Large scale interactive coupled modelling of environmental impacts of marine renewable energy farms

Lead Research Organisation: Queen's University of Belfast
Department Name: Sch of Natural and Built Environment

Abstract

For the UK to fulfil its energy demand and renewable commitments by 2020, it is recognised by the Government that it will be necessary to have a significant input from marine renewable resources, both wave and tidal. This will require the deployment of arrays of large numbers (>50) to provide electrical energy on a commercially viable basis. Such arrays would potentially extend along many kilometres of UK coastlines. While limited work has been carried out into the potential environmental impact of single devices, the impact that arrays may have on the flow-field together with possible resulting effects on marine ecosystem processes is unknown. Forecasting the hydrodynamic changes resulting from array installation is difficult but is a core requirement of the industry; considerable effort is being put in to this field by commercial and academic research groups. Ecological surveys and studies to investigate ecological effects are time consuming and costly and are generally reactive; a more efficient approach is to develop 2 and 3D linked hydrodynamic-ecological modelling which has the potential to be reactive and to allow forecasting of the effects of array installation.

Arising from this background, the overall aim of the project is to demonstrate the ability to numerically model the change in ambient hydrodynamics resulting from the installation of wave and tidal device arrays and to couple the model output to associated ecological models to allow prediction of associated changes in benthic habitats and dynamics, plankton growth and fish communities.

To achieve this aim the proposal incorporates a series of objectives based on the exploitation of different modelling approaches using both 2 and 3D modelling. The software to be used will include (i) MIKE, a family of modelling tools developed by DHI which is widely used by the majority of marine consultants in the UK. The package includes the associated Ecolab ecological processes model which is widely used in Australasia for a range of environmental assessments especially in the coastal zone. (ii) Other high resolution hydrodynamic models such as Fluidity-ICOM and GOTM and (iii) the ERSEM ecological model which will be linked to output from the hydrodynamical models in (ii). Models in (ii) and (iii) are all widely recognised within the research community. A major novelty of the project is that it will thus make use of a range of readily available commercial and open source software. This approach will allow two main goals to be achieved: (i) Demonstration that output and results are not model specific and (ii) the development of open source tools will have the potential for the research approach to be enjoyed by the wider community.

The proposal fully recognises the complexity of ecological processes. An initial objective of the project will therefore be to parameterise the relevant biological processes, especially relating to benthic detrital dynamics, plankton growth and fish population dynamics, in order to effectively run a coupled hydrodynamic-ecological model. These parameterisations will then be tested to give realistic results with respect to inter- and intra-annual variation of tidal and wave climate conditions without the presence of any Marine Energy Converters (MECs) before application to situations involving array deployments. Special focus will be given to the potential positive effects of array deployments arising from the changes in the hydrodynamics and establishment of no-fishing zones.

The importance of the work will be the value of this ground-breaking R & D for end-users, spanning the commercial developers of marine energy devices, environmental consultants and the regulatory authorities. The project has been designed specifically for use by all sectors of the industry in order to accelerate the development of marine renewable devices by allowing forecasting of the environmental consequences of array deployments.

Planned Impact

The outcomes of the project will principally benefit the UK marine renewable energy industry, particularly the commercial developers of marine energy device arrays, marine environmental consultants and national marine regulatory authorities. There will also be certain wider benefits to the general public primarily through optimising environmental sustainability and impact reduction against the urgent need to encourage the development of marine renewable resources.

The UK is, arguably, at the forefront in the development of marine renewable energy devices and arrays. However, with the deployment of any such devices there will always be a cost to the environment. Establishing the resulting change to the environment is not easy owing to the complexity of the factors contributing to the change including, for example, the specific design of the wave or tidal energy devices to be used, the design of the array and local physical and environmental influences. In addition the complexities of the marine ecosystem make it particularly challenging to carry out convincing observations. At present observational programmes are usually based on monitoring carried out before and following the installation of the device: such an approach is reactive in nature. It is much more desirable to take a pro-active approach which has the potential to allow forecasting of environmental consequences.

The impact of the project will be maximised by employing a modelling approach. Application of the model to proposed device array sites will allow forecasts to be made of the effects of the array on two main ecosystem components, the benthos and the fisheries. This in turn will allow predictions to be made of the device array on the economics of local fishing industries and on the effects on biodiversity and stability of the indigenous benthic communities. This will be of considerable assistance to national regulatory bodies and others in the drive to establish limits to ecosystem modification associated with commercial marine energy extraction. In a broader context the outcomes of the study will provide a solid component for the development of a national protocol for the marine renewable energy industry in relation to the environment. The establishment of such standards would be a major boost to the industry by shortening the consultation process on environmental acceptability of such schemes.

The project will also benefit the marketing base of the UK marine renewable energy industry by allowing developers to offer a more integrated management package to potential customers. The attractiveness of the model to be developed will be enhanced by its flexibility allowing a range of environmental parameters of local interest to be incorporated in the model as required. Development of the model, especially the ecological component, will be assisted by liaison with DHI, Denmark; the extensive international links of this company will enhance the impact of the project internationally. Underpinning the overall model are two state-of-the-art hydrodynamic sub-models which reflect the UK lead in the field of flow prediction in the vicinity of marine energy device arrays: this again will enhance the impact of the project by providing greater confidence to potential customers.

The benefits arising from the project will be realised at the end of the project and beyond. However essential foundations for gaining the full impact benefits will be laid over the course of the project: this will be done through an Advisory Forum and through wider contacts.

While the PDRAs employed for the project will be focussed on the hydrodynamic and ecological modelling, they will receive training in knowledge exploitation and will be expected to participate actively in establishing working links with end-users.

Publications

10 25 50
 
Description • Turbine correction parameter
For coarse grid resolutions (kilometre scale) the resulting force exerted on the flow agrees well with the theoretical value. However the force starts decreasing with decreasing grid sizes when these become smaller than the length scale of the wake recovery. This is because the assumption that the upstream velocity can be approximated by the local model velocity is no longer valid. Using linear momentum actuator disc theory however, we derive a relationship between these two velocities and formulate a correction to the enhanced bottom drag formulation that consistently applies a force that remains closed to the theoretical value, for all grid sizes down to the turbine scale. We show how the corrections can be applied (demonstrated here for the models MIKE 21 and Fluidity) by a simple modification of the drag coefficient.
Kramer S, Piggott M. A correction to the enhanced bottom drag parameterisation of tidal turbines. In review, Renewable Energy.
• Optimising design of tidal stream turbine farms
A new approach for optimising the design of tidal stream turbine farms is presented by a turbine density function that specifies the number of turbines per unit area and an associated continuous locally-enhanced bottom friction field. The farm design question is formulated as a mathematical optimisation problem constrained by the shallow water equations and solved with efficient, gradient-based optimisation methods. The resulting method is accurate, computationally efficient, allows complex installation constraints, and supports different goal quantities such as to maximise power or profit. The outputs of the optimisation are the optimal number of turbines, their location within the farm, the overall farm profit, the farm's power extraction, and the installation cost.
Funke SW, Kramer S, Piggott M. Design optimisation and resource assessment for tidal-stream renewable energy farms using a new continuous turbine approach. In review Renewable Energy.
• Potential environmental impact of tidal energy extraction at large spatial scales
A model study was carried out of the potential large-scale (>100 km) effects of marine renewable tidal energy generation in the Pentland Firth, using the 3D hydrodynamics-biogeochemistry model GETM-ERSEM-BFM. A realistic 800 MW scenario and an exaggerated academic 8 GW scenario were considered. The realistic 800 MW scenario suggested minor effects on the tides, and undetectable effects on the biogeochemistry. The academic 8 GW scenario suggested effects would be observed over hundreds of kilometres away with changes of up to 10% in tidal and ecosystem variables, in particular in a broad area in the vicinity of The Wash. There, waters became less turbid, and primary production increased with associated increases in faunal ecosystem variables. Moreover, a one-off increase in carbon storage in the sea bed was detected.
Van der Molen J, Ruardij P, Greenwood N. Potential environmental impact of tidal energy extraction in the Pentland Firth at large spatial scales: results of a biogeochemical model. Submitted to Biogeosciences.
• Tidal devices and benthic communities
Current speed, together with bottom type and depth, strongly influence benthic community distributions; however the interaction of these factors in controlling benthic dynamics in high energy environments is poorly understood. Over almost the 1 m/s velocity range, no changes in benthic communities were observed. This suggested that the high physical disturbance associated with the high current flows in the Strangford Narrows reflected the opportunistic nature of the benthic species present with individuals being continuously and randomly affected by turbulent forces and physical damage. It is concluded that during operation, the removal of energy by marine tidal energy arrays is unlikely to have a significant effect on benthic communities in high flow environments.
Kregting L, Elsäßer B, Kennedy R, Smyth D, O'Carroll J, Savidge G. Changes in current flows by marine tidal energy converter arrays are unlikely to affect benthic communities. Submitted to Plos One.
• Adaptive Haar wavelets for the angular discretisation of spectral wave models
A new framework for applying anisotropic angular adaptivity in spectral wave modelling is presented. The angular dimension of the action balance equation is discretised with the use of Haar wavelets, hierarchical piecewise-constant basis functions with compact support, and an adaptive methodology for anisotropically adjusting the resolution of the angular mesh is proposed. This work allows a reduction of computational effort in spectral wave modelling, through a reduction in the degrees of freedom required for a given accuracy, with an automated procedure and minimal cost.
Alexandros A, Buchan AG., Piggott MD, Pain CC, Hill J, Goffin MA. Adaptive harr wavelets for the angular discretisation of spectral wave models. Accepted Journal of computational physics.
• NZPD model using EcoLab coupled to a hydrodynamic model
Changes in hydrodynamics as a result of tidal turbine arrays may have an effect on the dynamics of biological systems. A Nutrient-Phytoplankton-Zooplankton-Detritus model was developed in EcoLab by DHI which was coupled to the idealised hydrodynamic domain developed in this project with (55 turbines) and without turbines. Both scenarios were run for a full year to capture the dynamics such as the spring bloom and later decline of phytoplankton concentrations and results were analysed statistically. Results suggest that natural occurring spatial variations in concentration of phytoplankton are greater than that can be attributed to an array of tidal turbines alone.
Schchert P, Kregting L, Pritchard D, Elsäßer B. Simulating ecological changes caused by marine energy devices. To be submitted Biogeosciences
• Five EWTEC conference papers
Schmitt P, Elsäßer B, Coffin M, Hood J, Starzmann R. 2015. Field testing a full-scale tidal turbine Part 3: Acoustic Characteristics, Proceedings of the European Wave and Tidal Energy Conference (EWTEC) 2015.
Avdis A, Jacobs CT, Hill J, Piggott MD, Gorman GJ, Shoreline and bathymetry approximation in mesh generation for tidal renewable simulations, Proceedings of the European Wave and Tidal Energy Conference (EWTEC) 2015. http://arxiv.org/pdf/1510.01560v1.pdf
Kramer SC, Funke SW, Piggott MD, A continuous approach for the optimisation of tidal turbine farms, Proceedings of the European Wave and Tidal Energy Conference (EWTEC) 2015.
http://amcg.ese.ic.ac.uk/~piggt01/publications/kramer_ewtec_2015.pdf
Culley DM, Funke SW, Kramer SC, Piggott MD, Tidal stream resource assessment through optimisation of array design with quanti?cation of uncertainty, Proceedings of the European Wave and Tidal Energy Conference (EWTEC) 2015. http://amcg.ese.ic.ac.uk/~piggt01/publications/culley_ewtec_2015.pdf
Kramer SC, Funke SW, Piggott MD, A continuous approach for the optimisation of tidal turbine farms, Proceedings of the European Wave and Tidal Energy Conference (EWTEC) 2015.
http://amcg.ese.ic.ac.uk/~piggt01/publications/kramer_ewtec_2015.pdf
• Conference General
Culley DM, Funke SF, Kramer SC, Piggott MD, A hierarchy of approaches for the optimal design of tidal turbine arrays, ICOE 2014 (5th International Conference on Ocean Energy), 9 pages, 2014. http://www.icoe2014canada.org/wp-content/uploads/2014/11/CulleyDavid_5-4.pdf
Exploitation Route The findings have and will be published in a number of journals. They will have significant impact on the understanding of how to assess the environmental impact of marine renewable energy devices.
The project is still ongoing.
Sectors Energy,Environment

 
Description Statement of Impact • Queen's University Belfast were part of a successful Horizon 2020 proposal led by Midroc Project Management AB, Sweden. This is a €5 million project developing the Power Take-Off System for a Subsea Tidal Kite (PowerKite) to begin in early 2016. QUB is leading the environmental impact work package. • Imperial College London were successful in a Standard Research EPSRC entitled 'A new simulation and optimisation platform for marine technology. This £434,711 is with project partners from Alstom Group, H R Wallingford Ltd, Renewable Energy Systems Ltd, Argonne National laboratory, MeyGen Ltd, Simula Research Laboratory, CEFAS and Numerical Algorithms Group Ltd. • Dr Louise Kregting was a successful candidate for a Queen's University Belfast Fellowship in the clean energy University research priority theme. The success of the fellowship is attributed to the knowledge gained via the LINC project. • Five PhDs have been funded o 1. A Cullen Fellowship that Elsäßer and Schuchert applied for entitled 'Developing Interdisciplinary Decision Support Tools for the Introduction of Marine Renewable Energy Sites' o 2. A CASE PhD between QUB and Aquamarine Power o 3. A EPSRC funded PhD supervised by Kregting and Elsäßer o 4. A NERC DTP PhD: Adapting to the Challenges of a Changing Environment between York University, ACCE Institute Shelffield, CEFAS. o 5. A NERC DTP PhD student at Imperial College London to incorporate economic penalty terms within array optimisation design tools Industry and Policy Partners (1/2 page) • DHI: Working with DHI to implement the turbine correction equation into the DHI software. This will be a significant development for implementing tidal turbines into the domain of different mesh resolutions. • Northern Ireland Environmental Agency: The groups knowledge and modelling tools are used in obtaining site licenses for testing scaled devices in Strangford Lough. • Minesto: Through involvement of QUB with SCHOTTEL in measuring noise of a full scale tidal device, we are able to provide input into the appropriate methods in obtaining noise data for Minesto. Community Engagement (1 page) Academic, industry and international conferences • Hosted and held a successful session at the European Geoscience Union (EGU) in Austria in April 2015 on Environmental Impacts of Marine Energy Devices. This was the first time ever that such a session was held at the EGU. The session attracted research groups from a range of European countries with a diverse range of topics including wind farms, wave and tidal marine energy devices as well as ocean thermal energy conversion. Due to the success of the session, another session is planned for the EGU in 2016. • European Wave and Tidal Energy Conference (EWTEC). There were five presentations this year at EWTEC 2015 • Industry presentations given to Alstom, MeyGen, HR Wallingford, DNV, RES International partnership • Workshop presentation at Dalhousie, invited talk at Canadian Workshop on Tidal Energy research development by Dr B Elsäßer • Invited to contribute to Annex IV which is a collaborative partnership among member nations of the IEA Ocean Energy Systems (OES). The purpose of Annex IV is to examine environmental effects of marine energy development. Annex IV seeks to bring together information and practitioners from OES nations to understand potential effects of marine energy devices on marine animals and habitats, and to make existing information available and accessible. Public and community engagement • Various presentations at public lectures, university presentations, university open days
First Year Of Impact 2014
Sector Energy,Environment
Impact Types Economic,Policy & public services

 
Description H2020 PowerKIte
Amount € 500,000 (EUR)
Funding ID 654438 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 01/2016 
End 06/2018
 
Title FLUIDITY 
Description A numerical modelling tool for simulation of fluid flow in both a fixed and adaptive mesh 
Type Of Technology Software 
Year Produced 2015 
Open Source License? Yes  
Impact Enhanced modelling capability