Tidal

Capturing energy from tidal fluctuations.

Tidal Energy

 

Gravity from the moon and sun cause water in the ocean to bulge in a cyclical pattern as the Earth rotates, causing water to rise and fall relative to the land in what are known as tides. Land constrictions such as straits or inlets can create high velocities at specific sites, which can be captured with the use of devices such as turbines. As seawater is about 800 times denser than air, tidal turbines can collect energy with slower water currents and smaller turbines than wind energy. Modern tidal power generating turbines operate on the same principles as wind turbines. While the moving water passes the turbine’s blades, the kinetic energy of moving water is converted into mechanical energy as the rotating blades spin a drive shaft. The mechanical energy in the drive shaft is then converted to electrical energy using a generator, often through a gearbox. Power may also be produced by extracting potential energy from the rise and fall of the tides in a manner similar to conventional hydropower.

 

Axial Flow Turbine

 

  • These turbines are the most similar to traditional wind turbines, where the kinetic energy of moving water is captured by spinning blades facing the direction of flow. Turbines can be open or ducted (shrouded) and placed anywhere in the water column, though bottom-mounted is the most common. Turbines may use active or passive measures to yaw or vane in the direction of flow. They can have pitching blades allowing them to change their hydrodynamic performance based on flow conditions or control settings.
  • The main environmental concern is collision between turbine blades and marine organisms due to natural animal movements, attraction to the device, or inability to avoid the turbines within strong currents. There is also concern that noise from turbines can affect animals that use sound for communication, social interaction, orientation, predation, and evasion. As with all electricity generation, there is a slight concern that electromagnetic fields generated by power cables and moving parts of the turbines may affect animals that use Earth's natural magnetic field for orientation, navigation, and hunting. Likewise, chemicals such as anti-corrosion paint and small amounts of oil and grease may enter the waterbody during spills, though some turbine designs do not require lubrication, and affect water quality. Large-scale tidal changes in flow (from arrays) may disrupt natural physical systems to cause degradation in water quality or changes in sediment transport, potentially affecting ecosystem processes

Photo Credit: BALAO-SABELLA

Cross Flow Turbine

 

  • These turbines capture kinetic energy of moving water with spinning blades oriented perpendicular to the direction of flow. They can be mounted in either vertical or horizontal orientations. When mounted vertically, these devices can operate regardless of the direction of flow. They typically have cylindrical cross-sections amenable to placement in confined channels or allowing tight array spacing. Turbines can be open or ducted (shrouded) and placed anywhere in the water column, though bottom-mounted is the most common. The electricity production mechanism is similar to axial-flow turbines.
  • There is typically less environmental concern for collision between turbine blades and marine organisms because, depending on the design, blades are spinning in the same direction to the flow of water. Concerns about noise, electromagnetic fields, changes in flow, and impacts on water quality are similar to that of axial flow turbines. 

Photo Credit: Ocean Renewable Power Company (ORPC)

Reciprocating Device

 

  • Reciprocating devices do not have rotating components and instead have a hydrofoil that is pushed back and forth transverse to the flow direction by lift or drag. Oscillating devices are the most common form of reciprocating devices. Oscillating hydrofoils operate via passive or active manipulation of one or more foils to induce hydrodynamic lift and drag forces due to pressure differences on the foils. They may be oriented horizontally or vertically, though like axial-flow turbines, they must face the direction of flow for maximum energy extraction. Linear motion of the foils may be converted to rotary motion for electricity generation, or linear generators may be used.
  • Reciprocating devices often move slower than turbines, but move more freely in the water, resulting in some concern for collision. Depending on the design and generator, reciprocating devices often produce little noise. Concerns about electromagnetic fields, impacts on water quality, and changes in flow are similar to that of other tidal devices.

Tidal Kite

 

  • A tidal kite is comprised of a hydrodynamic wing, with a turbine attached, tethered by a cable to a fixed point that leverages flow to lift the wing. As the kite 'flies' loops through the water, the speed increases around the turbine, allowing more energy extraction for slower currents. The kite is neutrally buoyant so as not to fall as the tide changes direction. Electricity production is by means of a generator coupled to the turbine. Power is transferred through a cable coupled to or as part of the tether.
  • Collision risk may be of some concern with tidal kites. Although animals are more likely to collide with the tether than the kite itself, little is known about the ability of animals to detect the free movement of some tidal kites. Tidal kites can emit noise over a larger frequency than horizontal axis turbines depending on the design and generator. Concerns about electromagnetic fields, impacts on water quality, and changes in flow are similar to that of other tidal devices.

Archimedes Screw

 

  • Historically designed to efficiently transfer water up a tube, an Archimedes screw is a helical surface surrounding a ventral cylindrical shaft. Energy is generated as water flow moves up the spiral and rotates the device. The slow rotation implies coupling to a generator through a gearbox.
  • The helical turbine moves very slowly relative to other tidal technologies and is likely to have little collision risk. Archimedes screws often produce little noise, though this depends on the design and generator. Concerns about electromagnetic fields, impacts on water quality, and changes in flow are similar to that of other tidal devices.

Tidal Lagoon

 

  • Tidal lagoons are comprised of retaining walls embedded with low-head turbines that surround a large reservoir of water. Functioning similar to a hydroelectric dam, tides cause a difference in the water height inside and outside the walls of tidal lagoons. The ecosystem within the reservoir undergoes significant transformation, potentially yielding positive impacts with a more diverse seabed, depending on site selection.
  • Changes to the physical environment are expected to be similar to conventional marine engineering projects and can include changes in flow and ecosystem processes. Decreased flushing of the reservoir may cause some problems for water quality. There are some collision concerns that arise if fish and invertebrates try to traverse the retaining wall through the turbines. Impacts from noise depend on turbine selection. There is little concern for electromagnetic fields because cables are embedded in the retaining wall and are not openly exposed to water. The new reservoir may also create calmer waters that allow for new recreation and tourism opportunities.

Tidal Barrage

 

  • Tidal barrages capture water in a holding area, making use of the difference in water height from one side of the barrage to the other. Water is then released through a large turbine or turbines as it flows out with the ebb of the tide. They are typically built across the entrance to a bay or estuary and generate electricity using the difference in water height inside and outside of the structure. A minimum height fluctuation of 5 meters (16.4 feet) is typically required to justify the construction of tidal barrages, so only 40 locations worldwide have been identified as feasible.
  • Installing a tidal barrage impacts bay or estuary ecosystems due to changes in flow and can have negative effects such as changing the shoreline and important tidal flats. Inhibiting the flow of water in and out of the bay, may also lead to less flushing of the bay or estuary, altering the water quality, and potentially causing additional turbidity (suspended solids) and less saltwater, which may result in the death of fish that act as a vital food source to birds and marine mammals. Migrating fish may also be unable to access breeding streams, and may attempt to pass through the turbines and risk collision. Impacts from noise depend on turbine selection, similar to tidal lagoons. Decreasing shipping accessibility can become a major socio-economic issue, though locks can be added to allow slow passage. However, the barrage may improve the local economy by increasing land access when used as a bridge and allowing for more recreation and tourism opportunities due to calmer waters.
Total Results: 686
Title Author Datesort ascending Type of Content Technology Type Stressor Receptor
The Reality of Environmental Compliance: A Tidal Perspective Barr, S. April 2009 Presentation Marine Energy (General), Tidal Human Dimensions
Comparing environmental effects of Rance and Severn barrages Kirby, R., Retière. C. March 2009 Conference Paper Marine Energy (General), Tidal Nearfield Habitat
In-Stream Tidal Energy Potential of Puget Sound, Washington Polagye, B., Kawase, M., Malte, P. January 2009 Journal Article Marine Energy (General), Riverine, Tidal Physical Environment
Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Polagye, B. January 2009 Thesis Marine Energy (General), Riverine, Tidal Changes in Flow Physical Environment
Environmental impacts of tidal power schemes Wolf, J., et al. January 2009 Journal Article Tidal Habitat Change Physical Environment, Nearfield Habitat
Modeling Tidal Circulation and Stratification in Skagit River Estuary Using an Unstructured Grid Ocean Model Yang, Z., Khangaonkar, T. January 2009 Journal Article Marine Energy (General), Tidal Changes in Flow Physical Environment
Potential Impacts of, and Mitigation Strategies for, Small-Scale Tidal Generation Projects on Coastal Marine Ecosystems in the Bay of Fundy Fisheries and Oceans Canada December 2008 Report Marine Energy (General), Tidal
Marine Renewable Energy Strategic Framework for Wales: Stage 1 Report Final Kazer, S., Golding, T. November 2008 Report Marine Energy (General), Tidal, Wave
Tidal Flows in Te Aumiti (French Pass), South Island, New Zealand Stevens, C., et al. November 2008 Journal Article Marine Energy (General), Tidal
Limits To Tidal Current Power Garrett, C., Cummins, P. November 2008 Journal Article Marine Energy (General), Tidal
Ramsey Sound Tidal Energy Limited Scoping Report Tidal Energy November 2008 Report Marine Energy (General), Tidal Invertebrates, Birds, Fish, Marine Mammals, Human Dimensions
Measurement and Assessment of Background Underwater Noise and its Comparison with Noise from Pin Pile Drilling Operations During Installation of the SeaGen Tidal Turbine Device, Strangford Lough Nedwell, J., Brooker, A. September 2008 Report Marine Energy (General), Tidal Noise Fish, Marine Mammals
Strangford Lough - MCT (SeaGen) July 2008 Project Site OES-Environmental Marine Energy (General), Tidal
OpenHydro at EMEC May 2008 Project Site OES-Environmental Marine Energy (General), Tidal
The Extractable Power From A Channel Linking A Bay To The Open Ocean Blanchfield, J., et al. May 2008 Journal Article Marine Energy (General), Tidal
Atlas of UK Marine Renewable Energy Resources ABP Marine Environmental Research May 2008 Website Marine Energy (General), Tidal, Wave, Wind Energy (General), Offshore Wind
A Review of the Application of Lifecycle Analysis to Renewable Energy Systems Lund, C., Biswas, W. April 2008 Journal Article Marine Energy (General), Riverine, Tidal, Wave, Wind Energy (General) Human Dimensions, Life Cycle Assessment
Life cycle assessment of the Seagen marine current turbine Douglas, C., Harrison, G., Chick, J. February 2008 Journal Article Marine Energy (General), Tidal Human Dimensions, Life Cycle Assessment
Strategic Tidal Stream Assessment for Alderney Craig, J. January 2008 Report Marine Energy (General), Tidal, Wave
Marine Energy: More than Just a Drop in the Ocean? Armstrong, J., Consultancy, F. January 2008 Report Marine Energy (General), Tidal, Wave Physical Environment, Human Dimensions
The Efficiency Of A Turbine In A Tidal Channel Garrett, C., Cummins, P. September 2007 Journal Article Marine Energy (General), Tidal
Scottish Marine Renewables Strategic Environmental Assessment Environmental Report Faber Maunsell, Metoc PLC March 2007 Report Marine Energy (General), Tidal, Wave
Fri-El Seapower - Messina Project January 2007 Project Site OES-Environmental Marine Energy (General), Tidal
Environment Description for the EMEC Tidal Test Site Fall of Warness, Orkney Finn, M. December 2006 Report Marine Energy (General), Tidal Nearfield Habitat
Summary Report on Environmental Monitoring Related to the Pearson College - ENCANA - Clean Current Tidal Power Demonstration Project at Race Rocks Ecological Reserve Thuringer, P., Reidy, R. December 2006 Report Marine Energy (General), Tidal EMF, Noise Invertebrates, Birds, Seabirds, Fish, Marine Mammals, Nearfield Habitat
Roosevelt Island Tidal Energy (RITE) Project Demonstration December 2006 Project Site OES-Environmental Marine Energy (General), Tidal
The Tidal-Stream Energy Resource in Passamaquoddy-Cobscook Bays: A Fresh Look at an Old Story Brooks, D. November 2006 Journal Article Marine Energy (General), Tidal
Race Rocks Tidal Energy Project September 2006 Project Site OES-Environmental Marine Energy (General), Tidal
The Regulation of Tidal Energy Development Off Nova Scotia: Navigating Foggy Waters Doelle, M., et al. September 2006 Journal Article Marine Energy (General), Tidal Human Dimensions
Skerries Tidal Stream Array: Environmental Impact Assessment Scoping Report Project Management Support Services July 2006 Report Marine Energy (General), Tidal Human Dimensions, Environmental Impact Assessment
Review and Analysis of Ocean Energy Systems Development and Supporting Policies AEA Energy & Environment June 2006 Report Marine Energy (General), OTEC, Tidal, Wave Human Dimensions
Methodology for Estimating Tidal Current Energy Resources and Power Production by Tidal In-Stream Energy Conversion (TISEC) Devices Hagerman, G., Polagye, B. June 2006 Report Marine Energy (General), Tidal
Instream Tidal Power in North America: Environmental and Permitting Issues Devine Tarbell & Associates June 2006 Report Marine Energy (General), Tidal Ecosystem Processes, Human Dimensions
Wave and Tidal Energy Its Emergence and the Challenges it Faces Ferro, B. May 2006 Journal Article Marine Energy (General), Tidal, Wave Human Dimensions
Tidal Current Energy Technologies Fraenkel, P. March 2006 Journal Article Marine Energy (General), Tidal
Tidal Barrages and Birds Clark, N. March 2006 Journal Article Marine Energy (General), Tidal Habitat Change Birds
An Overview of the Environmental Impact of Non-Wind Renewable Energy Systems in the Marine Environment OSPAR Commission January 2006 Conference Paper Marine Energy (General), Tidal, Wave
San Remo January 2006 Project Site OES-Environmental Marine Energy (General), Tidal
Galway Bay Test Site January 2006 Project Site OES-Environmental Marine Energy (General), Tidal, Wave, Wind Energy (General), Offshore Wind
Pilot Installation of Tidal Current Turbine in Kvalsundet, Tromsø County, Norway - Status and Possible Consequences for the Environment Systad, G., et al. December 2005 Report Marine Energy (General), Tidal
The Benthic Environment of the North and West of Scotland and the Northern and Western Isles: Sources of Information and Overview Wilding, T., Hughes, D., Black, K. October 2005 Report Marine Energy (General), Tidal, Wave Changes in Flow Invertebrates, Physical Environment
EMEC Fall of Warness Wildlife Observation Data July 2005 Dataset Marine Energy (General), Tidal Birds, Marine Mammals
EMEC Fall of Warness Grid-Connected Tidal Test Site July 2005 Project Site OES-Environmental Marine Energy (General), Tidal
Strangford Lough Marine Current Turbine: Environmental Statement Davison, A., Mallows, T. June 2005 Report Marine Energy (General), Tidal Human Dimensions, Environmental Impact Assessment
EMEC Tidal Test Facility Fall of Warness Eday, Orkney: Environmental Statement Foubister, L. June 2005 Report Marine Energy (General), Tidal Invertebrates, Marine Mammals, Human Dimensions, Environmental Impact Assessment
The Power Potential Of Tidal Currents In Channels Garrett, C., Cummins, P. April 2005 Journal Article Marine Energy (General), Tidal
Stingray Tidal Steam Energy Device - Phase 3 The Engineering Business January 2005 Report Marine Energy (General), Tidal
Wanxiang-II Project January 2005 Project Site OES-Environmental Marine Energy (General), Tidal
Renewable Energy Resources: Environmental Impact Chapter Tiwari, G., Ghosal, M. January 2005 Book Chapter Marine Energy (General), OTEC, Tidal, Wave
A Finite Element Circulation Model for Embayments with Drying Intertidal Areas and its Application to the Quoddy Region of the Bay of Fundy Greenberg, D., et al. January 2005 Journal Article Marine Energy (General), Tidal
The Impact of Energy Extraction on Tidal Flow Development Couch, S., Bryden, I. July 2004 Conference Paper Marine Energy (General), Tidal Changes in Flow
Silt-Proof Measures: Following Analysis of Data Measured out of Baishakou Tidal Power Station, Measures were Proposed to Control Sediment in the Reservoir Yunchen, L. February 2004 Magazine Article Marine Energy (General), Tidal Changes in Flow Physical Environment
Initial Consultation Document for the Roosevelt Island Tidal Energy Project Verdant Power October 2003 Report Marine Energy (General), Tidal
Kvalsund Tidal Turbine Prototype August 2003 Project Site OES-Environmental Marine Energy (General), Tidal
European Marine Energy Centre European Marine Energy Centre January 2003 Website Marine Energy (General), Tidal, Wave
Yell Sound September 2002 Project Site OES-Environmental Marine Energy (General), Tidal
Wake Effects in Tidal Current Turbine Farms Macleod, A., et al. January 2002 Conference Paper Marine Energy (General), Tidal Changes in Flow Physical Environment
Wanxiang-I Project January 2002 Project Site OES-Environmental Marine Energy (General), Tidal
The Practice of Comprehensive Silt Proof Measures in Tide Power Stations Liu, X., Fagong, L. September 2001 Report Marine Energy (General), Tidal Changes in Flow Physical Environment, Sediment Transport
Enermar Project January 2001 Project Site OES-Environmental Marine Energy (General), Tidal
Changes in Area, Geomorphology and Sediment Nature of Salt Marshes in the Oosterschelde Estuary (SW Netherlands) Due to Tidal Changes de Jong, D., de Jong, Z., Mulder, J. May 1994 Journal Article Marine Energy (General), Tidal Changes in Flow Physical Environment
Tidal Power and the Aquatic Environment of La Rance Retiere, C. January 1994 Journal Article Marine Energy (General), Tidal Changes in Flow Ecosystem Processes
Intertidal Ecology and Potential Power Impacts, Bay of Fundy, Canada Gordon, D. Jr. January 1994 Journal Article Marine Energy (General), Tidal Changes in Flow Ecosystem Processes, Physical Environment
Macrotidal Estuaries: A Region of Collision Between Migratory Marine Animals and Tidal Power Development Dadswell, M., Rulifson, R. January 1994 Journal Article Marine Energy (General), Tidal Collision Fish, Marine Mammals
Potential Impact of Large-Scale Tidal Power Developments in the Upper Bay of Fundy on Fisheries Resources of the Northwest Atlantic Dadswell, M., Rulifson, R., Daborn, G. July 1986 Journal Article Marine Energy (General), Tidal Fish
The Annapolis Tidal Power Project Head Pond Water Levels - Impacts and Mitigations Rice, R. September 1984 Report Marine Energy (General), Tidal Changes in Flow Physical Environment
Update on the Marine Environmental Consequences of Tidal Power Development in the Upper Reaches of the Bay of Fundy Gordon, D., Dadswell, M. June 1984 Report Marine Energy (General), Tidal Physical Environment, Nearfield Habitat
Assessing the Environmental Impact of the Annapolis Tidal Power Project Tidmarsh, W. January 1984 Journal Article Marine Energy (General), Tidal Fish, Nearfield Habitat, Human Dimensions, Environmental Impact Assessment
Annapolis Tidal Station January 1984 Project Site OES-Environmental Marine Energy (General), Riverine, Tidal
Jiangxia Pilot Tidal Power Plant January 1980 Project Site OES-Environmental Marine Energy (General), Tidal
Ten Years of Experience at the La Rance Tidal Power Plant Andre, H. December 1978 Journal Article Marine Energy (General), Tidal
BaiShakou Tidal Power Station August 1978 Project Site OES-Environmental Marine Energy (General), Tidal
Haishan Tidal Power Plant December 1975 Project Site OES-Environmental Marine Energy (General), Tidal
Argyll Tidal Demonstrator Project Planned Project Site OES-Environmental Marine Energy (General), Tidal
Sound of Islay Demonstration Tidal Array Planned Project Site OES-Environmental Marine Energy (General), Tidal
Westray South Tidal Project Planned Project Site OES-Environmental Marine Energy (General), Tidal
Perpetuus Tidal Energy Centre (PTEC) Planned Project Site OES-Environmental Marine Energy (General), Tidal
OpenHydro Alderney Planned Project Site OES-Environmental Marine Energy (General), Tidal
Torr Head Project Planned Project Site OES-Environmental Marine Energy (General), Tidal
Clarence Strait Tidal Energy Project Planned Project Site OES-Environmental Marine Energy (General), Tidal
Swansea Tidal Lagoon Planned Project Site OES-Environmental Marine Energy (General), Tidal
Western Passage Tidal Energy Project Planned Project Site OES-Environmental Marine Energy (General), Tidal
Brims Tidal Array Planned Project Site OES-Environmental Marine Energy (General), Tidal
Fair Head Tidal Array Planned Project Site OES-Environmental Marine Energy (General), Tidal
Admiralty Inlet Pilot Tidal Project Planned Project Site OES-Environmental Marine Energy (General), Tidal
West Islay Tidal Project Planned Project Site OES-Environmental Marine Energy (General), Tidal

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