A UK company has launched a retrofit diesel hybrid system pack called Epack that can be applied to many different urban vehicles, primarily those in goods and passenger transport, including buses. Epack, which uses a series hybrid design, (Short Field Guide to Hybrids) is designed for inner city and airport vehicles where the high number of stop-start journeys produce very high emissions.

Epack replaces a standard large internal combustion engine with a smaller ICE that functions as a generator for an electric motor (series hybrid). In its most recent demonstration, funded by the UK’s Energy Savings Trust, Eneco fitted a mid-size Optare bus with an Epack. (Diagram below left depicts the Epack system unit; diagram at right shows its placement in the Optare)

The Epack system for the Optare uses lead-acid batteries and a 1.9 litre VW diesel generator to replace a standard 5.7 litre diesel. Regenerative braking also contributes to overall efficiency. In a typical one-hour duty cycle, the diesel runs for only 20 to 25 minutes. Running on batteries only the bus has a range of some six to eight miles. With the diesel running, the range goes up to some 400 miles at highway speeds.

Compared to a standard Euro III diesel bus, the Epack Optare:

• Provided fuel savings of 33%

• Reduced PM10 emissions 85%

• Reduced NO_x emissions 38%

• Reduced CO₂ emissions 33%

• Reduced emissions of hydrocarbons (HC) and CO up to 99%

Eneco calculates that the retrofit will pay for itself in four years based on fuel savings. Currently the transport authorities in three UK cities (Bristol, Greater Manchester and Merseyside) have ordered Epack Solo buses, the first of which has just been delivered. ENECO says it expects at least 11 more bus orders in the near future.

Eneco plans to build a range of standard Epack modules to fit different commercial platforms using a variety of fuels—Diesel, LPG, CNG—for the generators.