Advanced monitoring, simulation and control of tidal devices in unsteady, highly turbulent realistic tide environments

Project Information

RealTide

Grant agreement ID: 727689

DOI

10.3030/727689

Project closed

EC signature date 12 December 2017

Start date 1 January 2018

End date 30 September 2021

Funded under

• SOCIETAL CHALLENGES - Secure, clean and efficient energy

Total cost

€ 4 974 990,02

EU contribution

€ 4 974 990,02

Coordinated by

BUREAU VERITAS SA
France

Periodic Reporting for period 2 - RealTide (Advanced monitoring, simulation and control of tidal devices in unsteady, highly turbulent realistic tide environments)

Reporting period: 2019-07-01 to 2021-09-30

Summary of the context and overall objectives of the project

Fast flowing tidal streams can be found in many places around our planet’s coasts. Electricity can be generated from these by installing underwater Tidal Energy Converters (TECs), most of which work in a way that superficially resembles wind turbines. The sea is, however, a harsh environment with tidal turbines exposed to large forces caused by the shape of the seabed and a combination of large scale turbulence and ocean waves induced by the presence of islands and headlands. Several companies have developed different TECs, often categorised as horizontal axis turbines, vertical axis turbines, or other concepts. The majority of promising designs that have progressed to MW scale power capacity use horizontal axis turbines. Once TEC’s have proven their cost-efficiency and reliability, the market will open to bigger grid-connected arrays and on to tidal farms.

The RealTide project, addressing tidal stream in a holistic manner, has performed critically important research focused on understanding both turbulence in tidal currents and the associated design and fatigue loads generated. This deeper understanding results in crucial new input to improved design and enhanced reliability, enabling much more cost-effective commercial machines to be deployed.
The RealTide project integrated innovative flow measurement instrumentation - deployed at sea -, reliability methodologies coupled with advanced condition monitoring, studies on new materials for blades and tide-to-wire modelling to deliver improved guidelines, design tools and input to global standards that supports the development and maturity of future tidal-stream power installations.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the 45 months of the project, the RealTide participants, working closely together, performed the key steps needed to achieve RealTide’s overall objectives. Thanks to their joint experience base, existing knowledge built through a string of precedent research, a Failure Mode and Effects Analysis (FMEA) report was published early in the work. The FMEA defined four generic concept classes that are representative of existing TECs: (1) bottom-fixed horizontal axis turbine termed “Complex”; (2) bottom fixed horizontal turbine termed “Simple”; (3) Floating multi-rotor horizontal axis turbine and (4) cross-flow turbines.

The RealTide FMEA methodology led to important recommendations for modification of the design structure and to new Advanced Condition Monitoring. In other closely synchronised work, the fatigue behaviour of tidal-turbine blades made from composite materials has been investigated and a new methodology for the fatigue assessment has been developed. The potential environmental and economic impact due to increased reliability has been evaluated. In parallel, an initial monitoring plan for TECs was also published, advancing on the state-of-the-art of already used monitoring techniques with a proposition for applying many of the new innovations to the full-scale, deployed at sea tidal turbine of project partner Sabella.

Another key objective addressed in RealTide is the characterization of real tidal flows, precisely the turbulence to improve the knowledge on the realistic sea conditions at highly energetic tidal-stream sites. After delivering exploitable data to all the partners and describing the methodology to use it, a Deployment and Instrument Specification for Advanced Flow Characterization has been released. RealTide has developed an open access, site characterisation and environmental database which can be accessed at https://tidalenergydata.org.

In addition, a Generalised Tide-to-Wire tool has been built from open-source software as a dedicated RealTide tool. The model uses BEMT to calculate the torque and thrust of a TEC from tidal-stream conditions input. The modelling calculation result is the electricity production. Two test campaigns in IFREMER and at the University of Edinburgh flumes have been performed. The outputs of the models and the experimental tests have enabled a series of synthetic load spectra and force/load time series to be created. These provide data for validating models and experiments, and provide important design information for turbine developers.

The importance and impact of reducing Opex (i.e. turbine O&M cost) was pronounced at all stages of market evolution, found to be an essential requirement contributing strongly to the achievement of competitive LCoE. The business case results are equally valid for bottom-fixed and floating twin-or multi-turbine installations. In this way the combined modelling effort provides insight on market-design mechanisms and public-policy measures to accelerate bringing the benefits of tidal-stream power to market, thus helping to mainstream tidal into the global renewables sector.

Interestingly, the UK Government very recently announced its new investment support scheme for tidal-stream power that could represent a first step to realise the phased-array development effort underpinning the conclusions of the RealTide business case (“UK government announces biggest investment into Britain’s tidal power”, https://www.gov.uk/government/news/uk-government-announces-biggest-investment-into-britains-tidal-power consulted on 30.11.2021.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

In total 31 Deliverables have been issued in the 45 months of RealTide project including 20 public reports available on the project websites as well as on CORDIS. The consortium has until end of the contract produced 13 technical-scientific publications presented in conference proceedings or in scientific Journals for disseminating results of the project.

Partners participated in several events such as ICOE 2018 (International Conference on Ocean Energy), Ocean Energy Cluster Event (2019, 2021) and Sea Tech Week (2020). Moreover, consortium has also organised 2 workshops as side event of EWTEC conferences. The first one took place in September 2019 in Naples, Italy, and the second was held in September 2021 in Plymouth, UK. Several accepted Papers and Posters were also exhibited at these same events. The associated Workshops were found to be excellent opportunities to communicate about the project and to disseminate results to the Marine Renewable Energy community. Concerning communication activities, the RealTide consortium was active on social networks, LinkedIn and Twitter, informing public about recent news of the project as well as publishing study cases on the RealTide website.

An important aspect of the dissemination concerns the standardisation, led and facilitated by the Coordinator Bureau Veritas in their capacity a world-leading certification and standardisation body. Several RealTide partners liaised with National Committees of IEC TC114 (UK, France, Spain) to make them aware of the key findings of the project. RealTide achievements could be used by Maintenance Team of published documents and Project Team for new Technical Specifications. RealTide results are also valuable for Classification Societies, and will largely contribute to the improvement of existing guidelines and standards. Additionally to IEC Technical specifications, the BV Guidance Note NI603 Current and Tidal Turbine will consider, for further editions, following RealTide developments:
- Fatigue methodology for blade made in composite materials (WP1),
- Reliability database access (WP1),
- Condition monitoring protocol (WP4),
- Testing procedures (WP4),
- Calculation methods: analytical (BEMT) and numerical (CFD) (WP3 and WP5).

RealTide banner

The RealTide Holistic Approach

The model tidal turbine undergoing deployment in UEdin’s FloWave facility

Full scale blade test at Ifremer facilities

Tidal turbine with structure – U70 oscillating inflow – Wake induced by the turbine at high TSR

Front page illustration of the RealTide tidal-stream database (tidalenergydata.org)

Sabella D10 turbine quayside with dimensions and weight

Illustrating the taxonomies of Concept classes fundamental to the developments of FMEA/RAM