|A Sprinter PHEV|
EPRI and DaimlerChrysler are about to enter the fleet feasibility testing phase of their investigation into plug-in hybrids with the pending deployment of six Sprinter vans of different configurations in different locations.
Dr. Mark Duvall of EPRI provided a brief update on the project at the recent SAE Hybrid Vehicle Technologies Symposium.
The Sprinter program has a number of objectives:
To design and test a PHEV commercial van with up to 20 miles of electric range (PHEV20);
To collect performance and field test data;
To verify the performance and durability of different types of advanced batteries in a PHEV application;
To use the results to improve design for a Phase 2 production prototype program.
The project is using six vans with different combinations of engine (either 2.7-liter gasoline or a 2.3-liter diesel) and battery (NiMH or Li-Ion). All use the same 90 kW motor.
|EPRI-DaimlerChrysler PHEV Fleet testing Vans|
|1||Cargo van||Diesel||NiMH||Hannover, Germany|
|2||Cargo van||Gasoline||NiMH||Schweinfurt, Germany|
|3||Bus body with paratransit equip.||Diesel||Li-Ion||Kansas City|
|4||Cargo van||Gasoline||Li-Ion||Los Angeles|
|5||Utility van||Gasoline||NiMH||Los Angeles|
|6||Cargo van||Diesel||Li-Ion||New York|
The battery packs in these vehicles are large: 14 kWh. By comparison, the Prius has a 1.5 kWh pack. Preliminary estimates give the Sprinter electric performance of 2 miles/kWh.
The motor, at 91 kW peak power (72 kW continuous) and 275 Nm peak torque (130–180 Nm continuous) was selected to support the program’s focus on urban driving—i.e., little if any higher speed driving that would require a motor of > 125 kW.
Optimizing the operating strategies for the vehicles will be a major component of the testing, the goal being to maximize stored battery energy, while balancing operation with low operating costs.
|Operating limits for electric mode.|
There are a number of possible triggers for mode changes, including vehicle speed, the state of charge (SOC) of the battery, acceleration, location and system temperature.
For this project, the team decided to limit electric operation to speeds below 50 km/h (31 mph) and with a battery SOC from 20%—100%. Although the system could support higher speeds, the battery would deplete more quickly.
On the question of CO2 emissions per electric mile travelled, EPRI estimates that in 2010, the national average CO2 emissions from power plants will be slightly more than 500 grams/kWh.
With the current Sprinter PHEV design, that would work out to about 250 grams per electric mile, or 157.5 g/km of CO2.
According to EPRI, in a base case for future power generation, with no additional nuclear, no carbon capture, and no new renewables, the 500 g/kWh will decline to about 350 g/kWh by 2050.
Depending upon technology and regulatory drivers, that could drop (as a national average) to as low as about 150 g/kWh—clearly offering great potential for simultaneous reductions in both utility and transportation sector CO2.
Clearly, though, the gating factor is the battery.
Driving the Solution: the Plug-In Hybrid Vehicle; EPRI Journal, Fall 2005