SeaGen Project. Strangford Lough SeaGen Tidal Turbine monitoring programme and mitigation, some initial results

Transcription

1 SeaGen Project Strangford Lough SeaGen Tidal Turbine monitoring programme and mitigation, some initial results

2 About SeaGen Free stream tidal energy device that converts energy from tidal flow into electricity. Twin 16m diameter rotors connected to a generator through a gearbox, with a rotor system supported on the end of a cross beam. The cross beam is, in turn, supported by a 3m diameter pile. The cross beam can slide vertically up and down the pile to allow access to the rotors, generator and gearbox for servicing and inspection, thus minimising the requirement for diver intervention. The top of the pile is approximately 9m above the average sea level; The twin rotors begin to generate electricity at a current speed greater than 1m/s. At a predetermined maximum tidal speed the rotors start to adjust their pitch to limit the maximum rotational speed to 14 RPM, resulting in a peak rotor tip speed of around 12m/s.

3 Location: Strangford Lough Narrows

4 Strangford Lough Narrows Significant tidal resource; Easy access; Grid connection; QUB marine station; and Local skills base for assembly and O&M. The site is within a European Marine Site and hosts European Protected species.

5 SeaGen: The journey Scoping Report Environmental Statement (ES) Environmental Impact Assessment (EIA) Environmental Action and Safety Management Plan (EASMP) Environmental Monitoring Programme (EMP) Scoping ES EMP EASMP Installation: March 2008 Postinstallation EMP coordination and reporting EIA FEPA licence granted/ re-issued ES addendum Design change: Quadropod base

6 Installation Installation of the moorings for anchoring the SeaGen was completed in March The SeaGen structure was positioned on the seabed on April 2nd 2008 by the crane barge Rambiz. Drilling for the pin piles, grouting and completion of assembly was achieved by late May Commissioning and Operation Commissioning commenced in July 2008, culminating in full 1.2MW power generation to the grid in December Operation is within the constraints of FEPA license conditions with the environmental monitoring and mitigation results contributing to an adaptive management strategy, advised by an independently chaired Science Group, where findings are periodically reviewed and improvements to the application of the FEPA restrictions are made.

7 Environmental Impact Assessment The EIA process identified various levels of uncertainty surrounding potential impacts on key marine species and features within the Strangford Lough Special Area of Conservation (SAC) Common seals Phoca vitulina 1) Are the patterns of usage of the Narrows by seals altered by the turbine installation and operation? 2) Are seals (or other large marine animals) being struck by the turbine rotors? Reef (rocky and biogenic) 1) Does the installation and operation of the turbine significantly effect the extent, quality or composition of seabed communities?

8 FEPA License Conditions Put required a number of tiers of mitigation, to summarise key elements : MMO presence on pile with ability to shutdown; Daylight operation only, initially; Active sonar development as further tier of mitigation. An adaptive management approach has been taken to operation of the device and the operation of the mitigation measures via advice of the SeaGen Science Group. More on this later!

9 Monitoring Mammal Northern Irish Coast study site - Aerial surveys (SMRU) - Harbour seal telemetry (SMRU) - Shoreline surveys Strangford Narrows study site - Shore-based visual surveys (QUB/SMRU) - TPOD monitoring (SMRU) Benthic Ecology Monitoring (RH and QUB) ADCP surveys (QUB) Mitigation - Active Sonar (SMRU) - Pile-based Marine Mammal Observation (RH)

10 Biannual Report (July 2009) Key environmental questions Set of operational objectives which are reported against Monitoring results Next report January

11 So, what have we found so far?

12 Marine mammals and sharks Effort limited visual surveys (QUB) Analysis of monitoring during the installation and initial commissioning period indicate that: Time of day, tidal state and spatial location all significant influences on data. No evidence for human disturbance effects during installation and no evidence for a change in seal abundance in the area during times of lower activity; and The natural variability in the system under study is large, which makes disentangling the effects of the turbine challenging. The level of survey effort has currently been increased to maximise the power of the current monitoring programme to detect genuine changes in marine mammal abundance Tidal Cycle Combined POD data Visual Observations

13 Marine mammals Passive acoustic monitoring (SMRU) Using T-PODs - to provide continuous data on harbour porpoise activity in proximity to SeaGen. Preliminary examination of the effect of limited turbine activity between July 2008 and May 2009 does not suggest any dramatic impact on porpoise activity; In the Narrows significantly more days without porpoise detections during the operational period compared to the baseline, however this may be an underlying seasonal effect; Detection Positive Minutes (DPM) per day lower within the Narrows and inner Lough during the operational period (July 2008 May 2009) compared to the pre-installation baseline period; No significant difference in the number of porpoise positive days recorded by PODs north and south of the turbine for either the pre-installation or operational period, indicating that SeaGen does not present a barrier effect; Tidal Cycle Combined POD data Visual Observations

14 Monitoring - Harbour seals Aerial survey outputs Distribution of seal haul out sites within and around Strangford Lough Abundance of seals surveyed during moult (August/Sept) and breeding season (November) SMRU Ltd Moult surveys in 2006 and 2007 show similar counts of harbour seals over the whole survey area; The number of hauled-out harbour seals was variable both within and between years; 2008 the breeding season adult counts for the Lough and Narrows were higher than in The pup counts also increased, as they did in other regions; SMRU Ltd

15 Monitoring - Harbour seals cont. Aerial survey outputs Overall more pups were counted in relation to adults in 2008 than in 2006 The consistent increase in numbers of pups in relation to adults across the whole survey area indicates that the Strangford Lough and Narrows counts showed changes consistent with the wider survey area; Grey seals are much less abundant in the survey area than harbour seals and numbers counted within each sub-region are variable within and between years, although there has been a general increase in numbers of grey seals since SMRU Ltd SMRU Ltd The increase in the number of adults and pups in the Narrows and Strangford Lough potentially indicates that the installation phase of the turbine did not cause any displacement of the seals prior to the 2008 breeding season.

16 Monitoring - Harbour seals GSM satellite tracking outputs 12 animals tagged in March 2006, 2008 and planned 2010 In 2008, as in 2006 there was considerable between-seal variability in movement data, but consistency within individuals; Some individuals travelled to distant haul out sites in the Irish Sea and clearly forage outside Strangford Lough. This indicates that seals in Strangford Lough/Narrows are not ecologically isolated from the remaining North Ireland population; SMRU Ltd SMRU Ltd No evidence for a change in daily transit rates past the turbine between years;

17 Monitoring - Harbour seals cont. GSM satellite tracking outputs There was no significant difference in the probability of hauling out within the Narrows between years; SMRU Ltd There was no evidence for a change in overall usage patterns between years, with usage concentrated in the Narrows and south of the Lough With just two years of data the effect of the installation and operation of the turbine cannot be separated from natural inter-annual variability. SMRU Ltd

18 Monitoring - Shoreline surveillance Incidental strandings: managed by NIEA None reported November 2008 to spring 2009 Standardised beach surveys: managed by QUB No surveys between September 2008 May 2009 due to SeaGen down time Weekly surveys re-commenced at the start of June All common seal, grey seal and harbour porpoise carcasses found within the study site have been post-mortemed by a Vet Pathologist at Stormont. No post mortem evidence for any carcasses is suggestive of interaction with the SeaGen turbine.

19 Robust Environmental Action Plan (Designed and coordinated by Royal Haskoning) Scenario tree

20 Monitoring - Benthic Ecology Broad scale mapping and diver surveys have significantly increased our knowledge of the seabed in the Narrows in proximity to the turbine Enabled the RH team to quantify the potential footprint of the installation, operational and decommissioning phases Benthic Monitoring The monitoring programme objective is to detect broad change in the benthic community structure (e.g. abundance shifts in dominant or characterising species) that may arise from increased sedimentation, changes in scour or flow pattern, or through direct physical damage.

21 Monitoring - Benthic ecology cont. The status of the seabed close to the turbine has been assessed on the basis of three sample time points; the first a pre-installation survey in March/April 2008, followed by a post-installation survey in July 2008 and the third in March 2009, just after the start of turbine operation. Communities at each sampling time and at all stations were different from the communities recorded at the previous sampling times, but changes largely due to subtle abundance adjustment; Dominant taxa (hydroids and sponges) in the pre-installation samples have maintained dominance throughout the following monitoring visits; Community changes across all stations broadly similar over time and are largely mirrored in the reference station. Data support a conclusion that the observed changes over the three sample times are relatively minor and result of a combination of normal seasonal variation and natural species competition and succession.

22 Mitigation - Pile-based MMO observations The MMO programme was primarily established as a mitigation measure, guarding against potentially harmful marine mammal interactions with the SeaGen turbine. An established systematic quantitative sightings protocol using a spatial grid system has, however, provided useful qualitative data on mammal activity close to SeaGen and has proved an important calibration element for the active sonar system. Confirm presence of marine mammal, shut down as appropriate, make detailed record of sightings (with focal follows of sightings within 200m) Provide detailed information relating to the behaviour and movements of marine mammals and sharks in proximity to the SeaGen turbine Date Species SeaGen operational activity (twin/ single rotor) Distance from turbine (m) Behaviour State of tide E-stop initiated by? 1 08/07/2008 Common seal Single 130 Drifting Flood MMO 2 06/10/2008 Common seal Single 50 Drifting Flood MMO 3 07/10/2008 Unidentified target Single 60 Travelling Flood ASO 4 15/10/2008 Common seal Single 80 Drifting HW Slack + 1 hr MMO 1 1 hr: 16 mins before HW Slack, 2 1 hr: 9 mins before HW slack, 3 1 hr: 10 mins before HW slack, 4 1 hr: 30 mins before HW slack 5 15/12/2008 Common seal Twin 50 Travelling HW Slack + 1 hr MMO 6 13/05/2009 Common seal Single 40 Drifting Flood 1 MMO 7 27/05/2009 Common seal Twin 40 Travelling Flood 2 MMO 8 27/05/2009 Common seal Twin 80 Milling Flood 3 MMO 9 27/05/2009 Common seal Twin 70 Travelling Flood 4 ASO 10 08/06/2009 Common seal Twin 40 Travelling Ebb ASO 11 10/06/2009 Common seal Twin 80 Drifting HW Slack + 1 hr MMO 12 22/06/2009 Common seal Twin 38 Travelling LW Slack + 1 hr ASO 13 02/07/2009 Common seal Twin 20 Travelling Ebb MMO 14 02/07/2009 Unidentified target Twin 44 Travelling Ebb ASO 15 06/07/2009 Common seal Twin 40 Travelling Flood MMO

23 Mitigation - Pile-based MMO observations cont. Confirm presence of marine mammal, shut down as appropriate, make detailed record of sightings (with focal follows of sightings within 200m). Provides detailed information relating to the behaviour and movements of marine mammals and sharks in proximity to the SeaGen turbine MMO surveys from SeaGen throughout operation until September 2009 Over 381 hours of survey, equates to approximately 55 days of survey effort (based on an average of 7 hours survey per day), between 8th July th June 2009 Shut down limit gradually reduced by Science Group from 200 to 50m based on data collected Date Species SeaGen Since July 2008 to July shutdowns MMO mitigation suspended in September and replaces with active sonar based on Science Group advice with NIEA agreement operational activity (twin/ single rotor) Distance from turbine (m) Behaviour State of tide E-stop initiated by? 1 08/07/2008 Common seal Single 130 Drifting Flood MMO 2 06/10/2008 Common seal Single 50 Drifting Flood MMO 3 07/10/2008 Unidentified target Single 60 Travelling Flood ASO 4 15/10/2008 Common seal Single 80 Drifting HW Slack + 1 hr MMO 5 15/12/2008 Common seal Twin 50 Travelling HW Slack + 1 hr MMO 6 13/05/2009 Common seal Single 40 Drifting Flood 1 MMO 7 27/05/2009 Common seal Twin 40 Travelling Flood 2 MMO 8 27/05/2009 Common seal Twin 80 Milling Flood 3 MMO 9 27/05/2009 Common seal Twin 70 Travelling Flood 4 ASO 10 08/06/2009 Common seal Twin 40 Travelling Ebb ASO 11 10/06/2009 Common seal Twin 80 Drifting HW Slack + 1 hr MMO 12 22/06/2009 Common seal Twin 38 Travelling LW Slack + 1 hr ASO 13 02/07/2009 Common seal Twin 20 Travelling Ebb MMO 14 02/07/2009 Unidentified target Twin 44 Travelling Ebb ASO 15 06/07/2009 Common seal Twin 40 Travelling Flood MMO

24 SMRU Ltd SMRU Ltd Mitigation - Active sonar (SMRU) Coordinated alongside MMO observations, allowing calibration. Trail of real time sub-surface sonar imagery of seals, cetaceans and basking sharks close to the SeaGen. Manned operation, initially on pile alongside MMO, now remotely. Detection from 80m, well within shut down action distance of 50m Now demonstrated effectiveness, removed MMOs and 24 hour operation. Next investigate mammal behaviour at night eventually remove shutdown protocol

25 Active sonar (SMRU) cont. Relationship between MMO and ASO records of marine mammal activity throughout the tidal cycle. Majority of marine mammal activity occurs around slack water. No noticeable difference between activity during turbine operation & nonoperation. Apparent over recording using active sonar. Possible under recording using MMO. SMRU Ltd SMRU Ltd

26 Summary of key findings: Shore based surveys during installation show no evidence for increased human disturbance or a change in relative seal abundance in the area; MMO and shore based observation data show low incidence of seal and porpoise sightings in the central portion of Strangford Narrows; Active sonar can detect marine mammals birds in real time. No seal carcasses to date have exhibited signs of any possible interaction with SeaGen; Aerial surveys during the 2008 breeding and moult seasons found an increase in the number of harbour seal adults and pups in the Narrows and Strangford Lough, suggesting installation did not cause displacement prior to the 2008 breeding season;

27 The key findings cont: TPOD data indicated lower detection positive minutes for harbour porpoises in the Narrows and inner Lough during the operational phase (July 2008 May 2009) compared to the pre-installation baseline. There has, however, been limited turbine activity during the operational phase and the reduced detection may be the result of an underlying seasonal variation. There was no difference in porpoise positive days to the north and south of the turbine indicating that SeaGen does not present a barrier effect to harbour porpoises. Harbour seal telemetry data shows no evidence of change in haul out behaviour within the Narrows or transit rates past the turbine; and Benthic community monitoring has detected no change in seabed communities attributable to the SeaGen installation or operation.

28 Finally - some interesting SeaGen facts SeaGen has already delivered over 350MWh of power into the Northern Irish electricity grid. The twin generators typically produce an average of 5MWh of electricity during the 6¼ hours of each ebb and each flood tide. This is enough energy to meet the average electricity needs for 1500 UK homes. The SeaGen turbine is officially accredited by OFGEM as a UK power station, the first tidal power system to secure this. SeaGen is earning revenue from the sale of the power that is being generated and it also earns ROCs, the Renewable Obligation Certificates that are awarded for clean renewable generation.

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30 Seagen Marine Mammal Mitigation Marine Mammal Observation and Active Sonar Data

31 Background Data collected between 08 July 2008 and 16 July Data collection continues during ongoing mitigation. MMO data filtered to within estimated 80m of Seagen (range of the active sonar). Provides relatively low no. of records (75 MMO sightings and 216 Active Sonar Operator records).

32 MMO sightings & potential for interaction with SeaGen Sightings categorised by potential likelihood of interacting with rotors : High less than 50m from the turbine resulting in the turbine being shutdown. Moderate between 50-80m from the turbine & no shutdown instigated. Turbine not turning.

33 MMO sightings & potential for interaction with SeaGen cont. 35 Number of sightings at less than 100m distance compared with state of tide for high* or moderate** potential interaction with turbine rotors Low water High water High Moderate Not Turning TOTAL No. of sightings LW - 2-3hrs LW - 1-2hrs LW - 0-1hrs LW + 0-1hrs LW + 1-2hrs LW + 2-3hrs HW - 2-3hrs HW - 1-2hrs HW - 0-1hrs HW + 0-1hrs HW + 1-2hrs HW + 2-3hrs

34 MMO sightings during Seagen operation and non-operation 35 MMO sightings during operation and non-operation Low water High water Turning Not turning TOTAL No. sightings LW - 2-3hrs LW - 1-2hrs LW - 0-1hrs LW + 0-1hrs LW + 1-2hrs LW + 2-3hrs HW - 2-3hrs HW - 1-2hrs HW - 0-1hrs HW + 0-1hrs HW + 1-2hrs HW + 2-3hrs

35 Active Sonar records Sonar records confirmed and unconfirmed by MMO Low water High water Confirmed sightings Unconfirmed records TOTAL 25 No. sightings LW - 2-3hrs LW - 1-2hrs LW - 0-1hrs LW + 0-1hrs LW + 1-2hrs LW + 2-3hrs HW - 2-3hrs HW - 1-2hrs HW - 0-1hrs HW + 0-1hrs HW + 1-2hrs HW + 2-3hrs

36 Active sonar and MMO records 35 Low water Total sonar compared with total MMO records High water 30 MMO sightings ASO records 25 No. sightings LW - 2-3hrs LW - 1-2hrs LW - 0-1hrs LW + 0-1hrs LW + 1-2hrs LW + 2-3hrs HW - 2-3hrs HW - 1-2hrs HW - 0-1hrs HW + 0-1hrs HW + 1-2hrs HW + 2-3hrs

37 Summary Relationship between MMO and ASO records of marine mammal activity throughout the tidal cycle. Majority of marine mammal activity occurs around slack water. No noticeable difference between activity during turbine operation & non-operation. Apparent over recording using active sonar. Possible under recording using MMO.

38 Conclusions Active sonar expected to provide conservative mitigation. No apparent need for an MMO to be present. ASO could provide mitigation through night.