Making current cars more efficient

Making current cars more efficient • Minimize the force required: • ma+msg+ Crmv+CD Af v2 /370 • Make m small • Make Cr small • Make CD small • Make Af small • Make v small • Or any combination of reducing these values

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.

The first Flex Fuel Vehicle • Any guesses?

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

Alternatives to the internal combustion engine • Flywheels • Electric batteries • Hybrids • Alcohol • Hydrogen

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 = Iω2 where I = moment of inertial of the flywheel, and ω 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.

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.

Hybrids • Still use gasoline powered engines, but combine them with (usually) batteries to achieve better fuel economy. • Different from a flex-fuel vehicle:Flexible 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

Hybrid cars

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 Volt’s battery runs low, a gasoline-powered engine seamlessly operates to extend the driving range another 244 miles on a full tank.

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

Electric Car Engine

Types of electric vehicles • Ford Focus EV due in late 2011 • Nissan Leaf - out now

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)

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

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

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

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.

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

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

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.

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

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

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, don’t do that!

Air pollution • If its in the air, its in your body • Components of the Earth’s 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.

Making current cars more efficient