Contribution of Automated Vehicles to Reduced Fuel Consumption and Air Pollution

Transcription

1 Contribution of Automated Vehicles to Reduced Fuel Consumption and Air Pollution November 2013 PREPARED FOR Tampa Hillsborough Expressway Authority PREPARED BY Jochen Eckart and Kala Vairavamoorthy Patel College of Global Sustainability University of South Florida

2 Disclaimer The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the information presented herein. The opinions, findings, and conclusions expressed in this publication are those of the authors and not necessarily those of the State of Florida Department of Transportation or the Tampa Hillsborough Expressway Authority (THEA). ii

3 Contribution of Automated Vehicles to Reduced Fuel Consumption and Air Pollution PREPARED FOR Tampa Hillsborough Expressway Authority PREPARED BY Jochen Eckart and Kala Vairavamoorthy Patel College of Global Sustainability University of South Florida November 2013 iii

4 Abstract An analysis evaluating the Strengths, Weaknesses, Opportunities, and Threats (SWOT) of automated vehicles for reducing fuel consumption and promoting alternative fuels technologies is provided. The SWOT analysis looks at two scales a single automated vehicle and the overall traffic system. Automated vehicles (AVs) themselves provide significant safety benefits, may improve urban core areas by reducing the need for parking, and hold a lot of strength in promoting fuel reduction and providing synergies with alternative fuel vehicles. A reduction of fuel consumption of 20 to 50 percent seems to be possible. Nevertheless, on the scale of the entire traffic system, there are both opportunities to improve fuel efficiency and the rebound effects resulting in an increased number of vehicle miles of travel (VMT). Combining the different opportunities and threats, the impacts range from a fuel reduction of 20 percent to an increase of fuel consumption of 50 percent. Automated vehicles provide the potential to reduce fuel consumption, but it is far from certain that this goal is actually achieved. Introduction The transport sector accounts for 70 percent of petroleum consumption in the U.S. and is the cause of significant greenhouse gas emission and local air pollution. To reduce the consumption of petroleum-based fuels and to address air pollution in the Tampa Bay region, current efforts are underway by the Tampa Bay Clean Cities Coalition (TBCCC). TBCCC embraces the use of non-petroleum-based transportation fuels, thereby leading to improved health and welfare for its citizens by maintaining a level of mobility that enhances the overall quality of life. The goal of this paper is to explore if, and how, automated vehicles (AVs) vehicles capable of fulfilling human transportation needs by sensing the environment and navigating without human input contribute to the overall goal of the TBCCC. The paper assesses the contribution of AVs limited to two TBCCC sub-goals: How do AVs contribute to reducing petroleum consumption through fuel economy improvements, environmentally-friendly driving practices, fewer vehicle miles traveled, and other fuel-saving practices? How do AVs contribute to the replacement of petroleum by alternative and renewable fuels? To answer these questions, an analysis evaluating the Strengths, Weaknesses, Opportunities, and Threats (SWOT) of AVs for reducing fuel consumption and promoting alternative fuels was performed. The SWOT analysis is supported by an extensive literature review and examines the internal and external factors that are favorable and unfavorable in order to achieve the sub-goals. For this, it is essential to define the boundaries of the system and the analysis: The assessment of strengths and weaknesses focuses on the narrow boundaries of a single AV. Future work could extend this focus on the potential to grow transit service/mobility through automated/connected vehicle (CV) technology. 1

5 The assessment of opportunities and threats examines the broader system of AVs considering the impact on the overall system traffic, if there is a broad adoption of alternative fuel vehicles. Assessing the Strengths and Weaknesses of Single Automated Vehicles The strengths and weaknesses focus on the narrow boundaries of single AVs, and the synergies with alternative fuel vehicles are presented. This analysis is supported by initial reported results from different test vehicles as well as from different model calculations. The strengths of AVs to reduce fuel consumption are: Automated vehicles facilitate fuel efficient driving behavior (foresight driving to reduce stops at intersections, steadier speeds and less frequent stop and go, vehicle platooning, driving at optimal cruising speed for fuel efficiency, minimizing unnecessary acceleration and braking, etc. [Schneeberger, 2013]). Predicted fuel reductions are up to 20 percent (Wadud et al., 2013) or a reduction of 20 to 40 percent (Brown, 2013). As AVs provide much more safety and significantly reduce the number of accidents (90%of accidents are caused by human error), they provide the opportunity to reduce passive safety features in the vehicle (such as crush-collapsing zone) resulting in much lighter and, hence, more fuel-efficient cars. A potential fuel reduction of 5 to 25 percent (Wadud et al., 2013) or 45 percent (Brown, 2013) is estimated. Automated vehicles with users no longer driving themselves may de-emphasize the current demand for powerful high performance engines that focus on the human recreational dimension of driving (Lynch, 2013). Reducing the performance of engines to match the intended cruising speed may reduce fuel consumption by 5 to 25 percent (Wadud et al., 2013). The environmental benefits of more efficient driving behavior of AVs will go beyond the benefits of fuel reduction. A 13 percent reduction of fuel equals significant emission reductions: CO 2, 12 percent; NO x, 37 percent; and HC, 41 percent (Boriboonsomsin, 2013). In addition, more steady-driving patterns could also result in a reduction of traffic noise and pollution runoff from streets. Shifts in propulsion sources to all-electric, hydrogen, compressed, or liquefied natural gas, or other sources will increase. The strengths of AVs to promote alternative fuel technologies are: The increased fuel efficiency resulting from more environmentally friendly driving patterns of automated vehicles is particularly beneficial to alternative fuel vehicles, such as electric vehicles, which have a shorter driving range per charge than conventional fuel vehicles. Range anxiety, a barrier to the EV market, could be eased. 2

6 AVs can help separate the refueling process from the travel (the car itself can search for next fuelling station, etc.), hence making alternative fuel vehicles more convenient to use. AVs are no longer designed from the driver perspective and, hence, may help shift away from traditional cultural expectations of cars (powerful engines promoting the joy of driving, etc.) and help to promote alternative fuels (Lynch, 2013). AVs and alternative fuel vehicles complement each other, as they are both wellsuited for the same type of trips, such as regular commutes in urban agglomerations (short trips, focus on mobility rather than joy of driving, driven by economic consumer behavior, etc.). AVs and alternative fuel vehicles attract the same type of consumers early adopters who are willing to test new technologies and appreciate economic and environmental benefits. The potential weaknesses of AVs with regards to promoting the reduction of fuel consumption and adoption of alternative fuel technologies are: There is uncertainty as to the potential and intention of auto manufacturers to build lighter and less powerful automated cars that use alternative fuel. The current AVs tested in the field are still conversions of conventional vehicles. In examining individual AVs, the analysis illustrates that there are overwhelming strengths and only limited weaknesses for promoting fuel efficiency and alternative fuel vehicles. Several synergies between AVs and alternative fuel vehicles are already being explored, such as the Google car being built on a Toyota Prius (Hybrid) and efforts to upgrade the electric Nissan Leaf to an AV (two out of five automated vehicles currently tested in the field) (Knight, 2013; Lynch, 2013). Again, the technology and benefit of AV/CV are independent of fuel. Assessing the Opportunities and Threats of AVs on the Overall Traffic Systems The impact of a broad-scale adoption of alternative fuel AVs on the overall traffic system and land-use system was explored. As automated vehicles are still at an early testing stage, it is, by nature, difficult to explore these impacts. These impacts can only be explored using possible future scenarios. The opportunities of AVs to reduce fuel consumption in the overall traffic system are: Platooning (AVs driving in convoys with reduced minimum distance between cars) will result in reduced aerodynamic drag and, hence, reduced fuel consumption. There is a particularly high potential to reduce the fuel consumption of truck traffic, estimated at 10 to 15 percent (Bullis, 2011), 20 percent (Knight 2013), and 5 to 25 percent (Wadud et al., 2013). Platooning also increases the capacity of streets, avoids costly investment in roadway expansion, and can contribute to the mitigation of congestion. The fuel savings from reduced traffic congestion is estimated at up to 5 percent (Wadud et al. 2013). 3

7 AVs combined with smart parking systems may reduce parking traffic, as they can directly locate the next parking spot, reducing traffic and idling related to searching for a spot. A modest reduction of fuel consumption of up to 4 percent is estimated (Brown, 2013). This also allows changes to existing parking land uses that could increase productivity for urban centers. AVs combined with Global Positioning Systems (GPS) can result in more effective route selection, providing a fuel reduction potential of up to 20 percent (Brown, 2013). AVs create opportunities to provide new forms of public transport and increase car occupancy. Innovative forms of public transport in low-density urban areas, such as automated car-sharing schemes or driverless taxis, could be possible. The potential for fuel replacement is estimated at 10 to 20 percent (Brown, 2012; Frazzoli, 2013). AVs can be incorporated into schemes for an environmentally driven operation of the whole traffic system. Possible solutions include smart signals (cars and signals coordinated to reduce stops at signals), smart lanes (lanes reserved for cars driving in efficient platooning patterns), environmentally controlled traffic information systems (steer traffic flows to reduce environmental impact), integrated corridor management (intermodal management of traffic corridors, e.g., smart promoting of switching between cars and public transport) (Schneeberger, 2013; Knoflacher, 2008). Possible fuel reduction savings are in the range of 5 to 10 percent (Schneeberger, 2013). The threats of AVs to reduce fuel consumption in the whole traffic system are: Platooning and increased active car safety may result in increasing average highway speeds. This increased speed can result in increasing fuel consumption of 5 to 40 percent (Wadud et al., 2013) or 30 percent (Brown, 2013), assuming conventional fuel sources. AVs may make access to auto trips possible for groups currently unable to drive (older adults, children, persons with disabilities, etc.) (Elkind, 2012). As a backdrop to this positive increase of individual mobility, there may be an overall increase of miles traveled, resulting in increasing fuel consumption of up to 40 percent (Brown, 2013). AVs may, in the short term, activate some latent travel demand as more efficient cars make driving cheaper. This rebound effect of increasing technical efficiency could lead to an increase in miles traveled, hence offsetting the initial perceived savings (Jevon s Paradox). The effect is assumed to equal the fuel efficiency savings of individual cars, resulting in an increase of up to 40 percent of fuel consumption (Wadud et al., 2013). In the long-term, AVs may induce some additional traffic demand. The reduced travel time due to congestion reduction, as well as the opportunity to use the in-vehicle travel time for productive purposes, may result in behavior changes and land-use changes. As a result, drivers may be willing to commute longer distances, 4

8 resulting in land use with longer distances between home and work. The resulting increase of fuel consumption is estimated to be up to 50 percent (Brown, 2013). The potential for AVs to use in-vehicle time more productively may result in changes of mode selection. As AVs provide similar benefits to public transport (working or relaxing during commute), this may reduce the attraction of public transport (Elkind, 2012). Conclusions When focusing on the individual AV, several strengths in promoting fuel reduction and providing synergies with alternative fuel vehicles have been projected. A reduction of fuel consumption of percent is estimated (Frazzoli, 2013). However, when examining AVs as part of the entire traffic system, both opportunities to improve fuel efficiency and threats by the rebound effects on system level may be realized, resulting in an increased number of vehicle miles traveled. Combining the different opportunities and threats of automated vehicles in different possible future scenarios gives a range of fuel reduction from 20 percent up to an increase of fuel consumption of 50 percent. This assumes the lower end of reduction and the higher end of consumption induced, but it does not include discussions on type of fuel being consumed with AV technology (Wadud et al., 2013). At this early stage, it is difficult to accurately predict the consequences of AVs on the traffic system, with the exception that safety improvements will be dramatic. To avoid the negative rebound effects on fuel consumption, it is key to have policies in place that encourage alternative fuel sources or discourage behaviors that cause additional consumption. The key benefits of AVs with respect to fuel consumption can be realized only if emphasis is placed on lighter, less powerful, and fuel-flexible vehicles. The combination of opportunities and threats at the system level remains highly uncertain and requires detailed research. AVs have the potential to contribute to the goal of the TBCCC to reduce fuel consumption, but it is far from certain that this goal actually will be achieved. In addition, the identification of appropriate accompanying policies is not well explored at the moment. There is a need to develop policies to ensure that AVs not only benefit individual drivers, but also exploit opportunities for system optimization efficient and integrated corridor management, environmental travel information, etc. (Knoflacher, 2008) to achieve an overall reduction of fuel consumption and related air pollutants. This SWOT analysis is just a first step in assessing the environmental fuel consumption impacts of AVs, and is intended to serve as a prelude to future detailed studies. 5

9 References Boriboonsomsin, Kanok. (2013). Role of vehicle automation in reducing traffic-related energy emissions of light-duty vehicles. TRB 2 nd Annual Workshop on Road Vehicle Automation, July 16. Brown, Austin. (2013). Automated vehicles have a wide range of possible energy impacts. TRB 2 nd Annual Workshop on Road Vehicle Automation, July 16. Bullis, Kevin. (2011). How vehicle automation will cut fuel consumption. MIT_Technology_Review.com, 10/24/2011. Elind, Ethan. (2012). Could self-driving cars help the environment? Blogs.berkeley.edu, 4/11/2012. Frazzoli, Emilio. (2013). Autonome Fahrzeuge können völlig anders fahren, 08/22/2013. Knight, Will. (2013). Driverless cars are further away than you think. MIT_Technology_Review.com, 10/22/2013. Knoflacher, Herman. (2008). Jedes ding hat zwei seiten auch die telematik. Elektrotechnik & Informationstechnik, 125(6), Lynch, Tyler Wells. (2013). Your car maybe automated before it s electric, and it s a good thing. Cars.reviewed.com, 10/9/2013. Schneeberger, J. D. (2013). Applications for the environment: Real-time information synthesis (AERIS) and vehicle automation. TRB 2 nd Annual Workshop on Road Vehicle Automation, July 16. Wadud, Zia, MacKenzie, Don, and Leiby, Paul. (2013). Energy savings and rebound effects of highly automated vehicles. TRB 2 nd Annual Workshop on Road Vehicle Automation, July 16. 6