One of Two Trucks to Be Used for Siemens Catenary Project,
The Other Is to See Genset Optimization for Range-Extension
San Diego-based TransPower is leveraging funding from two California agencies to develop two variants of a battery-dominant Class 8 plug-in truck with a 3.7-liter compressed natural gas engine as a range extender.
One, says TransPower president & CEO Mike Simon, will be used to perfect the vehicle’s CNG-fueled genset, reconciling control of the engine with drive cycle needs and perhaps even the local topography.
The other will be outfitted not only as a plug-in hybrid but with equipment to draw power from overhead catenary lines. It will be tested as part of a project with the South Coast Air Quality Management District and Siemens.
‘The Future of Hybrids’
In addition to SCAQMD, the California Energy Commission is supporting TrnasPower’s CNG hybrid work.
“We now have a critical mass of funding, roughly $2.5 million in total,” Simon says.
He explains that most hybrids today achieve fuel savings of just 10% to 15%, which is proving to be not enough to justify their extra cost. A battery-dominant hybrid with a sufficiently efficient driveline – TransPower’s specialty – can do far better, he says.
“The goal is to get from [TransPower’s already-achieved] 100 miles to 150 to 200 using natural gas to augment the battery pack,” Simon says.
“This is where we believe the future of hybrids lies.”
TransPower will fit a Navistar ProStar truck – also the basis for TransPower’s 100% battery electric “ElecTruck;” F&F, May 27) with a 3.7-liter gaseous-prep engine from Ford to be fueled from a back-of-cab CNG fuel cylinder rig holding about 25 or 30 diesel gallon equivalents. Additional DGE capacity could be added, Simon told F&F, depending on whether more range is desired later.
Engine Controls Are Key
TransPower will use a substantial lithium ion phosphate battery, likely with capacity for 100 kilowatt-hours of electricity but possibly as high as 150 kilowatt-hours, depending on variables like weight available packaging space, and optimal voltage, all to be determined as the project proceeds. TransPower produces its own battery packs using cells from Voltronix USA and CALB, the China Aviation Lithium Battery Company.
For the non-catenary CNG hybrid, “We’re mostly interested in optimizing the performance of the engine,” Simon explains. The assumption for most series hybrids is that the engine runs at a steady state, existing to charge the battery which in turns powers the electric drive. TransPower wants to do better, avoiding the losses of energy involved in charging and discharging the battery.
“You want to have some sort of load-following,” Simon says. “You want to be able to nudge the power output of the engine when you need it” – delivering extra electricity directly to the traction system. Devising the software to do so, taking into account road conditions, load, traffic, and driver habits, is a key project goal. The TransPower control unit may even draw on Google Maps-type data so that the system can adjust itself to hills.
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Source: Fleets & Fuels interview and follow-up