Tuesday, February 20, 2024

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Can Electric Vertical Takeoff and Landing (eVTOL) aircraft transform transportation?

These days, electric transportation is basically synonymous with light-duty electric cars and trucks. That is understandable. Sales of new electric vehicles (EVs) in the U.S. in 2023 surpassed one million for the first time and were up by over 50 percent compared to 2022. The momentum is expected to continue in 2024, with market research firm Cox Automotive forecasting that the combined purchases of EVs, plug-in hybrids, and hybrid vehicles account for nearly 25 percent of all sales.

View EPRI's eVTOL brochure

While EVs are quickly becoming mainstream on global roadways, another form of electric transportation is also poised to rise—literally. Electric Vertical Takeoff and Landing, or eVTOL, aircraft are attracting significant investment and development as companies seek to commercialize their use. Recently, EPRI published a Quick Insight report, Look Up for eVTOL: Overview on the Flying Vehicles that Could Revolutionize Air Transportation, which outlines the drivers for eVTOL development, technological challenges that must be overcome, as well as grid infrastructure and equity considerations.

Though not widely known by the public or utilities, eVTOL development has been brisk in recent years. “This industry has gone from just talking about what an eVTOL should look like and what to do if we have eVTOLs to getting certifications and talking to the FAA (Federal Aviation Administration) about certifications and getting ready to commercialize their products as early as this year,” said Purandhya Vij, an EPRI Strategic Insights Associate and co-author of the Quick Insight report. Indeed, there are currently over 600 eVTOL concepts at some stage of development, and the entire market could reach nearly $18 billion by 2040, according to an analysis by the consulting company Deloitte.

Cheaper, Quieter, and Cleaner

To understand why there is such a proliferation of eVTOL concepts and activity, it’s important to grasp what eVTOLs are and the use cases they can uniquely address. As their name suggests, eVTOLs feature electric propulsion systems that allow them to take off and land without the need for runways. Put simply, eVTOLs operate more like helicopters than airplanes, albeit minus the internal combustion engine. Besides their capacity to elevate and land vertically, eVTOLs are five times as fast as automobiles.

Though the concepts and features of eVTOLs are still in their infancy, current vehicles come in two basic categories. One is a wingless aircraft with multiple rotors and two or more thrust units that enable it to maneuver. For example, multicopters combine propulsion units that allow the aircraft to elevate and descend vertically with rotors that enable forward movement. The other common eVTOL category is powered lift, a winged aircraft that combines various thrust units that determine their maneuverability.

While eVTOLs have different features and capabilities, their appeal is driven by several common attributes. “The kind of utility that eVTOLs offer comes from the fact that they’re going to be cleaner, cheaper, and produce less air pollution or no emissions while in flight,” Vij said. Indeed, because eVTOLs have electric motors instead of gas-powered engines, they are easier and cheaper to maintain than helicopters. By one estimate, eVTOLs cost $1.50 per passenger mile to operate compared to $6 to $8 for helicopters. Electric propulsion also has other benefits, including the comparatively quiet operation that makes it more suitable for urban environments concerned about noise pollution.

The reduced or eliminated noise and air pollution eVTOLs offer, combined with the fact that they won’t get caught in traffic jams, helps explain the use cases operators are pursuing.

Challenges to eVTOL Deployment

Even though CEOs and executives at eVTOL companies are optimistic about their ability to launch their aircraft soon, numerous challenges are standing in the way of the vehicles becoming mainstream. As is the case with EVs, battery technology and charging infrastructure must both reach a level of performance and reliability to allow eVTOLs to scale.

“Energy storage density is one of the main issues for anything related to transportation,” Nicolas Sockeel said. Indeed, energy density—which is the amount of energy a battery can store per unit of mass—is a significant factor in eVTOL prospects because the aircraft needs to be able to store a lot of energy in a relatively small and lightweight battery. Cycle life, the number of times a battery can be charged and discharged before losing capacity, is also important. So, too, is power density, which is the amount of power that can be delivered quickly and is critical to generate the thrust eVTOLs need to takeoff. To be viable for a mass market, eVTOLs also need batteries to improve their energy density and reduce their cost of ownership.

Adequate charging infrastructure is also necessary for eVTOLs to scale. To serve hospitals and other emergency medical services, for example, eVTOLs will need to be able to recharge quickly. “The charging time for emergency medical services would have to be 10 or 15 minutes so that the eVTOL can turn around and make another trip,” Nicolas Sockeel said. “That would likely require updates and upgrades to the infrastructure at medical facilities to be able to provide that kind of fast charge.”

Currently, the infrastructure needed for emergency medical services, urban mobility, and other promising eVTOL use cases simply does not exist, which means that eVTOLs face the same chicken-and-egg dilemma that has challenged EVs. “The space is just developing, so there’s nothing really available in terms of charging infrastructure,” Vij said. “eVTOLs are only going to be economically viable if they’re commercialized. And they will only be commercialized if they have charging infrastructure. So, everything must move in tandem to work.”

For utilities, successful commercialization of eVTOLs could also result in significant load growth, requiring accurate transmission and distribution system planning. Especially important for utilities would be to prepare for increased load during peak demand. For example, a study by NASA found that a vertiport—the eVTOL equivalent of an airport—could consume 50 MWh per day. One potential solution to reduce the grid infrastructure investments needed to charge multiple eVTOLs could be to swap out depleted batteries for already-charged batteries, a process that takes only about five minutes.

Several other challenges must also be overcome, including integrating eVTOLs into existing air traffic management systems and garnering public acceptance of the novel technology. Because pilots are a significant expense, one strategy for decreasing the cost of eVTOLs is to make them autonomous. Developing and deploying the technology to make this possible will require significant investment. And that investment will only be worthwhile if the public is confident that flying in a pilotless aircraft is safe.

Unmanned aircraft vehicle prototype flying in the sky

Integrating Equity Early in eVTOL Projects

Although eVTOLs have not yet been commercialized, company executives, utilities, policymakers, and regulators should consider equity in all their investments and decisions. There are a wide range of equity issues related to eVTOLs, including accessibility for everyone who could benefit from the efficient transportation they potentially provide. “We will see eVTOLs for urban transportation in Manhattan, but what about Queens?” Vij said. “If you’re only giving access to the haves of society, then it’s not accessible, and it’s not solving the problem it was designed to address.”

Equity should also be incorporated into decisions about siting vertiports and charging infrastructure, as well as how a proliferation of eVTOLs would impact communities. “It’s making sure that not only air pollution is addressed, but we are also talking about visibility pollution and noise,” said Annette Mosley, an EPRI senior technical advisor.

Equity isn’t just about avoiding negative impacts. As with other aspects of the energy transition, eVTOLs offer the potential to deliver economic opportunity to disadvantaged communities. “There’s an opportunity to create jobs, but that requires workforce development,” Mosley said. “There could be opportunities to train or retrain workers in low-income communities but also to reach out to HBCUs (historically black colleges and universities) to establish career or entrepreneurial pathways in eVTOLs.”

What’s important, though, is that equity be integrated early in all eVTOL projects rather than as an afterthought. “It’s about making sure equity considerations are thought of even when they can’t be addressed immediately,” Mosley said. “It’s the golden thread that should go through everything.”

EPRI Technical Experts:

Purandhya Vij, Nicolas Sockeel, Annette Mosley
For more information, contact techexpert@eprijournal.com.