TransForum Vol. 7, No. 1

Diversity of Choices: Key to Improving Transportation Energy Efficiency

Argonne's Mobile Automotive Technology Testbed can be equipped to test the wide range of vehicle and fuel configurations that will likely factor into our nation's future transportation technology mix.

The U.S. Department of Energy (DOE) has identified plug-in hybrid electric vehicles (PHEVs) as having the potential to dramatically transform the light-duty vehicle sector to be much less dependent on petroleum, a key goal in DOE's strategic plans. As a consequence, says Lee Slezak of DOE's FreedomCAR and Vehicle Technologies Program, DOE is investing in PHEV research, in addition to other transportation technologies. Because Argonne National Laboratory possesses specialized staff expertise and technical capabilities, DOE has asked Argonne to assume a leading role in the Department's PHEV research efforts, particularly in the areas of analysis and evaluation of components, power electronics, energy storage, and vehicle technologies.

According to Slezak, "PHEVs offer the possibility of considerably improved fuel efficiency over today's hybrid vehicles, especially if they offer fuel-flexibility and are properly matched to the intended use scenario. They also produce fewer emissions in traffic and when operating at low speeds. Although the use of PHEVs would increase electrical demand, that increase could actually be beneficial, because the increased demand would typically occur at night, during utility companies' off-peak hours. This would allow the utilities to better balance their production loads, leading to improved operating efficiencies. Also, depending on economic and political factors at any given time, PHEVs could very well play an important role in reducing oil imports, which is, of course, an important DOE goal."

Slezak is quick to point out that, as with any new technology, there are hurdles to overcome before PHEVs can be considered commercially viable. "First, there is the concern about onboard storage. PHEVs require very different batteries than those used in today's hybrid vehicles. DOE's research is focusing on lithium battery chemistries in an effort to increase reliability and performance, while also reducing cost and size. Second, the cost of components such as power electronics, inverters, and controllers must be reduced in order to produce a faster payback period for PHEV buyers. And third, there is a dearth of information about PHEVs — as yet, there are no agreed-upon test and evaluation procedures for PHEVs. Argonne will be working together with the National Renewable Energy Laboratory and Idaho National Laboratory to address these issues," he says.

Slezak explains that there are other aspects to DOE's information- gathering mission as well. Manufacturers need to understand where the likely shortcomings in PHEV operation will occur, so they can make good engineering decisions as they design and produce their PHEV offerings. At the same time, consumers need to be educated to have realistic expectations and to analyze their driving patterns carefully before making a vehicle purchase decision. Good analysis and research will enable buyers to choose vehicles that best meet their needs while enabling them to consume less fuel, all the while minimizing the payback period for the increased purchase price. Because that information does not yet exist for PHEVs, DOE will play an important role in developing it.

Slezak stresses that DOE is developing PHEV research and development plans very carefully to ensure that good processes are in place to promote success. This involves working closely with industrial partners and other government agencies to develop the right assessment and analytical procedures and identify critical decision points along the way. "If research efforts proceed smoothly, DOE envisions that PHEVs with limited electric range could be commercially available within the next two to three years. These initial PHEVs would likely have a cumulative electric driving range of 10 to 20 miles per charge at driving speeds of up to 35 miles per hour. Within six years, we anticipate the availability of PHEVs with a cumulative electric driving range of 30 to 40 miles per charge at similar driving speeds," he says.

Most important, continues Slezak, "As with all of the vehicle technologies DOE researches, it is important to recognize that there is no single best solution to America's transportation challenges. We need to develop a diverse set of technology options from which vehicle operators can choose, so they can select a clean, efficient vehicle that best meets their needs at the lowest possible cost."

March 2, 2007