Hybrids, For Now | Green Energy News

February 26, 2006 – Vol.10 No.49

HYBRIDS, FOR NOW.

It seems possible that somewhere on the planet, in the back corner of a research lab or perhaps in an inventor’s garage, is an inexpensive, emission-free replacement for the conventional internal combustion engine and drive train that has been used in cars, trucks and buses for 100 years.

For now, until something better comes along, the most technologically advanced and most efficient replacement is the gasoline or diesel-electric hybrid. Unfortunately because of the extra components required - the battery pack and the electric drive motor - hybrids will always carry a premium price. For fleet operators that premium can be compensated for on the balance sheet. For consumers a drop in the price of fuel for an extended period could send hybrids into history.

A story of success in hybrids is the hybrid bus fleet operated by MTA New York City Transit. Its 325 DaimlerChrysler Orion VII hybrid buses are the subject of an ongoing study by the National Renewable Energy Laboratory (NREL). The results of an interim report on the fleet are positive. Data from September 2004 to May 2005 show that the buses achieved 45 percent better fuel economy than conventional diesels and a doubling of fuel economy compared with natural gas buses on an energy equivalent basis.

The Orion buses use a series hybrid system developed by defense contractor BAE. In them a diesel engine operating at optimum efficiency generates electricity to power electric traction motors. A battery pack is used to capture some of the lost energy of braking - regenerative braking - which also reduces wear and tear on the vehicle’s brakes. Buses in urban transit service brake and accelerate frequently thus are hard on brakes.

New York is so pleased with its hybrids that it has another 500 on order. Other transit systems, such as in the state of Maryland, are considering large hybrid bus orders.

Hybrid technology, too, is showing up in other types of commercial vehicles.

Recently Eaton Corporation announced it will be providing 50 hybrid drive systems to be incorporated in step vans to be built by International Truck and Engine and Freightliner Custom Chassis Corporation. Those delivery vans will be purchased for fleet use by the United Parcel Service (UPS) for service in Dallas, Texas beginning in June, 2006.

The Eaton system is for a parallel hybrid. A smaller-than-expected-for-the-size-of-vehicle diesel engine is used with an electric drive motor squeezed between the engine and the driving wheels making a mechanical connection. Eaton thinks the parallel system is less expensive than a series hybrid. The company expects fuel economy to improve up to 35 percent with the delivery vehicles.

Enova Systems is also working with International Truck and Engine to evaluate Enova's hybrid drive systems in trucks and school buses. In one truck application fuel savings were 31 percent, and miles per gallon increased by more than 48 percent according to the company.

Hybrid drive technology is not new. Its roots go as back nearly as far as the internal combustion engine itself. (Think diesel/electric submarines in World War I.) Yet for commercialized, roadworthy vehicles hybrid technology is in its infancy with each new variation an improvement over the last. The next big leap may be in energy storage and regenerative braking.

Whereas batteries capture a small fraction of the energy of braking (some say as little as 10 percent) flywheels or ultracapacitors should be able to capture nearly all the lost energy. The more captured, the more energy will be available for hill climbing and acceleration, and the less the conventional engine will be needed.

For now, ultracapacitors are taking the lead over flywheels in research vehicles with one company, Maxwell Technologies, frequently offering new commercial products. The latest offering is 16 new cells and multicell modules geared specifically for transportation and industrial applications. Installed in a hybrid, the cells could feasibly last the life of the vehicle.

Read NREL’s report on New York’s hybrid buses at http://www.eere.energy.gov/vehiclesandfuels/avta/pdfs/heavy/nyct_interim_report_final.pdf Visit Eaton at http://www.truck.eaton.com/hybrid.htm, Enova at http://www.enovasystems.com/ and Maxwell at http://www.maxwell.com/ .