celerate this and other efficiency improvements, such as “blended wings” and open fan propulsion systems.
In addition to technology development and deployment, there is a wide range of research needed on human behavior as it relates to transportation use and on the best policies for influencing both technology development and human behavior. For example, there are behavioral changes that increase the efficiency of existing vehicles, such as maintaining properly inflated tires, but we lack basic data on the prevalence of these behaviors as well as on how they might be effectively encouraged. Further research is also needed on factors that encourage the purchase of more efficient vehicles—fuel prices are certainly one factor, but, as with the adoption of any new technology, prices are only part of the explanation and a more nuanced understanding might lead to the design of effective policies. There may actually be substantial proprietary information on what influences consumer choice and technology adoption, but there is little open literature on this subject or on how policies, programs, and institutions might influence vehicle or mode choice. Finally, the history of U.S. fuel economy over the last 35 years, where efficiency improvements were offset by consumer demands for larger, more powerful vehicles (with little resulting fuel consumption penalty, because efficiency had increased), suggests a need for better understanding of how to design regulatory policies that have the intended results.
Accelerate the development and deployment of alternative propulsion systems, fuels, and supporting infrastructure. New, less carbon-intensive fuels and alternative propulsion systems will ultimately be needed to make major reductions in GHG emissions from the transportation sector. The two primary candidates for replacing internal combusion engines are batteries and hydrogen fuel cells, and major technological advances are still needed to make these methods competitive with current propulsion systems. Moreover, while these alternative propulsion systems would reduce petroleum consumption, they will only reduce GHG emissions significantly if the needed electricity or hydrogen is produced using low-emissions fuels and processes. As discussed in the companion report Limiting the Magnitude of Climate Change (NRC, 2010c) and elsewhere, widespread adoption of these technologies also implies a major restructuring of the nation’s transportation infrastructure, and reasearch will play an important role in optimizing that design.
Advance understanding of how climate change will affect transportation systems and how to reduce the magnitude of these impacts. One of the most difficult tasks for transportation planners in addressing climate change is obtaining relevant information in the form they need for planning and design (NRC, 2008g). Improved regional-scale climate information is needed, but so is a better understanding of how