Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - FloTEC (Floating Tidal Energy Commercialisation project (FloTEC))

Teaser

Tidal stream power is one of the newest entrants to the global renewables market. The resource and generating characteristics indicate that it has the potential to become a low cost, highly predictable form of low carbon energy. Currently, however, generating costs are high...

Summary

Tidal stream power is one of the newest entrants to the global renewables market. The resource and generating characteristics indicate that it has the potential to become a low cost, highly predictable form of low carbon energy. Currently, however, generating costs are high and long-term reliability has yet to be demonstrated.

Scotrenewables Tidal Power is the leading developer of floating tidal energy. This involves the mounting of turbine generators to a highly accessible, towable floating platform for ease of installation, maintenance and decommissioning. It has been independently recognised that floating tidal energy has the potential to deliver a step-change cost reduction to the tidal stream sector. In 2016, the company launched a 2 MW floating tidal turbine, the SR1-2000, the most powerful tidal turbine in the world.

The FloTEC project aims to drive the commercialisation of floating tidal energy, through the delivery of priority technical innovations in both the Scotrenewables platform design and subsystem areas to reduce cost and risk and deliver an enhanced SR2-2000 2MW model, which would be a template for volume manufacture. The core innovations being progressed are:

• 50% Increase in rotor swept area.
• All subsystems highly accessible for repair and maintenance
• Simplified superstructure redesign for series production
• Advanced, automated manufacturing techniques for blade manufacture:
• Centralised MV power conversion with energy storage integration;
• Mooring load dampers to reduce peak mooring loads.

The project consortium consists of leading supply chain, development, utility and research institutions. In additional to technical delivery, the project consortium would resolve a suitable risk sharing structure between supply chain, customer and financier and commercial contractual structure for first array(s) supply.

The project will run for 42 months from January 2016 to June 2019.

Work performed

Initially, a global market assessment was completed. This report recommended priority regions for Scotrenewables to develop first array opportunities and also fed into the product specification. A high level LCOE report for Scotrenewables Tidal Technology was also performed by DP Energy as part of a design review process for a number of potential project sites. Yield assessment and availability predictions were also derived. A lessons learned report on the design and fabrication and of the SR1-2000 was produced as an input to the FloTEC concept design process.
Since then a ‘ground up’ re-design of the turbine superstructure was developed. The main features of the new superstructure design are:

• Legs hinged axially to give a ‘gull-wing’ movement to present nacelles to surface for maintenance
• Legs attached above the waterline to simplify build, maintenance and provide improved cable routing with hull penetrations above the waterline.
• 20m rotor diameter;
Optimised for volume manufacture

Detailed design commenced in January 2017. The first phase of the detailed design process was hydrodynamic modelling and scale testing, to establish the design loads that will feed into the rest of the detailed design. Detailed design continued through February with structural layout optimized for stability and watertight integrity. Internal skid detailed design has commenced with block layout and top level service routes. Detailed design is underway on the structure and legs, leg retraction system, nacelle connections and internal layout including cable and hose routing and the locations of ancillary equipment.

Scale model testing commenced with initial results aligning well with predictions.

A preliminary plan & schedule for the construction and deployment of the turbine, including the roles and responsibilities of the FloTEC partners has been developed. A draft environmental monitoring plan was developed and provided design input into control and instrumentation specifications.

A power systems study of the project location was carried out and an electrical power conversion system design for the SR2-2000 was developed. Draft product specifications for power take off equipment and nacelles were produced and sent to prospective suppliers for consultation.

A battery technology update and review was competed. An energy storage model was developed to determine the storage requirement at EMEC to deliver energy storage objectives.
Work is ongoing to better understand the specific characteristics of the Orkney grid in terms of the active network management system, the high penetration of wind power, constraints and parallel EMEC storage initiatives to understand how the FloTEC battery storage project can best be integrated.

A manufacturing process following EC proprietary techniques has now been finalised and independently reviewed.. A blade design for a 20 m rotor has been completed that will deliver the power performance targeted and is compatible for manufacture with EC innovative manufacturing technique.

Scales model testing of a mooring damper for the SR-2000 is underway.

Final results

The FloTEC project aims to deliver a step-change cost reduction in the tidal energy sector. The design that has been developed is on track to deliver this aim. For the first time in the tidal energy sector, a utility scale (2 MW) turbine is being developed, where all components – power generating, power conversion and auxiliary can be accessed from above the water surface for low cost maintenance, avoiding the need for heavy lift vessels and allowing for much of the maintenance to be carried out onsite with small crew transfer vessels. This will reduce the risk profile of the tidal energy sector to a similar profile as other forms of renewable technologies, such as offshore wind, in turn allowing for standard project financing to enter the sector. All offshore operations can be carried out with locally based vessels and all device components will originate from the European supply chain.

The design furthermore advances floating tidal technology by delivering a design optimised for volume manufacture.
There has been significant progress beyond state of the art in the blades work package. A design has been developed for a 20 m rotor diameter blade. This would result in a device with the greatest swept area of any to date, increasing yield by up to 50% from the previous SR1-2000 turbine
Furthermore, the low cost, high quality blade manufacturing technique being progressed, is introducing manufacturing processes from other composites industries into the tidal energy sector for the first time and at full scale.

TfI are delivering a highly innovative mooring tether technology which had the potential to reduce peak mooring loads in a number of different offshore industries and applications including floating tidal energy. Its delivery in the FloTEC project will be the largest such tether developed to date, with a design force of up to x tonnes. Initial design of the mooring damper is complete.

A centralised MV power conversion specification has been developed and development activities for the integration of energy storage into the power conversion system are ongoing.

Website & more info

More info: http://www.scotrenewables.com/projects/flotec.