Efforts to gauge the feasibility of leveraging the nation’s highways for energy production and placement of transmission and distribution lines have been ticking up lately.
A study released in April, done for the Minnesota Department of Transportation, contributes to mounting evidence that rights-of-way may be ideally suited to integrating buried high-voltage direct current (HVDC) transmission lines.
On another front, Massachusetts sealed a deal to have solar panels built into highway sound barriers in a test of the concept — a move that furthers research into the prospect of utilizing elements of rights-of-way for energy infrastructure.
Both developments reflect a growing understanding that roadways could play a role in the nation’s energy future given prospects for growth of electric vehicles requiring battery charging and the need to harden and increase the capacity, flexibility, and responsiveness of the electric grid.
Utilizing right-of-way
The Minnesota study, “NextGen Highways Feasibility Study for the Minnesota Department of Transportation,” led by Seattle-based NGI Consulting’s NextGen Highways team, determined that building a buried HVDC transmission system on sections of the state’s thoroughfare network might someday be feasible and advantageous. The infrastructure examined would consist of sections of conductor buried in a 5-ft strip of right-of-way, connected every half-mile inside fully buried joint vaults. Converter stations that would convert DC power to AC would be located above ground along the route, but outside the right-of-way. The study also considered the simultaneous co-location of buried fiber, addressing the likely need for greater welding of digital communications and power transmission.
Laying the groundwork for continued investigation by the Minnesota Department of Transportation, the study also adds to a growing body of research into utilizing rights-of-way to help build a 21st-century electrical grid, says Laura Rogers, a project co-lead who is deputy director of The Ray, a Georgia-based non-profit that manages a net-zero highway testbed located on 18 miles of Interstate 85 between LaGrange, Ga., and the Georgia-Alabama state line. As more renewable energy comes online and electrified transportation advances, a refashioned grid will become increasingly essential and less vulnerable, she says, not to mention more easily sited transmission assets could be an important component.
“High-voltage DC can move a lot of power long distances, and a macro AC-DC grid opens up the possibility of swapping power from coast-to-coast in the U.S.,” she says. “But we’ve had a hard time building transmission infrastructure in this country because of public opposition to overhead power lines and issues of eminent domain. So, if we can use the public right-of-way and bury it — and utilize AC-DC technology — we could get around that barrier.”
Solar and noise barriers
The more-or-less permanent, protected, and sequestered nature of roadways opens other possibilities for energy infrastructure enhancement. That drove the Massachusetts Department of Transportation’s decision earlier this year to move ahead with a long-studied plan to build solar panels into an existing 3,000-ft-long, 20-ft-high section of highway noise barrier on Interstate 95 in Lexington.
Working with partners, Solect Energy, Hopkinton, Mass., will coordinate the project, which is slated to have a capacity of 637.5kW DC, generating 802,000kWh annually. Building on a concept that’s been utilized in some parts of Europe, the project will be the first of its kind in the nation and is envisioned as a testbed that could lay the groundwork for similar projects down the road, even ones that site new sound barriers that have solar panels built-in during the manufacturing process.
The Ray has extensively studied solar PV highway noise barriers as one way to fully utilize rights-of-way for energy infrastructure, but it has determined its 18-mile route doesn’t lend itself to the concept, Rogers says. However, it has merit under the right conditions, she says, and the Massachusetts project is a noteworthy step in the direction of determining its feasibility.
“This could be great, especially in urban areas where we don’t have the space to install ground-mounted solar,” she says. “As cities expand there probably will be more noise barriers going in so we could see more of this. This could also be a way for transportation departments to fund more noise barriers, by utilizing power purchase agreements.”
Tom Zind is a freelance writer based in Lees Summit, Mo. He can be reached at [email protected].
