Research Recap: Tidal Wave Energy
July 13, 2021 | Claris Lam
Is it possible that one day, our main source of energy could come from the sea itself? Tidal energy stations currently exist all over the world as alternative sources of energy, from Canada to South Korea! Researchers are looking into ways to further harness the ocean’s tidal waves, to use them as cleaner energy sources to replace the current main sources of energy in the near future.
What Is Tidal Wave Energy?
Tidal energy is power produced by the surge of ocean waters during the rise and fall of tides. Tidal energy sources use tidal movement to generate electricity in areas where there is a significant tidal range, which is the difference in area between high tide and low tide.
Tidal energy is considered renewable because the tides move on a predictable, daily schedule depending only on the orbits of the Earth, Moon, and Sun. Tides also are essentially inexhaustible. Mills using the tide for power, in fact, date back to the 8th Century CE! They were similarly designed to conventional water mills, with the addition of a dam and reservoir. The technology fell out of favour after the Industrial Revolution. However, it reemerged in the 1960s to 1980s, when experimental tidal barrages were built in France, Russia, China and Nova Scotia.
There are currently three different ways to get tidal energy: tidal streams, barrages, and tidal lagoons. Most tidal energy generators involve placing turbines in tidal streams. A tidal stream is a fast-flowing body of water created by tides. Turbines are machines that take energy from flowing fluid, such as air (wind) or liquid (water). Because water is much more dense than air, tidal energy is more powerful than wind energy. Unlike wind, tides are predictable and stable. Where tidal generators are used, they produce a steady, reliable stream of electricity.
Turbines are most effective in shallow water. This produces more energy and allows ships to navigate around the turbines. A tidal generator’s turbine blades also turn slowly, which helps marine life avoid getting caught in the system. Placing turbines in tidal streams, however, can be complicated. This is because the machines are large and disrupt the tide they are trying to harness. The environmental impact could be severe, depending on the size of the turbine and the site of the tidal stream.
Tidal barrages involve water spilling over the top or through turbines in the dam, because the dam is low. These barrages can be constructed across tidal rivers, bays, and estuaries. Turbines inside the barrage harness the power of tides. When the tide rises, the barrage gates open. These gates later close when a high tide occurs, creating a pool or tidal lagoon. The water is then released through the barrage’s turbines, creating energy at a rate that can be controlled by engineers.
One of the potential disadvantages of tidal power is the effect a tidal station can have on plants and animals in estuaries of the tidal basin. For instance, tidal barrages can change tidal levels in the basin and increase turbidity (the amount of matter in suspension in the water). Additionally, land within the tidal range is completely disrupted. The changes in a tidal lagoon’s water levels might harm plant and animal life, and also lower the salinity inside of the lagoon, changing the organisms that are able to live there. Fish are also blocked into or out of the tidal lagoon, and there is also the risk of marine animals being caught in turbine blades due to turbines moving quickly in barrages. This limits birds’ food sources, and they might have to find different places to migrate.
In addition to the environmental costs, tidal barrages are more expensive tidal energy generators than a single turbine. Although there are no fuel costs, barrages involve more construction and more machines. Unlike single turbines, barrages also require constant supervision to adjust power output.
A tidal lagoon is a body of ocean water that is partly enclosed by a natural or manmade barrier. Tidal lagoons might also be estuaries and have freshwater emptying into them. A tidal energy generator using tidal lagoons would function much like a barrage. Unlike barrages, however, tidal lagoons can be constructed along the natural coastline. A tidal lagoon power plant could also generate continuous power. The turbines work as the lagoon is filling and emptying.
Unlike tidal streams and lagoons, the environmental impact of tidal lagoons is minimal. The lagoons can be constructed with natural materials like rock and appear as a low breakwater (sea wall) at low tide, and be submerged at high tide. Animals can swim around the structure, and smaller organisms can swim inside it. Large predators like sharks cannot penetrate the lagoon, so smaller fish can thrive within the lagoon!
Despite the minimal environmental impact from tidal lagoons, however, their energy output is low. Additionally, there are no functioning examples yet, though some are currently being constructed.
What impact could Tidal Wave Energy have globally?
Currently, several tidal power barrages already operate around the world! The world’s first tidal power station was constructed in 2007 at Strangford Lough in Northern Ireland. Meanwhile, South Korea’s Sihwa Lake Tidal Power Station has the largest electricity generation capacity at 254 megawatts (MW)! The oldest and second-largest operating tidal power plant is in La Rance, France, with 240 MW of electricity generation capacity. Research suggests that in the UK over 20% of the national energy demand could be satisfied by exploiting tidal and wave energy sites around the country. Some tidal plants are currently under construction, such as the Meygen Tidal Project in the UK. Other plants include constructing a small tidal lagoon power plant in Swansea Bay, Wales.
What impact could Tidal Wave Energy have in Canada and KW?
Canada is also currently investing into developing tidal energy. In December 2019, a Scottish tidal energy business, Nova Innovation, was issued a permit to develop a project in the Bay of Fundy, Nova Scotia! Nova Innovation reported at the time that fifteen tidal stream turbines would be installed by the year 2023. This project will produce enough electricity to power 600 homes! Additionally, Nova Scotia’s Department of Energy and Mines said that electricity produced by the turbines will be sold to Nova Scotia Power for 50 Canadian cents (38 cents) per kilowatt hour.
More recently, in September 2020, the Honourable Bernadette Jordan, Minister of Fisheries, Oceans and the Canadian Coast Guard, on behalf of the Honourable Seamus O’Regan, Canada’s Minister of Natural Resources, accompanied by Lenore Zann, Member of Parliament for Cumberland–Colchester, announced a $9.4-million investment in four tidal energy projects that will bring clean energy technologies to the Atlantic region and help Canada build a cleaner future. These investments include 4 million dollars to Nova Innovation to build a tidal turbine array using sub-sea tidal technology in Petit Passage in the Bay of Fundy, 1.58 million to the University of Manitoba, in partnership with Sustainable Oceans Applied Research (SOAR), to advance research on river hydrokinetic and in-stream tidal energy technologies in the Canadian context, 2 million to Offshore Energy Research Association of Nova Scotia to research an environmental effects monitoring solution for the instream tidal energy industry in Canada, including fish and marine mammal interactions with tidal devices, and 2 million to Fundy Ocean Research Centre for Energy to outline a plan to assess the encounter risk for fish with tidal devices and create a tool to support the regulatory authorization process for tidal energy projects.
Though tidal wave energy is being used in many parts of the world already, researchers and developers hope to expand their reach further. However, with the potential environmental costs of these systems, especially with tidal barrage systems’ effects on the marine environment, it could have its drawbacks despite being a renewable energy source. This technology can still be used, but it will be up to developers and further research to find ways to solve the problems that come with the drawbacks if they wish to expand tidal energy’s usage further, especially if it will replace current main energy sources.
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