The primary advantages of tidal power plants are the following: 

• regularity of power production from year to year with less than 5% annual variation [2];

• permits the simultaneous use of the dam for a road or rail road;

• long-term operational lifetime of plant; 

• protects vulnerable coastlines from storm waves and flooding [6];

• provides a non-polluting and inexhaustible supply of energy.

The primary drawbacks of tidal power plants are the following:

• high capital costs for initial construction [7];

• limited number of potential sites.  A minimum tidal range (the difference between high and low tide levels) is needed if tidal power is to be practical.  A range of 5 m is often cited as the minimum [8].  Over the past three decades, the feasibility of using ocean tides to generate electric power has been investigated at many sites throughout the world.  Results suggest that the potential for economic development is small with only six suitable areas representing well over half of the potential for development of tidal energy [9] .  They are as follows:

 1. The headwaters fo the Bay of Fundy (Canada)
 2. The Severn estuary (United Kingdom)
 3.  The Gulf of St. Malo (France)
 4.  The south-east coast of China 
 5. The Russian coast bordering the White Sea 
 6. The Russian coast bordering the Sea of Okhotsk

Other potentially feasible sites include: the Mersey estuary and smaller sites bordering the Irish Sea and the Bristol Channel (United Kingdom), the Gulf of Kachch (India), the west coast of Korea, the north-west coast of Australia, Cook Inlet (Alaska), and the Gulf of San Jose (Argentina) [9];

• potential for negative environmental impacts such as water quality, estuarine feeding areas for birds and other animals, and the passage of migratory fish [2].  It is important to note that few studies have been conducted to assess the environmental impacts of constructing a tidal power plant and it has been generally determined that each specific site is different and the impacts depend greatly upon local geography.  Local tides changed only slightly due to the La Rance barrage, and the environmental impact has been negligible. This may not be the case for all other sites.  Very little is understood about how altering the tides can affect incredibly complex aquatic and shoreline ecosystems [7];

Tidal power is a proven technology and has the potential to generate significant amounts of electricity at certain sites around the world.  Although, our entire electricity needs could never be met by tidal power alone, it can be invaluable source of renewable energy.  The negative environmental impacts of tidal barrages are probably smaller than those of other sources of electricity, but are not well understood at this time.  The technological feasibility of both major and minor tidal power designs has been established and the main barrier to increased use of the tides is that of construction costs.  The future costs of other sources of electricity, and concern over environmental impacts, will ultimately determine the exploitation of tidal power [7].

1. Bernshtein, L.B., Wilson, E.M. and Song, W.O. (Eds.) 1996.  Tidal Power Plants, Korea Ocean Research and 
    Development Institute.

2. Charlier, R.H. and Justus, J.R.  1993. Ocean Energies: Environmental, economic, and technological aspects of 
    alternative power sources, Elsevier Oceanographic Series.  pp. 534.

3. Burnham, L., Johansson, T.B., Kelly, H., Reddy, A.K.N. and Williams, R.H.  (Eds.) 1993.  Renewable Energy: 
    Sources for fuels and electricity, Island Press.

4. DOE/CE-0258.  1989. U.S. Department of Energy Information.

5. Electricitie de France website: http://www.edf.fr/html/en/decouvertes/voyage/usine/retour-usine.html

6. Bernshtein, L.B. 1993.  Strategy of Tidal Power Stations Utilization to Provide a Number of Planet Regions with 
    Ecologically Pure Energy, In: Proceedings of International Symposium on Ocean Energy Development, Muroran, 
    Hokkaido, Japan, pp. 65-77.

7. Baird, M. and Hayhoe, D. 1993.  website: http://www.iclei.org/efacts/tidal.htm

8. SERI/TP-260-3674.  1990. The Potential of Renewable Energy: An interlaboratory white paper.

9. Baker, G.C.  1998. Chapter 14: Tidal energy, In: Survey of Energy Resources 18th Edition, World Energy 
    Council