In-stream tidal power generation

Article By:

Garrett, Chris Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia, Canada.

Last reviewed:2009

DOI:https://doi.org/10.1036/1097-8542.YB090132

The prospects of climate change and declining supplies of cheap fossil fuels have led to increasing interest in supplying at least part of humanity's energy needs from renewable sources. Insolation is the largest of these, with a global value of nearly 10⁵ terawatts (TW, with 1 TW = 10¹² W), so that a tiny fraction would provide all of humanity's current usage of approximately 15 TW. The global rate of dissipation of wind energy is close to 1000 TW, suggesting that useful amounts of power could be extracted without major environmental changes. The dissipation rate of ocean tides is only 3.5 TW, and simple arguments show that extracting more than a fraction of this would be impossible and lead to significant tidal changes. Tidal power is not “boundless.” It could, nonetheless, provide a significant and economically valuable contribution, possibly of the order of hundreds of megawatts (MW, with 1 MW = 10⁶ W) in some locations and perhaps tens of gigawatts (GW, 1 GW = 10⁹ W) worldwide, though associated environmental changes are a concern.

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