A Ford-funded study by the University of Michigan has examined the environmental credentials of electric VTOL aircraft for commuting, compared to both regular and electric cars over a range of commuting distances. The results paint an interesting picture of future mobility.
Published in the open-access Nature Communications journal, the study assumes that eVTOL flying cars will be powered by electricity from regular power plants rather than renewable sources – and that the VTOLS we're talking about will have the capacity to convert to efficient winged flight after the high energy draws of vertical takeoff and landing, which is a reasonable assessment.
The researchers took a bunch of realistic parameters to feed into their equations, assuming that the aircraft will look something like what's currently being developed by the likes of Joby, Airbus, Boeing and Lilium, among numerous others. Thus, they were able to take a reasonable stab at working out what the vehicles would weigh, their lift-to-drag ratios, battery-specific energy, and how much energy they'd be using during the different stages of flight: takeoff, hover, climb, cruise, descent and landing.
Presumably Ford funded this study hoping for eco-ammunition against a future competitive threat, but things didn't quite go that way – unless you're planning to fly less than 22 miles (35 km). That's the point at which a single-occupant eVTOL trip became cleaner than a single-occupant combustion car, taking urban traffic into account as well as the lack of traffic in the air.
Go further, say 62 miles (100 km), and the emissions savings pile up. Even with a fully loaded eVTOL carrying 4 passengers measured against a combustion-engine car with the average 1.54 occupants on board, the VTOL had emissions 52 percent lower than the car.
Even more surprisingly, over the same length of journey, the 4-passenger VTOL created some 6 percent fewer emissions than even an electric car. And this on top of offering massive time savings thanks to their three-dimensional traffic busting capabilities.
The researchers seem not to have expected the outcome. "To me, it was very surprising to see that VTOLs were competitive with regard to energy use and greenhouse gas emissions in certain scenarios," said Gregory Keoleian, senior author of the study and director of the Center for Sustainable Systems at U-M's School for Environment and Sustainability."VTOLs with full occupancy could outperform ground-based cars for trips from San Francisco to San Jose or from Detroit to Cleveland, for example."
Indeed, one of the biggest possible shifts we could see thanks to eVTOLs, once they're fully certified and in regular use, is a shift away from urban living for those who can afford to take these services to work. Why not live by the beach if you can replace a 20-mile, hour-long slog through city traffic with a 60-mile, 30 minute air taxi ride?
The study appears in the journal Nature Communications.
Source: University of Michigan