Volvo has lagged behind other automakers in fuel-saving hybrid-drive technology, so green-car enthusiasts took notice when the Swedish company recently announced plans to manufacture a plug-in diesel hybrid by 2012. After all, a safe, functional Volvo V70 wagon that could travel 30 mi (50 km) on plug-in electricity alone and then motor onward under efficient diesel power seems to be a natural fit.
Although company management agrees with that assessment, it has typically pleaded in the past that limited corporate resources have slowed its entry into the hybrid segment. Company engineers have not, however, entirely neglected development of the dual propulsion mode, according to Johan Konnberg, Business Director of Volvo Cars’ Hybrid Center in Gothenburg.
In the fall of 2007, for example, the company unveiled the ReCharge concept car, an aspirational design exercise in plug-in hybrid technology that featured wheel-mounted electric motors.
The automaker also worked for a year and a half with Range Rover and Ford Europe on a more conventional hybrid C60, but “at the turn of last year decided not to proceed,” he reported. “The C60 platform is too big and too heavy to reduce carbon dioxide emissions to 50 grams per kilometer,” a level that will be necessary to qualify for the generous green purchase subsidies that European nations are expected to offer in five years, Konnberg added.
To achieve these challenging emissions numbers, Volvo instead opted to continue an R&D collaboration with Vattenfall, the Swedish government-owned European energy utility and domestic battery manufacturer ETC Battery and FuelCells Sweden AB. The joint program was launched in January 2007 to test and develop new PHEVs. It originally also included Saab, which later left because of financial difficulties.
The resulting three-vehicle V70 demonstration fleet is being tested by employees on Swedish roads for the next six months to gather information about operational performance, driving experience, fueling options, and consumer preferences. Vattenfall is providing the charging stations.
“We went for diesel because the product will be introduced in the European market and because we need the diesel hybrid to achieve the strict emissions goals,” he explained. Low emissions will garner the car's European subsidies, which will be key to any success. “Figuring out how to get paid for the extra hybrid components is the big issue," Konnberg stated. “We can do the engineering; the tricky part is developing an effective business model.”
The Volvo hybrid team installed in the V70 platform an “off-the-shelf” 11-kW lithium-ion battery, a rear-mounted 75-kW electric motor, a home-grown 153-kW (205-hp) diesel engine in the front, and hybrid controls. The parallel hybrid, which operates in three drive modes—battery alone, diesel alone, or both—gets an effective fuel economy of 1.9 L/100 km or about 124 mpg. The controls kick-start the engine when the battery charge drops to around 4 kW.
Volvo engineers installed two recharging-plug ports in the demo wagons. The home-charging receptacle, which runs at 220 V and 10 A, typically takes about five hours to recharge the battery from a household wall socket. Topping up at recharging stations at parking lots or restaurants uses the other “semi-fast-charging,” 32-A port and takes an hour or so.
Volvo’s new PHEVs reportedly incorporate a “smart-charging” system developed at the U.S. Argonne National Laboratory. It combines a battery charger with a cell phone and GPS to make the power provider aware of the battery’s charge state and the vehicle’s location to help keep billing accurate and affordable.