AATA saves 100,000 gallons, $270,000 using hybrid electric technology

According to Manager of Maintenance Terry Black, AATA has reduced its fuel consumption by more than 100,000 gallons using the hybrid electric buses, which, at an average cost of $2.69 a gallon, has saved the bus system $270,000 to date.

“The introduction of hybrid electric buses into AATA’s fleet is one of many strategies to reduce our operating expenses and has been by far one of AATA’s most aggressive efforts toward ensuring a cleaner environment for the residents of Ann Arbor and the surrounding communities,” Black said.

The 11 new buses will bring the total number of hybrid electric buses to 31, or half of the daily fleet in service.

AATA’s hybrid buses, which feature an Allison electric drive as part of the General Motors hybrid electric bus system, are assembled by the Gillig Corporation of Hayward, California. The buses feature a combination of a battery-powered electric motor to provide most of the power at slower speeds and a smaller, clean-diesel engine that takes over at higher speeds.

“This technology uses a process known as regenerative braking to slow down the vehicle when letting off the accelerator. The process reduces brake wear and helps minimize stress on the engine and other related components, while recharging the batteries,” Black said, noting that this parallel system has proven very reliable in the transit industry.

The new technology has been easily incorporated into AATA’s operations and maintenance functions by its personnel, Black said, because the buses do not require special fueling or infrastructure changes.

AATA initially projected fuel savings of 25 percent with the hybrid electric buses, but has actually experienced more than 30 percent savings in fuel costs.

“The cost of a hybrid electric bus is approximately $600,000, about $200,000 more than that of a conventional diesel-powered bus. The purchases are made possible through various grant funding sources. AATA has been very aggressive in obtaining these funds for the benefit of our local community,” Black said.

The four buses now on order are being funded through the American Recovery and Reinvestment Act.

Major advantages of the hybrid electric buses in addition to fuel savings are reductions in maintenance costs, exhaust emissions and noise. AATA’s hybrid buses have logged 1,513,753 miles, saving 100,478 gallons of the B-10 ultra low sulfur biodiesel fuel used in all AATA buses. The hybrids average 4.7521 miles per gallon, a 31.5 percent improvement as compared with the remainder of the fleet -- conventional diesel buses which average 3.6126 miles per gallon.

Hybrid electric buses have been shown to reduce maintenance costs by 30 to 50 percent; particulate matter, carbon monoxide and hydrocarbons by up to 90 percent; and carbon dioxide and nitrogen oxide by up to 50 percent. AATA received its first 15 hybrid electric buses in October, 2007, and five in May, 2008. Black noted that AATA is continuing to acquire these buses, since it has experienced very minimal problems with these earlier purchases.

The latest information on AATA routes, schedules and detours is available at 734.996.0400 and on the AATA Routes and Schedules page.