A transit bus powered by a hybrid gasoline-electric drive system using ultracapacitors for electrical energy storage and power delivery has successfully completed a 15,000-mile durability and safety test conducted by the Federal Transit Administration at the Altoona Research and Testing Center in Altoona, Pa. The bus’ hybrid electric drive system—ThunderVolt—was supplied by ISE Corp., and its BOOSTCAP ultracapacitors were provided by Maxwell Technologies.
Dr. Richard Balanson, Maxwell’s president and CEO, said that the Altoona certification represents an important “stamp of approval” for ISE’s ThunderVolt drive system, which employs ultracapacitors to store electrical energy generated by the bus’s braking system and reuse that energy to assist acceleration, reducing fuel consumption and emissions.
“The transportation industry in general, and municipal transit agencies in particular, rely on certifications such as this to guide their purchasing decisions, so they are critical for broad adoption of new products that systems integrators such as ISE and components suppliers such as Maxwell are introducing,” Balanson said. “This is another in a series of milestones that demonstrate ultracapacitors’ growing acceptance as a standard energy storage and power delivery solution for transportation applications.”
Last year, ISE and Maxwell announced orders for 44 ThunderVolt-powered buses by transit agencies in the cities of Long Beach and Elk Grove, Calif.
David Mazaika, president of San Diego-based ISE, said that the bus that completed the Altoona test is a 40-ft New Flyer transit model equipped with a ThunderVolt system consisting of an ultralow-emission Ford Triton V10 gasoline engine, Siemens ELFA electric motors, motor controllers and generators and a ThunderPack II ultracapacitor-based energy storage system comprised of 288 Maxwell BOOSTCAP ultracapacitors.
Mazaika said that the ThunderVolt system is the only commercially available gasoline-electric hybrid drive system certified to meet the California Air Resources Board’s strict emissions standards. ISE’s hybrid systems are available with either battery- or ultracapacitor-based energy storage modules. Mazaika said that for urban transit buses, ultracapacitors offer several advantages over batteries.
“Ultracapacitor-based systems achieve higher fuel economy than comparable battery-based systems because they are more efficient in absorbing braking energy and do not require air conditioning,” Mazaika said. “They also are projected to perform reliably over hundreds of thousands of discharge-recharge cycles, which equates to years of maintenance-free service.”