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Several general areas of research offer important opportunities to make progress toward the technical goals identified in Section 2.4. Because these are interrelated, a systems approach toward innovation could make success more likely.

3.1 Fuels

Alternative fuels such as electricity, hydrogen, natural gas, and alcohols (e.g., ethanol, methanol) may offer opportunities to reduce petroleum consumption and emissions, although results could vary significantly by fuel, vehicle technology, and local conditions. Continued research is needed to reduce the capital investment required for a widespread and time-efficient electric vehicle recharging infrastructure, and to develop efficient, safe, and affordable ways to produce, distribute, and deliver hydrogen.

Changes in the characteristics (e.g., aromatic content, cetane number, density, oxygen content, sulfur content) of diesel fuel could also yield and/or facilitate important improvements in vehicular and full-fuel cycle emissions. Changes in corresponding feedstocks and processing technology could provide a means to reduce petroleum consumption and emissions. Potential research areas include: relationships between fuel characteristics and emissions formation, fuel/aftertreatment compatibility, durability and performance effects of reformulated fuels, and lower-cost processes for producing diesel fuel and blending agents from alternative feedstocks such as biomass and natural gas.

3.2 Energy Storage

Bulk energy storage remains an important issue for some potential fuels (e.g., hydrogen), and research is needed to reduce costs, improve performance, and ensure safety. Specific research needs include chemical battery technology (e.g., lithium ion, lithium polymer), absorptive and/or high-pressure gaseous fuel storage, and low-temperature liquid fuel storage.

3.3 Powertrain

Changes in drivetrains offer the potential for significant efficiency and emissions improvements. Hybrid electric drivetrains are particularly promising, especially for vehicles (e.g., urban buses) where stop-and-go operation provides an opportunity for significant energy recapture. Research is needed to improve the cost and performance of these systems and ensure safety. Specific research areas include peak energy storage devices such as chemical batteries and flywheels, electrical motors and controllers, electrical power management systems, and hybrid powertrain systems analysis.

Advances in diesel engine technology and exhaust aftertreatment systems also promise considerable potential gains in efficiency and reductions in emissions. Research needs include low heat rejection engines (LHRE) and aftertreatment devices to reduce NO_X and fine PM. Research may also be needed to improve compatibility with reformulated and/or alternative fuels. Finally, research is needed to develop and characterize innovative combustion engine technologies and other energy conversion devices—in particular fuel cells and fuel processors—that could significantly improve efficiency and/or emissions.

3.4 Materials

Changes in materials offer the potential to significantly reduce the weight of some vehicles—thereby reducing energy consumption—without compromising safety. However, cost remains a significant barrier for some materials. Further, while recycling of some materials (e.g., aluminum) is well established, considerable uncertainty remains regarding the potential to recycle other materials, in particular advanced carbon-fiber-reinforced composites. Research is needed to reduce the cost of these materials, develop improved technologies for manufacturing and joining vehicle components using these materials, develop tools for simulating crashes involving vehicles that use such materials, and improve recycling techniques applicable to some of these materials.

3.5 Vehicle Design

Changes in vehicle design that go beyond powertrain and materials could offer important opportunities to reduce energy consumption. Examples where research is needed include aerodynamic design and efficient tires. In addition, new materials, construction techniques, and powertrains offer the potential for considerable changes in the way vehicles are designed.

3.6 Accessories

Some vehicle accessories, such as air conditioners, can have a significant influence on vehicular energy consumption and/or emissions. Research is needed to develop lighter and more efficient accessories that are competitive in terms of cost and performance, and to develop and/or improve accessories, such as auxiliary heaters, that may be important as enablers of vehicles with highly efficient powertrains.

3.7 Information and Communications Systems

Advances in information and communications technology are already changing the nature of some activities in ways that has an influence on transportation demand. For example, internet-based shopping can influence both shopping trips and package deliveries, and telecommuting can influence both commuting travel and locational choice. Some of these technologies may also have a more direct impact on vehicular emissions and/or energy consumption. For example, using these technologies to improve traffic flow could reduce emissions under some conditions. Even more directly, these technologies could improve the diagnosis of vehicle deterioration and malfunctions that influence emissions and/or efficiency, and could lead to better maintenance through reporting to stationary locations.

Research is needed to better understand opportunities to use information and communications technology to achieve reductions in emissions and energy consumption, and where appropriate—including systems that link vehicle diagnosis to entities responsible for managing emissions and/or maintenance—to develop and demonstrate new systems. Such research would build upon ongoing research under the Intelligent Vehicle Initiative related to the use of such technologies as to make similar administrative processes more efficient, and could also help increase the availability of similar data to, for example, fleet managers and vehicle manufacturers.

3.8 Vehicle/Fuel Systems and Infrastructure Analysis

Vehicles and fuels operate together as an integrated system supported by very significant accumulated infrastructure that encompasses elements such as materials supply and processing; component manufacturing and vehicle assembly; fuel production, distribution, and delivery; vehicle maintenance, repair, and recycling; and supporting activities such as highway design, intermodal connections, and emergency response. Some of these areas represent accumulated investments in the hundreds of billions of dollars. This infrastructure can likely accommodate some new types of vehicles and fuels without significant change. However, others could require dramatic changes in infrastructure components. In order to anticipate such changes before making major long-term investments, research is needed to better understand what changes might be required by or result from shifts to different vehicle/fuel systems. Modeling and simulation of vehicles and fuels together as systems can help to identify and characterize potential barriers. This will enable a strategic approach toward making major transitions between established and emerging systems.

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