The electric grid to provides electricity to our homes, businesses and town facilities. Our current grid performs well for the most part, but was built and designed when power was generated solely by large plants and transmitted in one direction to customers. Today, with the proliferation of distributed energy resources (DER) such as solar, storage, combined heat-and power (CHP), energy is created in many locations and is transmitted in different directions. Moreover, the current grid infrastructure often limits on how much renewable energy can be built. Security is another important issue. Today’s grid is vulnerable to blackouts during major storms and attacks.
An important building block in modernizing the electric grid is the microgrid. A microgrid, as the name suggests, is essentially a subset of the larger grid. It comprises a range of different electric loads and distributed energy resources (DER) and can operate as a part of the larger grid or separately (aka “island mode”).
An important benefit of microgrids is resilience; by “islanding” from the grid in emergencies, a microgrid can continue providing power to critical services (e.g., hospitals, first responders, governmental functions and emergency shelters). Another important function of microgrids is that they increase the “renewable hosting capacity” of the grid. In other words, they increase the ability of the grid to handle intermittent resources like wind and solar. As renewable “penetration” on the grid increases, the power delivered Community Microgrids will be crucial to expanding renewables even further.
Historically, microgrids have been built around a single entity such as a military base, university or company. However, a form of microgrid of particular interest to cities and towns is the Community Microgrid. The California-based non-profit Clean Coalition defines one as follows:
A Community Microgrid is a coordinated local grid area served by one or more distribution substations and supported by high penetrations of local renewables and other distributed energy resources (DER), such as energy storage and demand response. Community Microgrids represent a new approach for designing and operating the electric grid, relying heavily on DER to achieve a more sustainable, secure, and cost-effective energy system while providing indefinite, renewables-driven backup power for prioritized loads.
Key elements of the Community Microgrid are:
An example of a community microgrid would be a collection of key municipal facilities, a number of community businesses such as grocery stores and gasoline stations, a solar array, battery storage and a backup generator. In the future, the grid might consist of a series of interconnected microgrids.
Completing a Community Microgrid project will require extensive preparation and planning and multiple partners. An important component of a town energy plan is to assess potential sites for a microgrid. With this step complete, the town and its partners will be more prepared to build a microgrid when an opportunity arises. Important partners in planning and implementing a microgrid include:
In Connecticut, the Department of Energy and Environmental Protection (DEEP) has conducted four rounds of a grant program for a diverse range of microgrids with a focus on resilience. This program or other funding opportunities may emerge in the future.