My colleagues at ARC recently published a report (available to ARC clients only) on electric vehicle technologies. It struck me that some of the information in it would be interesting to truck fleet owners.
According to the ARC report, there are four different types of e-vehicles: hybrid electric vehicle (HEV); plug-in hybrid electric vehicle (PHEV); pure electric vehicle (PEV); and fuel cell electric car.
Currently, the only realistic option for fleet owners is the hybrid electric vehicle (HEV). HEVs combine a conventional internal combustion engine for highway driving, with an electric drive train for both in-town driving and to provide an extra power boost when needed. The batteries for the electric drive train are recharged solely through regenerative power captured when the vehicle’s brakes are applied.
Last year, Walmart announced that between 2005 and 2008 it had increased the efficiency of its private fleet by more than 25 percent. The use of hybrid vehicles played a role in those gains. The company is now working toward doubling its fleet efficiency by 2015 (from its 2005 baseline). As part of this initiative, Walmart is testing two new types of heavy-duty commercial hybrid trucks: a full-propulsion Arvin Meritor hybrid and a Peterbilt Model 386 heavy duty hybrid truck. Peterbilt claims that its truck provides a 12 percent fuel economy savings over similar trucks that are not based on hybrid technologies. This would take Walmart a long way towards achieving its aggressive goals.
However, while HEVs are the only viable electric vehicle technology for truck fleets today, fleet owners should pay attention to alternative electric vehicle technologies that are rapidly evolving. Here is a brief overview from the ARC report:
The plug-in hybrid electric vehicle (PHEV) also combines a small conventional internal combustion engine with an electric drive train, but here, the electric drive train is the primary means of propulsion, with the internal combustion used largely as a backup for longer trips. With PHEVs, the vehicle is plugged into the electric grid to charge the battery or batteries [which is problematic because the infrastructure is not well developed].
The pure electric vehicle (PEV) has only an electric drive train and must [also] be plugged into to grid to recharge its batteries. (Warehouse folks have seen this technology in action for years, since it is commonly used for lift trucks).
PHEVs and PEVs will play an active role in the future electric grid, since their batteries can serve as an alternative power source for both the home and the grid, as well as for the vehicle. The vehicle’s batteries can be loaded from the grid (when electricity prices are low) and unloaded (when electricity prices are high).
Finally, there is the fuel cell electric car, which uses an on-board hydrogen fuel cell to generate the electricity to power an all-electric drive train. Fuel cells have long been the most promising technology, mainly due to the high energy density of hydrogen. However, the complex technology of fuel cells, the extremely heavy tank required for hydrogen (see table), and the lack of infrastructure to support this technology caused many (automotive) manufacturers to pull back from fuel cells. While a number of solutions can address the lack of a hydrogen infrastructure and the weight of the Li-Ion batteries will continue to decrease over time, the weight of the tank remains an obstacle to widespread acceptance, since it is bound to safety issues and the technology is already mature.
As fleet owners look to replace their aging trucks, they should pay attention not only to the hybrid tractors on the market, but emerging electric vehicle technologies as well.
