Tidal

Capturing tidal fluctuations with turbines, reciprocating devices, kites, screws, barrages, or lagoons.

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. Since seawater is about 800 times denser than air, tidal turbines can collect energy with slower water currents and smaller turbines than wind energy. While tidal currents are very predictable, challenges arise due to the need for devices to collect flow from opposite directions and survive the harsh corrosive marine environment.

 

Environmental effects will vary between the seven most common approaches: axial flow turbine, cross flow turbine, reciprocating device, tidal kite, Archimedes screw, tidal lagoon, and tidal barrage.

 

Axial Flow Turbine

 

These turbines are the most similar to traditional windmills, 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.

 

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. It should be noted that these turbines spin much slower than propellers on ships. 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 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. Large-scale tidal energy removal (from arrays) may disrupt natural physical systems to cause degradation in water quality or changes in sediment transport, potentially affecting the ecosystem.

Cross Flow Turbine

 

These turbines are generally cylindrical on a horizontal axis, where kinetic energy of moving water is captured by spinning blades oriented transversely to 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.

 

There is typically less environmental concern for collision between turbine blades and marine organisms because blades are spinning in the same direction to the flow of water, depending on the design. Concerns about noise, electromagnetic fields, chemicals, and energy removal are similar to that of axial flow turbines.

Reciprocating Device

 

Reciprocating devices do not have rotating components, but 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.

 

Reciprocating devices often move slower than turbines, but move more freely in the water, resulting in some concern for collision. Reciprocating devices often produce little noise, though this depends on the design and generator. Concerns about electromagnetic fields, chemicals, and energy removal 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 water 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.

 

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 emit noise over a larger frequency than horizontal axis turbines, though this depends on the design and generator. Concerns about electromagnetic fields, chemicals, and energy removal 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 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, chemicals, and energy removal are similar to that of other tidal devices.

Tidal Lagoon

 

Tidal lagoons are comprised of retaining walls embedded with reversible low-head turbines that surround a large reservoir. Tides cause a difference in the water height inside and outside of the walls, functioning very similar to a low-head conventional hydrokinetic dam that works in both direction.

 

The ecosystem within the reservoir undergoes significant transformation, potentially yielding positive impacts with a more diverse seabed, depending on site selection. The changes to the physical system are similar to conventional marine engineering projects and can include altering water flow and shoreline processes partially due to energy removal. Decreased flushing of the reservoir may cause some problems for water quality. There are some collision concerns that arise if fish and benthic invertebrates try to traverse the retaining wall through 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 better recreation.

Tidal Barrage

 

Tidal barrages are dams built across the entrance to a bay or estuary that captures potential tidal energy, similar to tidal lagoons. Energy is collected when the height difference on either side of the dam is greatest, at low or high tide. A minimum height fluctuation of 5 meters (16.4 feet) is required to justify the construction, so only 40 locations worldwide have been identified as feasible.

 

Installing a tidal barrage impacts bay or estuary ecosystems due to the alteration of tidal flows 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 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 opportunities due to calmer waters.

Total Results: 669
Title Author Date Type of Contentsort descending Technology Type Stressor Receptor
Fundy Ocean Research Center for Energy (FORCE) Test Site September 2009 Project Site OES-Environmental Marine Energy general, Tidal
EMEC Fall of Warness Grid-Connected Tidal Test Site July 2005 Project Site OES-Environmental Marine Energy general, Tidal
Clarence Strait Tidal Energy Project Planned 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
Fri-El Seapower - Messina Project January 2007 Project Site OES-Environmental Marine Energy general, Tidal
Söderfors Project March 2013 Project Site OES-Environmental Marine Energy general, Riverine, Tidal
Cobscook Bay Tidal Energy Project September 2012 Project Site OES-Environmental Marine Energy general, Tidal
Enermar Project January 2001 Project Site OES-Environmental Marine Energy general, Tidal
EMEC Shapinsay Sound Non Grid-Connected Nursery Tidal Test Site September 2011 Project Site OES-Environmental Marine Energy general, Tidal
Torr Head Project Planned Project Site OES-Environmental Marine Energy general, Tidal
Jiangxia Pilot Tidal Power Plant January 1980 Project Site OES-Environmental Marine Energy general, Tidal
Tocardo InToTidal - EMEC May 2017 Project Site OES-Environmental Marine Energy general, Tidal
La Rance Tidal Barrage November 1966 Project Site OES-Environmental Marine Energy general, Tidal
Roosevelt Island Tidal Energy (RITE) Project Pilot January 2012 Project Site OES-Environmental Marine Energy general, Tidal
Uldolmok Tidal Power Station May 2009 Project Site OES-Environmental Marine Energy general, Tidal
Western Passage Tidal Energy Project Planned Project Site OES-Environmental Marine Energy general, Tidal
Wanxiang-I Project January 2002 Project Site OES-Environmental Marine Energy general, Tidal
Wanxiang-II Project January 2005 Project Site OES-Environmental Marine Energy general, Tidal
Race Rocks Tidal Energy Project September 2006 Project Site OES-Environmental Marine Energy general, Tidal
Westray South Tidal Project Planned Project Site OES-Environmental Marine Energy general, Tidal
Yell Sound September 2002 Project Site OES-Environmental Marine Energy general, Tidal
Roosevelt Island Tidal Energy (RITE) Project Demonstration December 2006 Project Site OES-Environmental Marine Energy general, Tidal
Strangford Lough - MCT (SeaGen) July 2008 Project Site OES-Environmental Marine Energy general, Tidal
MORILD II Tidal Power Plant November 2010 Project Site OES-Environmental Marine Energy general, Tidal
Ocean Flow Energy - Sanda Sound August 2014 Project Site OES-Environmental Marine Energy general, Tidal
Seapower GEMSTAR System March 2012 Project Site OES-Environmental Marine Energy general, Tidal
OpenHydro Alderney Planned Project Site OES-Environmental Marine Energy general, Tidal
OpenHydro at EMEC May 2008 Project Site OES-Environmental Marine Energy general, Tidal
Ramsey Sound December 2015 Project Site OES-Environmental Marine Energy general, Tidal
San Remo January 2006 Project Site OES-Environmental Marine Energy general, Tidal
Sihwa Tidal Power Plant August 2011 Project Site OES-Environmental Marine Energy general, Tidal
Annapolis Tidal Station January 1984 Project Site OES-Environmental Marine Energy general, Riverine, Tidal
Admiralty Inlet Pilot Tidal Project Planned Project Site OES-Environmental Marine Energy general, Tidal
PLAT-O at EMEC September 2019 Project Site OES-Environmental Marine Energy general, Tidal
Kyle Rhea Tidal Stream Array Project Planned Project Site OES-Environmental Marine Energy general, Tidal
Voith HyTide at EMEC September 2013 Project Site OES-Environmental Marine Energy general, Tidal
Anglesey Skerries Tidal Stream Array Planned Project Site OES-Environmental Marine Energy general, Tidal
Fair Head Tidal Array Planned Project Site OES-Environmental Marine Energy general, Tidal
West Islay Tidal Project Planned Project Site OES-Environmental Marine Energy general, Tidal
Argyll Tidal Demonstrator Project Planned Project Site OES-Environmental Marine Energy general, Tidal
Perpetuus Tidal Energy Centre (PTEC) Planned Project Site OES-Environmental Marine Energy general, Tidal
Nova Innovation - Shetland Tiday Array (Bluemull Sound) March 2016 Project Site OES-Environmental Marine Energy general, Tidal
Paimpol-Brehat Tidal Demonstration Project August 2011 Project Site OES-Environmental Marine Energy general, Tidal
Brims Tidal Array Planned Project Site OES-Environmental Marine Energy general, Tidal
HS1000 at EMEC December 2011 Project Site OES-Environmental Marine Energy general, Tidal
Marine Energy Research and Innovation Centre (MERIC) October 2015 Project Site OES-Environmental Marine Energy general, Ocean Current, Tidal, Wave
Nautricity at EMEC April 2017 Project Site OES-Environmental Tidal
ScotRenewables SR2000 at EMEC October 2016 Project Site OES-Environmental Marine Energy general, Tidal
Swansea Tidal Lagoon Planned Project Site OES-Environmental Marine Energy general, Tidal
MeyGen Tidal Energy Project - Phase I November 2016 Project Site OES-Environmental Marine Energy general, Tidal
Minesto Holyhead Deep - Non-grid connected DG500 June 2018 Project Site OES-Environmental Marine Energy general, Tidal
Attitudes towards Marine Energy: Understanding the Values de Groot, J. March 2015 Thesis Marine Energy general, Tidal, Wave, Wind Energy general, Offshore Wind Socio-economics, Stakeholder Engagement
Alteration to the shallow-water tides and tidal asymmetry by tidal-stream turbines Potter, D January 2019 Thesis Marine Energy general, Tidal Dynamic Device, Energy Removal
The Ecology of Marine Tidal Race Environments and the Impact of Tidal Energy Development Broadhurst, M. January 2013 Thesis Marine Energy general, Tidal Static Device Benthic Invertebrates, Fish
Land-Based Infrared Imagery for Marine Mammal Detection Graber, J. April 2011 Thesis Marine Energy general, Tidal Marine Mammals, Cetaceans
Hydroacoustic Analysis of the Effects of a Tidal Power Turbine on Fishes Viehman, H. December 2016 Thesis Marine Energy general, Tidal Static Device Fish
Hydrodynamic Effects of Kinetic Power Extraction by In-Stream Tidal Turbines Polagye, B. January 2009 Thesis Marine Energy general, Riverine, Tidal Energy Removal Farfield Environment
Fish in a Tidally Dynamic Region in Maine: Hydroacoustic Assessments in Relation to Tidal Power Development Viehman, H. May 2012 Thesis Marine Energy general, Tidal Noise Fish
Marine Spatial Planning from an Irish perspective: Towards Best Practice in Integrated Maritime Governance Flannery, W. July 2011 Thesis Marine Energy general, Tidal, Wave Socio-economics, Marine Spatial Planning
Tidal Energy Scenario Analysis: Holistic Stakeholder Considerations for Sustainable Development McTiernan, K. January 2017 Thesis Marine Energy general, Tidal Socio-economics, Stakeholder Engagement
Learning from Early Commercial Tidal Energy Projects in the Puget Sound, Washington and the Pentland Firth, Scotland McMillin, N. January 2016 Thesis Marine Energy general, Tidal Socio-economics, Legal and Policy
Evaluating biological characteristics of marine renewable energy sites for environmental monitoring Wiesebron, L. January 2015 Thesis Marine Energy general, Tidal
Underwater Ambient Noise at a Proposed Tidal Energy Site in Puget Sound Bassett, C. January 2010 Thesis Marine Energy general, Tidal Noise Nearfield Habitat
Testing of a Ducted Axial Flow Tidal Turbine Lokocz, T. August 2010 Thesis Marine Energy general, Tidal
An Introduction to Marine Renewable Energy Sheilds, M. January 2014 Book Chapter Marine Energy general, Tidal, Wave, Wind Energy general, Offshore Wind
Strangford Lough and the SeaGen Tidal Turbine Savidge, G., et al. February 2014 Book Chapter Marine Energy general, Tidal
Tracking Technologies for Quantifying Marine Mammal Interactions with Tidal Turbines: Pitfalls and Possibilities Hastie, G., et al. February 2014 Book Chapter Marine Energy general, Tidal Marine Mammals
Wave and Tidal Energy: Environmental Effects Iglesias, G., et al. July 2018 Book Chapter Marine Energy general, Tidal, Wave Farfield Environment, Nearfield Habitat
Confusion Reigns? A Review of Marine Megafauna Interactions with Tidal-Stream Environments Benjamins, S., et al. August 2015 Book Chapter Marine Energy general, Tidal Birds, Marine Mammals
Strategic Sectoral Planning for Offshore Renewable Energy in Scotland Davies, I., Pratt, D. January 2014 Book Chapter Marine Energy general, Tidal, Wave, Wind Energy general, Offshore Wind
Rethinking Underwater Sound-Recording Methods to Work at Tidal-Stream and Wave-Energy Sites Wilson, B., et al. January 2014 Book Chapter Marine Energy general, Tidal, Wave Noise
Renewable Energy Resources: Environmental Impact Chapter Tiwari, G., Ghosal, M. January 2005 Book Chapter Marine Energy general, OTEC, Tidal, Wave Chemicals, Dynamic Device, EMF, Energy Removal, Noise, Static Device
Measurement of Underwater Operational Noise Emitted by Wave and Tidal Stream Energy Devices Lepper, P., Robinson, S. January 2016 Book Chapter Marine Energy general, Tidal, Wave Noise
Wave and Tidal Energy Johnson, K., Kerr, S. January 2018 Book Chapter Marine Energy general, Tidal, Wave
The Impact of Marine Renewable Energy Extraction on Sediment Dynamics Neill, S., Robins, P., Fairley, I. April 2017 Book Chapter Marine Energy general, Tidal, Wave Energy Removal Farfield Environment, Nearfield Habitat
The Physics and Hydrodynamic Setting of Marine Renewable Energy Woolf, D., et al. January 2014 Book Chapter Marine Energy general, Tidal, Wave
Effects of Underwater Turbine Noise on Crab Larval Metamorphosis Pine, M., Jeffs, A., Radford, C. January 2016 Book Chapter Marine Energy general, Tidal Noise Benthic Invertebrates
Challenges and Opportunities in Tidal and Wave Power Jacobson, P., Rao, K. December 2011 Book Chapter Marine Energy general, Tidal, Wave Socio-economics
European Marine Energy Centre European Marine Energy Centre January 2003 Website Marine Energy general, Tidal, Wave
Atlas of UK Marine Renewable Energy Resources ABP Marine Environmental Research May 2008 Website Marine Energy general, Tidal, Wave, Wind Energy general, Offshore Wind
Nova Scotia Tidal Energy Atlas Acadia Tidal Energy Institute, TEKMap Consulting, FORCE January 2017 Website Marine Energy general, Tidal
Environmental Effects of Tidal Energy Development: Proceedings of a Scientific Workshop Polagye, B., et al. April 2011 Workshop Article Marine Energy general, Tidal Socio-economics
Proceedings of the 4th Oxford Tidal Energy Workshop University of Oxford March 2015 Workshop Article Marine Energy general, Tidal
Impact of Tidal Energy Arrays Located in Regions of Tidal Asymmetry Neill, S. March 2013 Workshop Article Marine Energy general, Tidal Energy Removal
A Coordinated Action Plan for Addressing Collision Risk for Marine Mammals and Tidal Turbines Hutchison, I., Copping, A. August 2016 Workshop Article Marine Energy general, Tidal Dynamic Device Marine Mammals
Proceedings of the 2nd Oxford Tidal Energy Workshop University of Oxford March 2013 Workshop Article Marine Energy general, Tidal
Proceedings of the 3rd Oxford Tidal Energy Workshop University of Oxford April 2014 Workshop Article Marine Energy general, Tidal
ICES SGWTE Report 2011: Report of the Study Group on Environmental Impacts of Wave and Tidal Energy International Council for the Exploration of the Sea March 2011 Workshop Article Marine Energy general, Tidal, Wave Static Device Socio-economics
Proceedings of the Oxford Tidal Energy Workshop University of Oxford March 2012 Workshop Article Marine Energy general, Tidal
Depth Averaged Currents at Admiralty Inlet Pacific Northwest National Laboratory January 2012 Video Marine Energy general, Tidal
Depth Averaged Water Levels for Puget Sound Pacific Northwest National Laboratory March 2012 Video Marine Energy general, Tidal
San Juan Islands Tidal Currents Pacific Northwest National Laboratory August 2010 Video Marine Energy general, Tidal
Depth Averaged Currents for Puget Sound Pacific Northwest National Laboratory March 2012 Video Marine Energy general, Tidal
Depth Averaged Currents at Sequim Bay Pacific Northwest National Laboratory March 2012 Video Marine Energy general, Tidal
Depth Averaged Currents San Juan Islands Pacific Northwest National Laboratory March 2012 Video Marine Energy general, Tidal
South Puget Sound Tidal Currents Pacific Northwest National Laboratory September 2010 Video Marine Energy general, Tidal
Tacoma Narrows Tidal Currents Pacific Northwest National Laboratory August 2010 Video Marine Energy general, Tidal
Admiralty Inlet Basin Flow Model Pacific Northwest National Laboratory January 2012 Video Marine Energy general, Tidal Energy Removal
Depth Averaged Currents at Tacoma Narrows Pacific Northwest National Laboratory March 2012 Video Marine Energy general, Tidal
Fall of Warness HyTide 1000 Observational Data Informing Video Analysis June 2014 Dataset Marine Energy general, Tidal Dynamic Device Birds, Fish, Marine Mammals

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