New Undersea Turbines Harness Enormous Power From Local Tides
Two countries with the highest tides in the world, Canada and the UK, both claim to be the world leaders in creating electricity from the tides.
They are among a group of coastal states—including China, South Korea, the U.S. and Australia—that are hoping to harness the enormous power of their local twice-daily tides to tap a new and reliable supply of electricity.
There are all sorts of schemes in many countries, the most familiar being the tidal barrages that direct the ebb and flow of the tide through turbines to generate electricity.
Best known of these is the Rance tidal power station, which was opened in 1966 at Saint-Malo, northern France. At 240 megawatts (MW), it was the largest in the world for 45 years, until South Korea’s Sihwa Lake power station came into service in 2011, producing 254 MW.
But there is a new generation of tidal power schemes. They use undersea turbines, able to make use of the powerful tidal currents in estuaries and in relatively shallow water on continental shelves. Because water is far denser than air, the same area of turbine blade can produce four times more electricity than a wind turbine.
So far, 20 sites in the world have been identified where hundreds of underwater turbines could be deployed. These are in shallow water, where the tidal current moves swiftly and where cables can be connected to the onshore grid.
The best sites are between islands or in other narrow stretches of sea where the tide flows strongly. Eight of these sites have been identified in the UK and they could on their own generate around 20 percent of the country’s electricity needs—more than its 15 nuclear reactors are currently producing.
In Canada, which has two coasts with many offshore islands, there are also many potential locations—enough to replace a dozen large coal and gas plants.
The stretch of water between the northeast tip of Scotland and the Orkney islands is probably the best place in the world to generate electricity from the movement of the tides. Several companies are already testing prototypes.
It is here in the Pentland Firth, Caithness, that MeyGen has begun work on building 61 undersea turbines—out of a planned total of 269—that will make it the largest undersea power station in the world. In total, the scheme will generate 398 MW of clean power, which is enough for 175,000 homes.
Another large-scale scheme has been announced in Northern Ireland, where the Fair Head project will begin building undersea turbines in 2018 to provide 100 MW of power.
But, in one sense, Canada is already ahead. The Bay of Fundy in Nova Scotia has the highest tides in the world. The Fundy Ocean Research Centre for Energy project already has undersea cables connected to the grid and four power companies with turbines of different designs and has agreements to provide power for up to 10,000 homes.
With Canada’s vast array of offshore islands and its strong tides, the government has identified more than 100 possible sites, large and small, for undersea arrays. Small schemes could provide a steady power source for some of the country’s more isolated communities.
While there are still questions over the best design of turbine to generate the maximum amount of reliable electricity with the least maintenance, this is clearly a technology with a bright future.
It also has the advantage over all other generating systems of being out of sight. The turbines’ design will depend on the strength of the tidal current and on the height they are placed above the sea bed.
There are also still environmental issues to be resolved—for example, the effect on marine life and particularly the potential damage to fish and marine mammals. But, compared with wind turbines, the blades turn very slowly.
Because undersea arrays are limited to areas with high tidal flows, they could not compete with solar and wind power for a worldwide share of the renewable market.
But for those countries lucky enough to have shallow seas and big tides the technology is expected to be a significant and long-term source of clean power.
YOU MIGHT ALSO LIKE
EcoWatch Daily Newsletter
The 2020 hurricane season is now expected to be the most active since at least the early 1980s, meteorologists at Colorado State University, a standard bearer for seasonal hurricane predictions, announced Wednesday.
Three years ago, scientists predicted it would happen. Now, new NASA satellite imagery confirms it's true: two ice caps in Canada's Nunavut province have disappeared completely, providing more visual evidence of the rapid warming happening near the poles, as CTV News in Canada reported.
- Climate Explained: What the World Was Like the Last Time Carbon ... ›
- Polar Bears Could Be Nearly Gone by 2100, Study Finds - EcoWatch ›
- Greenland's Ice Sheet Is Melting at Rate That Surpasses Scientists ... ›
By Katell Ané
The European Commission launched a new Farm to Fork strategy in an effort to reduce the social and environmental impact of the European food system. It is the newest strategy under the European Green Deal, setting sustainability targets for farmers, consumers, and policymakers.
Facebook and Twitter removed posts by President Donald Trump and his campaign Wednesday for violating their policies against spreading false information about COVID-19.
- Rare Inflammatory Disease Linked to More Than 100 Childhood ... ›
- COVID-19: What Experts Think About Reopening Schools - EcoWatch ›
- Teens and Tweens Are Fastest COVID-19 Spreaders, New Study ... ›
- Researchers Are Creating a Drone to Study Wild Dolphins With Help ... ›
- These Whales Are Suffering a Slow-Motion Extinction - EcoWatch ›
By Alexander Freund
Lebanese Prime Minister Hassan Diab says he believes Tuesday's explosion in Beirut could have been caused by large quantities of ammonium nitrate stored in the port.
What Is Ammonium Nitrate?<p>Ammonium nitrate is a white crystalline salt that can be fairly cheaply produced from ammonia and nitric acid. It is soluble and often used as fertilizer, as nitrogen is needed for healthy plant development.</p><p>Ammonium nitrate in its pure form is not dangerous. It is, however, heat sensitive. At 32.2 degrees Celsius (89.96 degrees Fahrenheit), ammonium nitrate changes its atomic structure, which in turn changes its chemical properties.</p><p>When large quantities of ammonium nitrate are stored in one place, heat is generated. If the amount is sufficiently vast, it can cause the chemical to ignite. Once a temperature of 170 C is reached, ammonium nitrate starts breaking down, emitting nitrous oxide, better known as laughing gas. Any sudden ignition causes ammonium nitrate to decompose directly into water, nitrogen and oxygen, which explains the enormous explosive power of the salt.</p>
Deadly Disasters<p>As ammonium nitrate is a highly explosive chemical, many countries strictly regulate its use. Over the past 100 years, there have been several disasters involving the chemical.</p><p>In 1921, for example, a massive blast occurred at a BASF chemical plant in Ludwigshafen in the German state of Rhineland-Palatinate. About 400 metric tons of a mixture of ammonium sulfate and ammonium nitrate exploded, killing 559 people and injuring 1,977. The plant was largely destroyed in the blast, which could be heard as far away as Munich, some 300 kilometers (186 miles) distant.</p><p>In 2015, explosions caused by ammonium nitrate ripped through the <a href="https://www.dw.com/en/china-convicts-dozens-for-last-years-giant-explosions-in-tianjin/a-36324321" target="_blank">Chinese port city of Tianjin</a>. Eight hundred metric tons of the chemical were said to have been stored along with other substances in a warehouse for hazardous materials. The blasts killed 173 people and destroyed an entire city district.</p><p>Two years earlier, in 2013, an ammonium nitrate explosion occurred at the West Fertilizer Company site in Texas, killing 14 people. And in 2001, 31 people died in Toulouse, France, in an explosion caused by the chemical.</p>
Terrorist Favorite<p>In Germany, the purchase and use of ammonium nitrate is regulated by the explosives act. This is because the cheap, highly explosive and relatively easily obtainable material has in the past been used by terrorists to carry out attacks.</p><p>For example, in 1995, U.S. conspiracy theorist and gun enthusiast Timothy McVeigh used a mixture of ammonium nitrate and other substances to bomb the Alfred P. Murrah Federal Building in Oklahoma City. Norwegian far-right extremist Anders Behring Breivik also used ammonium nitrate in a car bomb attack in Oslo in 2011.</p>
- 5 Ways to Keep Unhealthy Nitrates and Nitrites Out of Your Body ... ›
- The Price of Our Fertilizer Addiction - EcoWatch ›
- 8 Disturbing Facts About Monsanto's Evil Twin—The Chemical ... ›
By Michelle D. Holmes
Most Americans know about the Dietary Guidelines for Americans primarily through their colorful representations: the original food pyramid, which a few years ago morphed into MyPlate. The guidelines represent the government mothering us to choose the healthiest vegetables, grains, sources of protein, and desserts, and to eat them in the healthiest portions.
As innocuous as the food pyramid and MyPlate seem, they are actually a matter of life and death.
- 6 Powerful Ways to Improve Mental Health - EcoWatch ›
- New, Improved Vegetarian and Vegan Food Pyramid - EcoWatch ›
- Dr. Mark Hyman: Here's How the Food Pyramid Should Look ... ›