What is a microgrid?
The DOE defines the microgrid as ‘‘a group of interconnected loads and distributed energy resources within clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid. A microgrid can connect and disconnect from the grid to enable it to operate in both grid-connected or island mode.’’
For more information from DOE, please review their Microgrids Overview, which includes cost estimates, design considerations, and best practice tips.
Credit: NORESCO
Why are microgrids beneficial?
Microgrids provide efficient, low-cost, clean energy, enhance local resiliency, and improve reliability of the regional electric grid.
Benefits:
- Resilience
- A microgrid provides customers with energy resilience by avoiding power outages in the first place, or quickly recovering if they do occur. In the case of an outage, the microgrid can be programmed to restore power to an entire facility, or just the most critical components. Once grid power is restored, the facility can resume normal operations more quickly because it did not have to shut down completely.
- The Microgrid for Community Resilience grant program focuses on enhancing resilience for community anchor institutions (such as schools, fire stations, and hospitals). In rural communities, those centralized community spaces are critical - especially in times of extreme weather or emergencies.
- Reliability
- Microgrids keep the power flowing during an outage by disconnecting from the grid in “island” mode. The system’s controller switches from grid power to the microgrid’s local power sources when it senses an outage. Solar, back-up generators, battery energy storage or the microgrid’s other distributed energy sources then serve its customers until the grid’s power is restored.
- A microgrid can be used to strengthen the broader electric grid by augmenting normal grid operations or easing the strain on the central grid during periods of peak demand.
- Cost savings
- Microgrids can reduce the energy costs of their customers by efficiently managing energy supply, which helps customers budget for energy costs in both the short and long term.
- Promoting clean energy
- Microgrids can use a wide range of clean energy generation technology (solar, wind, fuel cells, combined heat and power plants, energy storage). Using these diverse energy sources together ensures that the microgrid can overcome any downsides of a specific technology.
Examples of Microgrids as Community Resilience:
National:
New York University: During Superstorm Sandy, NYU’s microgrid successfully islanded from the local distribution grid and continued to provide reliable power to much of the NYU campus, also serving as a resilience hub for the community. Resilience hubs are community-serving facilities that support residents, coordinate communication, distribute resources, and reduce carbon pollution while enhancing quality of life.
Colorado:
- Red Feather Lakes Microgrid (Larimer County): Community-based microgrid and resilience hub serving library, post office, local businesses, and critical services such as fire response, EMS, and telecommunications in a rural, mountainous region
- Northside Aztlan Community Center (Fort Collins): Community center designed to provide backup power during the fire season to enable the center to host emergency operations and as a resilience hub. Partially funded by DOLA.
- San Miguel Power Association Microgrid: Microgrid system containing two solar PV and energy storage microgrid systems. The system connected two crucial parts of the San Miguel County sheriff’s department: the annex building in Norwood and the Ilium sheriff office near Telluride. This project centered around mission-critical loads. Partially funded by DOLA.
- Pueblo Community Health Center - East Side Center [in development]: This location will be the first net-zero energy health center site in the United States (as of 2020). Health centers considering solar microgrids and back-up battery systems may want to check out the Community Health Access to Resilient Green Energy (CHARGE) partnership. Charge is a collaboration between NACHC, Collective Energy, and Capital Link and provides energy options for health centers supporting communities that are vulnerable to grid outages and have patient populations disproportionately affected chronic disease, poverty and racial and ethnic health inequities.
To learn more about microgrids, visit Microgrid Knowledge or Think Microgrid websites.
Microgrid classification and types
Level 1 “Single Building Microgrid”
This classification of microgrid includes a single distributed energy resource (DER) system such as a solar photovoltaic (PV), combined heat and power (CHP), or fuel cell system that serves a single building interconnected to the grid at a single utility meter location.
- MCR Funded Project: San Miguel Power Association - Ridgway
- Resilience Hub supporting a public community room
- 4.8 kW solar and 37 kW battery, 1.5 days of backup power
Level 2 “Partial Feeder” or “Campus Microgrid”
This classification of microgrid includes either a single or multiple DER system serving multiple buildings, interconnected to the grid at a single utility meter location. Level 2 microgrids can island whole campuses or partial feeders from the distribution grid. A feeder is an electrical line from a utility substation, serving customers within a defined local distribution area. Examples of this classification are a campus setting such as a college or university, healthcare/hospital campus, pharmaceutical complex, or military base.
- MCR Funded Project: Poudre Valley Rural Electric Association - Livermore
- Battery installed at the Livermore Fire Station and serving a retail store, restaurant, school, post office, gas station & more
- 70 kW Solar (State funding) and 350 kW battery (Federal funding)
Level 3 “Full Feeder” or “Community Microgrid”
This classification of microgrid includes a single or multiple DER system serving multiple buildings or customers, however the loads and generation sources may not be interconnected at the same utility meter location. Instead, these advanced microgrids will have one point of common coupling (PCC), where the microgrid can be operated independently from the utility grid. The individual buildings or customers may be independently connected to the larger distribution grid and through the microgrid PCC and some customers may even have Level 1 or Level 2 microgrids that support the operation of the community microgrid.
- MCR Funded Project: Platte River Power Authority - Estes Park
- Leasing a 5 MW (20 MWh) battery on a feeder line in Estes Park, CO
- Serves critical facilities such as Protection District and Hospital