Tidal flow can be intense. If you’ve ever paddled against a tide-based rip current, or witnessed video of tidal bores pushing up a river, you know this. Some researchers, however, are taking this concept to an extreme by developing evolutionary methods of harvesting renewable energy from tidal movements.
Tide fluctuation is largely generated by the gravitational pull of the moon and sun with varying effects at different beaches and waterways. Some spots in Canada, Alaska, Europe, and northern Brazil experience extreme tidal swings (The Bay of Fundy in Canada has a tidal range of over 50 feet) while other locations, like Honolulu on Oahu, have tides that only alter by about three feet.
Tidal energy can be collected in a few different ways. Tidal barrages, underwater turbines, and tidal fences are some of the key instruments being used. Tidal barrages are similar to dams in that they stretch across entire bodies of water. They use sluice gates to manipulate the ebb and flow that filters through them, capturing energy as water pushes in both directions. Tidal turbines use rotating blades, similar to wind turbines, but are capable of harvesting more energy than wind turbines. Tidal fences employ a series of vertical axis turbines in a fence-like row at the bottom of the sea floor. They harness kinetic energy moving through them on both the incoming and outgoing tide.
While tidal energy can be viable, it’s not without problems. Tidal barrages, for example, can negatively affect individual plant and sea-life and ecological systems. They can also disrupt migration and recreation because they span across entire waterways. There are also restrictive costs involved in setting up large-scale operations.
One nation pushing ahead with tidal energy harvesting technology despite the drawbacks is Scotland. They’ve implemented the first large-scale tidal energy farm in the Pentland Firth straight and plan to power as many as 175,000 homes with it in the future. The Pentland Firth straight produces currents that flow at speeds of up to 18 miles per hour, providing a strong tidal current to convert into useable energy. As a leader in this movement, Scotland is seeking to power 100% of its energy from renewable sources by 2020, with tidal power making a significant contribution to this goal.
Other countries using tidal energy include Canada, France, South Korea, China, and Russia. Although there are a few potential sites for generating tidal energy in the United States, there are currently no functioning tidal energy harvesting systems in operation. As technology improves, though, and it becomes a more attractive option for generating money as well as power, hopefully progress on this front will also be made in the US.
sources and links:
“Scottish Government.” Renewable Energy, Scottish Government, St. Andrew’s House, Regent Road, Edinburgh EH1 3DG Tel:0131 556 8400 Ceu@Scotland.gsi.gov.uk, 1 Apr. 2003, www.gov.scot/Topics/Business-Industry/Energy/Energy-sources/19185.
“Tidal Power.” Tidal Power – Energy Explained, Your Guide To Understanding Energy – Energy Information Administration, www.eia.gov/energyexplained/index.cfm?page=hydropower_tidal.
“Where Is the Highest Tide?” NOAA’s National Ocean Service, 8 Oct. 2008, oceanservice.noaa.gov/facts/highesttide.html.
“World’s First Large-Scale Tidal Energy Farm Launches in Scotland.” The Guardian, Guardian News and Media, 12 Sept. 2016, www.theguardian.com/uk-news/2016/sep/12/worlds-first-large-scale-tidal-energy-farm-launches-scotland.
featured photo by Jake S.