NREL's fleet test and evaluation, electric vehicle grid integration, and fuel performance teams have partnered with Pacific Gas and Electric (PG&E) and Efficient Drivetrains Incorporated (EDI) to evaluate the performance of their Class 5 plug-in hybrid electric bucket truck.

The utility vehicle is equipped with batteries and an electric generator that can export up to 120 kW of power – enough to power a neighborhood while repairs are being made by electric crews. The truck has a 40-mile all-electric range, after which it switches to hybrid mode.

"NREL test results will help PG&E better understand vehicle system performance under controlled conditions, identify issues and requirements associated with vehicle operation, and fine-tune the design of such vehicles before expanding their use in the PG&E or other utility fleets," said NREL's Ken Kelly.

Collecting and Analyzing Vehicle Performance

"NREL has been working with PG&E to characterize vehicle operations and help guide technology choices that meet the company's bottom line and operational goals," Kelly said. "NREL recently installed data loggers on select PG&E trucks to determine how the vehicles are being used and to evaluate how well electric drive systems and electric accessories function in real-world operation."

To date, NREL has captured and is currently analyzing four months of in-use field data from 20 hybrid electric and conventional utility trucks operating in the PG&E service area. In addition to using the on-road performance data in its vehicle evaluation, NREL is using the data to develop chassis dynamometer drive cycles representative of actual on-road operation.

NREL ran the hybrid electric and conventional utility trucks on the chassis dynamometer at the Renewable Fuels and Lubricants Laboratory to capture energy efficiency metrics and emissions data and improve understanding of how the vehicles will function in large-scale commercial service.

Additionally, NREL is analyzing various vehicle parameters to help PG&E and EDI understand opportunities for improving efficiency and decreasing emissions during various modes of operation.

Testing and Analyzing the Vehicle's Exportable Power to the Grid

NREL also used the thermal chamber and research electrical distribution bus system at the Energy Systems Integration Facility - where researchers can literally plug in and test new energy technologies on real and simulated power systems before hooking them up to the grid – to simulate typical grid operation and capture output power quality data from the truck.

These testing and analysis activities are geared to improve understanding of the vehicle's export power mode and on-board thermal control under a variety of ambient conditions.

A member of the Clean Cities National Clean Fleets Partnership, PG&E operates one of the greenest utility fleets in the nation.