Monday, January 7, 2008

What is the Best Way to Power Our Cars? Part 2

For the second part of this discussion I want to talk about Hybrid Vehicles.

What is it? A hybrid automobile is any vehicle that combines two or more sources of power that can directly or indirectly provide propulsion power. You have heard of the Prius storming the nation and Toyota’s record U.S. sales. Are these hybrids the answer to all our problems?

How does it work? One popular type of hybrid is a parallel hybrid. This has a fuel tank that supplies gasoline to the engine and a set of batteries that supplies power to the electric motor. Both the engine and the electric motor can turn the transmission at the same time, and the transmission then turns the wheels.

The benefit to this system is that because the electric engine can assist in propulsion you can design a smaller gasoline for the vehicles. Smaller engines decrease the weight of the vehicle and use less cylinders (less gas). In addition, the electric power can be used exclusively until the vehicle has reached a cruising speed (15-40mph), at which time the gas engine can turn on and operate at its most efficient speeds.

The next advantage of parallel hybrids requires a quick and painless physics lesson. This is that “Energy can neither be created nor destroyed.” Whenever you step on the brake pedal in your car, you are removing energy from the car. The brakes of your car remove this energy and dissipate it in the form of heat. A hybrid car can capture some of this lost energy and store it in the battery to use later. This "regenerative braking” also will increase the life of your break pads.

One of the biggest ways to reduce emissions is to eliminate idling. When a hybrid comes to a stop at a light or in traffic, the gas engine shuts down. A hybrid car does not need to rely on the gasoline engine because it uses the electric motor to power the car from stopped to cruising speeds. So the hybrid car will turn off the gasoline engine, when the vehicle is stopped at a red light, which saves gas and reduces dreaded idling emissions.

Is this the answer? Yes and No. Hybrids are able to reduce tailpipe emissions and to improve mileage, but until recently even with increasing gas prices and new innovations in battery technology, hybrid cars and buses were not cost effective. It is inevitable, however, that with advances in technology the prices for these cars, trucks, and buses will be competitive with standard ICEV (internal combustion engine vehicles). Making them the obvious choice over standard ICEV. But maybe there is alternative?

Some hybrids require plugging in to recharge electric power. While some may avoid this, citing higher electric bills, plug in hybrids can achieve 150 mpg for their first 50 miles. Regular hybrids rely on the gas engine for the first part of a trip because the batteries need to be recharged by the alternator and the “regenerative breaking.” This means the gas engine would not shut off – when the car stops at a light and would kick on before the car reached cruising speeds – until the batteries have been charged.

My mother purchased a Ford Escape hybrid two years ago. It is an SUV and she was excited about having a more efficient large car. She didn’t do it for the money; she did it for the environment. The hybrid model cost about 7,000 more than the non-hybrid, she figures she’s not going to make that back, even with oil now at $100 a barrel.

· Escape FWD 4-cyl. - $19,995

· Escape AWD 4-cyl. - $23,235

· Escape AWD 6-cyl. - $27,145

· Escape Hybrid FWD - $26,970

· Escape Hybrid AWD - $28,595

Although this SUV is rated at 36 mpg City/ 25 mpg Highway, she has a computer on the dash that says she averages 27.8 mpg. This is despite that fact we live just outside of Washington, D.C., where she works.


Extra Reading and Sources:

Ford Escape "How Stuff Works"

Hybrid Cars "How Stuff Works"

Hybrid Vehicles Wikipedia

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