QED Naval and their selected fabricators, Cimpina based in Northern Ireland, are soon to complete the Subhub community demonstrator ready for deployment to EMEC in the next couple of months. Once at EMEC it is intended to use the FORESEA funding to conduct a phased set of sea trials to demonstrate that a tidal array can be installed and recovered in a single offshore operation using small vessel with low date rates.
Phase 1a installation and recovery trials at the scale tidal test site using replica turbines and equipment allowing marine operators to gain valuable experience of installation method.
Phase 1b aims to integrate Schottel Hydro SIT-250 turbines providing Subhub with a capacity of 190kW, capable of powering 50 homes. This collaboration includes SME who will be providing their ‘Flipper’ support structure for bi-directional flow, Platform Operation Module (POM), for controlling the platform at EMEC and Subsea Transformer Module (STM) to transmit the grid friendly power ashore.
Phase 2a will then move operations over to the Falls of Warness site. The aim is to demonstrate the installation and recovery over a wide spectrum of tidal flow and wave heights since the deployment method uses Subhub’s unique submersible stability characteristics that are less sensitive to extreme conditions.
Phase 2b will demonstrate the long term deployment capabilities, operational stability of its gravity based anchoring system and increased performance characteristics of the turbines which have shown insensitivity to cross flows in tank testing at Flowave. An O&M strategy will be developed for its customers assessing fatigue loads, marine growth and corrosion factors.
Phase 3 will be used to assess the environmental impacts of a longer term deployment and demonstrate the ability of the Subhub to be quickly and easily decommissioned from the site.
Once this testing is complete it is intended to offer the Subhub for sale and re-use it at another site. All going well Subhub will be further developed utilising a test berth at EMEC with a larger capcity machine rated at 1.2MW. QED Naval is in early stage discussions with several collaborative partners who would like to be involved in this larger scale development due to be deployed in 2018.
Cimpina based in Northern Ireland in Belfast Docks have been awarded the build contract for the Subhub. They were among 6 different fabricators contending for the business.
Work commenced in November and the outer shell was taking shape before Christmas. Completion is expected in the first quarter of next year.
The Community Subhub with a capacity of 200kW using Schottel tidal turbines will be launched and transported up to EMEC where long term testing will be conducted, as part of the FORESEA project, to demonstrate the Subhub’s capabilities with installation and retrieval. The performance of the Subhub and turbines will be monitored. Long term operations and maintenance strategy will be developed to validate the OPEX cost model and hence the LCOE for a Subhub related project.
QED Naval are excited to announce that they have been awarded funding for the open sea testing at the EMEC tidal test sites. This provides access to both the scale tidal test site along with the grid connected Falls of Warness site.
QED Naval have engaged in pre-commercial discussions for a contract at EMEC to carry marine operations at their test site that aims to validate claims of the Subhub tidal platform. These include:
Reduction in the cost of deployment of tidal turbines using a single marine operation to install the turbines ready for operation on the seabed within a broad range and tidal states and wave conditions.
Enhanced power output and site capacity factors.
Retrieval of the system for maintenance in a single marine operation using a low cost multicat vessel over a broad range of conditions.
Significant site feasibility work has already been carried out by QED Naval as part of the FORESEA application which will ultimately see them connect tidal turbines to the grid for verification of the enhanced performance characteristics provided by the Subhub foundation solution.
GIS mapping tool containing all the flow data, berth positions and bathymetry of the Falls of Warness tidal test site.
QED Naval are pleased to welcome Thomas Nevalainen to the team. Thomas joins QED Naval from Strathclyde University where he is about to complete his Ph.D. His thesis entitled “The effect of unsteady sea conditions on tidal stream turbine loads and durability” allows QED Naval to extend its wave and tidal loading capabilities and add BEMT methods to calculating turbine loads as part of a more streamlined optimisation process for QED’s Subhub foundation structure. CFD methods can then be used to assess the finalised design.
Thomas will take over the management of access to the Hartree supercomputer which is used to improve turnaround times on large models and increase the speed of learning from weeks to days. QED Naval have access to ANSYS Fluent and X-Flow on the Hartree supercomputer. Fluent is a sophisticated CFD package that provides access to a large number of turbulence models and mesh developments such as polyhedral meshes that streamline the size of the model and improve accuracy. However, despite its sophistication it tends to be sensitive cell quality so a great deal of time is spent generating good conformant meshes both in pre and post processing results.
Thomas also takes over responsibilities for utilising the other enhanced capability using X-Flow provided by FlowHD. It allows QED Naval to reduce the pre/post processing time using Lattice Boltzman cells domain that is self-adaptive and easily controlled by the user in terms of vorticity in the model in the areas of interest. It combines this with fully transient, LES turbulent model which resolves the largest turbulence fluctuations in the flow while the smallest eddies are approximated for increased efficiency. The self-adaptive cell capability makes it much easier to conduct rigid body motions such as assessing tidal turbine performance characteristics. From the work conducted to date the tools were well validated using the Subhub performance model tank testing results and assessment of Tocardo’s T1 tidal turbine against their specified performance data.
QED Naval offer these capabilities to other marine renewable companies at competitive rates. The main advantage of this work is it can be used to determine what the design loads are on full scale structures without having to go to the expense of building a prototype. Hence, these assessments can minimise the technical and commercial risks of developing marine renewable structures and turbines.
QED Naval commissioned renewable energy consultancy, SgurrEnergy, to undertake an independent technical and commercial due diligence design review of the Subhub tidal turbine transport, installation and foundation system. It encompassed a review of analysis reports that had been produced as part of the feasibility and R&D studies supported by Scottish Enterprise. These include an analysis of all the tank testing results and the calculations of extreme loads, together with an assessment of the assumptions that have been used in scaling up to anticipated loads in larger device iterations. SgurrEnergy has also reviewed the tidal and wave loading numerical modelling reports that were based upon the tank testing campaign. This forms part of QED Naval’s detailed design process of the 1:4 scale technology demonstrator to be tested at Strangford Lough”.
The report also reviews the status of the tidal market and makes recommendations for QED Naval’s testing programme to validate the suggested performance and operation of the Subhub. These include a requirement to provide clear evidence to support the claimed reduction in CAPEX and OPEX costs compared to other transport and installation solutions, to demonstrate the potential increase in power density by accelerating the flow into the turbines, and to consider means of reducing the effects of tidal shear, veer and turbulence on the turbines installed on the Subhub.
The latest community scale version of the Subhub has now been frozen ready for build. Manufacturing outputs have been completed for the new modularised version of the Subhub. This allows the bare hull to be fabricated on the quayside and lifted into the water by a smaller, more available and lower cost crane.
After launch the newly designed modular solid ballast blocks can be easily lifted slotted into the bottom of the hull to provide the impressive stability characteristics of the Subhub during transit and installation.
The pressure cabinets to support the 3 x Tocardo T1 turbines have also been modularised to allow them to be slotted into the top of the hull once the main hull has been launched. This allows the cabinets to be quickly connected up to the generators whilst afloat. Access panels allow simple maintenance operations to be completed at sea.
Successful Installation & Retrieval Trials in Real Tidal Conditions
Recent testing of the Subhub operations model in high tidal flow conditions proved its ballast system capabilities and installation and retrieval methodology with great success. QED Naval were able to install the model on the seabed safely and in a controlled manner within minutes. The model was then secured on the seabed overnight before being recovered to the surface gracefully within an equally short time period and control.
Despite onerous wind, wave and current conditions experienced during testing, the Subhub coped admirably during the installation and retrieval trials. Scaling these extreme conditions to the prototype size, based on a 4.0m diameter turbine, would be equivalent to over 2m/s or 4 knots with a significant wave heights over 1.0m
Frontal profiles of turbine blades were added to the cross beam to simulate three turbines being installed on the Subhub; the blades acting against the current presented no issues.
QED Naval have teamed up with Offler Marine Services Group (OMSG) to provide offshore expertise with the selection of installation and recovery methods, to help de-risk and reduce cost exposure of the Subhub project and its payload of tidal turbines.
QED Naval received a real boost to their plans to reduce the costs of deployment of the commercial scale (multi MW devices) from OMSG. They received a report this week from OSMG produced by the team who have significant experience within the tidal, wave and offshore wind power industry. Steve Offler lent his weight and credibility behind the Subhub project when it was recognised that the feasibility to install Subhub in 30-60 minute time scalesandat a fraction of the typical installation costs currently influencing the industry were achievable.
Recommendations from OMSG’s report are currently being implemented into the prototype structuredesign, based on a 4.0m diameter tidal turbine, tofurther fine tune the offshoreinstallation and recoveryprocess.
Jeremy Smith, Managing Director of QED Naval said, “This is a really exciting development for QED Subhub since the basis of our design is to remove the need for complex, large and hi tech installation vessels with equally high day rates and availability issues. This report along with what we have learned from our ballasting trials at Forth Estuary Engineering are the positive indicators that significant reductions in the costs of deployment of commercial scale devices are not too far away. We are steadily moving towards offering our customers and their investors a generic deployment solution no matter what the location, environment or turbine used“.
Steve Offler, MD at OMSG said “Marine Installation costs and risks are high, QED have identified this and sought to engage installation design expertise early to ensure costs and risks are mitigated, this is an extremely important part of the development process and one that will add significant value to Subhubs future success”
QED Naval have move their main office to satisfy their growing requirements. Their new city centre location on Castle Street is within Edinburgh’s ‘golden triangle’ (EH2 3AH) and provides improved access to transport links for their customers and clients.
The new accommodation was formally part of the old Northern Rock buildings and allows us to plug straight into the excellent IT facilities and office network which was left in place. The dedicated server room also allows QED Naval to upgrade their cluster to make best use of their High Performance Computing (HPC) capabilities provided by ANSYS HPC which provides a significant boost to the performance large fluid loading (CFD) and mechanical (FEA) models.
QED Naval launched the Subhub Operational model last week at Forth Estuary Engineering’s (FEE) dock in Leith. The last few weeks has been a hive of activity finalising the setup of the ballast systems, instrumentation, and the dock access and testing arrangements.
FEE have provided outstanding support during the preparation and will to be on hand through the testing phase. The Subhub will now be put through its passes to test the stability during installation, ballast system control and installation/retrieval methods.
The Director of QED Naval was on site to witness the launch and initial testing and has stated, “A lot of hard work has gone into getting the Subhub project to this point which is a credit to the team and supporting companies. The Operations model represents a big step forward for the Subhub project de-risking the ballast system and installation/retrieval methods which is a key selling point used to reduce the cost of deployment and overall the cost of energy”.
Marine renewable engineering and design consultants