World’s most powerful tidal turbine pumps out greener electricity in Scotland

The world’s most powerful underwater turbine is in operation in Orkney, off the northern shores of mainland Scotland. Capable of generating enough renewable electricity to meet the needs of 2,000 homes and offsetting around 2,200 tonnes of CO2 (per year), the most powerful wave-power turbine in the world has gone into service.

The Orbital O2 floating turbine is anchored in the notoriously fast-flowing waters of the Orkney archipelago, which lies less than 20km to the north of the Scottish mainland. It measures 74m in length and is destined to remain operational for the next 15 years. A subsea cable connects the Orbital O2’s 2 MW output to the onshore electricity network.

The need to make more progress toward the energy transition is as pressing as ever. Since 1992, when the United Nations Framework Convention on Climate Change was signed, CO2 emissions from energy and industry have increased by 60%. That’s despite all the subsequent agreements and pledges from governments around the world to tackle the matter urgently.

In the International Energy Agency’s (IEA) Net Zero by 2050 report, the organization warns that enough simply hasn’t been done to reduce global energy-related CO2 and that the Paris Agreement target of 1.5ºC warming above pre-industrial levels is in jeopardy.

Scotland is particularly well-placed to take advantage of wave power for generating greener electricity. It has an estimated 18,743 km of coastline and a sea area of approximately 462,315 km2. Harvesting power from waves and the tides could meet as much as 20% of the UK’s electricity demand, according to a 2013 government report. Since then, the withdrawal of public subsidies for some green energy projects has led to some tidal power developments being cancelled or postponed in the UK.

The Scottish Cabinet Secretary for Net Zero and Energy, Michael Matheson, in a statement on the Orbital website, said: “With our abundant natural resources, expertise and ambition, Scotland is ideally-placed to harness the enormous global market for marine energy whilst helping deliver a net-zero economy.”

Elsewhere in the world, there are tidal power plants in operation that dwarf the Orbital O2’s output. The largest of all is the Sihwa Lake tidal power station in South Korea, approximately 4km from the city of Siheung. It’s output capacity is 254 MW.

At 240 MW, the La Rance power plant in France is the world’s second largest. A similar-sized development near the UK city of Swansea was among those scrapped following changes in funding allocation.

The World Economic Forum’s Uplink programme is supporting an innovative wave-power technology in Australia.

Wave turbines follow the same basic mechanical idea as wind turbines – a large propeller or an array of blades gets turned by the force of the tide (or the wind) and in turn that spins the rotor shaft of the generator. They are more expensive to build than wind turbines, as they have to withstand a harsher operating environment. But they capture more of the available energy than wind turbines.

There could be, however, potential risks of harm to aquatic life from tidal turbines.

Tethys, a service run by the US Pacific Northwest National Laboratory, cites “collision between turbine blades and marine organisms due to natural animal movements, attraction to the device, or inability to avoid the turbines within strong currents,” as the greatest possible dangers.

“There is also concern that noise from turbines can affect animals that use sound for communication, social interaction, orientation, predation, and evasion,” it says on its website.

In 2018, Canada’s Fundy Ocean Research Center for Energy released a report in which it detailed the impact of a tidal turbine in the Bay of Fundy, Nova Scotia. It concluded there had been no significant impact on marine life.

The Scottish government backed the development of the Orbital O2 with $4.72 million of funding, from the Saltire Tidal Energy Challenge fund. Other funding for the project came via the European Union’s Horizon 2020 programme, and the European Regional Development Fund