Overview
Power outages can have a significant safety and operational impact to state departments of transportation (DOTs) including interruption to traffic signal equipped intersections, Intelligent Transportation Systems (ITS), and communication hubs. In California, Oregon, Washington, and other western states in particular, utilities may need to turn off power during severe weather to help prevent wildfires that can occur when dry conditions and high winds cause trees and debris to contact energized lines and damage utility equipment. Further, power companies typically initiate these Public Safety Power Shutoffs with one hour or less advance notice.
A traditional solution to mitigate power outages at field sites are gas- or diesel-powered portable generator sets. However, these portable generators must be refueled every few hours and need frequent maintenance, requiring extensive manpower commitments. In addition, portable generators are not sustainable and conflict with climate change goals seeking to reduce or eliminate fossil fuel usage. In California, recent legislation eliminates the sale of small gas-powered engines used by portable generators as soon as January 1, 2024. Battery backup power systems connected to the grid also require frequent maintenance and typically only provide power for less than a day.
A promising alternative that reliably and cost effectively mitigates power outages to traffic operations field equipment and other critical ITS elements is a hydrogen fuel cell (HFC) power backup system. The system generally consists of hydrogen fuel cylinders, an HFC cabinet, and electrical connections, switches, and controllers.
Benefits
- Increased safety of the traveling public by eliminating dark intersections and powering other ITS infrastructure, including dynamic message signs, traffic cameras, communication hubs, and other ITS equipment that contribute to safe operations of the transportation network.
- Reduced maintenance burden relative to alternative gas/diesel-powered portable generators or onsite battery backups. The runtime of an HFC is only limited by the amount of hydrogen stored onsite. Typical configurations using an electrical load of 750 watts yield runtimes of up to 80–90 hours, before the need to refuel. Longer runtimes can be obtained by increasing the number of hydrogen cylinders at the field site.
- Elimination of fossil fuel consumption and greenhouse gas emissions, as HFCs burn cleanly, producing water vapor as their emission.
Deployments
- Caltrans District 11 (San Diego) conducted a pilot in 2021 of an HFC to provide seven continuous days of backup power to the traffic signal, two traffic cameras, and a communication system at the intersection of SR-67 and Scripps Poway Parkway in Poway. See additional information in this white paper
- District 2 (Redding) and District 3 (Marysville/Sacramento) are piloting four HFC power backup systems during 2023–2024 (D3 also has one existing installation). If these pilots perform successfully, Caltrans could develop statewide policy and standards to allow easy integration into the design of future ITS/traffic signal field sites and/or the retrofit of current field sites. See additional information in this
Caltrans research summary.
- City of Santa Clarita HFC power backup for the traffic signal at the intersection of Soledad Canyon Road and Whites Canyon Road, which serves 80,000 vehicles per day and is situated along a fire evacuation route. The system provides 55 hours of backup power. See additional information in this
City of Santa Clarita news release.
Contact
Louie La Compte
Field Systems Engineer
California Department of Transportation, District 11 (San Diego)
louie.lacompte@dot.ca.gov
(858) 518-3850
