Case Study: Portsmouth Naval Shipyard achieves energy resilience and $6.2M annual savings with Ameresco microgrid and CHP solution

Portsmouth Naval Shipyard Relies on a Microgrid Solution When Off Is Not an Option

Portsmouth Naval Shipyard in Kittery, Maine needed a resilient, self-sufficient energy system to eliminate downtime during public utility outages and reduce long‑term energy costs. Ameresco was selected by the U.S. Army Corps of Engineers and the U.S. Navy to deliver a multi‑phase Energy Savings Performance Contract (ESPC) and a grant‑funded microgrid solution, including a Combined Heat and Power (CHP) plant, fast load‑shed microgrid controls, battery energy storage, and ongoing operations & maintenance.

Ameresco designed and installed comprehensive upgrades to the shipyard’s steam, power and control systems—including a 10.4 MW / 280,000 lb/hr CHP plant (two 5.2 MW turbines), two 70,000 lb/hr heat recovery steam generators, two 70,000 lb/hr package boilers, two 2 MW emergency diesels, a microgrid control system with fast load‑shed, and a 500 kW / 580 kWh BESS—under a $44M ESPC plus a $3.6M DoD grant. The work delivered 10 MW winter (5 MW summer) capacity and 14 MW emergency capability, retired 60‑year‑old boilers, and produced measurable benefits (2016 savings $6.2M; up to 43.165 million kWh annual energy savings), enhanced reliability and energy security, and enabled ancillary grid services.

Portsmouth Naval Shipyard

Russell Gagner

Production Division Director, PWD-Maine, NAVFAC MIDLANT