Grid-connected tidal test site

Our grid-connected tidal test site at the Fall of Warness is situated just west of the island of Eday - lying in a narrow channel between the Westray Firth and Stronsay Firth.  The site was chosen for its high velocity marine currents which reach almost 4m/sec (7.8 knots) at spring tides. As tides flow from the North Atlantic Ocean to the North Sea, they quicken as they are funneled through Orkney's northern islands.

Current meters characterise the tidal and wave conditions on site, and a purpose-built weather station is situated onshore providing real-time met data for the site. This data is fed into a sophisticated SCADA (supervisory, control and data acquisition) system.

EMEC offers seven cabled tidal test berths at depths ranging from 12 m to 50 m in an area 2 km across and approximately 4 km in length.

The 11 kV subsea cables feed into EMEC's substation at Caldale in Eday which houses the main switchgear, backup generator and communications room. The substation controls the supply from each tidal device and connection to the national grid. An adjacent laydown area offers developers the opportunity to use conditioning equipment for converting electricity from the level at which it is generated to grid compliant electricity. Another building on site holds the Scottish and Southern Energy transformer where the 11 kV is transformed to 33 kV. Eday is linked to both Westray and Sanday by subsea cables that form a ring through the Northern Isles and feed into the national grid.

In addition to transporting electricity, the cables contain fibre-optics which allow developers to communicate with the devices and transmit monitoring data back to our data centre and office facilities.

The test site has 7.2 MW export capacity and is being expanded further to meet industry demand and support the testing of multiple longer-term demonstrations on site.

To further increase the generation capacity, we have a 670 kW hydrogen electrolyser installed adjacent to the tidal substation. This plant enables production of high purity, fuel cell grade hydrogen from the tidal energy generated at the tidal test site. In 2017 the EMEC hydrogen production plant produced the world's first tidal generated hydrogen. Control switchgear inside EMEC's substation can determine whether power from tidal devices is to be exported to the national grid or directed to the electrolyser to generate hydrogen. In addition, a second electrolyser is due to be installed at the site to increase the quantity of electrolyser capacity by 500 kW, further supporting variable renewable generation.

We are also developing energy storage onsite with the installation of a 500 kW 1.5 MWh vanadium flow battery. The energy storage will be used to enable continuous hydrogen production, providing electrical power between the tides. The battery system is being installed in a purpose built building designed for future expansion as required.

EMEC Tidal test site awareness chart







Aquamarine Power


Atlantis Resources Corporation



Naval Group

Naval Group


Open Hydro


Orbital Marine




ScottishPower Renewables



Sustainable Marine Energy

Sustainable Marine Energy


Voith Hydro


Wello Oy

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