The promise of driverless electric taxis, aptly called robocabs, just got brighter.

Cheerleaders for futuristic cars, which can navigate roads with zero input from humans, have for years drummed up interest by focusing on how much safer these cars will be and how traffic jams would become history once these intelligent cars take to the roads. Now, a new study suggests that there may be another reason to embrace the new technology—substantial reductions in greenhouse gas emissions.

Authors of the study, published in Nature Climate Change yesterday, estimated that emissions per mile from light-duty vehicles like passenger cars could fall by as much as 94 percent by 2030.

“When Google announced the launch of their self-driving car project, there was a great deal of excitement,” said Jeffrey Greenblatt, one of the co-authors of the study, “but nobody seemed to be looking at how these cars could impact greenhouse gas emissions.”

Greenblatt and co-author Samveg Saxena at the Lawrence Berkeley National Laboratory developed a model that is essentially a “best-case scenario,” where the cars are not just driverless but also run on electricity. Their calculations showed that greater environmental benefits would be reaped if the cars were used as taxis rather than privately owned.

The latest avatar of Google’s self-driving car, launched this May, is also a battery-operated compact two-seater that functions as a taxi. While there is awareness among automakers that these technologies would yield benefits in terms of their environmental impact, its magnitude has been difficult to quantify.

In 2013, the contribution of the transportation sector to greenhouse gas emissions in the United States was 27 percent, according to U.S. EPA, second only to the power sector. Within the sector, light-duty vehicles like passenger cars and smaller trucks, including SUVs, pickup trucks and minivans, were responsible for more than 50 percent of the greenhouse gas emissions from transportation.

“Tailpipe emissions are the main source of greenhouse gases from cars that use fossil fuels,” explained Anthony Shaw, a transport program specialist at the Intelligent Transportation Society of America, a nonprofit research organization. Electric cars emit no tailpipe pollutants. This, experts agree, is the key reason why electric vehicles are better than conventionally powered vehicles.

The important issue, said Mark Delucchi, an expert on transportation and energy use at the University of California, Davis, was where the energy for the vehicle is coming from. Greenhouse gas emissions estimates for electric cars will have to take into account the greenhouse gases emitted by power plants, he said.

What makes battery-operated cars a game changer is that there are limits to how clean the production of conventional fuels can be. “For gasoline vehicles, we have pretty much gone as far as we can in reducing pollution,” Delucchi said. On the other hand, power generation is becoming cleaner and cleaner. The Nature study uses estimates for improving emission controls on power production to show that this is indeed the case.

“There is no future for the internal combustion engine,” Delucchi said. “It has to be electric.”

A shared driverless car? Uber is working on it
According to some estimates, more than 100,000 electric vehicles were sold in the United States last year. This is double the number sold in 2012. The Union of Concerned Scientists, an advocacy organization, estimated that almost 42 percent of U.S. households are already in a position to use electric vehicles based on their access to power sources and parking space, and their current travel patterns.

The advantages in terms of greenhouse gas emissions are compounded if these vehicles are autonomous, Greenblatt said. Better traffic flows and less congestion, promised by automation technology, lead to more efficient use of energy.

A taxi service, like the one envisioned by Google, would ensure the rides are customized to the transportation needs of passengers, again saving energy. Today, very few people in the United States use shared vehicles. Only about 4 percent of light-duty vehicles are shared, according to the study. But ride-booking companies like Uber are also in the process of developing their own fleet of robocabs. Earlier this year, they partnered with Carnegie Mellon University, relying on its renowned robotics research faculty, to develop driverless technology that would reduce their dependence on contract drivers.

While large automakers like Audi, BMW, Ford and Toyota are investing heavily in automation technologies, their primary focus seems to be improving the driving experience of users. The environmental benefits are not as well-advertised for high-end vehicles that are increasingly acquiring automation features. Many of the auto companies are working on models that are fully autonomous but are not electric. Greenblatt said that there needs to be more research to determine what the distinct advantages are from each of these features.

But the biggest hurdle in forecasting what the future of vehicle use looks like appears to be predicting consumer behavior. “A lot of people may still be freaked out by the idea of a driverless car,” Greenblatt said. However, others like Shaw contend that their research shows that people overcome their initial qualms about driverless cars quickly. There is also some apprehension that the ease of these options would increase people’s demand for transport, thus increasing the demand for fuels.

The authors of the study steered clear of making predictions about autonomous vehicle penetration in the United States in the coming years. “We focused on the technology and how that would impact greenhouse gas emissions,” Greenblatt said. But he is convinced that the appeal of a car that delivers the same or superior service, in a cleaner and cheaper way, is high.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC., 202-628-6500