L'énergie marémotrice en 1982

Abstract

Apart from two very low power plants, the Rance tidal plant is still, fifteen years after its commissioning, the only operational tidal power station in the World. Despite certain teething problems - easily explained in the case of such an original development which necessitated the successive shutdown of all the sets to overhaul the generators the concrete and steel structures have proven fully able to resist the onslaught of the marine environment and output is at the level originally envisaged, making due allowance for actual operating conditions. The year 1981 proves this in particular : the net effective output of 500 GWh (deducting the consumption of pumping and auxiliaries) should be increased by approximately 40 GWh to be compared with the scheduled level of output (exceptional outage of sets to overhaul generators, operating conditions making output advantageous at certain hours of the day, etc.). From a more general point of view, it is recalled that although the energy dispersed naturally by tide currents in the oceans is of the same order of magnitude as the energy dispersed by rivers (approximately one-third), it is impossible from this comparison to make an estimate of the share of this energy which could be harnessed. The main tidal sites known are listed in Table I, those which have been recently under study are in Table II, and those in operation or under construction in Table III. The descriptive parameters used are in particular : - the average inter-annual tide range A ; - the area of basin S (in km2) at a level exceeding the average sea level by one-fourth of the average tidal range ; - the quantity 1/2 SA 2 then gives the order of magnitude of the annual production potential of the site. Although none of the large tidal plants listed are presently under construction, five recent events of significance for tidal energy must be mentioned : 1) The completion in 1981 of the report on the Severn development by the Committee created for this purpose by the British Government. 2) The order placed for an experimental set with a rim generator to be installed in an existing dyke on the Annapolis site in Fundy Bay (Canada). 3) The completion at end 1981 of the Garolim development project in Korea by the SOGREAH-LCHF group with EDF support. 4) The initiation of feasibility studies lor the Kutch project in India. 5) Resumption of the study on the possibility of harnessing tidal energy on the Channel coast by EDF in 1980. The main characteristics of these developments are given in Tables II and III.