Voices of Experience: Microgrids for Resiliency

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Estimated reading time: 30+ minutes

Why This Matters for Rural Electric Co-ops

This guide gathers what roughly 105 utilities learned about using microgrids to keep critical services running during long outages. It is not a how-to, so the value to a co-op is the vocabulary and the sequence of questions to work through before money is committed.

One caveat shapes how to read it. The economics and utility role sections assume a commission deciding whether costs can be socialized through rates, which is not how many co-ops answer for an investment, so a reader on a board-governed co-op has to translate that material before it means much. The parts that need less translating are Georgia Transmission Corporation's four-option comparison, NCEMC's work with its member co-ops, Holy Cross Energy's DER tariffs, and Lincoln Electric System's islanding redesign.

Key Takeaways

Implementation Considerations

• Cost or Funding Requirements: A 2018 NREL/NLR study put mean total microgrid costs between roughly $2 million and $4.4 million per MW, with controllers averaging $155,000 per MW. Most projects profiled here combined several funding sources, including grants, city or customer investment, and ratepayer cost recovery.
• Staffing or Technology Requirements: Controller selection, interconnection studies, and operating agreements require engineering capacity that most distribution co-ops do not hold in-house. The NCEMC model, where the G&T develops projects alongside member co-ops, and regional collaboration generally, are realistic paths for smaller co-ops.
• Time-Sensitive Information: Published November 2020. The battery price data stops at 2018, the microgrid cost ranges come from a 2018 study, and several projects described as pending (the Bronzeville build-out, Xcel's Colorado PUC decision, PG&E's temporary microgrid procurement) have since moved on. Treat all cost figures as directional and re-price before using them in an analysis.

Notable Examples

• Georgia Transmission Corporation (G&T cooperative): Compared four resiliency options for a rural community served by a 16-mile radial line with chronic outages, and found the traditional wires solution still won on a 35 year net present worth basis. The one case in the guide where a microgrid loses on the numbers and the reasoning is shown.
• North Carolina EMC (NCEMC): G&T that partnered with member distribution co-ops on the Ocracoke Island, Butler Farms, and Heron's Nest projects, and shares what it learned about contracting.
• Holy Cross Energy: Colorado co-op using an advanced distribution management system and DER tariffs to deliver what it calls a functional microgrid.
• Lincoln Electric System: Municipal utility, but the lesson transfers without translation. Widening the islanding boundary to cover a whole downtown area proved cheaper than automating a narrow one around critical facilities.
• ComEd (Bronzeville Community Microgrid): Utility-operated community microgrid cluster, paired with a framework for measuring energy, infrastructure, and community resilience.
• Portland General Electric: GIS suitability analysis for siting that weighs critical facilities, flood and landslide risk, population density, and median income.

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Estimated reading time: 30+ minutes