7/31/2019 Wave Tidal FactSheet 07April4
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Wave and Tidal Energy page 2
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revised 4/07
as the water is released. The vast ma-jority of recently
proposed wave en-ergy projects would use offshorefloats, buoys or
pitching devices.
The worlds first commercial off-
shore wave energy facility will beginoperating by the end of
2007 off theAtlantic coast of Portugal. The firstphase of the
project, which Scottishcompany, Ocean Power Delivery(OPD)
developed, features threePelamis wave energy conversiondevices and
generates a combined2.25 MW of electricity. OPD plansto expand the
facility to produce 22.5MW in 2007.5
Until recently, the common model fortidal power facilities
involved erect-ing a tidal dam, or barrage, with asluice across a
narrow bay or estuary.As the tide flows in or out, creatinguneven
water levels on either side ofthe barrage, the sluice is opened
andwater flows through low-head hydroturbines to generate
electricity. For atidal barrage to be feasible, the differ-
ence between high and low tides mustbe at least 16 feet. La
Rance Stationin France, the worlds first and stilllargest tidal
barrage, has a rated ca-pacity of 260 MW and has operatedsince
1966. However, tidal barrages,have several environmental
draw-backs, including changes to marineand shoreline ecosystems,
most nota-bly fish populations.6
Several other models for tidalfacilities have emerged in
recentyears, including tidal lagoons, tidalfences, and underwater
tidal tur-
bines, but none are commerciallyoperating. Perhaps the most
promis-ing is the underwater tidal turbine.Several tidal power
companies havedeveloped tidal turbines, which aresimilar in many
ways to wind tur-bines. These turbines would beplaced offshore or
in estuaries instrong tidal currents where the tidal
flow spins the turbines, which thengenerate electricity. Tidal
turbineswould be deployed in underwaterfarms in waters 60-120 feet
deepwith currents exceeding 5-6 mph.
Because water is much denser thanair, tidal turbines are smaller
thanwind turbines and can produce moreelectricity in a given area.7
A pilot-scale tidal turbine facility the firstin North America was
installed inNew Yorks East River in December2006. The developer,
VerdantPower, hopes to eventually install a10 MW tidal farm at the
site.8
Unlike fossil-fueled power plants,wave and tidal energy
facilities gen-erate electricity without producingany pollutant
emissions or green-house gases. Since the first wave andtidal
energy facilities are currentlybeing deployed, the full
environ-mental impacts of wave and tidalpower remain uncertain but
are pro-jected to be small. Concerns includeimpacts on marine
ecosystems and
fisheries. Environmental impactstudies are currently underway
andseveral pilot and commercial projectsare undergoing
environmental moni-toring. The East River tidal turbinepilot
project includes a $1.5 millionsonar system to monitor impacts
onfish populations, for example.9 Care-ful siting should minimize
impacts onmarine ecosystems, fishing and othercoastal economic
activities. Waveand tidal facilities also have little orno visual
impact, as they are eithersubmerged or do not rise very farabove
the waterline.
1Wave energy resource figure andgraphic from: Project Definition
Study:
Offshore Wave Power Feasibility Dem-
onstration Project, Electric Power Re-search Institute (EPRI),
(Jan 2005), p 12.
-Wave energy levelized costs from corre-spondence with Des
McGinnes of Ocean
Power Delivery (Nov 2006).
-Tidal energy levelized costs fromNorthAmerican Tidal In-Stream
Energy Con-
version Technology Feasibility Study,
EPRI (June 2006), pgs 5-6.
2 EPRI op. cit. note 1, p 28.3 Tides hold promise of
electricity. TheDaily Herald(Everett, WA),
2/11/07.http://www.heraldnet.com/stories/07/02/1
1/100loc_a1sunpower001.cfm.4 Current Projects, AquaEnergy
Group,
Ltd. (2006), http://aquaenergygroup.com/projects/index.php,
accessed 10/18/06.
-Agreement to Develop Wave Park
inOregon,RenewableEnergyAccess.com,2/23/07,
http://www.renewableenergyac-cess.com/rea/news/story?id=47546&src=rss,
accessed 4/2/07.
- The Daily Herald, op. cite. note 3.5 Energy Portugal: Riding
the Wave ofthe Future,InterPress News Agency,9/27/06,
http://ipsnews.net/news.asp?idnews=34898, accessed 10/19/06.
6Renewable Energy Fact Sheet, Envi-ronmental and Energy Study
Institute,(May 2006).7 Depth and current speed requirementsfrom
Background, Marine CurrentTurbines (MCT),
(2002),http://www.marineturbines.com/background.htm, accessed
10/17/06.8The Daily Herald, op. cite. note 3.9 Energy From the
Restless Sea,NewYork Times, 7/3/06.
Graphic: Artists representation of an
underwater tidal turbine. (Source and
copyright: Marine Current Turbines, Ltd.)
