Resilient Integrated-Coupled FOW platform design methodology (ResIn)

Lead Research Organisation: University of Exeter
Department Name: Engineering Computer Science and Maths


This project will enhance the design and development of floating offshore renewables, in particular offshore floating wind as commercially viable electricity infrastructure through a risk based approach allowing to build resilience against extreme events. The socio-economic challenge is the increasing energy need in emerging economies, such as China, which causes grave air pollution and CO2 emissions. The project work focusses on China, where heavy air pollution alone is estimated to have caused 2.2million premature deaths. Sustainable energy generation, thus replacing coal-fired power plants is one of the solutions to address this problem. In China specifically, the energy demand is at its highest along the industrialised and densely populated coastal regions. The challenge for a renewable energy supply is that the solar, wind and hydro resource are primarily located in the NW and SW of China and electricity transmission via the grid is already constrained. The Chinese government therefore has identified offshore wind energy as one of the primary energy resources with a potential of over 500GW of installed capacity, capable to produce up to 1,500 TWh of electricity per year, which would offset as many as 340 coal-fired power stations. Whilst initial installations in shallow waters near the coast have been made, over 1/3rd of the resource is located in deeper water (>40m) and will require floating installations.

Offshore wind energy generation is currently more expensive than fossil fuels in China, and the risk of typhoon damage is high. The project has a fourfold approach: 1.Enhanced environmental modelling to accurately determine extreme loadings; 2. Assessment of novel, porous floating offshore wind structures and active damping mechanisms; 3. Enhanced numerical modelling techniques to efficiently calculate the complex coupled behaviour of floating wind turbines; 4. Risk based optimisation of devised designs and engineering implications.

This combined approach is carried through distinguished scientific research expertise and leading industry partners in the field of offshore wind. To maximise the impact and benefits of this research the project places large emphasis on knowledge exchange activities, industry liaison and the establishment of cross-country research capacity to foster the global commercial realisation of offshore floating wind energy.

The project is an interdisciplinary, cross-country collaboration with leading research Universities and industry partners. The academic expertise from the University of Exeter, the University of Edinburgh and University of Bath in the areas of Environmental assessment and modelling, Hydrodynamic design, Advanced computational modelling and risk based reliability engineering is matched with Dalian University of Technology and Zhejiang University as two of the leading Chinese research institutions in Ocean Engineering and Offshore Renewable Energy.

Whilst the project carries out fundamental engineering research, strong industrial partnerships in both countries will facilitate industry advice and subsequent research uptake. The strong industrial UK support for this project through the ORE Catapult, DNV-GL, ITPE is matched with wider international support through EDF (France) and DSA (Canada), as well as the Chinese project partners MingYang Wind Power Ltd (3rd largest wind manufacturer in China), the National Ocean Technology Centre, NOTC, (institutional responsibility for marine spatial planning) and the 'Shanghai Investigation, Design & Research Institute', SIDRI (State-owned offshore wind project developer in China), demonstrates the timeliness and industrial relevance of the proposed research. All partners are committed to support the establishment of a long-lasting research base to develop resilient and cost effective offshore floating wind energy systems through collaborative research and innovation efforts, as well as capacity building and knowledge exchange.

Planned Impact

The challenges facing the development of offshore renewable energy (ORE), in particular floating wind energy in China have led the research focus for this proposal. The project impact will be achieved through innovative designs and an enhanced understanding of the complex aero-hydro-elastic coupling of floating offshore wind turbines in order to improve their resilience in extreme environmental loadings. The impact of the proposed research will be in three different domains: i) industrial application of innovative research; ii) supporting planning decision-making through enhanced environmental characterisation for offshore wind and iii) sustained cross-country collaboration:

i) The research targeted in this proposal will directly benefit the innovation capacity of the research institutions and industry partners. In this capacity, the project will bring together the research expertise in hydrodynamics with a leading offshore wind company in China, MingYang Wind Power Ltd, the Shanghai Investigation, Design & Research Institute (SIDRI) and the National Ocean Technology Centre (NOTC) in China. SIDR and NOTC are instrumental for offshore wind planning, consenting and installation activities in China. The national importance for the UK is twofold, strengthening and export of research and offshore wind services for floating offshore wind to China and beyond. The proposed research innovation will further enhance the market opportunities for UK plc, incl. DNV-GL; ITPE. Moreover, the research uptake of key international actors for floating offshore wind, such as EDF and DSA will strengthen the UK research leadership in this area.

ii) The Chinese project partner NOTC, is a subsidiary of the State Ocean Administration (SOA) which is closely consulting with the National Energy Administration (NEA) and the Ministry of Environmental Protection (MEA) in China. These governmental institutions and wider ORE community will benefit from enhanced environmental and engineering assessment methodologies and engineering designs directed to ORE technologies. Advancing environmental resource assessment techniques and generating resultant data, with a focus towards localised environmental conditions and extremes, will be an essential criteria for the project. The research vision is to support the development of FOW through cost reduction, which in turn enables social and economic benefits, primarily to address implications of high levels of air pollution.

iii) The project emphasises the strategic importance of the research areas and the sustained collaboration between research institutes and industrial stakeholders. The project will aim to establish a cross-national UK-China knowledge exchange that is strongly aligned with other successful ORE call projects as well as the UK Centre for Marine Energy (UKCMER) and the upcoming ORE Supergen, allowing a strong bilateral interface to UK and Chinese academic institutions, governmental and non-governmental organisations and industry partners. Whilst this project addresses present knowledge gaps associated to current FOW in China, a continued knowledge exchange culture will enable a long-term strategy to address technical and socio-economic challenges and to translate research outcomes into a sustainable growth of FOW. All partners are committed to support the establishment of a long-lasting research base to address the sustainable infrastructure challenge by focusing fundamental research towards the commercial realisation of Floating Offshore Wind (FOW).


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Description A large scale computational domain of South China and East China wave and current numerical model has been constructed. The model will be run by wind boundary input to include swell and wind wave generation. The model outputs will be used to inform conditions in which floating offshore wind (FOW) turbines will operate in the Chia Sea and provide the details of environmental parameters to inform the engineering design innovation and computational modelling studies. Work has also been conducted in parallel on the statistics of extreme individual wave and crest heights. The estimation of return periods of individual waves is important for the design of offshore and coastal structures such as offshore wind turbines. New methodologies have been developed for calculating return periods of individual waves, which both simplify and improve on the accuracy of existing methods. The new methods have been reported in two papers, submitted to the OMAE conference and the journal Coastal Engineering
In order to support the studies on the proposed design innovations for FOW turbines a new method has been developed, which extends the commonly used linear boundary element method (BEM) to be able to compute wave loads on combined solid and porous structures with arbitrary geometries. Two conference papers have been submitted on this topic) - one on the formulation of the BEM model and the other on the verification against published results for simple geometries. The BEM model is currently being developed and verified. Furthermore, initial design for hybrid system of FOW and OWC wave energy converter are investigated. An analytical solution for wave interaction with the hybrid system was developed based on potential theory and eigen-function expansion technique. A pneumatic model is adopted to describe the relationship between air pressure in the chamber and turbine characteristics.
The whole system modelling approach has been started applying CfD approaches using OpenFOAM and PIC allowing to expand the modelling of 3D floating bodies and modelling wave interaction with 3D floating platform. The PIC model has been expanded for simulating 3D floating body and a trial for simulating a simple floating buoy has been implemented.

ResIn Phase 1 Tank Tests were conducted at Dalian as a cross-border activity within the ResIn project, enabled through a collaborative design effort. The work took place between March and June 2018. The purpose of the tank tests was to validate the numerical models for wave interaction with porous structures, developed as part of WP2. Two sets of tests were conducted in parallel. One set of tests measured the loads on flat porous sheets of various specifications (porosity, hole-spacing, thickness).

The other set of tests measured the loads on porous cylinders both with and without a solid inner cylinder. The graphs below show some comparisons between the experimental results (circles) and the BEM model predictions (dashed lines) for tests with porous cylinders. The plots show the nondimensional surge force against nondimensional wavenumber. The first plot shows results for a cylinder diameter of 0.5m, wave steepness kA=0.05 and porosity t = 0.1, 0.2 and 0.3. The second plot shows results for constant porosity of t = 0.2, wave steepness kA=0.05 and three diameters D = 0.375, 0.5 and 0.75m. The third plot shows results for a single cylinder of porosity of t = 0.2 and diameter D = 5m in waves of steepness between kA = 0.05 and 0.15. The numerical predictions and experimental results show good agreement in all cases.

From further numerical and experimental studies implemented during the ResIn project it has been found that the quadratic model for the pressure loss using Molin's model [8] for the friction term gives good predictions for the amplitude of the wave loads on a thin porous wall. The model generally agrees well with experimental measurements of the variation in the force as a function of wave frequency, amplitude and sheet porosity. The experimental data showed some differences with numerical results for low frequencies and porosities. It is believed that these differences were caused by wave interactions with the raised section of the tank floor. This hypothesis will be investigated in further work. In contrast, the results showed that the assumption of a linear pressure drop across the porous boundary is not a tenable model as it is not capable of predicting the variation in the force with wave frequency or amplitude. The findings will now be used to define a scaled floating offshore wind platform that wil be tested in Dalian Universtiy of TEchnology, China.
Exploitation Route Working in collaboration between UK and Chinese researchers the ResIn project itself has implemented various research activities and outputs within the first six month of the project to aid in the realisation of the aim and objectives. Knowledge engage activities will allow effectively to communicate and progress research activities, and an engagement/network plan has been established with activities are currently taken place realising the cross-country engagement activities.
Sectors Energy,Environment

Description This project is an industrial and educational partnership between the UK and China for the Offshore Renewable Energy sector. The overall aim of the project is to achieve carbon reduction and to demonstrate the social impact of this. This will be done through the sharing of knowledge and research between the UK and China to encourage innovation and generate productivity in the energy sector. Generating productivity and encouraging innovation in industry with carbon reduction in China. Education, from grass roots right through to the highest level, is important in changing cultures and influencing the young entrepreneurs of tomorrow. Website: The Offshore Renewable Energy (ORE) programme has started on the 1st of July 2017 and aims to develop the next generation of offshore renewable energy technologies to enable the safe, secure, affordable and efficient provision of clean energy in a collaborative approach between the UK and China. The five funded projects will use a collaborative and multidisciplinary approach tackling key challenges affecting the development of ORE systems, such as offshore wind, wave and tide facilities, and maximise their environmental and socio-economic benefits. The projects will determine where the best energy resource is available and where would be best to implement ORE technologies, and inform the development of technology so that structures are resilient to extreme events such as typhoons and earthquakes. In order to promote equal opportunities and diversity of employees in offshore energy research the projects have implemented a high agenda to promote gender participation in all project activities, from management to technology development, exploitation, dissemination, internships, and communication. An ORE UK-China cross project Network/Engagement plan and Management plan has been established. The goals of this ORE UK-China Newton Fund Network are: - To enable coordination between projects and facilitate logistics - To secure guidance from a high level board and ensure high quality governance - To manage, coordinate and deliver reporting - To develop a knowledge exchange strategy which incorporates a plan of co-ordinated activities and details how the research teams will work together to engage stakeholders and maximise impact of the awards and of the programme as a whole - To develop, implement and monitor adherence to the programme Data Management Plan - To drawing the programme together scientifically through integration and synthesis activities The following papers have been submitted and/or published during the ResIn project so far: Journal papers: - C. Yang, Y. Wang, S. Weller, De-Zhi Ning, L. Johanning; (2018). Experimental and numerical investigation on coupled motion characteristics of a tunnel element suspended from a twin-barge; Ocean Engineering 153 (2018) 201-214, doi: 10.1016/j.oceaneng.2018.01.112 - Mackay E, Johanning L. (2018) A generalised equivalent storm model for long-term statistics of ocean waves, Coastal Engineering, volume 140, pages 411-428, DOI:10.1016/j.coastaleng.2018.06.001 - Mackay EBL, Johanning L. (2018) Long-term distributions of individual wave and crest heights, Ocean Engineering, volume 165, pages 164-183, DOI:10.1016/j.oceaneng.2018.07.047. Conference papers: - E. Mackay, L. Johanning. A Boundary Integral Method for Wave Forces on Combined Porous and Solid Structures. 33rd International Workshop on Water Waves and Floating Bodies (IWWWFB), 4-7 April, 2018 in Guidel-Plages, France. - E. Mackay, L. Johanning. A Simple and Robust Method for Calculating Return Periods of Ocean Waves. Proceedings of the ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering, OMAE2018, June 17-22, 2018, Madrid, Spain. - E. Mackay, A. Feichtner, R. Smith, P.R. Thies, L. Johanning. Verification of a Boundary Element Model for Wave Forces on Structures with Porous Elements. RENEW 2018, 3rd International Conference on Renewable Energies Offshore, 8 - 10 October 2018, Lisbon, Portugal. - Smith RE, Pillai AC, Tabor G, Thies PR, Johanning L. (2019) Impact of Rotor Misalignment Due to Platform Motions on Floating Offshore Wind Turbine Blade Loads, Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE2019, Glasgow, Uk, 9th - 14th Jun 2019. PhD Placements and Supervisor Mobility Grants China-UK (The Newton Fund) for Anna Feichtner and Prof. Lars Johanning: Anna Feichtner (PhD student at the University of Exeter)and Prof. Lars Johanning (PhD supervisor) have been successful in the PhD Placements and Supervisor Mobility Grants China-UK application. Anna will spend 6 months (between April and September 2019) at the Dalian University of Technology (DUT) in China where she will work on a model to assess extreme load and response characteristics on a floating offshore wind (FOW) structure enabled with a porous shield, allowing to inform the development of a resilient and robust approach for offshore renewable energy (ORE) systems in the South China Sea. Anna has made significant contribution to the research tasks within her first year and has become familiar with relevant software and tools, which will also be essential during the PhD placement at DUT. As part of the ResIn project, Anna has also been included in the joint BEM-code development by researchers at DUT and UoEx that will be used for verifying of future CFD results. Supergen ORE Poster Prize for Dr Ed Mackay: Dr Ed Mackay, a Research Fellow at the University of Exeter, was awarded first prize at the Supergen Early Career Research Forum, held at the University of Plymouth on 21st January 2019. The award was for his research poster, titled "The use of porous materials for motion damping of floating offshore wind turbines". The poster described the development and validation of a novel boundary element method for modelling wave loads on offshore structures with porous elements, together with initial design studies on the effect of including a porous outer layer on platforms for floating wind turbines. Initial results indicated that a significant reduction in the motions of the platform could be achieved, which has the potential to improve energy capture and reduce fatigue damage.
First Year Of Impact 2017
Sector Energy,Environment
Impact Types Societal

Description Joint Offshore Energy Engineering and Innovation Partnership (JOIN)
Amount £71,000 (GBP)
Organisation British Council 
Sector Charity/Non Profit
Country United Kingdom
Start 04/2019 
End 03/2024
Description PhD Placement Programme China
Amount £11,740 (GBP)
Funding ID 424495777 
Organisation British Council 
Sector Charity/Non Profit
Country United Kingdom
Start 04/2019 
End 09/2019
Description Resilient Integrated-Coupled FOW platform design methodology (ResIn); ResIn - 1st UK-China workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A UK-China ResIn workshop was held from the 10th - 14th November 2017, International Convention Center, Dalian University of Technology, Dalian, China. Over 30 UK and Chinese delegates from industry and academia took place in this workshop exchanging industry requirements to enable floating offshore wind (FOW) in China and academics presented research capabilities and outcomes supporting the development of FOW in Chinese sea. The workshop resulted in multiple cross-disciplinary collaboration opportunities that will be fostered during the lifetime of the ResIn project.
Year(s) Of Engagement Activity 2017