A small passenger boat about 10 miles north of Kirkwall, Orkney, at the point where the Atlantic Ocean meets the North Sea, shows a huge yellow structure. This is the most powerful tidal energy generator in the world, O2 of Orbital Marine Power. Its shadow quickly overshadows the small vessel.
Today, the turbines of the generator are raised above sea level for maintenance. It is difficult to understand the scale of O2 until a worker appears, a small figurine on the rod opposite the huge turbine.
Map of the Orkney Islands
Orkney, chosen as the headquarters of the European Marine Energy Center (Emec) for its combination of strong tides and waves, as well as its connection to the energy grid, has become a center for tidal energy innovation. Along with the Scottish company Orbital, the Spanish-based Magallanes is also testing at Emec, and the American company Aquantis has just signed up for a six-month demo program.
Orbital O2 at the Emec Fall of Warness test site. Photo: Orbital Marine Power
Tidal energy, although not yet widely commercialized, is seen by many as the next frontier in global renewables. This is the only renewable energy source that comes from attracting the Moon to Earth. “Unlike other renewable energy sources that rely on the sun or wind, for example, tidal resources are predictable and continuous,” said Prof. Abu Bakr Bahaj, head of the Department of Energy and Climate Change at the University of Southampton.
The extraction of energy from the waves can be done in three ways: tidal barrages, in which the turbines are attached to a dam-like wall; tidal lagoons, where a body of water is enclosed by a barrier similar to a barrier; and tidal flow, where turbines are placed directly in fast-flowing water bodies.
Only tidal barrages are used commercially – mostly at Lake Sihwa in South Korea and La Rance in northern France – but tidal current technology is being tested in Orkney. Tidal flow is cheaper to build and has less impact on the environment than barrages, which change tidal flow and can affect marine life and birds.
Tidal energy alone can provide 11% of the UK’s current electricity needs, according to a study from the University of Edinburgh in 2021.
Tidal power usage schedule
Despite the promise, progress has been slow. On board the boat, Lisa Mackenzie from Emec tells a scandalous story about the renewable energy sector in the United Kingdom. In the 1980s, Orkney was home to experimental wind turbine technology that could make the UK a world leader in the sector. But the government is not investing – and Denmark and Germany have rushed to monopolize the market.
“The United Kingdom was losing wind energy and we lost it,” she said. “Now the tidal energy is ours to lose. We can’t let that happen again. “
At Orkney, testing aims to reduce the costs and risks of tidal energy to make it commercially viable. “We have some of the best conditions in the world for testing new technologies,” says Mackenzie. “More ocean energy converters have been tested here than any other site.”
Orbital’s O2 turbine, launched at the Orkney Fall of Warness test site last July, is the third iteration of its tidal technology. This is the version that the company hopes to launch. It consists of a 74-meter floating structure with a submerged two-bladed turbine on each side. A submarine cable connects it to the local onshore grid, where the energy it produces can meet the needs of about 2,000 homes each year.
The blades of the Orbital 02 turbine are submerged under the waves. Photo: Orbital Marine Power
“All new technologies in every space are more expensive than the market, so we can’t compete outside the box with mature generation technologies,” said Andrew Scott, CEO of Orbital Marine Power. “What we need is market intervention to level the playing field.
The United Kingdom is considered a world leader in the development of tidal energy technology, but while the government provided full support to the sector since 2008, it was abolished in 2016. Last year, the government reintroduced short-term support, but what is needed is a long-term vision, says Scott.
“If we can’t rest assured that there will be a long-term market, we are still in first place,” he said. “Private investors will not be willing to invest money because there is a feeling that the carpet can be taken out from under you at any moment.”
Just minutes from O2, a test platform installed by the Irish company OpenHydro in 2006 was abandoned. The company went into liquidation in 2018 after being bought out by the French company Naval Energies, which eventually withdrew its funding. That same year, plans for a tidal lagoon in Swansea Bay, once thought to be the UK’s first commercial tidal power generator, collapsed when the government failed to secure financial support to cover energy costs.
This is a global challenge, Bahaj said. “The work environment requires high-specific designs and technologies, as well as specialized installation and maintenance ships,” he said. “All these activities require money from developers, who, unlike oil and gas, are mostly SMEs with limited financial resources. The availability of funding, including government technology support, is a major challenge that limits scaling up and reducing costs.
Graph showing Orbital O2 in action. Photo: Orbital Marine
Some governments are responding. In 2020, the Canadian government announced a $ 28.5 million investment in floating tidal energy, developed by the Scottish company Sustainable Marine in Fundy Bay, home to the world’s most powerful tides. In May, it delivered the first energy from a floating tidal stream to Nova Scotia’s energy grid.
The Faroe Islands are also home to ambitious investments in tidal flows. Under a 2018 agreement, Swedish-based developer Minesto will install and operate two grid-connected tides, and the island’s main energy company, SEV, is committed to buying electricity. At the time, the deal was hailed by Minesto CEO Dr. Martin Edland as playing a “significant role” in the Faroe Islands’ planned transition to 100% renewable energy by 2030.
Scott of Orbital wants the United Kingdom to take such an ambitious approach to the power of tides. “We have the ability to grow a local industry here that can help with net zero, the equalization program, the fair transition,” he said. O2 was built with the help of a supply chain in the United Kingdom, which generates about 60 jobs, he added. “The industry does not have to become massive and we can make a very meaningful contribution.”
Back on the boat, as he moved around the Orkney Islands, Mackenzie watched for killer whales, which were spotted near O2 earlier in the day.
With the development of tidal technology, some scientists have expressed concerns about the potential effects on marine life. Mackenzie says marine mammals and fish are well aware of the avoidance of boats and other structures, and research conducted at Emec test sites shows little impact on wildlife. Some studies suggest that tidal and wave systems may even have a positive effect on marine life by acting as artificial reefs.
The ships needed for installation and maintenance generate potentially destructive noise, but it is believed that the tide itself in these stormy seas is stronger than the turbine. Turbine blades can pose the greatest dangers, but research shows that their effects are rare and mostly non-lethal.
With the ability to generate large volumes of predictable renewable energy, some experts believe that tidal energy may play an important role in the global energy mix.
“There is a global interest in tidal flow, and with the current rise in gas and electricity prices, tidal-powered energy is likely to compete favorably,” Bahai said. “In a way, the future looks brighter than a year ago.”
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