The integrated microgrid will be connected to the utility, but engineered to operate indefinitely in island mode, according to developer AlphaStruxure.
An integrated microgrid infrastructure project in Rockville, Maryland will be the largest renewable energy-powered bus depot in the nation and the first on the East Coast to produce green hydrogen on-site, according to developer AlphaStruxure.
The microgrid will be constructed at Montgomery County’s David F. Bone Equipment Maintenance & Transit Operation Center (EMTOC), which is the County’s fifth largest energy user. With the depot eventually powering 200 zero-emissions buses, it will support the County’s climate goal of reaching 100% reduction in carbon emissions by 2035.
The 7 MW microgrid will consist of 5 MW of Sunpower solar modules, a 2 MW/7.35 MWh Schneider Electric battery energy storage system, and 4.5 MW of charging capacity. It will also use SMA inverters and feature EV chargers from Heliox and PowerCharge.
The integrated microgrid, which is expected to be operational in the fall of 2025, will be interconnected to the utility, but engineered to operate indefinitely in island mode, according to AlphaStruxure. Once built, it will be able to power not just electrolysis but the depot’s five existing buildings and battery electric bus charging. As a self-sufficient microgrid, it will do so with or without utility electricity, and can export up to 2 MW back to the grid, the company reports.
Unique to this microgrid is the 1 MW hydrogen electrolyzer that will be powered by the on-site solar energy and used to support fuel cell electric buses and enhance the county’s Bus Rapid Transit (BRT) network.
The County’s 2024 fleet transition plan calls for replacing 100% of its nearly 400 fossil-fuel-powered buses with a mix of battery-electric and hydrogen fuel-cell electric buses, while also scaling the entire fleet to about 600 buses by 2035. With this microgrid, the County is planning in advance how to power these zero-emissions vehicles by strategically coupling procurement of both the vehicles and the infrastructure.
“What you don’t want is to get these vehicles on site and have no way to charge them. It’s a balance between infrastructure done and the fleets in at the same time,” said Michael Yambrach of the County’s office of energy and sustainability.
Montgomery County created a public-private partnership with AlphaStruxure to design, build, finance, own, and operate the microgrid. The Counted used AlphaStruxure’s Energy as a Service agreement under which AlphaStruxure designs, builds, owns and operates the infrastructure, and taps an investment firm for financing.
