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Public Roads - Winter 2019

Winter 2019
Issue No:
Vol. 82 No. 4
Publication Number:
Table of Contents

Renewable Roadsides

by Tina Hodges and Amy Plovnick

Increasingly, State transportation agencies are exploring solar power technologies to reduce electricity costs and promote energy security.

The Massachusetts Department of Transportation installed these solar panels in the right-of-way at Exit 13 North on the Massachusetts Turnpike (I–90) in Framingham. The State DOT has installed several solar projects at multiple sites.


State highway departments have many responsibilities, from fostering roadway safety to plowing and mowing roadsides to implementing major repair and replacement projects. Often overlooked is the fact that these agencies require significant electricity to power their operations. For example, roadway signs and lights, maintenance buildings, rest areas, and other facilities all require electricity.

After considering costs and benefits, some State departments of transportation have chosen to meet a portion of their electricity needs by installing solar energy projects in highway rights-of-way (ROW) and at other State DOT facilities. Some agencies are finding that pursuing renewable energy generation not only benefits the environment but can also save money on energy costs.

The price of solar photovoltaic systems dropped more than 60 percent between 2010 and 2017. In many cases, solar power is cost-competitive or even cheaper than fossil fuel sources of electricity. Twenty-nine percent of all new electricity-generating capacity came from solar installations in 2017, second only to natural gas (46 percent), and slightly ahead of wind (22 percent).

As renewable energy technologies have matured, the business models serving public entities have expanded as well. Many State and local government agencies are able to work with private-sector partners to install renewable energy at no upfront cost to them and save money on their electricity use, all while helping the environment and serving the public.

The Federal Highway Administration supports highway renewable energy through developing resources and funding workshops where agencies can learn about efforts to implement renewable energy projects. By sharing their challenges and successes with their peers, State DOTs are learning from each other, and the share of transportation agencies that are pursuing renewable energy continues to grow.

“We’re thrilled to see [State] DOTs innovating by generating clean, renewable energy on their properties where feasible,” says Michael Culp, team leader of the FHWA Sustainable Transportation and Resilience Team. “This gives us an opportunity to help them save money and also protect the natural environment.”

Benefits to State DOTs

As interest in renewable energy projects increases, staff at State transportation departments across the country are championing these efforts. They are navigating the complicated world of electricity production and regulation, and ensuring that these renewable energy projects meet their departments’ missions and requirements.

States across the country are using renewable energy sources in the highway ROW. This map shows a snapshot of highway renewable energy projects known by FHWA.


State DOTs have recognized many potential benefits of implementing solar energy projects.

Identifying secondary purposes for ROW. In many cases, the highway ROW owned by State DOTs is close to electrical loads, free from development, and already disturbed, making it an attractive location for solar power.

Saving money on electricity costs. Installing solar power can help State DOTs offset their electricity costs. The electricity produced can directly power department assets and facilities, such as roadside lighting or maintenance buildings. Depending on State policies, the electricity produced may also be sent to the electrical grid and used to offset the DOT’s electricity bill through net metering.

Producing clean energy and promoting energy security. Compared to burning fossil fuels, obtaining electricity from solar or wind reduces harmful pollutants such as mercury, nitrous oxides, and heat-trapping carbon dioxide. Solar energy also helps DOTs meet State environmental goals and requirements, and promotes energy security by diversifying energy generation and delivery methods.

Fostering green jobs. Highway solar projects help promote the local green job market and the Nation’s growing clean energy economy. Nationwide, the solar workforce increased by 168 percent in 7 years, from about 93,000 jobs in 2010 to more than 250,000 jobs in 2017.

State DOT Experiences

Most State DOTs that have installed renewable energy technologies have used solar power, either ground-mounted solar panels along the ROW and at rest areas or rooftop solar on carports, maintenance buildings, rest areas, or other facilities. A few State DOTs have installed small-scale, pilot wind turbines at rest areas. As technologies advance, more opportunities may arise to incorporate additional types of renewable energy beyond pilot projects, such as solar roadway surfaces, photovoltaic noise barriers, tidal turbines under bridges, or micro-wind turbines.

The Oregon DOT installed this nearly 7,000-panel solar array at the French Prairie Rest Area on I–5 in 2012.


Each highway renewable energy project has a unique context, and State DOTs interested in pursuing this option must consider applicable State and Federal requirements—for example, whether the site is located on an interstate highway (which would introduce operational and safety issues), uses for the power, and project goals.

As they explore the possibilities, State DOTs are learning from their peers. Early adopters of ROW solar and State DOTs that are currently pursuing renewables provide lessons based on their experiences for those considering options for the future.

These solar panels are located at the Framingham Service Plaza on I–90 in Massachusetts.


Oregon: An Early Adopter

In 2007, Oregon Governor Ted Kulongoski directed State agencies to meet 100 percent of their electricity needs with renewable energy by 2025. Motivated by this challenge, the Oregon Department of Transportation (ODOT) began looking for renewable energy opportunities and implemented the first large-scale solar roadway projects in the United States as demonstration projects. In 2008, ODOT completed a 104-kilowatt system with 594 solar panels located at the interchange of I–5 and I–205 near Portland.

In 2012, ODOT implemented a much larger project at the French Prairie Rest Area on I–5 in Clackamas County. This 1.75-megawatt project includes nearly 7,000 solar panels and sits on a 7-acre ODOT property at the rest area. ODOT did not need such a large property for the rest area, so it was able to use a portion of it for the solar array. The solar array produces approximately 1.97 million kilowatt-hours of renewable energy annually. ODOT pursued both projects as public-private partnerships with Portland General Electric.

Massachusetts: Solar Power at Multiple Sites

The Massachusetts Department of Transportation (MassDOT) began exploring the potential of ROW solar in 2012 by identifying approximately 60 sites that could be used for solar power generation and vetting the most promising sites within the agency. MassDOT awarded a contract in 2014 for the development of 6megawatts of ROW solar projects across multiple sites. The contractor has completed projects at eight sites totaling 4.3 megawatts; seven sites (3.75 megawatts) are located within the ROW, and another 550 kilowatts of solar canopies and rooftop solar panels are installed at the recently constructed Research and Materials Lab in Hopkinton.

The majority of the ROW sites that MassDOT selected are located along the Massachusetts Turnpike (I–90). One site is located on Route 3 in Plymouth.

MassDOT’s solar projects were public-private partnerships and required no upfront funding from the State. MassDOT leased the sites to the developer for 20 years, and agreed to purchase all the energy generated through power purchase agreements. MassDOT also benefits from a net metering policy in which the agency receives credits on identified utility accounts. The developer benefits from the guaranteed sale of electricity to MassDOT and through State renewable energy credits and Federal tax incentives.

As of August 2018, the eight sites produced 10,750 megawatt-hours of electricity combined. That amount has resulted in net savings to MassDOT of more than $1 million. MassDOT expects to save approximately $525,000 annually, in addition to the $75,000 received in annual lease payments for the sites.

Moving forward, MassDOT plans to determine which potential solar photovoltaic sites it wants to advance under a new State renewable energy incentive program. The new program favors solar canopies. MassDOT plans to explore installing canopies at Park & Ride facilities.

Renewable Energy Partnerships

Several States with ROW solar installations have used power purchase agreements (PPAs) to finance their projects. PPAs are allowed in at least 26 States and provide one option for State DOTs to implement renewable energy projects with no upfront costs.

Under a solar PPA:

  • A contractor finances, installs, operates, and maintains the solar arrays.
  • A private-sector partner (either the contractor or another entity) takes tax incentives and sells the electricity produced by the panels to the State DOT.
  • The State DOT agrees to a long-term contract to purchase the electricity from the solar panels, typically at a lower rate than it had been paying.


Maryland: DOT-wide Solar Program

In February 2018, the Maryland Department of Transportation (MDOT) announced plans to install solar power on up to 35 MDOT sites, including buildings and parking lots. Through a bidding process, MDOT selected six master contractors who will compete to provide solar power at MDOT facilities. MDOT will license land to the developer, who will construct, own, operate, and maintain the renewable energy infrastructure. MDOT will buy power at a fixed rate for 20 to 25 years, and expects electricity cost savings of 30 to 40 percent. In addition, the program is expected to generate 298 construction and 28 operations and maintenance jobs, with more positions added as solar expands to other MDOT sites.

“This innovative project allows MDOT to save money, support jobs, and create a resilient, renewable energy source that will benefit Marylanders for decades to come,” says Maryland Transportation Secretary Pete K. Rahn.

MDOT estimates that the 35 sites will generate 46,000 megawatt-hours per year, or approximately 12 percent of MDOT’s annual electricity usage. The electricity will be used at MDOT facilities or by neighboring residents or businesses, which can subscribe as part of Maryland’s Community Solar Pilot Program.

MDOT is also planning for a second phase of the program, which will begin after project implementation at the initial 35 sites. The second phase may involve implementing solar projects at locations such as Baltimore/Washington International Thurgood Marshall Airport, ports, transit-oriented developments, and also on noise barriers and unimproved land.

MassDOT installed these solar panels along Route 3 in Plymouth and worked with FHWA to obtain the necessary approvals.


Utah: Exploring ROW Solar

The Utah Department of Transportation (UDOT) has installed several small-scale renewable energy projects at its facilities over the last 10 years. They include a small wind turbine and solar panels on maintenance facilities, UDOT buildings, and parking lot canopies. A total of 321 kilowatts of photovoltaic modules are installed, and they generate approximately 632 megawatt hours annually. These projects help UDOT reduce its electricity bills with the renewable energy produced.

To fund these installations, UDOT relied on matching grants from utilities, the U.S. Department of Energy, and American Recovery and Reinvestment Act programs. However, as a public entity unable to take advantage of tax incentives, UDOT found it difficult to get funding for larger projects.

UDOT is implementing solar canopies in a parking lot at its headquarters in Salt Lake City. This aerial view shows the first phase completed and the second phase underway (to the far right).


In 2017, UDOT began to consider ROW solar installations. In December 2017, the department issued a request for information about the feasibility of pursuing solar projects in UDOT ROW. UDOT received six responses, all of which found that UDOT could break even or save money by putting solar power in the ROW. UDOT has identified several potential sites for ROW solar projects and is moving forward with developing a request for proposals for a PPA.

Supporting State Efforts

FHWA offers several resources intended to help State DOTs develop renewable energy projects. Resources are available at Some examples include:

  • A briefing book, Renewable Energy Generation in the Highway Right-of-Way (FHWA-HEP-16-052), which provides an overview of highway renewable energy project business models, funding sources, and regulatory requirements, as well as case studies and sample pilot projects.
  • A Quick Guide that points transportation agencies to the relevant Federal regulations on ROW renewable energy projects.
  • Reports documenting four peer exchanges at which State DOTs and other practitioners shared information on accommodating renewable energy technologies in the ROW.
  • Research reports on topics related to alternative uses of the ROW, including photovoltaic noise barriers and sustainable rest area design and operations.

As interest in ROW renewable energy continues to grow and the technologies available expand and drop in price, FHWA plans to continue to support transportation agencies in their renewable energy efforts.

Tina Hodges is an environmental protection specialist at FHWA. She conducts research, technical assistance, and outreach to improve the sustainability of transportation networks and enhance the resilience of transportation to climate change impacts. She has 13 years of experience on these issues at FHWA and the Federal Transit Administration. She holds a master’s degree in public policy from the University of Maryland.

Amy Plovnick is a community planner at the U.S. Department of Transportation Volpe Center. Her work involves research, coordination, and policy analysis for projects related to resilience, sustainability, active transportation, and transportation planning. She has a master’s degree in city planning from the Massachusetts Institute of Technology and a B.A. in political science and environmental studies from Washington University in St. Louis.

For more information, see or contact Tina Hodges at 202–366–4287 or