This report presents the findings from a review of state-of-the-art sensing and imaging (SIS) technologies relevant to Tidal Turbine Collision Detection (TTCD) application. The study includes an assessment of the approximate technology readiness and the applicability of marine animal collision detection technologies and devices being proposed, in testing and development or already deployed in prototype tidal turbine projects.
There are a number of challenges in collecting the supporting evidence of marine animal collision events; the principal challenge is the monitoring environment and the deployment and operation of sensor systems in this. Highly energetic tidal flows are characterised by high levels of noise from the turbine and from the moving water, variable levels of water turbidity and abrasive materials moving at high velocities. Another challenge is the low maturity of some applicable sensor technologies and the need in each case to collect a sufficient body of data in a short time span to validate the technology design, conclude an optimal system and determine with high certainty that a turbine blade has collided with, or nearly collided with a marine animal.
This report attempts to identify benefits, constraints, barriers to implementation, technology readiness level (TRL1 ) and recommendations on the next steps to further development. The report describes available and emerging sensor technologies against the following stated TTCD detection needs:
- proximity/collision warning
- collision detection: object striking tidal turbine blade
- post-event condition monitoring: identify and warn of structural damage to turbine blade (e.g. hairline fracture)
- post-event object identification: differentiate between animal or debris following impact
The SIS technologies explored in this report include hydrophones active sound navigation and ranging (sonar), video camera and optical imaging, blade mounted strain gauges, blademounted accelerometers, electromagnetic field sensors and tactile sensing technologies. Also addressed are approaches to system architecture. The principal knowledge gap area is SIS to monitor post collision events. The principal evidence gaps are data for sonar imaging and tracking and blade collision impact. A collaborative mechanism to share relevant evidential SIS data would be helpful in progressing the closure of some of these gaps. Seven areas for further study have been suggested including the identified knowledge and evidence gaps, and also suggests feasibility studies to explore emerging technologies that may have additional value in TTCD. Financial resources remain a barrier to progression, with some tidal developments reaching the point of implementation but lacking sufficient funding to deploy and run comprehensive trials with the application. A common test and development site that implements some of the SIS that require further data input may help standardise experimental results and provide an economically viable opportunity to trial new approaches and technologies.