Can Vehicle Automation Help Us Save Energy?

Technology for automated vehicles has developed rapidly over the past few years. The vehicles’ safety and convenience make them increasingly popular. At the same time, it has necessitated the introduction of new legislation to regulate an expanding market. On September 12, 2017, the National Highway and Transportation Safety Administration (NHTSA) released the updated voluntary federal guidance for Automated Driving Systems (ADS), which focuses on relatively high levels of automated vehicles (those that require less human attention and operation).

While many studies have estimated the impact of shifting to autonomous technology and how society can regulate that impact, relatively little attention has been devoted to analyzing the energy use of automated vehicles. To partially address this question, authors Zia Wadud, Don MacKenzie, and Paul Leiby develop innovative economic models to estimate the net effects of automation on energy consumption in the article “Help or hindrance? The travel, energy and carbon impacts of highly automated vehicles.”

In the study, the authors investigate three leading factors of variation in vehicular energy consumption: the change of energy intensity, the increase in travel demand, and the introduction of alternative fuel technologies. The authors then discuss the relationship of these factors with vehicle automation.

The study finds that the automation of vehicles may decrease energy intensity through several mechanisms, including optimizing the driving cycle, platooning, using lighter safety devices and introducing new business models. Automation enables the optimization of the driving cycle (or change of speed over time), allowing energy efficiency to improve. The effect is especially significant for urban traffic conditions, in which automated vehicles can prevent potentially 50 percent of total energy use. The study also finds that automation may further reduce energy waste by 25 percent through platooning (vehicles following each other closely), by 5 percent through removing weight of safety devices, and potentially by 45 percent through automated car-sharing and on-demand mobility models that match the capacity of vehicles with customer numbers.

However, the study also demonstrates some cases in which automation may actually increase energy intensity. For instance, automation may result in boosted highway travel speeds. As speed increases, aerodynamic loss also increases, leading to a 22 percent higher energy intensity. Automation may also prompt higher demand for features that improve travelers’ comfort but that also make the vehicles heavier, potentially increasing fuel consumption by about 11 percent. Moreover, automation has the potential to encourage new users and increase ridership at a rapid pace, increasing total energy use by an estimated ten percent from today’s levels.

While automation has the potential to save energy in our transportation sector, these savings are not assured and are dependent on the strategy of technology deployment. If lower-level automation is widely adopted, many energy saving mechanisms mentioned above could be effective, outweighing the drawbacks produced by higher travel demand. Fortunately, the researchers conclude that the latter is likely to be the case in the near future. In the long-term, however, higher level of automation may lead to considerably more travel, which could significantly undermine energy savings.

The policy implications of this analysis suggest that legislators may need to pay more attention to facilitate lower levels of automation. Furthermore, policymakers should consider how to best inhibit the potential surge in vehicle congestion caused by ease of transportation. Policies like road-pricing may be a good method to control travel demands and, ultimately, energy consumption and greenhouse gas emissions. However, autonomous technology does have the potential to significantly decrease energy consumption. Now more than ever, additional research and policy considerations are needed to ensure that these gains are achieved.

Article source: Wadud, Zia, Don MacKenzie, and Paul Leiby. “Help or hindrance? The travel, energy and carbon impacts of highly automated vehicles.” Transportation Research Part A: Policy and Practice 86 (2016): 1-18.

Featured photo: cc/(JIRAROJ PRADITCHAROENKUL, photo ID: 874338508, from iStock by Getty Images)