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Next Evolution in Materials and Models for Ocean energy

Periodic Reporting for period 3 - NEMMO (Next Evolution in Materials and Models for Ocean energy)

Période du rapport: 2021-10-01 au 2023-09-30

Despite possessing a high potential of energy generation in Europe, tidal energy has not created a huge impact in the renewable energy sector at present, and its potential is progressing at a slower pace than expected. Ocean energy targets achievement is at risk due to the lack of accurate and efficient testing and design methodologies resulting in slow development, optimisation, scale-up and validation processes for tidal energy generators. Available simulation tools and testing procedures have a limited capacity to predict the behaviour of components and devices at real operational conditions. Consequently, during the real scale testing phase in real environments deviations are found, major failures usually occur, and tidal generators operate at non-optimised conditions impacting on final LCoE and delaying tidal energy the development and its massive deployment.
The NEMMO project scopes comprises the development of a set of technologies and tools to finally conclude with the TRL 5 development of a tidal turbine composite blade concept with increased performance (+20 % Annual Energy Performance), lifespan (over 20 years) and compatible with over 2MW generators. To do so the NEMMO project will:
a) Generate the necessary knowledge to design composite blades able to operate with enhanced performance (+20% hydrodynamic performance, -34% OPEX) for over 20 years in over 2MW tidal generators including technologies, behavioural models, testing procedures and testing methodologies.
b) Will apply the developed LES solver, the newly testing procedures and models and the designing methodology to generate an optimized tidal blade design integrating novel shape, AFC appendages and nano-enhanced materials.
c) Will manufacture this blade to a 1:1 scale and will validate its performance to TRL5 (large scale lab testing and first tidal cycle trial).
These objectives will enable reaching LCOE values of 14.9 c€/kWh (2025) and 9.8c€/kWh (2030), fulfilling the objectives established in EU’s SET-PLAN for ocean energies.
The main technical work performed and results is sum up here:
Models & test procedures
• The Reduced Order Models of the mechanical properties of the materials developed in WP3 has been obtained and analyzed.
• The Finite Element calculation of the original blade according to load conditions obtained in WP1 has been analyzed and the most critical sections has been located.
• The SLS test campaign has been completed. Fatigue characterization has been started.
• Different modules of the Qblade are used to obtain the different performance characteristics of the Magallanes turbine for varying tidal velocities and for varying turbulent intensities.
• Establishment of a modified accelerated ageing procedure for composite material immersed in sea water based on the characterization of samples to assess the ageing status of composite material after artificial (laboratory accelerated ageing test) and natural ageing (in harshlab buoy and Pasaia port).
• Method for cavitation erosion testing using sonotrode described
• Test rig for blade testing at SSPA cavitation tunnel was designed and tested
• Two AFC designs were tested on constant cross-sectional profiles
• LDV (Laser Doppler Velecometry) were used to capture the flow field created by the rotating blades.
Blade design
• Compared the results of Magallanes simulations with ALM-URANS/LES results for varying external pitch (for new/bi-directional blades)
• The internal structure of the new blades was achieved with the collaboration of a specialist subcontractor, Aeroblade, as there was no partner in the consortium that had this expertise.
• The length of the blades was expanded in order to increase the swept area and therefore increase the annual energy production (AEP). This will maximize the energy generation in areas where there are low-speed currents, and therefore reducing the LCOE for tidal energy.
New materials for blades
• 12 formulations were mechanically characterized, and 2 formulations were selected as the best one regarding mechanical properties improvement: 0.5% Carbon Nanotubes ref CS1-25 and 2,5% impact modifier XT100 (until +15% for tensile max stress at +/-45° and +25% for ILSS)
• More the 50 composites plates with or without fillers were manufactured by infusion process for partners (DCU, FUNDITEC, TECNALIA, ITA INNOVA)
• Optimization of carbon nanoparticles (CNT, graphene, carbon black) dispersion processes and different mixing procedures with additional materials before and after coating the glass fabrics
• Chemical modification of nano-complexes to promote dispersability, wetting and covalent bonds formation with the resin
Demonstration
• Some Downscaled blades (1:38) were manufactured to perform cavitation test in SSPA’s tunnel and validate LES model developed by Technion.
• A novel sea platform is being designed by DCU to allow for dynamic testing of novel material solution in realistic marine conditions.
• Accelerated test procedures were designed and samples were exposed in real environment sites at Tecnalia.
Cross-cutting activities
• Further development and completion of the Life Cycle Inventory, including (1) components manufacturing; (2) installation; (3) operation and maintenance; and (4) end of life stages.
• The materials forming the components and subcomponents of the NEMMO device were identified and quantified in terms of mass (tonnes) and cost (€).
• LCA ongoing (preliminary LCA results for the blades, mooring and cable systems for the manufacturing phase).
Exploitation, communication & dissemination
• Project results have been presented at major ocean energy events, e.g. OEE’s annual industry conference, International Conference on Ocean Energy (ICOE 2021), and European Wave & Tidal Energy Conference (EWTEC2021).
• A full draft of Technology Development and Exploitation Roadmap (D7.4) has been circulated to partners for review.
• 1 open access publication (2 in total since launched, 14 media/online mentions, 11 social media posts and 116 followers. Presentation & dissemination at 2 key industry events. 1838 visits to project website.
• Development and application of suitable computational fluid dynamics (CFD) workflow for simulating tidal turbine cavitation in open source CFD package (OpenFOAM), which will allow design studies to the tidal scientific community.
• Recently, Luis and Meneveau, JFM (2019) developed a new Filtered-ALM (F-ALM) which allows coarser-grid simulations with the aid of a sub-grid velocity correction, in turn corrects the wrong induced velocities near the blade to prevent the over prediction of thrust and power. This method was implemented in the in-house high fidelity MIRACLES solver and a good match against the previously published experiments was obtained.
• Two enhance formulations based on the reference vinylester resin providing a better ILSS and in-plane shear strength to the composite (until 15% and 25% improvement respectively)
• Two novel coating formulations based on polyurethane resins (2k solvent-based and 1K water-based) with remarkable anti-cavitation erosion resistance and antifouling properties.
• Large Eddy Simulations (LES) are performed to study cavitation sheet dynamics associated with the modified scaled-down Francis turbine (hydrofoil) at 9° angle of attack (AOA), with the focus on elucidating and analyzing the re-entrant jet dynamics. An elucidation of the limited effect of wall injection on cavitation is provided.
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