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Stronger Systems: Integrating Electric Vehicles and Microgrids

Jennifer Wallace-Brodeur, Director of Transportation Efficiency -


Martha’s Vineyard sits off the shore of the Massachusetts mainland, just south of Cape Cod. The island community is home to 20,000 year-round residents and it is only accessible by boat or plane. The region is home to beautiful ocean vistas, sandy beaches, and fertile farmland. The community is known for being environmentally conscious and it has taken steps to keep the surrounding environment as pristine as possible. Reducing the use of diesel fuel on the island has been one such step.

The Martha’s Vineyard Transit Authority (VTA), provides year-round public transit service to the six towns on the Vineyard. In recent years, the VTA began considering ways to clean up its fleet and ensure reliable service for its passengers. Their goals for a cleaner, greener, and quieter fleet made vehicle electrification a natural next step. Electric buses bring the benefits of quiet engines and cleaner air to communities, while also reducing global greenhouse gas emissions. And while electric buses have a higher up-front cost than diesel buses, their lower maintenance and fuel costs make them an economically wise investment in the long run.

The benefits are compelling. However, there are some challenges associated with adopting electric buses. For instance, fuel cost savings can be eroded if buses are plugged in at times when there is high demand on the grid, and if the power goes out and the buses can’t charge then service is interrupted; a primary concern for an island community that it is often the last to have power restored. As the VTA began to consider electrifying their fleet, questions of how to address these challenges arose.

“We knew we wanted to go electric, but there were unanswered questions that we needed to address first - How can we integrate charging without disrupting service? What happens if the power goes out? We wanted to ensure we had adequate resiliency and flexibility for our charging capabilities and energy sources to ensure we could always charge the buses.” said VTA Administrator Angie Grant. “By engaging with VEIC and other key stakeholders, we were able to establish a path forward that will meet the needs of the community.”

The result of this collaboration is the planned launch of what could be the nation’s first fully integrated, clean, resilient, and flexible public transportation system.

Integrating transit and electric systems

The answer to the VTA’s questions and the challenges of getting an electric fleet up and running is a single-customer microgrid. Microgrids are small, self-contained distribution, storage, and generation networks which typically are connected to the grid, but can be fully self-sufficient when needed. They use local energy generation and energy storage to produce and provide power. These attributes of independent control and renewable generation are particularly valuable in the event of a power outage.

Microgrids are a natural pair for electric vehicles. The VTA is putting this integration into action as they take on their all-electric fleet aspiration. Their microgrid, which is currently in development, will provide solar panels and energy storage infrastructure to charge buses at their maintenance facility overnight. With a microgrid-supported charging system, the VTA will be able to “fill up” their vehicles during the day without incurring high electric demand charges. The VTA will also be able to use higher-powered charging systems, without straining the grid. On-route chargers will be installed and powered by smaller solar and storage systems on high volume bus routes. These systems will help the VTA manage their fuel costs and provide overall electric reliability.

Collaboration between electric utilities and transit agencies is paramount. With an established partnership, it is possible to more strategically integrate an all-electric transit system with the grid. For instance, the solar and storage redundancies of the microgrid enable off-grid charging, as needed, to prevent peak electrical use during high-demand hours. This helps to meet the demand for electricity at any time of day and reduce energy costs.

Benefiting the community and the grid

VEIC assessed alternative fuel options and energy storage systems, wrote grants, and provided technical support to help the VTA to electrify their fleet and create this microgrid-supported bus-charging network. The VTA now has six all-electric buses on the island, with four more on the way, and six depot chargers installed. Energy storage at their main facility will be funded by a grant from Advancing Commonwealth Energy Storage (ACES)

The project has promising benefits for the VTA and the Martha’s Vineyard community. Public transit agencies are integral to community emergency response plans. Therefore, having a system that allows the transit agency to charge their vehicles when transmission lines and / or fuel supplies are down makes high-quality service possible, even during a power outage, extreme weather event, or other disaster.

The Martha’s Vineyard project is an example of pairing systems to create more sophisticated, strategic, and efficient operations across multiple areas of the energy sector. The result is a more sustainable and resilient community. The VTA and VEIC are working together to learn what works well and what challenges exist in this project, and will develop and demonstrate a roadmap for a viable, integrated electric transit microgrid system. With a widespread rollout of this model, the future of our communities would be stronger, more resilient—and emission-free.  

Contact VEIC to learn more about this project and other innovative system-wide benefit projects taking place at VEIC.

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