Driverless electric taxis would slash costs, energy and emissions
Cameron Jewell | 3 April 2018
Switching to a fleet of driverless electric taxis in Manhattan, New York would cut greenhouse gas emissions by 73 per cent and energy use by 58 per cent while reducing costs by an order of magnitude, a new study out of the US Department of Energy’s Lawrence Berkeley National Laboratory has found.
Published in Environmental Science & Technology, the study compared a taxi fleet using driverless technology and electric vehicles (EVs) to the current taxi fleet. Using models built from more than 10 million taxi trips in New York City, the researchers found that using smaller cars with smaller batteries (a range of 80-145 kilometres) would be sufficient for the vast majority of trips, meaning cheaper build costs, though requiring the existing charger network to be tripled in size.
Co-author Jeffery Greenblatt said the EV industry was focused on the personal car market, meaning that it was spending efforts attempting to overcome “range anxiety”.
“The standard now is 200 miles [32km],” he said.
“We suspected you wouldn’t need as much for taxis. We found plenty of times during the day when a portion of taxis could slip off to recharge, even if just for a few minutes. This greatly reduces the need to have a big battery and therefore drives down cost.”
He said the model necessitated having “a fairly dense charging network”, either 66 11kW Level 2 chargers per square mile or 44 22kW Level 2 chargers per square mile.
“Manhattan currently has about 500 chargers for public use, which include Tesla chargers,” lead author Gordon Bauer said.
“We found that we would need to at least triple that capacity.”
Dr Greenblatt said electrifying the taxi fleet could overcome some of the barriers that have stopped EVs being taken up more widely, such as high cost.
“By switching to a shared fleet that’s automated, you can provide electric service to people essentially now,” he said.
Co-author Brian Gerke said shared autonomous vehicles promised to solve some of the big challenges of personal transport, particularly in dense urbanised areas. And he thinks the change could come sooner than we think, referencing the switch from incandescent bulbs to LEDs, an area he previously worked in.
“It was a better product and it was cheaper overall,” Dr Gerke said of LEDs. “When you have those together, people adopt it really fast.
“I suspect there will be a similar transformation that will occur in the transportation sector in the next decade – it will occur faster than people think.”
Parking requirements to be slashed
Even if the shared autonomy future doesn’t play out, there’s still good(ish) news regarding parking requirements, with a new study out of the University of Toronto finding that driverless cars could increase parking lot capacity by 62 per cent.
“In a parking lot full of AVs, you don’t need to open the doors, so they can park with very little space in between,” University of Toronto Professor Matthew Roorda said.
”You also don’t need to leave space for each car to drive out, because you can signal the surrounding AVs to move out of the way.”
The Toronto researchers created a computer model to simulate the effects of various layouts for AV parking lots, and used an algorithm to optimise design, including minimising the number of relocations and maximising the proportion of the lot that was used for parking space versus space for relocation, entering or exiting.
Square-shaped AV parking lots could boost capacity even further, by up to 87 per cent, the study found.
The researchers said the boosted efficiency could mean much smaller parking lot footprints.
Professor Roorda said he hoped parking authorities could use the findings to improve design of new car parks and enhance urban spaces.
“Right now, our downtown cores have giant municipal parking lots next to major attractions,” he said.
“AVs could allow us to both shrink and relocate these parking lots, opening up valuable space in cities.”