and only when it can be run at peak
  efficiency.
• Use excess power to recharge the battery (no need
  to tap the power grid)
• Use energy from braking (regenerative braking) to
  also charge the battery
• Work best in stop and go driving.
• Major initiative in the auto industry right now.
• Result in using less gas-stretching our fossil
  fuels

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Hybrid cars
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Hybrid Models

• Hyunai Sonata Hybrid
• Honda CRZ and Fit
• Mercedes Benz ML 450
• BMW
• Dodge Ram
• Chevy Silverado
• Toyota Prius
• Chevy Volt WKU president drives one
• has a total driving range of up to 379 miles. For
  the first 35 miles, it can drive gas free using a
  full charge of electricity stored in its 16-kWh
  lithium-ion battery. When the Volts battery runs
  low, a gasoline-powered engine seamlessly
  operates to extend the driving range another 244
  miles on a full tank.

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Pure electric vehicles

• Powered by an electric motor, rather than a
  gasoline engine
• Needs batteries current generation of batteries
  have 520 times less energy density than gasoline.
• Need to be charged from the power grid
• If all the vehicles in the US were converted to
  electric cars, it would triple the current
  electric energy generation
• Recharging electric vehicles takes time- several
  hours, whereas it takes minutes to refill your
  gas tank
• Batteries have a finite lifetime, need to be
  replaced every 2-3 years at a current cost of
  1000
• Limited range (less than 100 miles before
  recharging is needed)
• Ultimate limit is current battery
  technology-current lead acid batteries have not
  changed much in 100 years.
• Environmental effects from the disposal of lead
  acid batteries
• No new promising battery technologies on the
  horizon to substantially help electric cars

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Electric Car Engine
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Types of electric vehicles

• Ford Focus EV due in late 2011
• Nissan Leaf - out now

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Fuel cells

• An electrochemical conversion device
• Chemical reactions cause electrons (current) to
  flow
• Requires a fuel, an oxidant and an electrolyte (
  a substance that contains free ions and acts as a
  conductor)
• Typical type of fuel cell is called a proton
  exchange membrane fuel cell (PEMFC)

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Hydrogen Fuel Cells

• Clean-only emission is water
• Expensive to produce
• Highly efficient-in an automobile, efficiencies
  of converting fuel energy to mechanical energy of
  60 could be achieved, almost double the current
  efficiencies
• Hydrogen itself has issues as a fuel source

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Issues with Hydrogen

• Abundant in nature, but not a freely available
  fuel
• Must be unbound from compounds
• Currently obtained via steam reforming
• Steam and a nickel catalyst react, producing H
• Need steam at very high temperatures, 1600F
• In the future, H is anticipated to be produced by
  the electrolysis of water, requiring large amount
  of water and electricity

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Electrolysis

• Pass an electrical current through water and
  obtain H
• Pass a direct current from a battery or other DC
  power supply through a cup of water (salt water
  solution increases the reaction intensity making
  it easier to observe).
• Using platinum electrodes, hydrogen gas will be
  seen to bubble up at the cathode, and oxygen will
  bubble at the anode.
• Choice of the electrode is critical, you do not
  want a metal that will react with oxygen

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Issues with Hydrogen

• Storage-occurs in gas form at room temperature,
  hard to contain
• As a liquid, it can be stored, but needs
  temperatures of -253 C.
• As a liquid, its energy density increases 1000
  times
• In principle, could replace gasoline as a liquid
  fuel, but not practical at this time
• One solution is to store it as a metallic hydride
  (the negative ion of Hydrogen in a compound with
  another element) at room T.

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Issues with H

• Highly explosive
• Forms a volatile mixture with air
• A mixture of 4-75 of H in air is explosive,
  compared with natural gas which is only explosive
  in a range of 5-15 concentration in air
• Ignition energy is small, needing only 2 x 10-5 J
  (basically a spark of static electricity can
  ignite H)
• Only good news is its low density means if there
  is a H leak, it disperses quickly

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Hydrogen

• Hindenburg disaster
• Hindenburg was a German passenger airship
  (zeppelins) built for transatlantic air flight.
• Filled with Hydrogen
• Something caused ignition of the Hydrogen-cause
  is debatable
• 36 fatalities out of 79 people onboard

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Alchohol

• Use methanol or ethanol as a fuel
• Already gone over ethanol
• Methanol is already in use at Indy 500 race
• Proven that no significant loss of performance is
  experienced (though they are in the process of
  switching to ethanol)
• About ½ the energy content of gasoline
• Produces only CO2 and water
• Some nitrogen oxides produced in the engine
• Can be manufactured from re-newable sources
  (biomass for example)
• Technologies exist now.

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Disadvantages

• Very dangerous
• Burns with no visible flame-needs a colorant
  added
• Fumes are toxic
• CO2 is a greenhouse gas
• Currently made mostly from natural gas-a
  non-renewable fossil fuel
• Possibly more corrosive than ethanol to engine
  parts

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Use in liquid fuel cells

• Another use is as a input to a liquid feed fuel
  cell
• In these cells, Methanol replaces hydrogen
• Methanol has a much higher energy density and is
  easier to store than H
• Current methanol fuel cells produce power too low
  for vehicles, but can be used in cell phones,
  laptops etc
• Advantage is that they store lots of power in a
  small space, which they over a long period of
  time

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Environmental effects of energy production

• All of our energy producing mechanisms have some
  effect on the environment
• Production of waste products pollutes air, water
  and ground
• Disruptions to local ecosystems
• Our job is to understand and mitigate these
  effects to the best of our ability
• Philosophy If it hurts (the environment) when
  you do that, dont do that!

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Air pollution

• If its in the air, its in your body
• Components of the Earths Atmosphere
• Nitrogen 78.08
• Oxygen 20.95
• Argon 0.93
• Also small amounts of Neon, Helium, Krypton,
  Hydrogen
• In addition, there are compounds whose
  concentrations vary with height water vapor,
  carbon dioxide, methane, carbon monoxide, ozone,
  ammonia
• These are naturally occurring concentrations, any
  additional influx or destruction of these
  compounds via human beings alters the system.