Final Report Summary - TIDALSENSE (Development of a condition monitoring system for tidal stream generator structures) Executive summary: Tidal energy is an embryonic industry playing an increasing role within the renewable energy sector. There has been an increasing number of reports describing the occurrence of defects within the turbine blade leading to turbine failure. There is currently no standard condition monitoring technique available that can perform routine autonomous inspection providing details of the tidal blade integrity. The turbine blade comprises a complex composite structure of glass fibre reinforced plastic (GFRP) and carbon fibre-reinforced plastic (CFRP). The objective of the TIDALSENSE project was to focus on the development of a structural health monitoring system (SHM) for the purposes of incipient defect detection on tidal turbine blades. Application of an early warning system will extend the blade life expectancy, lower maintenance costs and optimise the efficiency of the delivery of energy to meet industry and community demands. The TIDALSENSE project objective was to design an SHM system that utilises long-range ultrasonics (LRU) to actively interrogate the blade structure for the onset of incipient defects. automated defect detection (ADD) and system management reports the status of the blade to the operator for high-level decision making. TIDALSENSE project research involved analysis of composite materials when excited by LRU sensors with the purpose of reporting parameters such as signal attenuation, signal-to-ratio (SNR), and reflections. Signal conditioning using signal processing techniques were applied to the signal characteristics most sensitive to material changes within the structure. An analysis of sensor types was conducted. Macrofibre composites (MFCs) provided a good match with excellent detection of in-plane LRU activity. For the purposes of underwater implementation, the sensors were marinised to ensure no water ingress into the sensor cavity. An ADD system (ADDS) was integrated to provide defect classification and evaluation. Wireless communications technology was developed for the purposes of data transfer from the blade to a control centre with accompanying software for data management and signal visualisation. The main results of the complete TIDALSENSE SHM system are: (1) Successful detection of material coupling change and component disbond with a sensitivity difference of 20 % and 40 % respectively for distances up to 500 mm. (2) Marinised PVC caps able to withstand pressures up to 5 bar with a safety factor of 1.5. (3) Detect a change in cable bonding conditions causing a 3 dB drop in the acquired time-series data using the L(0,1) mode at a distance of 3 m. (4) Wirelessly transmission of data at 2 Mbits per second over distance of 40 m maintaining 100 % signal integrity. (5) ADD comprising a neural network with accuracy in classification and evaluation of 77 % for full blade inspection. (6) Software visualisation of acquired LRU data with simple navigation tools for signal analysis, tabulated parameter display and report facility. The TIDALSENSE project has been very successful and achieved all of its objectives. The field trials carried out on the mock-up blade confirmed that the SHM development is an effective and reliable inspection device that can perform quick and simple inspection of composite components. The public website address for the project is http://www.tidalsense.com/ this website will be kept as the main platform for any communications related to the TIDALSENSE project beyond the project term. TIDALSENSE is collaboration between the following research organisations and small and medium-sized enterprises (SMEs) from 6 different EU countries: TWI LIMITED, IT POWER, Innotec, I&T NardonI, IKnowHow, Tidal Sails, Enerocean, Cereteth, Kaunas University of Technology. Project context and objectives: The main objective of the project is for the consortium to develop an advanced integrated system for real-time SHEM and impending failure detection using LRU technique (LRUT) on both tidal turbine blades and cables. The capability of the system will be demonstrated in laboratory experiments at the end of the project. The project objectives for this period include: Work package (WP)1: Selection of a sample to represent a tidal turbine blade - WP2: Appropriate modelling of guided waves in selected components to identify a defect and settle upon a transducer configuration - WP3: Optimisation of the transducer configuration appropriate for under-water operation - WP4: A process of signal generation and selection of the most appropriate communication system for the purposes of data transfer - WP5: Development of an ADDS for defect classification and evaluation together with suitable software WP6: System integration of project component parts - WP7: Field trials of a fully integrated system WP8: Provision of training material WP9: Provision of a plan for use and dissemination of knowledge. To accomplish the strategic objectives, the work activities have been organised into a number of discrete WP. Those were divided into a data acquisition and design phase (WPs 1 - 5) and the implementation phase (WPs 6 - 9). The project has suffered a number of unexpected setbacks during the first half of the project mainly due to partnership changes. As a result, the consortium decided that the focus of the project should be on LRU as this technique is more sensitive to the defects reported on tidal turbines. In addition, an LRU system is more unobtrusive in terms of weight and profile and has more flexibility when considering mechanical coupling conformability. In addition to this technology, the consortium decided that since cables are often an integral part of any tidal energy system, cable-inspection should be incorporated into the TIDALSENSE monitoring system. The work reported in this report summarises the work performed to select and optimise a sensor array for the purposes of defect detection on composite blade components. Because the selected sensor is flexible, it is suitable for the purposes of any guided wave technology including acoustic emission (AE). The TIDALSENSE sensor array is able to excite and detect LRU signals - an active technique - whilst also being able to detect propagating elastic waves arising from external perturbation: AE - a passive technique. This project offers the knowledge and full understanding on how to use guided waves to inspect and monitor complex geometries such as composite blades and multi-wire steel cables. Project results: WP1: Project specifications Mainly consisted of discussions with consortium partners. The aims were to establish the industrial requirements for the system to be developed and to establish the critical component parts of a turbine blade that typically experience the onset of defects. It was agreed at the kick-off meeting the high power consumption of the AE technique in a marinised environment meant that this inspection technique would have minimum impact. Therefore at the kick-off meeting, the partners decided they would focus on the LRUT development and use this technology in sensing the structure within more often regular time periods in order to compensate for the originally proposed AE contribution. This was detailed in D1.1. At the same meeting, it was reported to the consortium by Tidal Sails that a significant number of tidal energy systems include steel cables. These cables are subjected to extreme loads and have shown significant signs of deterioration. It was therefore suggested that the scope of the project should be extended to include research into implementing a monitoring system for cables where they exist. Currently, stationary blade visual inspections are typically performed. When cracking is observed, the practice is to consult the original equipment manufacturer (OEM) either under the terms of a warranty agreement or on a consultancy basis to decide on the appropriate action given the size and location of cracking. IT Power reported to the consortium that the majority of faults on reported blades were cracks and disbond from the strengthening blade member from the blade inner shell. The TIDALSENSE consortium discussed the inspection possibilities to be able to detect such defects as and when they occur and be able to identify the crack at an earlier stage in the development cycle. These discussions resulting in confirmation of the project taska and aims concluded Task 1.1. Details of a representative sample suitable for demonstration purposes were then discussed. IT Power provided drawings of the hydrofoils presently in use and of hydrofoils that are being proposed for future developments. The only essential difference between the two is the size: the structure and design are largely similar. This contribution completed Task 1.2. For the purposes of defect detection, the transducers must be arranged as an array to focus the ultrasound energy at a fixed point. However it was discussed that the focusing may not provide sufficient resolution to detect defects. Sensor resolution is largely dependent upon the frequency range - therefore, it was agreed that transducer types would have to be examined for optimisation purposes. This completed Task 1.3. Other system specifications (Task 1.4) were examined such as the requirement for marinisation of the inspection sensors, signal integrity issues arising from EM interference and power consumption. All of these points were discussed and used as benchmark parameters during the design process. System specification pertaining to the cables were also analysed to address the modes of failure such as loss of metallic cross section (LMA) due to wear or corrosion and localised failure (LF) such as broken wires or pitting. WP2: Theoretical technique development and modelling The objective of WP2 was to develop a theoretical model to understand the properties of guided waves in composite materials and provide a numerical simulation of the novel sensors. This analysis assessed the interaction of guided waves with defects and help improve the probability of defect detection. Task 2.1 focuses on the properties of guided waves propagating through composite materials. This analysis involved identification of wave modes, wave-speeds and frequency response. By modelling and through experiments it was demonstrated that using a single contact type transmitter, it is mainly the A0 and S0 guide wave modes in the frequency range 50 - 300 kHz that are excited. In some cases other modes were also excited (but not identified), however; they possess too small amplitude to be applicable for measurements. A literature review was conducted on simulation of ultrasonic guided waves propagation in the composite materials. The semi-analytical, finite difference and finite element methods were reviewed. The advantages and limitations of each technique were clarified. It was concluded that there are two methods which can be useful in the investigation: semi-analytical finite element method for estimation of dispersion curves and finite difference or finite element methods for overall analysis of the wave propagation in the non-uniform, complex structure of composite components. Task 2.1 involved the analysis of the multi-layered structure of the hydrofoil to be inspected using ultrasonic guided waves was performed: - The materials from which the composite structure is made were defined (as reported in D2.1). - The geometry of the multi-layered hydrofoil, spatial thickness deviations of each-layer, cross-section view and top view were defined. - The regions of the hydrofoil that should be tested using the guided waves, also possible excitation places and possible arrangement of the transducers were estimated. The dispersion curves of phase velocity of the guided waves propagating in the multi-layered structure of hydrofoils have been determined using SAFE method. The propagating modes of guided waves in the hydrofoil skin and in the main spar were identified using the modelling and experiments. The frequency range of operation below 200 kHz should be used for inspection of the skin and even lower for inspection of the main spar. In these frequency ranges mainly two fundamental modes A0 and S0 are propagating. The attenuation losses of propagating guided wave have been estimated. For A0 mode they are 153 dB / m and for S0 mode 117 dB / m. So, the S0 is better for use and may provide an estimated coverage of up to 1m. It was identified that the transducers should be closely situated to each other so that the field pattern of the transducer can be exploited to increase the signal energy and also to provide better directivity for the purposes of focusing to enable long distance inspection. This completed Task 2.2 and Task 2.3. In summary, the TIDALSENSE project successfully extended the scope of defect detection in tidal turbine systems to include multi-wire steel cables with re-enforced polypropylene core materials. electromagnetic acoustic transducers (EMATs) were identified as a suitable sensor for optimised cable inspection. The L(0,1) wave mode was identified as the mode with the required level of sensitivity to defects. Good agreement between FEA modelling and experimental analysis of propagating ultrasonic guided waves from a single point of access over several metres was achieved. WP3: Development and evaluation of suitable transducer arrays The objective of WP3 was to develop an array of sensors for LRU inspection techniques of composite materials and steel cables. Guided wave analysis on composite materials was reported in Periodic Report 1. This included analysis on attenuation and modal analysis. MFC sensors were used because they are light, flexible, unobtrusive and are conformable to uneven surfaces. They also operate well within the frequency range of interest: 30 - 300 kHz.. As previously specified, the S0 mode is best suited to the detection of defects due to its smaller attenuation loss over distance and also because the mechanical motion of displacement is predominantly in-plane - resulting in good directionality for the purposes of in-plane defect detection. The characterisation analysis achieved in reporting period 1 was then used to inform the design of an array of MFCs suitable for the detection of propagating S0 lamb waves - this mode was established as being the mode most sensitive to boundary and material changes. This array successfully detected defects within composite materials, hence completing Task 3.1. In addition, analysis of the multi-wire steel cables that are regularly a feature of tidal systems was also conducted. Experiments revealed the sensors most suited to the generation and reception of guided waves were EMATs. The suited mode for this purpose was the L(0,1) mode. A configuration of EMAT sensors were developed with the purpose of detecting a change in the coupling conditions of the cables surface. Task 3.2 focused upon the marinisation of the transducers. PVC caps for MFC sensors were manufactured. Experiments demonstrated that the developed encapsulation technique is suitable for the purpose. Of the adhesives analysed (e.g. Araldite 2022), Henkel Hysol 9461 was the only adhesive to successfully bond the cap to the glass fibre surface. The design was tested to a depth of 50 m and no corrosion or ingress of water was detected. It was concluded that the PVC caps can adequately sustain the harsh environmental conditions of the application and provide excellent protection and water tightness to the MFC transducers. An additional cap was developed for the purposes of housing a sensor array without compromising signal integrity. The specification concerning the hydrostatic pressure during tidal turbine operation is 5bar. As required by Task 3.3 single and quadruple transducer caps were designed in accordance with this specification. In summary, the TIDALSENSE project successfully designed an array of light-weight, unobtrusive, robust and conformable sensors. Utilising the mode of greatest sensitivity to defects - S0 mode - the sensors were arranged spatially to optimise the received SNR. Array optimisation was achieved by analysing sensor separation of: (a) sensors touching - 20 mm between centre of one sensor to centre of next; (b) (26.8 mm) between centre of one sensor to centre of the next; (c) (40.2 mm) between centre of one sensor to centre of the next; (d) (53.6 mm) between centre of one sensor to centre of the next; (e) (67 mm) between centre of one sensor to centre of the next. The optimised distance for maximum SNR is (67mm) between centre of one sensor to centre of next operating at a frequency of between 40 and 60 kHz. High standard PVC marinisation caps to ensure the TIDALSENSE sensors remain water-tight have been designed. Features include: (1) PVC encapsulation with: (a) low susceptibility to water absorption: 0.02 - 0.15 %; (b) high-tensile strength: 30 - 40 MPa; (c) single sensor encapsulation withstanding 5 bar hydrostatic tests with a safety factor of 1.5; (d) quad sensor encapsulation withstanding 5 bar hydrostatic test with a safety factor of 1.1. (2) Henkel Hysol 9461 epoxy adhesive exhibiting: good PVC to epoxy-based GFRP adhesion; good shear and composite strength; good flexibility. The impact of TIDALSENSE marinisation process is minimal, resulting in a loss of 1.5 dB in terms of SNR when compared with the non-marinised array. The TIDALSENSE cable inspection sensor system detects: (1) a change in bonding conditions causing a 3dB drop in the acquired time-series data using the L(0,1) mode at a distance of 3m. WP4: Development of instrumentation and wireless communication protocol As contribution to Task 4.1 and task 4.1 a pulse-receiver unit (Teletest®) was used to inspect the cables on the Tidal Sails system and also used for the generation of guided waves to inspect the composite blades in the tidal stream generator structures. A multiplexor was included as an interface to the transducer array. A coaxial cable connects each transducer with the main unit, carrying power and analog data. Data is gathered from the pulse-receiver to a PC for further processing. Selectable amplification and filtering can be utilised to improve the SNR of the acquired signal. The wireless communication protocol for Task 4.3 used the 2.4 GHz wireless communication - Nordic NRF24L01+ technology. For low power efficiency, a custom board was designed and implemented based on an ultra-Low power microprocessor from Texas Instruments (MSP430F2274). The microprocessor was interfaced to the wireless IC via the SPI communication bus whilst being simultaneously connected to an on-board SD card - then used for logging the data before sending the data to the central unit. In summary, the TIDALSENSE system comprises instrumentation capable of transmitting up to 300 kHz at a signal amplitude of 250 Vpp with variable gain (in 1dB steps) with facility for low and high-pass filtering. The TIDALSENSE wireless communications systems has the capability to successfully transmit data over a distance of 40m maintaining 100 % signal integrity. The communications link (Nordic NRF24L01+) is able to transfer data up to speeds of 2 Mbits per second in under 20 seconds. A 'sleep mode' function between data-transfer ensures power consumption is close to zero. WP5: Development of software for data collection post processing and automatic defect detection Software for the control, analysis and ADD was the main focus of work for WP5. Task 5.1 completed the visualisation of data acquired from the LRU sensors on tidal turbine blades, the graphical user interface (GUI) allows the user to connect to the TIDALSENSE database and retrieve data on demand to perform common processing tasks. In addition, the software provides information from the automatic defect detection system permitting the user to instantly see details of the incipient defect. Signal integrity issues were addressed as part of Task 5.2. This involved the development of signal processing techniques to reduce noise. A numerical estimation of defect detection on collected time-series data was created using a normalised cross-correlation function with a set of reference data. Correlation limits were assessed and adjusted accordingly in order to establish a sensitive test. Analysis of the acquired data was successfully able to detect the defect. Task 5.3 on the ADDS, provided a system for defect classification and severity. The developed routines filter the signal-noise using Gaussian techniques. Once the signal had been suitable screened, the data was then fed into a perceptron neural network - and signals were subsequently classified as defective or non-defective. A series of experiments performed on the mock-up sample featuring defective and non-defective analysis was supplied to train the neural network. Both pulse-echo and pitch-catch sensors configurations were deployed. The acquired signal - with details on boundaries, fibre orientation and defects - provided the following data for discrimination: - estimated central frequency, - central frequency deviation, - bandwidth, - dominant pulse power, - deviation, - covariance, - correlation with reference non-defective signal, - correlation with reference defective signal, - covariance with reference non-defective signal, - covariance with reference defective signal. It was registered that some features are more suited to the recognition of defects based on the sensor configuration. These features were able to provide distinguishable classes for defect detection. These features were subsequently input to the neural network. The ADDS successfully classified and evaluated defects. Additional field data will continually improve the efficiency of the neural network to detect defects. In summary, the TIDALSENSE system comprises an ADDS comprising a neural network able to provide: - 100 % confidence defect detection level based on high resolution experimental data acquired from analysis of a 250 mm x 250 mm x 1 mm disbond defect, - 77 % confidence defect detection level based on lower resolution (mock-up) blade inspection contiaing 16 mm x 16 mm x 1 mm, 64 mm x 64 mm x 1 mm and 250 mm x 250 mm x 1 mm disbond defect, - continued detection improvement as additional data is input to the neural network. The TIDALSENSE system GUI provides signal visualisation and blade representation. Easy-to-use navigation tools with pull-down menus and a user request facility provides simple access to relevant data sets Time-stamped status reports provide a summary health analysis detailing defect size, defect location, temperature, blade and turbine identification. WP6: System Integration and testing System integration of the various project technologies was realised. Task 6.1 was conducted by integrating system components and testing them on representative samples (Task 6.2). Successful analysis using Guided waves was conducted on both the 4m x1m hydrofoil sample and the 1m x1m hydrofoil sample by TWI and KTU respectively with support from TidalSails, IT Power, EnerOcean, I&T Nardoni, InnoTec and IKnowHow. The experimental process was optimised to ensure the MFC transmitter array and receiver provided the required level of sensitivity for the Guided waves to propagate through the sample. A clear indication of the presence of a disbond defect was indicated by the LRU sensor array. The PVC caps have been rigorously tested by Cereteth to ensure that there is no water ingress. A suitable short-range wireless link has been selected: provision of a low-power wireless communications system using the Nordic Semiconductors' NRF24L01+ (802.11 protocol) researched by Cereteth for the purposes of data transfer from the turbine blade to the central control. The 2.4GHz range provided sufficient SNR. The transmitted LRU array data from the prototype experiments was subsequently provided to Cereteth to further train the neural network. The training of the neural network provided a level of detection as good as the experimental data used to develop the network. Additional and planned experimental input to the network will help ensure ever greater defect accuracy. Experiments were performed on cables typically used within the tidal energy industry. Guided waves were successfully propagated through the cable for several metres from a single point of cable access. With respect to the excitation and reception conditions, only one wave mode propagated in the cable: L(0,1). This is considered to be suitable inspection conditions in order to determine different features within the cable such as defects and bonding conditions between clamps and the multi-steel wire cable. System modification (Task 6.3) were identified, recorded and acted upon for the purposes of the field trials. Areas for further modifications included the sensor array, the wireless communications system, cable inspection and neural network training. In summary, the TIDALSENSE system sensors are able to detect artificial defects - plexiglass (10 mm x 150 mm x 150 mm) - located at a distance of 500 mm. Cross correlation techniques recorded amplitude variations of up to 20 % when compared with reference data. The TIDALSENSE system array is able to detect and locate 250mmx 250 mm disbond defects with recorded amplitude changes of typically 5 dB. Wirelessly transmitted over a distance of 40m, the LRU data can be remotely visually displayed. The TIDALSENSE cable inspection sensor system is able to detect a change in bonding conditions causing a 3 dB drop in the acquired time-series data using the L(0,1) mode at a distance of 3m. WP7: System integration and testing Field trials and system evaluation (Task 7.1 and Task 7.2) were conducted on the large-scale mock-up sample at TWI's premises. Suitable cables were identified for suitable defect detection. Most of the project partners attended: IT Power, EnerOcean, InnotecUK, KTU, Cereteth and TWI. The trial demonstrated the system integration for different technical developments within the TIDALSENSE project including the designed sample selected as part of WP1; the results of the modelling undertaken in WP2; the transducer selection and transducer configuration; marinisation analysis of WP3; implementation of the pulser / receiver and utilisation of a wireless comms system (WP4); signal processing techniques and ADD described in WP5; and system integration of core components as outlined in WP6. The encapsulated sensors on the submerged sample (under 0.5 m of water) successfully detected the presence of a disband defect. Post processing analysis using signal processing techniques was able to further validate the presence of a defect. The neural network that forms the ADDS achieved 100 % accuracy evaluating the standard deviation and the covariance of the defect data set with the non-defective data set. A similar comparison assessing the covariance only resulted in a detection accuracy of 77 %. The EMAT sensors, connected to the multi-wire steel cable with re-enforced polypropylene core materials, were arranged into an array. Clamps were attached to the cable to change the boundary conditions at that point. The array was able to generate and assess changes to the L(0,1) mode suggesting that the system was sufficiently sensitive to the bonding condition at the point at which the clamp was attached. Finally, the inspection data was transmitted over a wireless communication link to a receiving node where further analysis or processing can be applied. In summary of system evaluation, the TIDALSENSE SHM system is able to: (A) detect coupling changes of dimensions 10 mm x 150 mm x 150 mm at a distance of 500 mm with a sensitivity in SNR of up to 20 %; (b) detect disbond defects of thickness 1 mm at a distance of 200mm with a sensitivity in SNR of up to 40 %; (c) provide water-tight conditions (using the TIDALSENSE marinisation caps) up to a pressur of 5 bar with a safety factor of 1.5; (d) detect a change in cable bonding conditions causing a 3dB drop in the acquired time-series data using the L(0,1) mode at a distance of 3 m; (e) wirelessly transmit the data overa distance of 40 m maintaining 100 % signal integrity at the receiving node; (f) provide ADD with accuracy in classification and evaluation of 77 % for full blade inspection using optimised feature vectors; (g) software visualisation of the acquired LRU data with simple navigation tools for signal analysis, tabulated parameter display and report facility. WP8: Training Training material as part of Task 8.1 was created and distributed amongst consortium partners. In addition, the physical fundamentals of ultrasonic guided waves were explained thoroughly in D8.1 for the purposes of LRUT in composites and cables. A step by step manual installation of how to use the hardware inspection system as well as the software configuration was provided. Feedback was provided based on personal experience and knowledge. The document was modified accordingly. As part of Task 8.2 the information provided as part of Task 8.1 will assist in the development of industry standards when such inspection systems are implemented on tidal turbines. A process of fine-tuning is expected to take place until standards of an identified quality and reliability are realised. In summary, the TIDALSENSE Systems training provides a guide on how to inspect multi-wire steel cables and composite materials using the pulser / receiver and the software for data manipulation and interrogation. A best-practice approach is provided so that engineers are able to replicate the results as characterised in WP7 efficiently and with relative ease. WP9: Exploitation and dissemination The work carried out during the first period guided the dissemination and exploitation activities in the second half. The main dissemination was delivered via the TIDALSENSE project website. The key selling points of the TIDALSENSE technology were identified as: - Cost efficient monitoring: Providing uninterrupted power during health monitoring (energy saving) and reducing the risk of incurring costs due to dismantling of the blade for inspection, stoppage and downtime. - Advanced failure warning: Proven integration of the LRU technologies able to detect and locate flaws in the blades and cables, reducing risk and cost through use of remote inspection techniques. Enabling operators to decide whether to shut down the tidal turbine, and plan to replace or repair the blade to avoid unnecessary accidents. - Reduced onsite maintenance: Reducing the frequency of labour intensive inspection will provide more efficient maintenance service for operators. Alternatively, regular tests can be run safely from a central base. - Data transfer without human intervention: Provides remote access to the inspection data. - Reduced insurance premiums: Detection of growing defects at earliest possible stage limits damage, enhances system robustness and extends blade life-expectancy. The overall exploitation and dissemination planning in TIDALSENSE has been geared towards maximising the economic benefit to the SMEs as quickly as possible following the end of the project. Marketing flyers in different languages to promote TIDALSENSE technology have also been created for wider audience dissemination. Dissemination was further provided by attending and presenting technical papers at conferences and exhibitions throughout Europe during the project term (details provided in Section 4.2 (A)). In addition, a marketing brochure was designed and disseminated at exhibitions attended by project partners. Further to this, a TIDALSENSE poster was created and put on display at KTU. The project website was regularly updated with details of project activities. Consortium member sites contained a link to the project website to attract more hits. Potential Impact: The TIDALSENSE project has been very successful. The field trials carried out on the mock-up blade sample and multi-wire steel cable confirmed that the SHM development is an effective and reliable inspection device that has the potential to be of considerable interest for the tidal energy industry. It is a unique system that can perform quick and simple system inspections. The consortium had identified the need for such a system for utilisation in what is a growing tidal energy market. The development of the project has been widely available on the TIDALSENSE website (see http://www.tidalsense.com/ online) launched by TWI in the opening weeks of the project in order to facilitate project dissemination. A Google search of the word 'TIDALSENSE' or 'tidal sense' provides details of the project as the first item. The website was maintained by the project coordinator (TWI) with the facility for updates by consortium partners. It remains the principal internet platform where information, contacts, news and developments about the TIDALSENSE project system were accessible to the public for the duration for the project and will remain so beyond project completion. In addition, all partners were asked to add a link of the TIDALSENSE project website onto their respective websites. Whilst conducted by all partners, IT Power and EnerOcean have provided the momentum behind dissemination activities. The investment cost for such a system is considered to be high in the current status. This is mainly due to the electronic instrumentation that can be easily replaced by a more simple and affordable instrument. At the final stage of the TIDALSENSE project, the price of the prototype was discussed but not defined. It was agreed that a drive to lower the costs should be taken seriously without the threat to system capability and integrity. In terms of benefits, this project will benefit the SMEs and reduce long-term costs for utility companies. There is currently no standard condition monitoring technique available that can perform routine autonomous inspection providing details of the tidal blade integrity. The technique involves a P-scan (also ultrasound based) NDT system that requires very high resolution mapping of finished composite components to look for manufacturing errors and material voids - a relatively slow, expensive technique of providing the user with the blade information sought. At present, the industry deploys hands-on-action as deemed necessary - usually long before a critical failure occurs. The aim is to confine repairs to a straight-forward ongoing reportage of incipient repairs to prevent serious repairs that may require extended shutdowns which are costly. The benefits of fitting an SHM system such as TIDALSENSE will become apparent to the industry when a way to calculate the point at which a condition monitoring system becomes cost-effective from the perspective of the owner-operator. There are a variety of reasons for the delay in standard implementation of a condition monitoring system. These include the complicated nature of tidal turbines and the installation environment. Indeed, the argument regarding the challenging environment of tidal installations can be converted into a case for a cost-saving monitoring system. This is where a monitoring system like that developed by the TIDALSENSE consortium has a part to play. An additional strength of the TIDALSENSE project is the high-level ADD that can classify and evaluate defects leading to statistical analysis that can feed back into the design process. There is considerable potential that a project such as TIDALSENSE will find a market-place in the medium-term: tidal turbines are generally under the warranty of the OEM. When these warranties expire, costs will automatically transfer to the owners. When the costs of repairs become apparent to owners, mass implementation of condition monitoring will be expected to take place. Thus, the SMEs within the TIDALSENSE consortium are well-placed to exploit this cycle of maturity set to occur within the tidal energy industry. With further improvements, additional features can be brought to the TIDALSENSE system and this will contribute to increased viability. The price of the TIDALSENSE system has to be addressed to make it a viable option in the industry sector. After lengthy discussion with the TIDALSENSE partners, it was concluded that there are two ways in which the TIDALSENSE project can be brought to the market: (1) As a factory-installed system controlled by the OEM. However, one 'threat' of this approach is that it permits the OEM to control the data and hide flawed equipment. This can be averted by buyers through a process of negotiation at the contractual stage. (2) Retro-fitting the system onto ageing turbines. Whilst this may not be possible whilst the turbine is under warranty, when the owner takes full responsibility for turbine operation, there is considerable scope for mass implementation. A number of dissemination activities were performed during the course of the project to expose the project results and to make the developments visible to the industry. Conferences and seminars related to tidal energy technology were attended by the project partners and presentations were given. However, since information explaining how to use the TIDALSENSE technology are commercially sensitive (because the TIDALSENSE consortium is planning to exploit the results beyond the project), it was decided that this information will not be published in any format (report, guideline or wall chart) other than in the deliverable reports only visible to project partners. The successful implementation of the plan for use and dissemination of knowledge (PUDK) by the established continuing exploitation SME partners - IKnowHow, I&T Nardoni, InnoTec & IT Power - together with feedback from their licensee EnerOcean has the real potential of achieving NDT Equipment sales to SME service NDT companies with potential additional revenue from service inspection SMEs working to help validating new system and techniques for tidal generator monitoring. Flyers and marketing brochures were the main marketing tools for the project and were handed out at conferences by partners. Dissemination activities after completion of the project were considered critical for the successful implementation and commercialisation of the product. List of Websites: http://www.tidalsense.com/ Contact details: Kenneth Burnham kenneth.burnham@twi.co.uk Project coordinator TWI Granta Park Cambridge, CB21 6Al Tel: +44-012-23899334 Related documents Final Report - TIDALSENSE (Development of a condition monitoring system for tidal stream generator structures)
