Solar-Powered Microgrid to Power Electric Buses in Maryland, Washington

Several electric buses will be powered by a microgrid, making it the first of its kind in the Washington region. The Brookville Smart Energy Bus Depot will be the first of many transit agencies to look to the sun to power the microgrid.

Montgomery County seeks to convert publicly owned vehicles to zero-emission by 2035. The fight against climate change in the DC region has made transit agencies look into replacing fossil fuel buses with more electric buses. The county has more than 370 gas-powered buses and will add ten electric buses to its fleet. These electric buses are powered by the traditional electricity grid.

The county will also install microgrids in more depots, integrating renewable energy and battery storage for resilient vehicle charging. Afterward, a depot like the Brookville Bus Depot will charge up to 60 buses. While microgrid technology is used in Washington, the depot will witness its first use to charge electric buses.

During a recent tour at the Brookville Depot, Montgomery County Executive Marc Elrich said, ‘This is the kind of thing we have to do to meet our climate goals. The grid is clean, so the cleaner energy we use as a source, the more likely we are to be successful in reducing our total greenhouse gas emissions. That’s the goal.’

For this project, the county is partnering with AlphaStruxure in a public-private partnership. AlphaStruxure sought Arup’s engineering capabilities to upgrade the existing depot infrastructure. They will install the microgrid and connect all the necessary components. The system includes 2MW of photovoltaic panels on an overhead canopy, natural gas generators, and a battery energy storage system. The solar panels will capture energy to charge the bus batteries. Then the microgrid can store excess energy from the sun, natural gas power generators, and the traditional electricity grid.

Also, the microgrid will operate in multiple modes. The operators can switch between grid connectivity and the island mode, This system will help to achieve total resilience against grid outages during weather disturbances.

While the tools for installation and buildup are available, there is a need for market analysis and coordination among other vendors. Therefore, the county is partnering with the Carlyle Group, an asset management company, and energy provider Schneider Electric.

Upfront costs remain a barrier to electrifying bus fleets by transit agencies. The county purchased electric buses with Federal Transit Administration grants. AlphaStruxure began the project, fronting the capital, and the county is expected to pay back monthly over 25 years, alongside its power bill.

Transportation agencies drive more miles than private vehicles, resulting in the largest source of carbon emissions. This project aims at reducing carbon emissions by 62%, adding a lifetime greenhouse gas benefit of 155,000tons for the microgrid-powered bus fleet. Residents along the bus routes will enjoy cleaner air and a quieter environment.

Sebastian Castellanos, a senior research associate at the World Resource Institute’s Ross Center for Sustainable Cities, said, ‘Diesel engines and gasoline engines are very inefficient machines. Even if the grid is not 100 percent clean, gains in efficiency are mostly sufficient to offset any additional emissions from the grid.’

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