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.