• In tests the new three-bladed and seven-bladed turbine designs showed an increase mechanical power output of 31% to 35% compared to the baseline turbine.
• A medium voltage converter for the actual tidal kite application was designed, built and tested. The electrical conversion efficiency of a medium-voltage system will be a few percent better than the low-voltage baseline system and facilitate the integration in an array of generators.
• The tether was redesigned using swiveling segments which was critical for the improvement in power quality and predictability of the flight trajectory control.
• The overall improvement of powerplant energy output from the baseline due to the PowerKite project is calculated to between 15% to 21%, representing the combined effect of the improved turbine, the improvement of the low-voltage system and the increased drag of the improved tether.
• A life cycle assessment was performed on Deep Green. For the base case (based on the DG500 prototype) the global warming potential (GWP) per kWhe produced was 26.2 g CO2 eq, comparable to other marine renewable energy technologies
• Noise measurements and acoustics modelling have improved the understanding of the technology in the marine environment. While the largest variation in noise is from the turbine revolution, overall the ¼ scale kite has limited interference with marine fauna. Essentially, seals would have to be within the kite flying volume (within 62 m of the turbine) where their listening space reduction (LSR) would exceed 90%
• The (LSR) method provides a significant advance to the marine renewable energy (MRE) community as not only can the cumulative noise field from an array of turbine devices be modelled using this approach, the LSR method can be applied to any MRE device.
• No impact on benthic communities were detected owing to the operation and deployment of the infrastructure with the kite at the Minesto site.
• To date no collisions of mammals with the ¼ scale or full scale devices have occurred. While the sonar system is not fully operational, significant advancement has been made to develop an autonomous and user-friendly observation system. It is anticipated that re-deployment of the sonar system in 2019 will be able to detect, track, and differentiate marine megafauna.
• The development of the collision risk model (CRM) will be ongoing beyond the end of the project. A fully three-dimensional, transient model of the kite and animal shape has been developed and published. Work on the CRM will remain ongoing via an Interreg funded Bryden Centre PhD that involves academia, industrial and Governmental partners.
• Components have been simplified to reduce complexity and the associated operation and maintenance costs (O&M) as well as capex costs. The bottom joint development is an excellent example where the design was simplified reducing capex costs whilst retaining the required performance and simplifying the O&M procedures when the joint is connected and disconnected.
• The Powerkite project has guided the decision to shift the focus away from surface structures in the array more towards a subsea infrastructure.
• The Powerkite project deepened the understanding of costs associated with different array configurations and the associated kite design requirements
• The Deep Green technology is suitable for installation sites with low velocity currents, where no other technologies are known to be efficient. Improving the technology (turbine, converter, tether, etc…) will not only lead to an improved performance and lower LCOE, but it will also allow the power plants to operate in even lower flow conditions, expanding the potential even more.
