At the end of April, high-ranking state officials met in Boston to talk with entrepreneurs and technologists about the prospects for self-driving cars. Economic Development Secretary Jay Ash and Transportation Secretary Stephanie Pollack hope to make Massachusetts a center for the development of autonomous vehicles.
You’ve probably read about self-driving cars. You may be looking forward to the day when you can read the newspaper while your car nimbly guides itself across town or down the highway with other similarly intelligent vehicles. But if self-driving cars become as common as experts forecast, they’ll bring changes that go well beyond enabling us to browse our email on the way to work.
You may be looking forward to the day when you can read the newspaper while your car nimbly guides itself across town or down the highway with other similarly intelligent vehicles.
Researchers predict that autonomous vehicles will have an impact on efforts to combat climate change. The question is: Will it be for better or for worse?
If the broad acceptance of self-driving cars were to lead to more rapid adoption of electric vehicles, then, assuming that we continue to taper the use of fossil fuels for generating electricity, self-driving cars would help to reduce carbon emissions.
MIT Professor Emilio Frazzoli studies mobile robotics and transportation systems and believes the simultaneous emergence of electric vehicles and autonomous vehicles is largely coincidental. “The two are not necessarily directly related,” he said. “Conceivably, there could be autonomous vehicle fleets using internal combustion engines.” In other words, there’s little hope that self-driving cars would be a catalyst for the growth of electric cars.
So, if self-driving cars aren’t going to significantly accelerate the transition to an all-electric fleet, what effects on carbon emissions can we expect from them?
If your robotic chauffeur can drive you point to point, there’s less motivation to walk, ride a bike or use public transit. The elderly who’ve given up their cars for lack of confidence in their driving skills might return to the roadways. Rush-hour congestion would become more tolerable, or even productive. People might choose to live at a greater distance from their jobs, leading to a whole new wave of urban sprawl. And some autonomous trips wouldn't even have passengers, as when cars shuttle themselves off to remote parking areas or make deliveries.
Each of these outcomes implies more vehicles traveling more miles. In economic terms, time spent behind the wheel is a cost, and reducing or eliminating that cost will lead to more car trips. So, if we simply replace existing vehicles with comparable self-driving vehicles, we’re bound to rack up a lot more miles on the road. That means more carbon in the atmosphere.
Only when we consider how self-driving vehicles could fundamentally change our transportation systems do we see significant opportunities to reduce energy use. One climate-friendly vision of self-driving cars draws on the notion of autonomous — or driverless — taxis. Professor Frazzoli, in addition to his position at MIT, is chief technology officer at nuTonomy, a startup that is developing an autonomous taxi service in Singapore. The venture is premised on the idea that people will find an urban taxi service that utilizes driverless vehicles to be more economical and convenient than driving their own cars. In the end, fewer people would own cars and rely instead on autonomous taxis for their transportation needs.
Frazzoli maintains that the benefits of driverless taxis go beyond labor cost reduction. “In order for Uber-like services to really reach their potential, autonomy is necessary,” he said. In theory, lower fares would inspire more people to use the service, to the point where the fleet of autonomous taxis can serve as a distributed public transit system.
Sophisticated routing algorithms and communication between vehicles will reduce traffic congestion and minimize energy costs. Deploying taxis of varying capacity can realize substantial energy savings by ensuring that every trip uses a vehicle with an energy requirement that fits the number of passengers.
Merely substituting [driverless cars] for today’s cars will work against efforts to combat climate change.
Vehicles operating within a coordinated network can be dispatched, parked, recharged and serviced in a highly efficient manner. Frazzoli’s research suggests that automation could reduce the total number of vehicles needed to provide personal mobility in Singapore by about two thirds.
So the effect of self-driving cars on climate change depends on choices yet to be made. Merely substituting them for today’s cars will work against efforts to combat climate change. We’ll end up taking more and longer trips, sometimes at higher speeds, and it's probable that we would make less use of cleaner modes of transportation.
Alternatively, we can use these cars in intelligent networks of shared, cooperating vehicles that reduce both emissions and congestion. Advanced software can sharply decrease the total number of miles traveled by cars and ensure that each trip uses only as much energy as is needed.
Setting the right course of action will take some serious planning. Let’s hope our policy makers aren’t asleep at the wheel.