Redwood Coast Airport Microgrid

This report describes the Redwood Coast Airport Microgrid project, the first front-of-the-meter, multi-customer community microgrid in Pacific Gas and Electric Company’s service territory, and key takeaways and lessons learned from the project. The 100-percent renewable microgrid features a grid-forming, front-of-the-meter 2.2-megawatt (direct current) solar photovoltaic array direct current coupled with a 2.3-megawatt (alternating current), 8.87-megawatt-hour lithium-ion battery energy storage system, and a grid-following, behind-the-meter 300-kilowatt (alternating current) solar photovoltaic array, along with four 20-kilowatt (direct current) bi-directional, behind-the-meter electrical vehicle chargers. The microgrid serves 19 retail customers at the end of the Janes Creek 1103 distribution circuit with an aggregate peak load of approximately 330 kilowatts, including the California Redwood Coast-Humboldt County Airport and the U.S. Coast Guard Sector Humboldt Bay Air Station. The microgrid provides dispatchable solar power, as well as regulation up and regulation down ancillary services in the wholesale electricity market. The microgrid features seamless transitions to and from islanded mode and has provided reliable, safe, grid quality renewable power to critical loads during 63 islanding events (including a 6.4-magnitude earthquake and winter storms) covering 71.8 hours of grid outage over a 38-month period.

The project team developed a community microgrid tariff and an associated microgrid operating agreement that allow a third-party-owned, grid-forming generator to supply power to an islanded section of the utility’s circuit. The team’s policy work led to the development of the Community Microgrid Enablement Tariff and the Community Microgrid Enablement Program, and eventually to the statewide Multi-Property Microgrid Tariff and the statewide Microgrid Incentive Program. These developments codified much of the work accomplished in the project and created a regulatory pathway for replication. However, replication of community microgrids still faces significant barriers.

Key challenges include:

• A challenging business model — costs outweigh monetizable benefits partly because the value of resilience is difficult to quantify.
• Complexities involved in developing and deploying a multi-customer community microgrid.
• The high cost and complexities involved in owning and operating a multi-customer microgrid that participates in the wholesale electricity market.