Ensuring Success of Marine Operations
in Tidal Energy
Installation analysis of OpenHydro Tidal Turbine using ProteusDS
Overview
Cape Sharp Tidal is a joint venture between OpenHydro Tidal Turbine and Emera with the aim to deploy a grid-connected 4MW tidal array in the Minas Passage, located in the Bay of Fundy, Nova Scotia. This project has the potential to be one of the world’s first interconnected multi-megawatt tidal arrays, providing energy to more than 1,000 customers initially.
OpenHydro is a DCNS company that specializes in the design, manufacturing, and installation of marine turbines generating renewable energy from tidal streams. A world leader with a vision to deploy tidal turbine farms throughout the world’s oceans to silently and invisibly generate electricity with minimal impact on the environment.
Background
The Minas Passage has some of the strongest tides in the world. Flow speeds range from zero to 11 knots in the 5 km wide, 40m deep channel. Due to these unique environmental conditions and this vast potential resource, Nova Scotia can claim what the industry refers to as “The Fundy Standard.” If a tidal energy device can successfully work in these extreme conditions, it can work anywhere in the world.
Perhaps the most significant technical barrier the tidal industry faces is merely installing and maintaining turbines and cables in challenging sites like the Minas Passage. Traditionally, sea trials and experience would have solely guided marine operations. However, there are many unknowns and little experience in working in extreme tidal environments. A combination of maritime expertise and advanced engineering analysis with tools like ProteusDS are necessary to ensure the successful installation and maintenance of equipment to safeguard the economic viability of the tidal energy project.
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Challenges
- Manoeuver the Scotian Tide deployment barge into position with tugs while maintaining control of export cable.
- Lower OpenHydro’s 21m (69 foot), 1100T submerged weight open-centre tidal turbine to the sea floor.
- Align turbine into optimal orientation relative to flow at the seafloor.
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Scope of Work
- Develop a numerical model capable of simulating the seakeeping behaviour of the Scotia Tide deployment barge with a tidal turbine in place to be lowered.
- Simulate the tugs, tow lines, turbine lifting lines and associated installation operations in the ProteusDS simulation software.
- Verify the power requirements of the tugs.
- Simulate the towing and lowering of the 16m OpenHydro tidal turbine in the Minas Passage.
- Determine optimal tow configuration for turbine and Scotian Tide deployment barge (i.e. positioning of tugs, deployment barge, tow hawser lengths)
- Simulate and assess turbine lowering.
- Conducted simulations of maneuvering and aligning the turbine on the sea floor.
- Provide recommendations and feedback on operations to OpenHydro and Atlantic Towing based on the dynamic analysis that will minimize installation risks.
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Outcomes
- Reduced operational risk of ferrying OpenHydro’s turbine to deployment site by identifying optimal tow arrangement.
- Identified tow arrangements which were less stable and provided less overall seakeeping control of the Scotia Tide.
- Verified that the hydrodynamic and tow loads on the critical electrical export cable during lowering of the turbine.
- Identified the deflection of the OpenHydro turbine and loading on the winch and lifting lines under the presence of the tidal flow through the lowering simulations.
- Identified the optimal tug operations/configurations to provide ideal control and final alignment of the turbine on the seafloor.
- Provided in-depth 3D visualizations of all critical simulations and comprehensive final report that can be used to inform OpenHydro operations in Minas Passage and other projects across the globe with similar environmental conditions.
