TIDAL POWER

The paper reviews the physics of tidal power considering gravitational effects of moon and sun; semidiurnal, diurnal, and mixed tides; and m ajor periodic components that affect the tidal range. Shelving, funnel ling, reflection, and resonance phenomena that have a significant effe ct on tidal range are also discussed. The paper then examines tidal en ergy resource for principal developments estimated from parametric mod eling in Europe and worldwide. Basic parameters that govern the design of tidal power schemes in terms of mean tidal range and surface area of the enclosed basin are identified. While energy extracted is propor tional to the tidal amplitude squared, requisite sluicing area is prop ortional to the square root of the tidal amplitude. Sites with large t idal amplitudes are therefore best suited for tidal power developments , whereas sites with low tidal amplitudes have sluicing that may be pr ohibitive. It is shown that 48% of the European tidal resource is in t he United Kingdom, 42% in France, and 8% in Ireland, other countries h aving negligible potential. Worldwide, approximately 200, 50, 27, 20, 17, 17, 15, and 14 TWh of tidal resource annually are identified at Pe nzhinskaya Cauba (former USSR), Mezen (former USSR), Tugur (former USS R), San Jose (Argentina), The Severn (U.K.), Turnagain Arm (U.S.A.), G ulf of Cambay (India), and Cobequid (Canada), respectively. Smaller po tential tidal energy developments are mentioned. Existing tidal energy plants at La Rance (France-240 MW), Annapolis (Canada-17.8 MW), Jiang xia (People's Republic of China-3.2 MW), Kislaya Guba (former Soviet U nion-0.4 MW), and others are discussed. Tidal barrage design and const ruction using caissons is examined, as are alternative operating modes (single-action generation, outflow generation, flood generation, two- way generation, twin basin generation, pumping, etc), development tren ds and possibilities, generation cost at the barrage boundary, sensiti vity to discount rates, general economics, and markets. Environmental effects, and institutional constraints to the development of tidal bar rage schemes are also discussed.