Tidal Energy Conversion at an Estuarine Bridge - Integration of a Tidal Turbine into the Living Bridge Project

A tidal energy conversion system was installed at Memorial Bridge, a vertical lift bridge over the tidal Piscataqua River connecting Portsmouth, NH and Kittery, ME, as part of the "Living Bridge" project. The project created a self-diagnosing, self-reporting "smart estuarine bridge" powered by a locally available renewable energy source and transformed Memorial Bridge into a living laboratory for engineers, scientists, and the community.

Estuarine bridges could serve as ideal locations to deploy marine hydrokinetic (MHK) energy conversion systems. The hydrokinetic resource is often strongest at the narrow locations where bridges are usually located. The bridge piers can serve as supporting structure for both the bridge and hydrokinetic turbines, and the permitting process for MHK energy conversion can take advantage of the permitting work and studies required for bridge construction. Utilizing locally available tidal energy can make bridge operation more sustainable and transportation infrastructure more resilient against prolonged grid outages. The Memorial Bridge location in Great Bay Estuary is well-suited as a tidal energy test site, reaching tidal current speeds greater than 2 m/s during spring ebb tides.

A 3.2 m diameter marinized 25kW prototype cross-flow turbine manufactured by New Energy Corporation was deployed in June 2018. The turbine will remain deployed for approximately one year to assess the long-term reliability and suitability to this environment. The tidal turbine will power instrumentation and offset bridge energy usage.

Data from the turbine and estuarine and bridge instrumentation will be reported. The instrumentation system includes acoustic Doppler current profilers (ADCP) and velocimeters (ADV), a Valeport CTD+ (Conductivity, Temperature, Pressure, Turbidity, Chlorophyll), underwater cameras, weather stations, turbine performance data, strain gauges and load cells and bridge structural health monitoring sensors. The data provide insight into the length and time scales present in this tidal flow, and how the tidal energy conversion system interacts with them. Data are available through the Living Bridge web site, https://livingbridge.unh.edu/

The project received funding from NSF-PFI (grant IIP #1430260), FHWA, NHDOT and DOE.