Nautricity is testing its second generation tidal turbine CoRMaT, a full-scale 500 kW prototype device suitable for deployment in water depths of 8 – 500 m. This follows deployment and testing of a full-scale mooring system at the European Marine Energy Centre (EMEC) which included Nautricity's 'Hydrobuoy' – a hydro-dynamic subsurface float whose lift varies with tidal flow velocity, and deployment of the full-scale turbine onto the mooring assembly at EMEC and observation of its performance in wave and tidal environments, both in 2013.
The CorMaT turbine employs two closely-spaced contra-rotating rotors, which drive the rotor and rotating stator sections of an electrical generator. The first rotor has three blades rotating in a clockwise direction while the second rotor, located directly behind the first, has four blades rotating in an anti-clockwise direction. Buoyancy chambers at the front and rear sections of the nacelle are tuned to achieve neutral buoyancy. The turbine is connected to a tensioned mooring at a point in the water column where the flow velocity is greatest and surface wave action minimized.
The device is installed in berth 3 at EMEC’s tidal device test facility at Fall of Warness, Orkney, UK. Water Depth: 33m. Tidal range: 3m. Tidal speeds up to 3.7 m/s.
59° 8.114’N, 2°48.962’ W
59° 8.114’N, 2°48.857 W
59° 7.928’N, 2°48.858’ W
59° 8.928’N, 2°48.962’ W
Installation of mooring infrastructure began at the beginning of March 2017, and the CoRMaT device was deployed in April 2017. In March 2018 the device was retrieved for investigation and analysis of the turbine, its supporting systems and data to assess the impact of extended exposure.
The CoRMaT project has an installed capacity of less than 1 MW, therefore no Section 36 Consent was required. A Marine License was granted under the Marine (Scotland) Act 2010 by Marine Scotland (the licensing authority) on 22nd February 2017 (Licence no. 06260/17/0), which can be viewed here.
The site’s seabed ranges from eroding sub-littoral sandbanks in the east to smooth scoured bedrock ridges and platforms with occasional boulders towards the center of the site. Fall of Warness is not a protected area; however, there are protected sites in close proximity. These include:
- Faray and Holm of Faray SAC – protected for its grey seal populations.
- Sanday SAC – Protected for its harbor seal populations, intertidal mudflats and sandflats, inshore sublittoal rock and subtidal sandbanks.
- Muckle and Little Green Holm SSSI – Nationally important grey seal breeding colony (Around 3% of the national breeding population).
EMEC has produced a specific Environmental Appraisal (EA) for the Fall of Warness site which can be downloaded from here.