People are clamouring for more action on climate change and demanding more renewable energy sources. Marine energy provides a perfect opportunity for governments to show they are listening. The world’s first large-scale tidal array is operating in European waters, off the coast of the UK and costs are set to plummet as the industry scales up. The UK’s tidal stream industry alone could bring economic benefits worth EUR 1.6bn by 2030 and support 4 000 jobs, according to the EU’s CLEARWATER project. CLEARWATER is the first ever multi-turbine project using commercial-scale technology. Previously, only single devices were tested at centres like EMEC in Scotland. “What has been done here is absolutely a world’s first, and sets a benchmark for future projects,” says Mr Drew Blaxland, Director of Turbine and Engineering Services at Atlantis Operations (UK Limited), the company behind the CLEARWATER project. “We are paving the way towards larger and more cost-competitive tidal stream projects.” CLEARWATER transitioned into formal operations in April 2018, after the successful commissioning and initial operation checks. As of April 2019, the array where the CLEARWATER turbine is located has generated over 15GWh of renewable electricity. According to Blaxland: “Improved installation techniques demonstrated at CLEARWATER, including the development of a subsea wetmate connection system, halve the required installation time offshore. The installation of a turbine now possible in less than an hour. Not only does this facilitate quicker marine operations, it also reduces the weather window required to work offshore.” Atlantis Operations will now continue to innovate to ensure the levelised cost of energy for tidal stream technology continues to fall. The levelised cost of electricity (LCOE) represents the installed capital costs and ongoing operating costs of a power plant, converted to a level stream of payments over the plant’s assumed financial lifetime. “When we do this we look at the entire system, not just the turbines,” Blaxland explains. Building on the work of the CLEARWATER project, the company has developed its tidal technologies with several forthcoming innovations such as an increased rotor diameter from 18m-20m, with an increased turbine rated capacity of 2MW, compared to the 1.5MW deployed during the CLEARWATER project. “This will lead to a 25 % yield improvement per turbine, power generated at grid frequency and ‘voltage-to-shore’ increase, reducing electrical losses.” Standard monopiles will replace the gravity base structures used at CLEARWATER, reducing the amount of steel required by 90 %. The company has also introduced a change to the turbines so that up to 7 turbines can be connected to a single export cable to shore. This reduces the amount of cables and the marine operations necessary the installation. Furthermore, the export cable voltage can increase from 4kV to 33kV, reducing electrical losses to the grid by over 6 %.
CLEARWATER, tidal arrays, tidal technology, subsea transformer, tidal stream industry, climate change, renewable energy