The Unique Charging Infrastructure Needs of Airport EV Fleets

America’s airports are increasingly motivated to electrify their operations and vehicle fleets, including rental cars, ground equipment, and taxis. This transition entails a multi-megawatt expansion with high-power charging infrastructure and optimization via advanced controls, energy storage, and flexible building loads. 

 

An electric rental car refuels at one of DFW’s charging stations. Image used courtesy of NREL/by Werner Slocum

 

The National Renewable Energy Laboratory (NREL)’s Athena ZEV program helps transportation hubs like airports evaluate their infrastructure and charging demands using energy system integration tools and digital twins. The effort begins with the Dallas Fort Worth International Airport (DFW), one of the country’s busiest and largest facilities, with seven runways, 170 gates, and a 26-square-mile footprint, larger than the island of Manhattan. The initial focus identifies strategies to accommodate DFW’s electric rental car fleet. 

The program’s initial analysis found that a rapid high-power charging transition may add a peak load of at least 10 MW—enough power for an average airport terminal. The increased load may cause major grid impacts if not paired with intelligent controls and optimal integration of renewable generation, energy storage, and flexible building loads. 

Future analysis will cover electrical system upgrades and cost-effective charging strategies. The researchers will use NREL’s Advanced Research on Integrated Energy Systems platform, existing digital twins measuring DFW’s buildings and transportation, plus NREL’s other infrastructure tools. NREL will also study charging demands for rideshare services, freights, electrified aircraft, shuttle buses, and ground service equipment. 

 

A model of Dallas-Fort Worth International Airport helps determine infrastructure needs for electrification strategies. Image used courtesy of NREL 

 

The goal is to configure low-cost, behind-the-meter energy storage and solar photovoltaic systems based on weather or climate, building type, and utility rate structure. NREL expects the tools to be replicable for other airports, ports, and transportation operations. 

 

Airport Electrification

Earlier this year, DWF piloted a series of EV charging stations with five demonstrations across customer parking lots. Customers could test different charging solutions like autonomous robotic wireless charging, on-demand charging, and control apps. Lightning eMotors supplied its mobile charging unit for DFW’s demos, with 105 to 420 kWh of battery capacity, standard Level 2 AC charging, and DC fast charging. EV Safe Charge provided ZIGGY, an autonomous robotic EV charger. 

 

ZIGGY, a mobile EV charging robot, was deployed in a pilot program at DFW. Image used courtesy of EV Safe Charge

 

DFW, which aims to reach net-zero carbon emissions by 2030, recently started building a $234 million electric central utility plant (eCUP) to provide sustainable cooling and heating capacity via electricity purchased from renewable energy sources. According to DFW’s 2022 ESG report, the airport’s largest carbon segment is natural gas used in the existing terminal heating plant. The new facility will transition most of its heating load from natural gas to renewables, including electricity purchased from Texas wind farms. It also self-generates renewable electricity via its solar array. 

DFW is also researching on-site energy production and storage infrastructure, battery systems for outage backup, and the use of demand response to optimize peak demand. 

Many of the country’s busiest airports are currently pursuing similar electrification and emissions strategies. Some will use NREL’s insights as official stakeholders in the Athena program, including Georgia’s Hartsfield-Jackson Atlanta International Airport, Colorado’s Denver International Airport, and California’s Los Angeles International Airport. 

 

The Unique Needs of Airports: What Do Existing Models Say?

The announcement marks the second phase of Athena ZEV, which started in 2018 and finished in 2021, with some interesting results and tools that will inform future work in the program. NREL’s researchers developed models of current and future mobility requirements for efficient transportation. They used machine learning and real-time sensor data to make a digital twin of DFW’s roadways and transport systems. They also simulated the impacts of conditions on energy needs and traffic. 

One research project involved developing a novel optimization model previewing airport decisions from 2025 to 2045. It was tested with more than 30,000 operational circumstances, resulting in over 200 million decision variables. 

The model showed that combining remote parking and remote curb infrastructure reduces emissions and accommodates EVs and autonomous vehicles (AVs) while managing airport passenger growth. A remote curb infrastructure expansion could apply to the front shuttle fleet and vehicle staging areas, for example, making way for road improvements and a dedicated AV road network. 

The model also recommended $336 million in infrastructure improvements over 25 years. That includes 314 EV buses with 550 kWh batteries at $800,000 per vehicle and 37 90-kW chargers at $100,000 each. 

Other studies in Athena’s first phase focused on traveler behaviors, parking and traffic trends, road network and curb congestion, and the rise of transportation network companies (TNC) like Uber and Lyft. 

 

An overview of the digital twin framework. Image used courtesy of NREL

 

In one study on traffic patterns, NREL built a digital twin informed by two years of vehicle arrival and departure data, weather, and aircraft movements at the DFW airport. The digital twin uses time series methods to forecast curbside traffic demand, combined with a traffic microsimulation network to measure congestion under different conditions and policy impacts.