An extensive new US study has demonstrated that electric VTOL (vertical takeoff and landing) vehicles could deliver significant time and energy savings for certain journeys.
Compiled by researchers at the University of Michigan in partnership with Ford Motor Company, the study looked at the primary energy use and greenhouse gas emissions during the five phases of VTOL flight: takeoff, climb, cruise, descent and landing. As VTOLs use the bulk of their energy during takeoff and climb, they are less efficient over shorter distances, needing a sustained period of low-energy cruise to deliver gains.
During trips of 100km, for example, it was found that a VTOL carrying a pilot and three passengers had lower greenhouse gas emissions than ground-based cars, which have an average vehicle occupancy of 1.54. According to the research, published in Nature Communications, emissions tied to the VTOL were 52 per cent lower than petrol-powered cars and 6 per cent lower than battery-electric cars.
“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 Centre 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.”
Akshat Kasliwal, first author of the study and a graduate student at the Michigan School for Environment and Sustainability, said the findings can help guide the sustainable deployment of an emerging mobility system prior to its commercialisation.
“With these VTOLs, there is an opportunity to mutually align the sustainability and business cases,” Kasliwal said. “Not only is high passenger occupancy better for emissions, it also favours the economics of flying cars. Further, consumers could be incentivised to share trips, given the significant time savings from flying versus driving.”
To build their physics-based energy and emissions model, the researchers used publicly available information from sources such as Airbus, Boeing, NASA and other organisations that have designed VTOL prototypes.
“Our model represents general trends in the VTOL space and uses parameters from multiple studies and aircraft designs to specify weight, lift-to-drag ratio and battery-specific energy,” said Noah Furbush, study co-author and a master’s student at the U-M College of Engineering.
“In addition, we conducted sensitivity analyses to explore the bounds of these parameters, alongside other factors such as grid carbon intensity and wind speed.”
I am glad that there is a link to the paper quoted as you need to drill down into the numbers to get an understanding of how sustainable VTOL aircraft would be in real world conditions. You might not pick up from the article above that the research says that “ICEV performs better than the VTOL up to ~35 km, where aerial flight is dominated by the energy-intensive hover mode.” and that “VTOL emissions approach, but do not match, those from BEVs for distances > ~120 km”. Given that the average commute by car in the UK is ~16km, it doesn’t seem a very sustainable alternative for the vast majority of journeys.
The article says VTOL can have a ‘sustainable role’ for ‘certain journeys’ and that ‘they are less efficient over shorter distances’. It’s quite clear that not all journeys will be more efficient.
What utter rubbish! ….. Lets sort our driver less vehicles before we launch a few million idiots into the stratosphere!
The talk about occupancy is laughable in that most 5 seater cars are driven with only one occupant. 1.5+ tonnes to move 80/90 kgs.!!! I agree with Cameron we are continually bumping into one another when we have roads what we could do in the air does not bear thinking about. Walk before we run.
Would be great anywhere (outside of London I guess). I travel the M6 regularly, would be lovely to look down on the traffic jams! Would need to be autonomous to avoid crashes and set allowable routes.