A tidal farm is a group of multiple tidal stream generators assembled in the same location used for production of electric power, similar to that of a wind farm. The low-voltage powerlines from the individual units are then connected to a substation, where the voltage is stepped up with the use of a transformer for distribution through a high voltage transmission system.
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Technology
Tidal Farms utilize tidal stream generators that are grouped together to produce electricity. These generators use the moving tides to turn turbines that are very similar the wind turbines used on land. The power of the ocean and the turbines advance technology guarantee a much more predictable energy output then regular wind turbines. The turbines are usually located in areas with high tidal activity in order for the generators to be as efficient as possible. What makes tidal farms unique is that they are set up in groups to allow much more energy production. The generators are connected to substations on shore to transform voltage from high to low, or low to high. These generators can be semi-submersible or fixed into the sea floor, which means they would be out of sight and not an eyesore for the public. The turbines that would be used would be very slow moving due to the density of the water, this is very beneficial to the aquatic life because fish would be able to freely pass through without being in danger of dying. Some turbines can also be used in irrigation canals, rivers, and dam whether the flow of water is fast or slow.
Operators
Scotland is one of the main leaders in the effort to utilize tidal energy as an alternative energy resource. In 2012, Scottish Power installed a 30 ft. turbine off of the Orkney Islands. The currents off of these islands are very fast moving and the tests conducted had shown that the generator produced one megawatt of electricity, enough to power 500 homes. Scotland is also looking to install a more powerful generator off of the Sound of Islay that would be capable of powering in upwards of 5,000 homes once fully operational. In January 2015, production of a 400-megawatt tidal generator was being constructed in Northern Scotland. This generator would be capable of powering 175,000 homes. Ocean power is a clean and efficiency with an energy source that never turns off. Using Tidal farms is a much cleaner and efficient way to produce electricity. One of the drawbacks to tidal farms is marine life and how it will affect it. They would also need to set the tidal farms deep in the ocean where it won't affect fishing boats or large ship passing by. The United States of America has nearly 12,380 miles of coastline, and is undergoing an 18-month study to see how well the tidal farms work source. The project could cost up to $10 million, including $2 million on fish monitoring equipment and if everything goes to plan the U.S. could be seeing tidal farms along the US coast. The zero-emission tidal farms could be the way to a cleaner planet, a better future and maybe reducing the cost of electricity in the long run.
Types
• Double and Three Bladed Turbine are turbines attached to a stationary pole and rotate axial to chase the ocean currents. Some of the double and triple bladed turbines can have two sets attached to the pole for better efficiency. This type of turbine has to be detached from the stationary pole and lifter with cranes attached to ships when maintenance is to be performed.
• Semi Submersible Turbines is a more expensive turbine but in the long run it is cheaper and is more cost efficient. The turbines are connecting to a stationary post and the turbine generator can be raised and lowered anytime for maintenance.
• Duct Style Turbine uses duct all the way around the entrance of the turbine to guide and accelerate the tidal stream toward the rotor. By using a duct, more energy can be extracted from the same amount of water with smaller diamter rotor blades thereby keeping costs of manufacture and maintenance down.
• Cable Tethered Turbine floating turbines are attached by a chain to a stationary point in the bottom of the ocean and follow the ocean current in a horizontal 360 degrees. These turbines are easy to bring up to the surface for maintenance because they are pressurized with air. They are also equipped with sensors to detect any water trying to make its way into the pressurized generator.
Problems
One of the few environmental unknowns about tidal farms is the threat they may pose to the plant life in the areas that the turbines would be set up. But by having the blades turn at a slower than normal speed wind turbines can eliminate some of the potential environmental problems. Another problem that can occur is making the turbines water tight to prevent seawater from corrosion the metal parts inside the turbine. Underwater turbines would have to be position away from shipping lanes, too close to shore, and in deep enough waters for them not to interfere with everyday shipping traffic. Having countries like Scotland position underwater turbines can help other countries learn and explore betters ideas for creating energy by learning from the successes and the failures achieved by the leading countries. Scotland expects the rest of the world to follow their example and install tidal farms all over the world in the efforts to help stop pollution and make producing energy cleaner and safer.