Dulles International Airport serves the US capital of Washington DC and is set to join a growing number of American airports that are putting the grassy territory around their runways to use producing solar energy. Planners of Dulles’ proposed solar farm and storage facility hope it will become the largest airport-based project in the US.

There is stiff competition for the title. According to a 2020 study conducted by the University of Colorado Denver School of Public Affairs, 20% of US public airports have adopted solar photovoltaic (PV) systems over the last decade. Solar farms converting sunlight into electricity using semi-conducting materials are a good fit for airports, whose runways, taxiways and terminals are generally surrounded by plenty of land, unobstructed by trees or tall buildings.

Dulles International Airport  
The Dulles International Airport solar project is located in northern Virginia and has been under discussion since spring 2018. Interest has grown since the passage of the Virginia Clean Act in 2020. The Act requires Dominion Energy, which supplies power to the area, to deliver electricity from 100% renewable sources by 2045.

The Metropolitan Washington Airports Authority, which oversees Dulles airport, proposes to sub-lease about 835 acres of land to Dominion Energy for development of a major solar PV system. This is according to the Federal Infrastructure Projects Permitting Dashboard, an online tool for tracking the federal government’s environmental review and authorisation processes for large or complex infrastructure projects.

The proposed facility is planned to consist of arrays of 350,000–400,000 solar PV modules to provide about 100 MW of generating capacity to the public electricity grid for Dominion Energy customers, including the Metropolitan Washington Airports Authority.

Under an arrangement between the Authority and Dominion Energy, the energy company would not lease the land directly, but would help make the airport more sustainable. Dulles International Airport would construct, operate and maintain a 2 MW ‘behind-the-meter’ solar carport (a solar energy-trapping canopy placed over a parking area) and provide the Airports Authority with electric buses, light-duty electric vehicles (EVs) and vehicle charging infrastructure.

Behind-the-meter systems do not involve power retailers but supply electricity directly from a power purchase agreement (PPA) provider to the client.

By contrast, front-of-meter solar panel systems, such as in Indianapolis International Airport (IAA), see PPAs delivering electricity from solar panels to consumers through power lines owned by the local energy company.

America’s largest solar project 
One of the largest airport solar farms in operation is in Colorado, near the Rocky Mountains. Denver International Airport (DIA) is the largest airport by landmass in North America, covering 53 square miles, according to Scott Morrissey, DIA’s Senior Vice President of Sustainability. DIA is home to 150 acres of solar panels, providing 35 MW of on-site solar capacity.

‘It’s one thing to have a lot of land area, but it’s another thing to put it to productive use. That’s the linkage for us,’ says Morrissey. ‘The giant solar array allows the land to support us in what we’re trying to do.’

The US Department of Energy encourages US airports to host solar energy projects
Photo: US Department of Energy

The DIA solar project began in about 2008. Supply chain concerns and uncertainly about incentives at the federal level have caused headaches, Morrissey admits. Today, however, he says ‘the programme works well’ and that: ‘We have been adding new projects every couple of years since it began and are continuing to look for more.’

About 30% of the airport’s electricity use currently is offset by the solar panels. Morrissey expects that to increase to about 45% next year, after yet more capacity is added. However, he does not foresee the airport producing enough excess energy to sell power to the grid for profit in the near future. The Denver airport system is an onsite system, behind-the-meter, working with utility Xcel Energy to operate and draw power from solar panels on the airport.

US solar survey 
Serena Kim, a researcher at University of Colorado Denver School of Public Affairs, conducted a survey of 488 public airports across the US in 2020. She discovered that: ‘While only 20% of airports have adopted solar energy in the last decade (about 100 airports), airport solar energy is more likely to appear in the service area of investor-owned utilities, which have greater resources and expertise to invest in renewable energy.’

Kim suggested: ‘Policymakers who wish to facilitate on-site solar use should consider strategies for addressing resource and information gaps across investor-owned utilities, municipal utilities, and rural electric cooperatives.’ 

Indianapolis initiative 
Indianapolis International Airport (IAA) leases land at its central Indiana facility. Private sources funded the solar farm. IAA’s partners are the City of Indianapolis, AES Indiana (formerly the Indianapolis Power & Light Company), General Energy Solutions, Cenergy Power, Telamon Corporation and Johnson Melloh Solutions. The energy produced by the airport solar farm is sold to AES Indiana, the city’s electric utility company, through a PPA and feeds into the grid of existing surface transmission lines connected to the airport.

IAA unveiled its 44,000-panel solar farm on 75 acres in central Indiana in 2013. Since then, the project has grown to 183 acres, with 87,500 panels that generate enough electricity to power over 3,600 average US homes annually. Each panel can produce 280–305 Watts at peak power production. The panels are installed on fixed ground-mounted racking systems and ground-mounted tracker systems that can turn to face sunlight.

‘While only 20% of US airports have adopted solar energy in the last decade, airport solar energy is more likely to appear in the service area of investor-owned utilities, which have greater resources and expertise to invest in renewable energy.’ – Serena Kim, University of Colorado Denver School of Public Affairs

Smaller projects 
Smaller airports are also seeking to turn land unusable for aviation purposes into solar farms.

Late last year (2021), a proposal was approved to build a 7.5 MW solar farm on 18 acres at the Augusta State Airport, owned by the state of Maine but run by the city of Augusta, which is also the state capital. Once in operation (no date has yet been announced), the project would feed electricity into the power grid, offsetting the state’s electrical costs over the 21-year lease with a private developer that would build, operate and maintain the system for the state.

Chattanooga Metropolitan Airport (CMA), operating on 950 acres in south-eastern Tennessee, launched its solar project in 2011. The phased programme was expanded in 2013 and was completed in 2019. Starting with a 1 MW solar farm of 3,948 solar panels, the second phase was a 1.1 MW solar farm comprising 3,542 panels each with 72 cells. The third was a 641 kW solar farm, consisting of 1,886 panels. The three phases together produce 2.73 MW, meeting all the airport’s energy needs.

The CMA solar farm was funded through a US Federal Aviation Administration (FAA) Voluntary Airport Low Emission (VALE) grant, according to Blake Poole, Vice President, Air Service and Economic development, for the Chattanooga Airport Authority.

VALE grants help airports meet state-related air quality responsibilities under the US Clean Air Act, the country’s primary federal air quality law. The grants are issued to airports that are in ‘non-attainment’ or ‘maintenance’ areas with poor air quality as per the National Ambient Air Quality Standards (NAAQS), assessed under the Act. Chattanooga became eligible for air quality grant funding in 2010. As of September 2022, VALE grants have funded 138 projects at 59 airports.

The renewable energy produced by the Chattanooga airport solar array is sold to the Tennessee Valley Authority (TVA), a US federally-owned electric utility corporation. The airport then buys its power from the local electric power distributor EPB of Chattanooga, which works with the TVA.

Poole notes that during the early days of the COVID-19 pandemic, passenger traffic dropped. ‘But even during COVID, the sun was out so we were producing electricity to sell to TVA. That’s one of the things that helped us to get through the pandemic and it continues to help us keep our cost down. We’re continuing to produce electricity and selling it back,’ he says.

Sustainability is the goal 
Sustainability is the ultimate goal of many US airports that have installed or are planning solar farms. Mario Rodriguez, Executive Director of the Indianapolis Airport Authority, says the midwestern airport has always been conscious of sustainability. ‘We meet standards but really go a step beyond’, he comments, also noting that the Indianapolis terminal was a pioneer in securing Leadership in Energy and Environmental Design (LEED) certification in 2011.

Rodrique maintains: ‘We have one of the largest all-electric shuttle-bus fleets in the nation. We are the largest carbon-accredited airport in North America, and we are currently rebuilding a $190mn runway using carbon capture and recycled concrete.’

Meanwhile, Denver airport continues to find ways to increase sustainability throughout the facility and is close to completing a rooftop solar array, according to Morrissey. ‘The mandate comes from the top. Our CEO says we are going to be one of the most sustainable airports in the world.’

Chattanooga airport has long sought several ways to increase sustainability also. According to Poole: ‘We got into this because of the issues with pollution in the city. The airport wanted to contribute to the solution.’ Chattanooga broke ground on a solar energy project in 2021, securing LEED platinum certification, and has adopted green cleaning products, green pest control, green landscaping practices and recycling programmes.

The solar farm fits right into the airport’s green plans. ‘It’s all part of the big picture,’ says Poole.