TIDAL POWER

Ashburton Guardian, Volume XLV, Issue 10350, 13 March 1925, Page 7

TIDAL POWER

A DIFFICULT PROBLEM.

SEVERN BARRAGE PROJECT.

In a lecture at Manchester University Professor A. H. Gibson explained some of the difficulties in the way ol developing “Tidal Power,” and suggested that it would probably not be long before some means had been found to make such a scheme as the Severn barrage an efficient instrument of power development. Professor Gibson pointed out that up to the present no single scheme of any size had been successfully applied, to the tides. A British Technical Commission was now considering the possibility of using the Severn, and its findings would bo very interesting. Ine trouble was usually that inventors had not fully realised that power derived from the tides must be produced at least as cheaply as from other forms or energy. The fault with schemes using wave pulsations on paddles and on floats was that they were all very costly, with one possible exception, in which the inflow of water down a vertical pipe drew in air through the pipehead and compressed it in a submarine chamber^t sC } iemt . s see med to be those which used the water in an estuary where tides were high, and ol such places the Bristol Channel was one of the first. If tidal power could not be efficiently used there, he did not believe it could be successfully used anywhere. The lift of the tides at Partishead varied between 20 and 46 feet, ana in this great variation there was a difficulty, since it implied that the turbines employed must be sufficient to use both the spring tides and the neap tides. The balancing of the power and the storage of power were both difficult problems. The first system suggested was the simple one of building a barrage and using the falling tides running through turbines. If the tide were used both ways it would nearly double the powei, but would require enormous sluice rates and would probably cause much scouring A third scheme provided a barrage of turbines and no sluice gates; but this required the yet unknown invention of a perfect reversible turbine. In a fourth the estuary was dammed by a barrage, and the remaining triangle was divided again by a barrage of turbines. The upper basin would feed the lower, and' there wou d be no idle period; hut the cost of the dams would be greatly increased. Professor Gibson compared these systems statistically. Using a falling tide only, the power constantly avai ab e through eight hours would be ooO.fXJU h.p., and the capacity of the turbines required would be 740,000 h.p. l he , e ™' plovment of boith rising and tailing ticies would produce a constant supply c 860,000 h.p., but the turbines must be capable of 2,500,000 h.p.; with the more elaborate system employing both tides alternately the Severn would produce 820,000 h.p. in the eight-hour period, and would require a turbine capacity of 1,200,000 h.p. The first and simplest scheme was therefore the most efficient, ana it had been indicated that it would be the favoured scheme. Actually to house the turbines necessary to this scheme would take a dam about a mile and a half loner The power thus at hand would be transmitted electrically to a power station and there applied to pumps dining sea water to elevated storage reser--1 voirs.