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.
A mathematical optimization approach is used design turbine farm layouts. Using the environmental parameters such as water depth and incorporating them using mathematical formulas, a farm layout can be developed and tested. Through this research and development, factors such as the number of turbines, location of turbines and overall farm profit could be accurately tested and predicted.
In Brittany, France, a French tidal farm has deployed its first of two 500 KW turbines. The Project is located 16 miles offshore and has a depth of 35 meters. Once the power is generated it will be converted and transported to an onshore site located in the Arcouest Peninsula in Ploubazlanec. This project contributes towards the progress in a shifts towards renewable energy and tidal energy in particular.
In Iran there have been interest in development of tidal stream energy due to its predictability, and consistency. Faculty of Civil Engineering at the university of Tarbiat Modares University have identified potential sites of interest of these farms. Locations include the Persian Gulf, the Oman Sea, Khowran Straight, Hengam Island and Greater Tunb Island. Cost of energy, power output, Tariff rates and expected return on investments have also been factors analyzed and studied by the university research group.
Methods have been developed in order to determine the most suitable sites for tidal farms. Factors considered in the selection of locations include potential to provide the greatest power performance, the least amount of cost, and the least amount of inconvenience towards marine life. A case study done in the Bristol Channel used a hydrodynamic model on a Matlab-based program in order to obtain its results.
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.
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 currently offering up to $22 million in funding for research into marine power sources.
The company Ocean Flow used Siemens technology to design a semi-submersible turbine. The models created have proven to be able to withstand sea conditions excellently. The company claims its model creates less disturbances to its surrounding ecosystem, and cost less to deploy. A key feature to this model set up is the platform that the turbine rest on. It was developed at Newcastle University School of Marine Science and Technology in 2006. The Platform is suitable to withstand harsh conditions in deep depth of the ocean. Senior development engineer at OceanFlow Mark Knos commented on the project and stated that they had created a 1/40th scale model to test and a 1/10 scale model as well. Both models were tested and have provided promising results.
North America has fewer tidal power stations than any other comparable geographical area, in terms of GDP or population. Tidal power has been estimated to be able to account for fifteen percent of the United States’ power consumption if harnessed correctly.The first tidal instillation in North America to connect to a power grid was laid down in 2012, in Cobscook Bay, Maine by the Ocean Renewable Power Company. The preliminary device generates 180 Kilowatts at full capacity. Plans to install two more devices were shelved as of 2013. Tidal generators were installed in 2009 by OpenHydro and Emera the Bay of Fundy. These tidal generators suffered damage, losing several blades in the process, due to the powerful tides in the Bay. In the autumn of 2016 a joint venture by the same two companies successfully placed a 2-Megawatt tidal generator in the Bay of Fundy, of which Cobscook Bay is a constituent area. The successful integration of the new tidal generators to local power stations, and the connected power grid supplies an estimated 150 to 200 homes per day.
• 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 diameter 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.
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 better 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.
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Tidal farms present many possible environmental and ecological changes to the environment they are placed in. The structures of these farms produce changes in tidal patterns, sediment flow, and water column turbulence.Tidal patterns can be affected in different ways depending on the structure of the farm itself. The structure is referring to the size and cross-sectional area because the number of blades or the load that is put on the farm doesn't make much of a difference on the overall height of the water. These effects can be seen to lower both the high tide and low tides which means that the water level will be lower in total. The number of blades and load on the system however does affect the tidal range vastly. Tidal range can be reduced up to 42% with observations of the densest farms which can cause destruction to 32% of the areas around them, but it can be controlled. Damage can be reduced to 19% by using a two-rotor spaced turbine and only 5.4% with five-rotor spaced turbines. This is done by spreading the water's work over a large surface area on the turbine itself to mitigate the alteration of the flow in the water column.
Sediment flow is affected by the introduction of tidal farms to an area. Not only does it create turbulence that moves the sediment, but it changes the ecosystem around it. By moving more sediment into areas that didn't gain much before, places like grass beds could be wiped out by being covered in sediment. The geography on the ocean floor would be changed by the new sediment flow patterns because of the new turbulence. New things like sandbars could form around the farms causing even more of an impact to the surrounding environment by influencing more changes than originally expected.
The water column also faces multiple chances since the force it transfers through turbulence is being absorbed by the tidal farms. Waves would be directly affected by the reduced energy behind the water causing them to be weaker which too could destroy multiple ecosystems. There would also be an effect on the inter-tidal zones with there being less turbulence which many species like fish and crabs use for sustenance and survival. Other things like noise and electromagnetic fields also pose problems for the environment, but not to the scale that the last effects had on the geography and life in an ecosystem.
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The prime placement of tidal farms occurs in tidal barrages, marshes, lagoons and other intertidal bodies of waters most commonly home to migratory wetland birds. The placement of tidal farms raises the water levels to a point where the feeding areas of the birds are submerged. With the loss of feeding areas, mortality rates increase.Furthermore, studies were conducted by University of Exeter faculty for wetland birds in the Solway Firth, UK. These studies concluded that the effect of certain types of tidal farms are negligible. The impacts of tidal farms on water foul habitats in the Solway Firth were found to be relatively low, even for the largest case. The study highlighted that current installations with similar capacities as the simulations had a lower loss of intertidal area than that of its computer-generated counterpart . One conclusion reached was that future studies should focus on the vulnerability of an individual species, as compared to the effect on maritime birds as a whole.
The construction of tidal barrages within a bay, inlet, or estuary is one of the few cases where inter species relations were universally affected. The retention of tidal water alters the timetable of species which dominate the upper to intermediate shore habitats. Simultaneously the lower shore remains submerged for longer periods of time. The resulting forced ecosystem is disruptive to the majority of species present, with the exception of fish whom are tidal feeders. The extended periods of high tide allow for greater foraging opportunity, hence a growth in population can be observed in these cases.
The structures of larger tidal barrages alter the scour and deposition in their respective habitats. Scour and deposition refers to the movement and exchange of sediment along the floor of a water body. The U.S. Army Engineer Research and Development Center in Vicksburg, Mississippi stated that the interruption of natural sediment deposits directly led to an increased mortality rate of seabed grass, as the shoot could not properly grow in the altered seafloor. This would be even more devastating for benthic life which resides under the ocean floor since they are easily affected by changes in the flow over the bottom of the ocean. It would be hard to prevent this too since these organisms aren’t easily relocated since they are so sensitive to changes in their atmosphere.
A turbine is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating electrical power when combined with a generator. A turbine is a turbomachine with at least one moving part called a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades so that they move and impart rotational energy to the rotor. Early turbine examples are windmills and waterwheels.
A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid.
Tidal power or tidal energy is the form of hydropower that converts the energy obtained from tides into useful forms of power, mainly electricity.
Electric power systems consist of generation plants of different energy sources, transmission networks, and distribution lines. Each of these components can have environmental impacts at multiple stages of their development and use including in their construction, during the generation of electricity, and in their decommissioning and disposal. We can split these impacts into operational impacts and construction impacts. This page looks exclusively at the operational environmental impact of electricity generation. The page is organized by energy source and includes impacts such as water usage, emissions, local pollution, and wildlife displacement.
Wave power is the capture of energy of wind waves to do useful work – for example, electricity generation, water desalination, or pumping water. A machine that exploits wave power is a wave energy converter (WEC).
Marine currents can carry large amounts of water, largely driven by the tides, which are a consequence of the gravitational effects of the planetary motion of the Earth, the Moon and the Sun. Augmented flow velocities can be found where the underwater topography in straits between islands and the mainland or in shallows around headlands plays a major role in enhancing the flow velocities, resulting in appreciable kinetic energy. The sun acts as the primary driving force, causing winds and temperature differences. Because there are only small fluctuations in current speed and stream location with minimal changes in direction, ocean currents may be suitable locations for deploying energy extraction devices such as turbines. Other effects such as regional differences in temperature and salinity and the Coriolis effect due to the rotation of the earth are also major influences. The kinetic energy of marine currents can be converted in much the same way that a wind turbine extracts energy from the wind, using various types of open-flow rotors.
The Gorlov helical turbine (GHT) is a water turbine evolved from the Darrieus turbine design by altering it to have helical blades/foils. It was patented in a series of patents from September 19, 1995 to July 3, 2001 and won 2001 ASME Thomas A. Edison Patent Award. GHT was invented by Alexander M. Gorlov, professor of Northeastern University.
Specialized wind energy software applications aid in the development and operation of wind farms.
SeaGen was the world's first large scale commercial tidal stream generator. It was four times more powerful than any other tidal stream generator in the world at the time of installation. It was successfully decommissioned by SIMEC Atlantis Energy Limited in summer 2019, having exported 11.6GWh to the grid since 2008.
Marine Current Turbines Ltd (MCT), a Siemens business, is a United Kingdom-based company which is developing tidal stream generators.
A wind turbine, or alternatively referred to as a wind energy converter, is a device that converts the wind's kinetic energy into electrical energy.
New Zealand has large ocean energy resources but does not yet generate any power from them. TVNZ reported in 2007 that over 20 wave and tidal power projects are currently under development. However, not a lot of public information is available about these projects. The Aotearoa Wave and Tidal Energy Association was established in 2006 to "promote the uptake of marine energy in New Zealand". According to their 10 February 2008 newsletter, they have 59 members. However, the association doesn't list its members.
Low head hydropower applications use tidal flows or rivers with a head of 20 metres (66 ft) or less to produce energy. These applications may not need to dam or retain water to create hydraulic head. Using the drop in a river or tidal flows to create electricity may provide a renewable energy source that will have a minimal impact on the environment.
Evopod is a unique tidal energy device being developed by a UK-based company Oceanflow Energy Ltd for generating electricity from tidal streams and ocean currents. It can operate in exposed deep water sites where severe wind and waves also make up the environment.
Marine energy or marine power refers to the energy carried by ocean waves, tides, salinity, and ocean temperature differences. The movement of water in the world’s oceans creates a vast store of kinetic energy, or energy in motion. Some of this energy can be harnessed to generate electricity to power homes, transport and industries.
A tidal stream generator, often referred to as a tidal energy converter (TEC), is a machine that extracts energy from moving masses of water, in particular tides, although the term is often used in reference to machines designed to extract energy from run of river or tidal estuarine sites. Certain types of these machines function very much like underwater wind turbines, and are thus often referred to as tidal turbines. They were first conceived in the 1970s during the oil crisis.
A tidal barrage is a dam-like structure used to capture the energy from masses of water moving in and out of a bay or river due to tidal forces.
Ocean Renewable Power Company is a marine renewable energy company based in Portland, Maine. The company develops technologies which generate electricity from tidal, river, and ocean currents. The turbines are a cross-flow design in the helix shape of DNA with the axis of rotation perpendicular to the flow of water and work on the same principle as water wheels. As the tide comes and goes, the turbine foils spin in the same direction producing mechanical power that a permanent magnet generator converts to electricity and then sends to the electrical grid via an underwater power cable and onshore power station. The TidGen® power system and RivGen® power system are the company's trademarked systems.
Lam Wei Haur, also known as Wei-Haur Lam, WH Lam, W Lam, is a Malaysian scientist and professor in ocean engineering.