Published: 23 July 2020
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The ENFAIT project gave its last annual progress report in July 2019 (see our press release on EnFAIT’s first 18 months). Achievements included an overall 15% reduction in LCOE from tidal energy and building the supply chain for the Shetland Tidal Array to 14 European countries (with more than 60% of spend going back into businesses in Scotland’s North East).

In the ensuing 12 months, the team has built upon these initial successes to drive the project forward. With deployment of the fourth turbine to the Shetland site imminent, we recap on progress in the past year.

1. Record-breaking performance
The Shetland Tidal Array has had its best performing year to date, setting new records for availability, generating hours and output. For the 12 months from June 2019 to May 2020, Nova’s three turbines clocked up more than 14,000 operating hours and generated 469 MWh of clean, predictable electricity. Performance will continue to show big improvements as Nova’s new direct drive turbines are deployed in Shetland and the enhanced technology is installed in more energetic sites.

2. Reduced operation and maintenance costs
For the first time, Nova undertook annual maintenance on all three of the turbines at the same time. All three turbines were removed from the sea, serviced at Nova’s Edinburgh workshop, and redeployed in the array within a three-week period in May 2019. Breaking their record for turbine downtime and maintenance costs, the team was able to reduce operational costs by 50%.

3. Extended Service Intervals
The array achieved and exceeded its annual service target, running for more than 12 months since the last service in May 2019. With the exceptional performance of the turbines, Nova has now extended the designed service period for maintenance beyond a year. The longer the turbines are able to operate without the need for servicing, the lower the cost of tidal energy.

4. New Improved Tidal Turbine
Over the past year the Nova team completed the new 100 kW direct drive tidal turbine it developed in its D2T2 project, funded by the European Commission. The new turbine used the learnings from Nova’s existing tidal turbines and clever simplicity to lower costs. This has been achieved by removing the need for a gearbox, significantly improving the performance and efficiency of the device. Fewer moving parts in the turbine increase its reliability and extend the period between service intervals from one year to more than two years. This turbine will be installed as the fourth turbine in the EnFAIT project this autumn.

5. Optimising array availability
SKF is developing the Array’s maintenance strategy using its own Asset Management Support Tool. The SKF team have installed their IMx8 condition monitoring system at the site with monthly data reporting and cloud-based access. This includes more than 2,000 hours of analysis of the operation of the main shaft, forensic analysis performed upon seals and bearings, gear and grease inspections and design failure mode effect analysis.

6. Predicting impact of different array configurations
Nova Innovation is collaborating with the Offshore Renewable Energy (ORE) Catapult and the University of Edinburgh to model and predict the impact of different array layouts on turbine fatigueand extreme loads. Below the surface, acoustic doppler current profilers (ADCP) in the array measure flow conditions; above the surface, vessel surveys map wake locations, paths and behaviours. This data is fed into a number of models including an Array Interaction Model (AIM), a flow model and a turbine blade loading model. These are helping to inform planned locations for turbines 4, 5 and 6, and predict turbine loading changes according to location.

7. Commercial prospects for ocean energy mapped
Wood has developed an array commercialisation strategy for ocean energy arrays, identifying a tidal energy market worth €117 billion. The report provides an overview of the immediate addressable markets for tidal power deployment detailing the size of the economic and energy resource. Real world investor appetite in renewable energy markets was considered to assess conditions for tidal energy to compete for a share in traditional infrastructure project finance.

8. Proving economic and social benefit for coastal communities
More than 40 local businesses in Shetland have benefited from the tidal array since the project began, with 60% of project spend going to the Highlands and Islands of Scotland. Consultations and school visits continued throughout the year, led by IDETA, RSK Environment and Nova, in order to answer residents’ questions and ensure knowledge of the technology is embedded amongst young people on the islands.

9. Environmental monitoring
There has been continuous environmental monitoring of the Shetland Tidal Array since 2010, focused on understanding how marine wildlife interacts with the turbines underwater. Nova has carried out comprehensive analyses of the data, which includes thousands of hours of land-based visual observations of seabirds and marine mammals and subsea video footage. No collisions or near misses between marine wildlife and the turbines have been observed, indicating that the risk of negative environmental effects is very low. A cloud-based system has been developed to efficiently capture, transmit and store subsea video.

Watch this space for more project updates throughout 2020. You can also contact the EnFAIT team with your questions and requests.

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