The truck unveiled Tuesday is one of several new approaches that could potentially make garbage collection cleaner, quieter and more energy efficient, said Bill Van Amburg, senior vice president of Calstart, a Pasadena non-profit that provides green technology consulting services for the trucking industry.
Hybrid and electric trucks make sense for garbage collection because their braking systems recapture energy as the vehicles make hundreds of stops in neighborhoods.
“Think of the energy a loaded refuse truck uses going from a stop, up to speed and then hard stopping again 200 feet later, and multiply that by 1000,” Van Amburg said.
Both the fuel use and brake wear are exceptionally high in a conventional garbage truck.
“It is not uncommon for three brake replacement/service intervals a year, which is very expensive.”
The garbage truck is based on Mack’s LR model and features a range-extended electric powertrain. The system uses electric motors to drive the the front wheels and allows the truck to benefit from more load-hauling low-end torque than conventional diesel engines.
The motors are powered by batteries that can be recharged while the truck is operating via regenerative braking and also through a turbine generator that can use natural gas or diesel fuel.
The powertrain was developed by Wrightspeed Inc., a San Jose, Calif., company founded by Ian Wright, Tesla Motors’ co-founder and vice president of vehicle development. He left the Palo Alto, Calif. electric car company in late 2004.
The technology is designed to replace vehicle components like the truck’s diesel engine and transmission system with electric drive.
“We’re always looking for opportunities to advance our technology we use for our customers’ trucks,” said Roy Horton, Mack’s director of product marketing.
The industry, he said, is looking for more efficient powertrain technology that performs on par with existing vehicle propulsion systems while improving the environmental impact.
The Wrightspeed powertrain can significantly reduce fuel consumption compared to conventional garbage trucks, delivery vehicles and buses, according to Mack, a division of Volvo Trucks. It also helps reduce emissions and noise.
Wright said his experience at Tesla provided valuable lessons for what not to do for the Wrightspeed business.
For example, “we don’t make vehicles, we just make powertrains,” Wright said.
The company is also focusing its technology on trucks and buses (excluding long-haul rigs) instead of cars, and range extender EVs rather than battery extender EVs, he said.
Both extenders will help increase the amount of time drivers can operate a vehicle just on electricity. However, the on-board range extender EV also uses a turbine generator to charge the battery as it drains so drivers don’t have to stop and plug-in their vehicle, unlike regular battery-powered EVs.
Wright’s technology is capable of powering vehicles weighing up to 66,000 pounds up slopes as steep as 40 percent, according to Mack.
“There’s a battery pack that you can charge from the grid, and there’s a range-extender generator which can burn fuel, make electricity and keep the battery pack charged so that you don’t run out of range,” Wright said.
“Wrightspeed is certainly a very promising company with a very solid technology design and a vision for the market,” Van Amburg said. “Their driveline scales from lighter applications to heavier applications, which can help them address multiple markets without having to start from scratch each time.
Other companies are playing in this arena with both hybrid technology and all-electric vehicles.
Motiv Power Systems of Foster City, Calif. has been an “early leader” Van Amburg said. It is testing all electric garbage collection in Chicago as well as building units for a demonstration project in Sacramento.
Parker Hannifin Corp. of Cleveland said its hybrid drive system for refuse vehicles reduces fuel consumption by about 48 percent. Orlando, Fla., has purchased 29 of the vehicles for garbage collection.
While Mack’s electric garbage truck made its first public appearance at WasteExpo, there is no plan for commercial sales until Mack and Wrightspeed have finished testing the truck, Horton said.
Refuse vehicles are a small, but important segment of heavy duty truck sales. They accounted for about 4 percent to 5 percent of the 242,000 Class 8 truck registrations in the U.S. last year, according to Mack's analysis of IHS Automotive data.
Volvo Trucks, a sister brand to Mack Trucks, also displayed several models at WasteExpo that are designed for the refuse industry. The vehicles all feature Volvo’s I-Shift automated manual transmission for enhanced efficiency.
I-Shift works with some of the truck’s electronic features to monitor grade, speed, weight, and engine load, and it shifts or holds a gear when necessary to help save fuel, according to Volvo.