根據(jù)《自然通訊》雜志發(fā)表的一篇文章，電動(dòng)垂直起降（eVTOL）城市空中飛行器（UAM），也就是大家所謂的“飛行汽車”將更適合行程較長(zhǎng)的旅程。具體來(lái)說(shuō)，這項(xiàng)有關(guān)“飛行汽車在可持續(xù)交通系統(tǒng)中角色”的研究由“密歇根大學(xué)可持續(xù)系統(tǒng)研究中心（Center for SustainableSystems）”和“福特汽車公司研究與高級(jí)工程團(tuán)隊(duì)”的工程師共同完成，是全球首份針對(duì) UAM 系統(tǒng)可持續(xù)性的全面評(píng)估報(bào)告。
研究結(jié)果顯示，在一些地理?xiàng)l件受限和交通環(huán)境擁擠的城市地區(qū)部署空中交通系統(tǒng)將大有裨益，尤其可以將其打造成共享交通服務(wù)的空中延伸。報(bào)告中指出，在類似“從舊金山到圣何塞”或從“底特律到克利夫蘭”等較長(zhǎng)行程中，滿員情況下的 UAM 飛行器將比地面車輛更加高效。
通過(guò)來(lái)自多家 UAM 開(kāi)發(fā)商的數(shù)據(jù)，研究人員發(fā)現(xiàn)，UAM 飛行器的耗能在起飛和爬升期間較大，但在巡航階段很平穩(wěn)，因此可以在一定程度“中和”完整行程的耗能情況。具體來(lái)說(shuō)，在一次長(zhǎng)約 62 英里的旅程中，一輛滿載乘客的 eVTOL 飛行器的人均溫室氣體排放量低于普通私人汽車（后者平均乘坐 1.54 個(gè)人）低 52%，甚至比電動(dòng)汽車低 6%。但速度卻比小汽車快 80%。
密歇根大學(xué)可持續(xù)系統(tǒng)中心主任及資深作者 Gregory Keoleian 袒露，“我開(kāi)始并沒(méi)有想到 VTOL 飛行器在某些情況下的能源消耗和溫室氣體排放水平會(huì)具有競(jìng)爭(zhēng)力。”
然而，研究人員同時(shí)發(fā)現(xiàn)，對(duì)于 22 英里以下的旅程，私人汽車比 UAM 飛行器的油耗更低、排放更少且速度也更快。報(bào)告指出，地面車輛的平均通勤距離為11 英里。
“因此，在地面車輛全年總行駛里程中，VTOL 飛行器僅在極少數(shù)場(chǎng)景下比地面車輛更具有可持續(xù)性優(yōu)勢(shì)。”研究作者 Jim Gawron 表示，“因此，VTOL 飛行器在可持續(xù)交通系統(tǒng)中的貢獻(xiàn)和作用均將相對(duì)有限。”
此外，該研究還同時(shí)覆蓋了電動(dòng) UAM 飛行器配套基礎(chǔ)設(shè)施的排放和發(fā)電情況，比如 UAM 飛行器充電站等。
“我們可以將 VTOL 飛行器的可持續(xù)發(fā)展目標(biāo)和商業(yè)案例相互協(xié)調(diào)起來(lái)，”研究作者 Akshat Kasliwal 表示，“提高乘客滿員率不僅有利于降低人均排放，而且還可以優(yōu)化飛行器的經(jīng)濟(jì)性。此外，考慮到飛行器可以幫助乘客節(jié)省大量時(shí)間，因此乘客可能將采用共享行程的方式。”
《飛行汽車在可持續(xù)交通系統(tǒng)中的作用》（Role of flying cars in sustainable mobility）一書(shū)的作者承認(rèn)，在技術(shù)真正可行之前，我們還需要解決 UAM 通勤的用戶成本、噪音污染和“社會(huì)和消費(fèi)者接受度”等難題。
According to a new study published in Nature Communications, electric vertical takeoff and landing (eVTOL) urban air mobility (UAM) vehicles – commonly referred to as “flying cars” – are better suited to longer flights than shorter commutes. The study, “Role of flying cars in sustainable mobility,” was authored by engineers from the University of Michigan’s Center for Sustainable Systems (CSS) and from the Ford Motor Company’s Research and Advanced Engineering team and is the first comprehensive sustainability assessment of UAM.
The authors determined that deploying UAM systems in geographically constrained and congested urban areas would be beneficial, especially as part of a ride-share service – citing that fully-booked UAM vehicles would be more effective than ground vehicles in transporting passengers “from San Francisco to San Jose or from Detroit to Cleveland.”
Using data from several UAM developers, the authors found that through efficient cruise phases of the flight envelope, UAM vehicles made up for the energy expended during takeoff and climb. For a 62-mile trip, an eVTOL UAM vehicle full of passengers emitted 52 percent less greenhouse gas than a typical personal automobile (and 6 percent less than an electric automobile) with an average occupancy of 1.54 people. UAM vehicles also completed the 62-mile example route 80 percent faster than a personal automobile.
“To me, it was very surprising to see that VTOLs were competitive with regard to energy use and greenhouse gas emissions in certain scenarios,” says Gregory Keoleian, senior author and director of University of Michigan’s CSS.
However, for trips under 22 miles, the researchers found that single-occupant automobiles used less energy, expended less greenhouse gas emissions, and completed the route quicker than UAM vehicles. According to the study, the average ground vehicle commute is 11 miles.
“As a result, the trips where VTOLs are more sustainable than gasoline cars only make up a small fraction of total annual vehicle-miles traveled on the ground,” says study author, Jim Gawron. “Consequently, VTOLs will be limited in their contribution and role in a sustainable mobility system.”
The study also accounted for emissions and power generation for electric UAM vehicle infrastructure like charging stations.
“With these VTOLs, there is an opportunity to mutually align the sustainability and business cases,” says study author, Akshat Kasliwal. “Not only is high passenger occupancy better for emissions, it also favors the economics of flying cars. Further, consumers could be incentivized to share trips, given the significant time savings from flying versus driving.”
The authors of “Role of flying cars in sustainable mobility” concede that user-cost of UAM transportation, noise pollution, and “societal and consumer acceptance” also need to be addressed before the technology becomes truly viable.
Author: William Kucinski
Source: SAE Automated & Connected Knowledge Hub
一輛電動(dòng)垂直起降（eVTOL） 城市空中交通飛行器（UAM），也就是“空中出租車”正在城市中心上空飛行，圖為渲染效果圖。（圖片來(lái)源：密歇根大學(xué)環(huán)境與可持續(xù)發(fā)展學(xué)院 Dave Brenner）
