Tuesday, March 16, 2021

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EPRI is assessing the state of electric aviation—from companies and technologies to designs and research gaps

The 2019 Paris Air Show—one of the global aviation industry’s premier events—was full of hints that the future of air travel increasingly may be electric. One big headline at the event: Massachusetts-based regional carrier Cape Air became the first airline to order battery-powered commercial airplanes. Beginning in 2023, Cape Air will fly nine-passenger electric planes called Alice, unveiled at the Paris Air Show by Israeli manufacturer Eviation. Alice can fly up to 650 miles on a single charge of its lithium ion batteries.

Other aviation news points to the increasing momentum to electrify airplanes. For instance, United Kingdom–based Rolls Royce announced its planned purchase of Siemens’ electric and hybrid-electric aerospace propulsion division. France-based Airbus unveiled plans to test hybrid airplanes by 2022. In the United States, NASA is working with industry giants such as Boeing, GE, and United Technologies to develop electric propulsion systems as part of its Advanced Air Transport Technology Project.

Scouting an Emerging Industry

These and other such developments are on the radar of EPRI’s Technology Innovation (TI) program, which is assessing the state of electric aviation. The program’s innovation scouts have catalogued companies developing aircraft, assessed the maturity of their designs and technologies, and identified research gaps that challenge commercialization.

Innovation scouts work to provide electric utilities with a useful understanding of emerging technologies that could impact their operations. Also, they assess how EPRI expertise can help advance commercialization.

Eviation’s “Alice” electric airplane. Photo courtesy of Eviation.

“EPRI’s role is still to be determined but there are obvious alignments,” said Stephen Stella, who manages EPRI’s Technology Innovation program. “Electric planes typically require energy storage, and we have that research. There are charging systems, electric propulsion, and power management systems, and we have that research as well. In many areas, we won’t need to reinvent the wheel but rather figure out how to adapt existing technologies to new uses.”

EPRI’s innovation scouts have identified more than 100 companies involved in electric aircraft development. The list includes big manufacturers such as Boeing and Airbus and small startups such as Ampaire. The rideshare company Uber is investigating the use of small electric aircraft in its business and in 2016 released a white paper about electric aviation.

Some designs are essentially drawings while others are prototypes or demonstration vehicles. The innovation scouts’ main takeaway for utilities is that commercially available versions of electric and hybrid airplanes are likely 18 to 24 months away.

Lower Emissions and Costs

According to the non-profit Air Transport Action Group, the global aviation sector produces about 2% of the world’s carbon dioxide emissions. Electrifying aviation can lower those emissions significantly. It also can save money.

“Aviation fuel is expensive, and electricity is lower cost across the board. That can make a big difference,” said John Halliwell, a technical executive in EPRI’s Electric Transportation Group. “The mechanical structures in electric aircraft are likely to be simpler than those in internal combustion engines, so you’d have less maintenance.”

Advances in battery technologies also are expected to lower costs for electric aviation. Electric aircraft manufacturer Ampaire claims that a hybrid electric plane could potentially reduce fuel costs by 50% to 70% and maintenance costs by 25% to 50%.

The early focus of technology development is small aircraft—typically those with just one or two seats.

“You can’t electrify large planes with today’s battery technology because of inadequate energy density,” said Halliwell. “At takeoff, jets require megawatts of power, which is why you see some initial large aircraft concepts with battery designs that don’t exist yet—and you see hybrid designs that still rely on internal combustion engines.”

A Utility Perspective

According to Halliwell, utilities will need to play an important role in addressing electric aviation’s technical challenges. At the top of that list is how to charge batteries. The first electric and hybrid airplanes are expected to be small and to fly in and out of regional airports. While most of these airports will be able to handle the charging requirements, others may need to bolster distribution lines or transformers. As electric airplanes become more common at regional and major airports and require fast charging for quick flight turnarounds, the need for grid upgrades will increase along with the ability to charge and replace onboard batteries quickly.

Halliwell points to the importance of cultivating more discussion among airplane manufacturers and utilities, particularly regarding how aircraft will interface with the electric distribution system. As chair of a committee on energy storage and charging launched by the aerospace standards organization SAE International, Halliwell understands firsthand that the utility perspective is essential in developing electric aviation.

“I was at a meeting examining how much power and charging energy you would need for aircraft and how much it would cost,” he said. “The group used the average wholesale rate in the U.S. when they were talking about multi-megawatt charging, but average rates aren’t helpful for this sort of economic analysis. Actual costs depend on the amount of power needed, local rate structures, and when the charging takes place. Delivering high power for short durations will generally include a more complex rate structure that includes demand charges.”

Halliwell sees a precedent for EPRI’s role in electric aviation development. In the early 1990s, EPRI launched the Electric Transportation Infrastructure Working Council, which has fostered collaboration among automakers, regulators, and utilities interested in the development of electric vehicles (EVs). The council serves an important role in informing industry standards for connecting EVs to chargers as well as in electrifying truck stops, ports, and other transportation systems. It continues to meet three times a year to identify and address technical challenges.

“You have to make those connections between aircraft designers and utilities,” Halliwell said. “Aircraft designers have to consider and understand the consequences of how they choose to charge an aircraft, including factors like power levels and timing. Those connections help everyone gain a full understanding about how electricity is delivered and what electric aviation needs to succeed.”

Key EPRI Technical Experts:

Stephen Stella, John Halliwell
For more information, contact techexpert@eprijournal.com.

Artwork by Ariel Davis