The paper by the MIT Center for Transportation and Logistics, to be published in the proceedings of last month’s IEEE Power and Energy Society Innovative Smart Grid Technologies Conference, evaluated electric trucks’ use for making everyday deliveries in large cities.
Such vehicles cost nearly $150,000, compared to about $50,000 for the same kind of truck with a standard internal-combustion engine. But the operational cost of an electric truck enabled to use a vehicle-to-grid (V2G) system is about 68 cents per mile, compared to 75 cents for internal-combustion trucks.
And the researchers found that most of the savings scale down to the individual vehicle, so companies don’t need big fleets to save money.
In a V2G system, vehicle batteries are plugged into the electric grid overnight to enhance the electric system’s reliability, and the truck owners are paid by utility firms for their power services. The trucks help improve reliability because utilities can depend on them to plug in at certain hours – as opposed to electric passenger vehicles, which consumers plug in at more random times.
MIT says several utility companies are testing V2G systems.
Staples’ director of fleet equipment, Michael Payette, said the MIT analysis corresponds with his company’s findings so far, although it is still early in Staples’ post-deployment analysis. He also said he was surprised by drivers’ response – not only do they accept the electric trucks, they say they don’t ever want to drive diesel again.
Staples currently uses 53 all-electric trucks from Smith Electric Vehicles in several U.S. cities. Last July, it joined the Obama administration’s National Clean Fleets Partnership, under which companies work with the Department of Energy to develop a comprehensive strategy to reduce petroleum and diesel use in their fleets.
At the time it said it had increased the fuel economy of its fleet by more than 20 percent since 2007 through fuel-saving steps such as automatically limiting truck idling to no more than 3 minutes and limiting the top speed of its vehicles to 60 miles an hour.
The study uses data from Staples and ISO New England, the organization that that runs New England’s electric power grid, to model the costs for a fleet of 250 delivery trucks. Researchers examined scenarios in which the whole fleet used one of three kinds of engines: purely electric, hybrid gas-electric and conventional diesel. They assumed each truck was driven 70 miles a day for 253 days a year, with diesel at $4 a gallon.
The study found that internal combustion engines averaged 10.14 miles per gallon, compared to 11.56 miles per gallon for hybrids, and the electric-only trucks averaged 0.8 kilowatt-hours per mile.
The researchers also modeled a V2G system in which the truck batteries were plugged into the electric grid for 12 hours a night. They found that businesses could earn about $900 to $1,400 per truck per year in V2G revenues in current energy markets, equal to a 7 to 11 percent reduction in vehicle operating costs. Firms would also save on brake maintenance, because electric trucks cause less wear and tear, they said.
Jarrod Goentzel, director of the Renewable Energy Delivery Project at CTL and one of four co-authors of the study, said electric delivery trucks’ economic model will continue to improve as battery costs drop.