Modelling Environmental Effects of Marine Renewables. Dr Louise Kregting & Dr Björn Elsäßer

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1 Modelling Environmental Effects of Marine Renewables Dr Louise Kregting & Dr Björn Elsäßer AWATEA 19 th May 2016 SPACE SCHOOL OF Planning Architecture & Civil Engineering

2 Environmental Concerns of Large Arrays of Wave and Tidal infrastructure Concerns relate to the interaction of the technology with the environment Placement of the infrastructure in suitable areas and how this influences physical and biological processes AWATEA 2016 Environmental Effects of Marine Renewables 2

3 You will need one of these Site licensing remains one of the key constraints AWATEA 2016 Environmental Effects of Marine Renewables 3

4 But there are no large arrays of wave or tidal devices in operation Need to use predictive tools such as coupled hydrodynamic with ecological models AWATEA 2016 Environmental Effects of Marine Renewables 4

5 There are a range of potential environmental impacts that may occur during operation: Collision Entanglement Evasion Avoidance Potential issues result from the presence of the infrastructure in the environment AWATEA 2016 Environmental Effects of Marine Renewables 5

6 Physical and biological environmental processes that may be influenced as a direct result of changes to the hydrodynamics Sediment transport Organism transport Pollution dispersal processes Biogeochemical processes Benthic community distribution Noise radiation AWATEA 2016 Environmental Effects of Marine Renewables 6

7 Modelling Approach: Considerations Tide Hydrodynamic Model Coastal Process Wave No universally applicable wave model AWATEA 2016 Environmental Effects of Marine Renewables 7

8 Modelling Approach: Considerations Necessary to take a system-view approach and consider a range of temporal and spatial scales Temporal = Seasonal Spatial can be split into four levels I. Near-field - Device II. Far-field 1 10 km III. Regional > 10 km IV. Global large scale changes in circulation patterns AWATEA 2016 Environmental Effects of Marine Renewables 8

9 Modelling Approach: Considerations The development of a hydrodynamic or wave model requires knowledge of the following parameters: Water level Bathymetry Boundary conditions (wind, wave, tidal elevation data) Calibration and validation data Current speeds (if relevant) These parameters can be obtained relatively easily AWATEA 2016 Environmental Effects of Marine Renewables 9

10 Modelling Approach: Considerations Spatial scales will determine type of model, area of model domain, size of mesh Modelling the marine energy device also is an input BUT Acquiring environmental data to calibrate and validate the model is difficult. AWATEA 2016 Environmental Effects of Marine Renewables 10

11 Modelling Approach: Considerations e.g. Sediment: Largely unknown about sediment transport in areas of interest Often temporally and spatially varying Difference in size, density, settling velocity AWATEA 2016 Environmental Effects of Marine Renewables 11

12 Modelling Tools: Transport Transport Two main mechanisms: ADVECTION describes transport from A to B (mean water flow ( ) Modiolus sp. larvae by: Jose Farinas Franco DISPERSION influenced by turbulence and concentration gradients AWATEA 2016 Environmental Effects of Marine Renewables 12

13 Modelling Tools: Particle Tracking Particle tracking models used to address ocean transport questions Key results: Large differences in spatial patters of transport into the lagoon In areas where 95% of the mass accumulated (first 1/3 of the basin), we observed a maximum 2% change between simulations (control vs. turbines). Kregting L, Schuchert P, Pritchard D, Elsäßer B Using particle tracking models to simulate the effects of tidal arrays of devices on transport processes In preparation AWATEA 2016 Environmental Effects of Marine Renewables 13

14 Modelling Tools: Biogeochemical models Large scale effects (>100 km) of TED arrays on phytoplankton dynamics using GETM-ERSEM-BFM 3-D model AND Small and local scale ( km) effects using 2-D NPZD (Nutrient, Phytoplankton, Zooplankton, Detritus) models in DHI Van der Mole 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. Biogeosciences,13, , Schuchert P, Kregting L, Pritchard D, Savidge G, Elsäßer B Using coupled hydrodynamic biogeochemical models to predict the effects of tidal turbine arrays on phytoplankton dynamics, Submitted Biogeosciences. AWATEA 2016 Environmental Effects of Marine Renewables 14

15 Currents can influence benthic community distribution Kregting L, Elsäßer B, Kennedy R, Smyth D, O Carroll J, Savidge G. Energy removal by tidal energy arrays is unlikely to affect benthic communities in high flow (> 1.5 m/s) environments. In revision, PlosOne AWATEA 2016 Environmental Effects of Marine Renewables 15

16 Noise propagation models can be developed and there are a number of simulation models to choose from AWATEA 2016 Environmental Effects of Marine Renewables 16

17 Summary Models can be used to predict the effect of marine energy converters on ecological processes including sediment transport, organism transport, pollution, biogeochemical Can also be used to predict changes in flow rate or generate sound propagation from devices The effects may occur at a range of temporal and spatial scales AWATEA 2016 Environmental Effects of Marine Renewables 17

18 For more information, please contact Louise Kregting: AWATEA 2016 Environmental Effects of Marine Renewables 18