By: Matt Panopio and Heather Hochrein
Part 2 of 2
In Part 1 of this series, we compared the impacts of autonomous vehicle (AV) adoption over conventional vehicles (CVs) and determined that AVs could have the potential to provide considerable economic, social, safety and environmental benefits. As discussed before, light-duty AVs can reduce petroleum use and resulting emissions through improved efficiency, better routing, lower traffic congestion, and the enabling of electric powertrains. In Part 2, we look at the effects of AVs on the environment in detail with regards to the combination of changes in use intensity, energy intensity and fuel intensity.
Impacts on use intensity
Increased travel — The use intensity (vehicle miles traveled [VMT] per vehicle) of AVs is expected to increase due to increased travel by underserved populations and faster travel overall. One study estimates there will be a 40% increase in use intensity from increased travel, assuming that all people over the age of 16 will now have the same average VMT.
Although this effect may have negative environmental consequences, it also provides significant social benefits by expanding valuable transportation services and increasing equity to all riders.
Faster travel — AVs will likely enable faster and increased traveling due to higher vehicle speeds and reduced traffic. People on average are willing to travel a very consistent amount of time across a wide variety of purposes. When that is true, it is estimated that VMT per person could increase by approximately 50% due to vehicle automation. Not to mention, people may be willing to spend more time in autonomous vehicles since they will be able to do other activities in the car besides drive.
Impacts on energy intensity
Efficient travel — AVs save energy by improving vehicle operation compared to the average human driver. Eco-driving incorporates smoother starts and stops and has been demonstrated to improve fuel economy for aggressive drivers by 33% on highways and 5% on city streets. Fewer collisions will result in less vehicle-related deaths and injuries, and safety-enabled vehicle lightweighting may also have further energy reduction benefits.
Faster speeds — The widespread adoption of AVs may also lead to an increase in average car speeds due to safer autonomous driving. However, faster vehicle speeds incur more air resistance, resulting in more energy loss. While faster speeds could result in a significant loss in energy efficiency, this effect could be minimized by well-informed law making to ensure that AVs will be programmed to abide by all state highway laws and legal highway speeds.
Size optimization — Another effect of widespread AV adoption is optimization of vehicle size and powertrain. With an all AV fleet, size optimization may occur due to a lesser need for safety features, and the ability to match the vehicle use with the duty required, which is enabled by car sharing (i.e. a two-person smart car for two individuals). These two effects will depend largely on the speed at which consumer preferences and safety concerns surrounding AVs change.
Impacts on fuel intensity
As mentioned in Part 1, AVs could reduce fuel intensity significantly by promoting the adoption of electric powertrains. AVs could be fully powered by electricity if used in shared fleets as point-to-point on-demand cars. An on-demand electric AV could be dispatched to meet a user’s specific need, significantly increasing the battery utilization and improving the economics of electric vehicles (EVs).
EVs provide a huge energy and environmental benefit, and its combination with vehicle automation would increase that impact. It is estimated that a 91% reduction in liquid fuel could be achieved with electrification of AVs. While some electrification will certainly happen on its own, ultimately a key component to the environmental benefits of AVs is to what extent they adopt electrification and increase the EV market.
How will AVs affect the environment overall?
Depending on the combination of specific effects mentioned above, AVs can lead to huge fuel savings and dramatically reduce mobile greenhouse gas emissions. While AVs can offer major potential benefits, they can also be harmful to the environment if they increase demand, safety, and speed, but are not designed to operate more efficiently, be electrified, or be resized. In order for autonomous vehicles to provide net environmental benefits, efforts must be made to ensure unintended consequences do not outweigh their potential advantages.
Nevertheless, the widespread adoption of autonomous vehicles is underway, and its combination with ride-sharing platforms and electric vehicle markets can help reduce significant environmental impacts. For example, as part of its future climate goals, Lyft, Inc.’s shared platform is proposing to provide at least 1 billion rides per year using electric autonomous vehicles by 2025. This effort would cut CO2 emissions for the U.S. transportation sector as a whole by at least 5 million tons per year. Disruptive transportation goals such as these are helping AVs become more accessible to the public, improving the way we get around, and lessening our impact on the environment.