Green Mountain Power (GMP), Vermont’s largest utility, plans to create new microgrids and community resilience zones as part of a plan to “radically transform” the grid that is outlined in the utility’s new integrated resource plan (IRP).
IRP filings are closely watched within the energy industry because they signal how utilities intend to invest capital in the future. GMP, which delivers over three-quarters of Vermont’s electricity, files an IRP every three years.
In the latest plan, the utility said it wants to transform the grid into a two-way sharing system, generate more renewable power close to where it will be used, and foster electric vehicles.
“This work is imperative and requires that we evolve quicker than we ever have before. The climate challenges and catastrophes experienced across the country are heartbreaking and motivate us to move even faster as we radically transform the greater grid here in Vermont and deliver something much more resilient and dynamic,” said Mari McClure, GMP president & CEO, in the IRP’s introduction.
Hyper local planning
To prepare for a distributed energy future, GMP plans to engage in “hyper local planning,” leveraging technological innovations to “drastically improve” resiliency. The plan calls for designating up to six resiliency zones within its service territory. The utility is determining where the zones will be located based on electric reliability data, communications/broadband connectivity data and social vulnerability indicators. So far it has identified four communities that it is working in partnership with to improve resiliency.
One is Rochester, where a microgrid will serve an area along Route 100 that has town water pumps and an emergency shelter at an elementary school. A request for proposals went out in August for the project’s renewable generation and storage. The town and utility have identified a potential site for solar behind an unused former high school. The utility expects the microgrid to be operational by December.
Microgrids with advanced inverters
Another microgrid will be installed in the town of Stafford. Located downtown, the microgrid will serve emergency shelters at the Newton School, Rosa Gym, Barrett Hall, and the general store and post office. It will tap into a smaller solar project owned by the town along with a 7-MW solar installation that was built at the Elizabeth Mine, a former superfund site.
In building the Stafford microgrid, the utility plans to replicate what it achieved with its now operating Panton Microgrid — a solar-plus-storage project that can island a distribution circuit using inverter-based sources with no reliance on fossil fuel generation backup.
With 1 MW of solar and 4 MWh of energy storage, the Panton microgrid serves 51 customers, including 45 residential customers, town facilities, a farm and three other commercial customers.
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The utility partnered with Schweitzer Engineering Laboratories and Tesla to design the Panton system. The project was commissioned in October 2021.
“This took a tremendous engineering effort but most importantly shows that we can make this transition and create new ways to assure resiliency and reliability in more difficult to serve areas,” said the utility in the IRP.
The utility plans to also use the Panton project to test and evaluate other benefits of advanced inverters and explore use of the microgrid for reactive power support and conservation voltage reduction.
Other grid resiliency zones
Two other grid resiliency zones are being planned, one in Grafton and the other in Brattleboro.
A pocket of Grafton has poor cell coverage and residents rely on fiber for internet. When the power goes out, so do their modems and they lose the ability to communicate with the outside world. A conventional correction would cost $456,801 for 3.5 miles of new single-phase tree wire. Instead, GMP intends to undertake a pilot program that will offer customers solar and storage.
The utility also plans to offer battery storage to a cooperative housing community in Brattleboro that is vulnerable to flooding. The batteries will support the community’s load during severe weather and provide resiliency for a local water pumping facility. During normal conditions, the batteries will provide peak savings and other grid services.
In addition, the IRP tackles the issue of how to manage the growth of behind-the-meter distributed energy resources and points to microgrids as one solution.
“In response, integrated resource planning is expanding to require additional analysis to capture multisystem level impacts. A redesign of radial subtransmission systems to looped systems, load control, generation curtailment, storage and microgrids are some mitigation solutions,” the IRP said.
Electrification to drive up demand
IRPs typically examine future load growth, and this one does as well. It finds that demand for power will start to rise because of electrification, after years of decline.
The plan also describes transmission and distribution upgrades, renewable energy additions, use of energy storage for flexible demand, power purchase plans, and other investments and innovations the company plans to pursue.
Available on GMP’s website, the IRP is being reviewed by the Vermont Public Utility Commission in a proceeding that will include opportunity for public input.
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