Announcing its decision to field seven hydraulic hybrid vehicles (HHV) — the first fleet application of the technology — UPS disclosed some significant data on road testing that has taken place in the Detroit area over the past two years.
Compared to conventional diesel delivery trucks in use by the world’s largest package delivery company, a prototype HHV achieved a remarkable 45% to 50% improvement in fuel economy. Equally significant, a 30% reduction in CO2 is achievable in daily use.
“There is no question that hydraulic hybrids are ready for use on the streets of America,” said David Abney, chief operating officer at UPS. “We are not declaring hydraulic hybrids a panacea for our energy woes, but this technology certainly is as promising as anything we’ve seen to date.”
While the use of hybrid-electric vehicles (HEV) is growing in many light- and medium-duty fleet applications, less is known about HHV technology. Originally developed in a U.S. Environmental Protection Agency (EPA) federal laboratory, the HHV systems being purchased by UPS for use on Navistar chassis were designed by Eaton Corp. under a Cooperative Research and Development Agreement.
An HHV stores energy by compressing hydraulic fluid under pressure. With a diesel “series” hydraulic hybrid of the type being purchased by UPS, a high-efficiency diesel engine is combined with a unique hydraulic propulsion system that replaces the conventional drivetrain and transmission. The vehicle uses hydraulic pumps and tanks to capture and store energy, similar to what is done with electric motors and batteries in a hybrid electric vehicle. In this case, the diesel engine is used to periodically recharge pressure in the hydraulic propulsion system.
Fuel economy is increased in three ways in an HHV: vehicle braking energy is recovered that normally is wasted; the engine is operated more efficiently; and the engine can be shut off when stopped or decelerating. The EPA estimates that when the hybrid components are manufactured in high volume, the added costs can be recouped in less than three years through lower fuel and brake maintenance costs.
UPS will deploy its first two HHVs in Minneapolis during the first quarter of 2009 where Eaton will monitor the vehicle’s fuel economy performance and emissions. The additional five vehicles will be deployed later in 2009 and early 2010.
The HHVs are the latest “green” vehicles to join the UPS fleet, which now includes more than 2,100 all-electric, hybrid electric, compressed natural gas (CNG), liquefied natural gas (LNG) and propane-powered trucks. The HHV order follows the May 2008 purchase of 500 hybrid electric and CNG vehicles and the April 2008 deployment of 167 new CNG vehicles in Atlanta, Dallas, Los Angeles, Ontario, San Ramon, Fresno and Sacramento.
“We continue to be pleased with the progress and potential of the hydraulic hybrid system,” Alexander M. Cutler, Eaton’s chairman and CEO said. “The market for this technology is truly global, and it can provide significant improvements in fuel economy and emission reductions for trucks, buses and off-road vehicles of many shapes and sizes.”
EPA agrees, noting that HHV technology can perform equally well in other applications, such as shuttle and transit buses, and refuse trucks. While the HHV may be just the latest environmentally friendly vehicle to take to the streets –– UPS has also road-tested hydrogen fuel cell delivery trucks, for example — it now appears to be ready to join the growing list of alternative vehicle options for fleets to consider.
