Some have called 2023 the “year of the electric vehicle (EV),” noting the dozens of new battery-powered models set to come available in the United States across all vehicle classes.
That milestone is owed, in part, to rigorous research and development (R&D) that has helped propel EVs into the mainstream. EVs now charge faster, go farther, and have access to a growing network of public charging stations.
With growing success of R&D in preparing EVs for the road, National Renewable Energy Laboratory (NREL) researchers are applying their expertise to non-road transportation modes. Like EVs, battery-powered aircraft and seacraft can not only decrease emissions, but can reduce noise, save money, and better connect rural communities with urban cores.
“Battery powered airplanes and ferries are looking increasingly attractive for certain applications across the country,” said NREL engineer and electric technology analyst Jesse Bennett. “But we have to think carefully about operational requirements, as well as a range of questions about charging infrastructure, grid integration, policy and regulatory requirements, noise, and emissions impacts.”
Through a pair of ongoing studies—one on electric aviation in Colorado and another considering battery-powered ferries in North Carolina—Bennett and others at NREL are analyzing key opportunities and challenges to getting electric technologies off the ground and into the air and sea.
Electric Flight From Small-Town Nebraska to the Denver Metro: Closing the Rural–Urban Service Gap
It is neither easy nor cheap to catch a direct flight from Chadron, Nebraska, to Denver International Airport. The dynamic is familiar across rural America: Some residents want to be more connected to urban centers—for specialized healthcare, for businesses meetings, to catch the big game, or to connect with friends and family—but their means of getting there are limited.
They must either drive many hours, secure access to a private aircraft, or take a heavily subsidized direct flight. Every choice is fuel and emissions intensive.
According to the NREL technical report, “Electrification of Aircraft: Challenges, Barriers, and Potential Impacts,” that dynamic stands to improve with the emergence of small electric aircraft. Initial options will have the battery capacity needed to carry up to nine passengers for up to 400 miles. Leveraging potentially lower operating costs, these aircraft could make it more attractive for operators to provide direct service between rural communities and large-hub airports, closing the rural–urban transportation gap.
“The cost to provide regional flights is difficult to justify currently without subsidies for many of these markets,” Bennett said. “We found that the reduced operation and maintenance costs for e-aviation could increase the viability for equitable flight access and improved service to those communities.”
As detailed in the report, Bennett and report co-authors examined Denver International Airport as a case study on the operational requirements and technical challenges of supporting an influx of electric flights. One challenge stood out: Expanding electric charging to service such flights could expand rural transportation options but would also represent a large new source of electricity demand.
“Just a small number of flights—if they begin to stack up their charging needs—could be rather significant,” Bennett said. “The scale of power these sites could require has the potential to become some of the largest interconnections at one site—in the same category as large data centers and potential long-haul trucking charging stations.”
The report outlines a few options aviation stakeholders could consider to prepare for growing charging demand. It could mean careful planning with local utilities to ensure adequate service from the grid. Investments in local renewable energy generation could also play a role.
Beyond technical strategies, airports might stagger the charging rate and frequency of incoming electric aircraft. That, of course, involves a balancing act between high charging demand, charging times, and operators’ goals to keep aircraft in the air and moving passengers.
“In examining these issues in Denver, we were able to note both nearer-term solutions and longer-term interventions that require further R&D,” said Scott Cary, an NREL ports and airports project manager who contributed to the report. “I think this is where NREL’s offerings really come into focus: We can both clearly articulate challenges ahead and offer aviation and community stakeholders expertise and capabilities for solving them from a variety of perspectives, including electrification of transportation, grid modernization, and use of clean energy technologies such as solar and hydrogen.”
Electric Ferries in the Outer Banks: Supporting Charging Off the Mainland
Far from land-locked Denver, the town of Ocracoke huddles on a strip of islands a few miles off mainland North Carolina. As in coastal communities around the world, residents and visitors of the small town must often rely on ferries to navigate the sea constantly lapping at its borders.
Through a pilot project with the North Carolina Department of Transportation and Tidelands EMC, NREL is analyzing key opportunities and challenges for electrifying ferries. Photo by North Carolina Department of Transportation.
Ocracoke is eyeing the benefits of adding batteries to its ferry fleet to help get the job done. Electric ferries can support regular service demands while reducing the carbon intensity of transporting residents and visitors to and from the mainland.
“We are leveraging some of the lessons learned from Washington State and Norway to find best solutions to electrify these ferry miles,” Bennett said of NREL’s ongoing work with the community. “Given that electric motors are already common—with diesel generators as the primary energy source—it’s not a stretch to look at increasing e-nautical miles from these ferries by adding batteries.”
With electric motors already on board, Ocracoke’s existing ferries can be retrofitted with batteries, lowering the barrier of entry for decarbonizing marine travel. Still, Bennett cautioned against a narrow focus on the vehicles themselves.
Adding batteries to Ocracoke ferries may be somewhat straightforward. Supplying enough energy to charge them—often rapidly—requires a unique set of tools, strategies, and investments.
Sitting on a barrier island, Ocracoke has lower electrical capacity than mainland North Carolina. To electrify its fleet, the transportation district will need to ensure the grid can support the added load. Transportation planners must also balance on-board energy storage, charging power capabilities at origin and destination, and energy requirements needed for ferry operators to complete their route.
“Understanding these requirements in near-term electrification opportunities will help plan for future grid capacity needs as electrification expands,” Bennett added.
Through a pilot project with the North Carolina Department of Transportation and the electric utility Tidelands EMC, NREL analysts and mobility experts are working on a toolkit for making the smartest decisions possible to ensure safe, reliable ferry and grid operations. By early fall 2022, the team will have scoped potential routes and which ferry designs and specifications suit them best.
NREL Accelerates the Evolution of Electric Aviation and Marine R&D
Back on the road, EV technologies continue to mature, and with them growing confidence in their cost and performance.
Numerous corporations are stepping up commitments to transition their fleets to EVs and offer EV charging for staff and customers. Major car manufacturers—including Volvo, Ford, General Motors, Volkswagen, and others—have announced plans to phase out production of combustion vehicles in less than two decades in markets across Europe and the United States. By 2030, nearly half of medium- and heavy-duty trucks will be cheaper to buy, operate, and maintain as zero emissions vehicles than traditional diesel-powered combustion engine vehicles, according to NREL analysis.
In reflecting on the rapid evolution of on-road EVs, Cary said that a similar R&D roadmap is at play when thinking about emerging aviation and marine technologies.
“These pilot projects and localized studies really hinge on collaborating with public and private partners invested in accelerating the evolution of the aviation and marine ecosystem,” he said. “They provide us with a sounding board for understanding the complex regional and industrial dynamics that impact the adoption of new technologies, which ultimately benefits everyone invested in these sectors.”
In concert with major airports and seaports around the country, NREL already provides solutions and research capabilities for decarbonizing transportation. If the growing relevance of on-road EV technologies is any indication, that R&D blueprint could be critical for ushering battery-powered planes and ferries into the mainstream, too.