Ground Broken on Nation’s Largest Self-Sustaining Bus Depot

In a strategic partnership with developer AlphaStruxure, Mortenson Construction has been assigned as the engineering, procurement and construction partner for the Montgomery County David F. Bone Equipment Maintenance & Transit Operation Center fleet depot EV charging and microgrid project in Derwood, Maryland.

The EMTOC microgrid will include up to 2.25 MW of electric bus charging capacity powered by 5.5 MWDC of rooftop and canopy solar generation, 2 MW battery energy storage and existing backup generation, along with plans for an onsite 1 MW hydrogen electrolyzer.

The microgrid will not only power a mixed fleet of battery electric and fuel cell electric buses, but also the EMTOC campus’ five existing buildings, ensuring uninterrupted service in the event of a loss of utility power. It is engineered to operate in island mode indefinitely, guaranteeing the county’s operations during extended power outages, thereby enhancing the project’s reliability and the community’s resilience.
As the project’s EPC partner, Mortenson plays a crucial role in coordinating with all stakeholders to ensure alignment and clarity throughout the design and construction processes.

The EMTOC project is a pivotal stride toward Montgomery County’s ambitious goal of achieving 100% emissions reduction by 2035 by reducing emissions from public transportation, while bolstering the community’s resilience and infrastructure assets. By 2035, the facility is projected to house over 200 zero-emissions buses.

When completed, EMTOC will be the largest renewable energy-powered transit depot and transit microgrid in the United States.

The project recently broke ground, and operations are expected in fourth quarter 2025.