Last December at EVS 23, the Electric Vehicle Symposium, Enova Systems presented hybrid vehicles that made use of ultra-capacitor technology. The display included a production Commercial Bus, for which Enova also provided key components.
Enova Systems offers Electric, Hybrid Electric and Fuel Cell Drive Systems in three sizes 60-90 kW, 120 kW and 240 kW. These systems can recover kinetic energy during regenerative braking, charging the batteries when the vehicle is slowing down. This provides additional power for acceleration, making them ideal for frequent stop and go driving. Enova will convert conventional transport vehicles to plug-in hybrids, or simply as hybrids
We now learn from Green Car Congress that “UK-based Traction Technology Plc. is using the Enova 120kW hybrid drive system in combination with a super capacitor energy storage system in four series hybrid Optare Solo Buses contracted by Merseytravel.”
Optare’s Solo is a low-floor midi-bus that is available in six lengths ranging from 7.1 to 10.2 meters. Conventional models are powered by either a Cummins 5.9L, 150 kW (201 bhp) ISBe Euro4 six-cylinder turbodiesel or a MAN 4.6L 132 kW D0834 Euro 4 four-cylinder turbo diesel.
Traction Technology replaces the conventional power train with a 1.9L Volkswagen diesel generator set and hybrid drive system. Traction’s systems are based on the Eneco EPack, introduced for the Optare line in 2004.
Traction, formed to exploit the growing demand for environmentally friendly transportation technology, acquired the assets, including the intellectual property, of Eneco in May 2006. Eneco had been in administration.
Testing of the Traction Technology hybrid systems showed that carbon dioxide emissions are reduced by 33%, NOx emissions by 38%, HC emissions by 99% and particulates by 39%. In addition, fuel savings of over 33% have been regularly achieved in trials, according to the company.
Testing at Millbrook on the LT buses test cycle of the earlier Eneco hybrid system applied in an Optare Solo resulted in an average fuel consumption of 25.4 L/100km over five tests—a 28% decrease in consumption compared to the 35.4 L/100km of a comparable conventional model. [A GCC commentator noted that 25.4 L /100 KM is equivalent to 9.3 mpg. "That's great for a bus!"]
In November 2007, Traction Technology signed a Memorandum of Understanding with The Optare Group for the joint development of a range of single-deck series hybrid vehicles for the UK bus market. (Earlier post.)
This is other than the first time that this blog has mentioned the use of ultra capacitors in buses. Indeed, a Hybrid Booster Drive was patented as early as 2002.