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Montgomery County to Build Nation's Largest Renewable Energy Electric Bus Depot

Updated: Jul 1

Montgomery County to Build Nation's Largest Renewable Energy Electric Bus Depot

Montgomery County, Maryland, has commenced construction on the Brookville Smart Energy Bus Depot near Rockville. This innovative facility will enable up to 70 electric buses to be charged through a solar canopy and battery storage system. Transitioning these buses from diesel to electric—powered by an on-site clean energy microgrid—will cut lifetime emissions by 62%, which equates to over 160,000 tons of greenhouse gases over the next 25 years, according to Arup, the engineering firm behind the project.

By late 2025, Rockville’s David F. Bone Equipment Maintenance and Transit Operations Center will become the nation’s largest renewable energy-powered transit facility. The depot’s microgrid will provide uninterrupted power for transit buses and is designed to run entirely on renewable energy in the long term. This transformation aligns with Montgomery County’s ambitious goal of achieving net-zero emissions by 2035.

The 5.5-megawatt microgrid will boast a solar array, electric bus chargers, battery storage and a hydrogen electrolyzer powered by solar panels. It’s also self-contained allowing independent operations during power outages. Specifically, the microgrid will include:  

  • 5.65 MWDC of rooftop and canopy solar generation 

  • 2 MW/6.88 MWh battery energy storage 

  • Up to 2.25 MW of charging capacity 

  • 1 MW hydrogen electrolyzer 

  • Software tools and IoT-connected hardware  

According to the Montgomery County Government, the microgrid will not only support on-site production of green hydrogen, a resilient fuel source for FCEBs, but also contribute up to two megawatts (MW) of renewable energy back to the utility grid through a Pepco net metering program.

The project is financed with minimal to no upfront cost to taxpayers. County contractor AlphaStruxure handles financing, design, construction, operations, and maintenance. By providing a microgrid through an Energy-as-a-Service (EaaS) contract, AlphaStruxure ensures no capital expenditures for the County. This long-term agreement guarantees predictable operating expenses, performance, and energy pricing.

"By breaking ground on America's largest electric bus depot, Montgomery County continues to lead the country with investments in creating a clean energy future for our children and grandchildren," U.S. Representative Jamie Raskin said. "I'm confident this project will serve as an inspiration for other local governments exploring sustainable energy transitions, and I'm committed to continue strongly advocating for commonsense pro-climate legislation in Congress to benefit Maryland and the nation." 

Benefits of Electric Buses

Switching to electric buses brings a myriad of benefits that extend beyond just environmental advantages. These benefits encompass improved public health due to reduced air pollution, significant cost savings over time, and enhanced energy efficiency. As communities strive to create more sustainable urban environments, adopting electric buses stands out as a crucial and impactful step towards achieving these goals. The specific advantages of transitioning to electric bus fleets include:

1) Improves Local Air Quality

By eliminating diesel exhaust emissions, particulate pollution, and pollutants that contribute to ground-level ozone, electric buses significantly enhance air quality in our communities. This improvement is crucial for densely populated urban areas where air quality is often a major concern. Moreover, electric buses reduce noise pollution, fostering a quieter and more peaceful environment for residents and workers near bus routes. Additionally, by mitigating air pollution, electric buses offer substantial societal benefits, including reduced healthcare costs due to cleaner air.

2) Cost Savings

Electric buses have lower operating costs compared to traditional diesel buses. They require less maintenance, as they have fewer moving parts, and electricity is generally cheaper than diesel fuel. Additionally, with the integration of renewable energy sources through microgrid systems, municipalities can save money on energy costs in the long term.

3) Lowers Greenhouse Gas Emissions

Electric buses generate far fewer greenhouse gas emissions compared to traditional diesel, diesel hybrid, and natural gas-powered buses. Transitioning the nation's entire fleet of diesel transit buses to electric could cut over 2 million tons of greenhouse gas emissions annually. This substantial reduction would help combat climate change and bolster global initiatives for a sustainable future.

Benefits of Microgrids

Microgrids provide a range of significant advantages that support both energy resilience and sustainability. One of the key benefits of microgrids is their ability to operate independently from the main power grid in the event of outages or natural disasters. This ensures uninterrupted power supply for critical infrastructure, such as public transit systems, hospitals, and emergency services, enhancing the community's overall energy security. Other advantages include:

1) Enhances Energy Resilience

Microgrids improve energy resilience by incorporating multiple generation sources, such as solar panels, wind turbines, and battery storage, which can continue to provide power when the central grid fails. This diversification of energy sources reduces the risk of prolonged outages and helps maintain essential services during emergencies.

2) Supports Renewable Energy Integration

Microgrids facilitate the integration of renewable energy systems, such as solar and wind power, into local energy networks. By combining these renewable energy types with storage solutions, microgrids can deliver clean, renewable energy consistently, even when the sun isn’t shining or the wind isn’t blowing. This not only supports environmental sustainability but also reduces dependency on fossil fuels.

3) Reduces Energy Costs

Deploying microgrids can lead to significant cost savings over time. By generating and storing their own energy, communities can reduce reliance on expensive peak-time electricity from the main grid. Additionally, microgrids can participate in demand response programs, selling stored energy back to the main grid during periods of high demand, thereby generating revenue.

4) Improves Grid Stability

Microgrids contribute to overall grid stability by smoothing out fluctuations in energy supply and demand. They can modulate their output to match immediate consumption needs, reducing the strain on the main grid and lowering the risk of blackouts. This dynamic capability is particularly valuable as more intermittent renewable energy sources are integrated into the power system.

5) Boosts Local Economic Development

The implementation of microgrid projects can spur local economic development by creating jobs in the design, construction, and maintenance of these systems. In addition, the reliable and affordable energy provided by microgrids can attract businesses to the area, fostering local economic growth and sustainability.

Overall, microgrids and similar solar plus storage systems not only enhance energy resilience and integrate renewable power but also offer financial and societal benefits, making them a pivotal component of future smart-energy infrastructure.

The Future of Electric Buses

With increasing concerns about air pollution, climate change, and the need for sustainable transportation solutions, electric buses are becoming an increasingly popular option for cities around the world. In addition to benefits such as improved air quality and cost savings, advancements in battery technology are making electric buses a viable option for long-distance travel as well.

As we continue to prioritize sustainable practices and invest in clean energy, the widespread adoption of electric buses will play a significant role in creating a cleaner and healthier environment for generations to come.  So, while Rockville's microgrid project may be the largest in the nation now, it is only one step towards a more sustainable and environmentally-friendly future. In fact, many major cities have already committed to transitioning their entire bus fleets to electric by 2030 or sooner. With this momentum, it is clear that electric buses are not just a passing trend, but rather the future of public transportation.

Government agencies, including counties and school districts, should consider transitioning to electric buses in the near future. Other ways that government agencies can contribute to local clean energy production and decarbonization efforts are to lease their properties (land, rooftops, parking canopies) for renewable energy. Not only does this contribute to sustainability efforts, it can generate revenue through lease payments while transforming government properties into assets.

LandGate helps government agencies lease their properties to renewable energy developers at no cost. Book a call with LandGate's government team for your free site analysis and consultation:


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