In-Stream Tidal Technology in the Bay of Fundy
The present considerations for tidal power conversion in the Bay of Fundy are primarily based upon new designs for tidal in-stream energy conversion (TISEC) devices, although there are also proposals for tidal lagoons or shore-fast impoundments. TISEC devices have a long history at the concept level, including in Canada, where the development of the Davis vertical axis turbine (based on the Darreius design) was initiated with the assistance of the National Research Council more than 30 years ago. Most of the more mature TISEC technologies are either horizontal or vertical axis designs. The designs closest to commercial development for grid-connected application tend to be horizontal axis.
In early 2008, the Nova Scotia government selected Minas Basin Pulp and Power Company Limited to lead the development of a Fundy Tidal Energy Test Centre as a demonstration and test facility for TISEC devices. Three turbines- Openhydro Turbine (top left) Clean Current MK.lll (top right), and MCT ‘SeaGen’ (bottom left)- were approved and took the first three berths at the test site in Minas Passage.
The pilot testing of demonstration TISEC devices in the Bay of Fundy offers an opportunity to examine the effects of the environment on a range of TISEC technologies, as well as the impact of these devices on the environment. The research issues are interrelated, requiring a holistic approach, and a high degree of coordination and communication.To faclitate such cooperation, the Fundy Energy Research Network (FERN) was initiated in 2008.
FERN members identified priority research needs that require long term and/or large scale, collaborative approaches that would build the knowledge base required for assessing the potential for commercial-scale marine renewable energy from the Bay of Fundy. Research challenges fall into three general areas-device and monitoring technology and grid integration, resource assessment and modeling, and ecosystem responses to energy extraction.
It was recognized that very little background information existed for the sites of highest priority for TISEC devices, especially the Minas Passage. However, numerous ecological changes noted in the Upper Bay since the 1980s indicate our understanding of the Bay of Fundy ecosystem is still limited. Hence, a coordinated approach to addressing the impacts of tidal power development is critical. The highest priority research areas identified were:
- To assess the size of the energy resources available and to refine hydrodynamic models that will enable the environmental effects of energy extraction to be forecasted. At present, estimates of resource available are highly variable. Accurate and validated models are essential both for estimating the commercial potential of different sites and as a foundation for effects assessment.
- To assess the implications of commercial arrays of TISEC devices for marine fauna, especially migratory fish and mammals. This requires better understanding of the behavioral responses of animals to TISEC devices, which is expected to be technology-specific to some extent.
- Modeling of sediment behavior and movements. Suspended and deposited sediments play a major role in the ecology and productivity of the Upper Bay of Fundy and vary dramatically over time. Forecasting the sedimentological effects of commercial energy extraction is a major challenge.
- Occurrence of non-buoyant debris (e.g. logs) and sediment-laden ice cakes, and their implications for TISEC devices.
Similar questions are faced by TISEC demonstrations elsewhere (e.g. Strangford Lough, EMEC, and East River, New York), but the results of such studies cannot be transferred easily to the Bay of Fundy because of its unique features- tidal range (up to 16m), extreme currents (5m/s), high suspended sediment loads, sediment laden ice, and diverse and abundant migratory species. In addition, technologies for monitoring environmental parameters and animal behavior in relation to turbine infrastructure are still very much ‘works in progress’, and are not always well suited for deployment under such extreme conditions. If the technologies- both TISEC and monitoring/research technologies- can be shown to work in the Bay of Fundy, they can probably be applied to almost any other site proposed for TISEC development.
Visit Fundy Energy Research Network (FERN) for information on the progress made thus far with the demonstration TISEC devices in the Bay of Fundy.