Wairakei May Be Sure Of Steam For 100 Years

Press, Volume XCVII, Issue 28536, 15 March 1958, Page 10

Wairakei May Be Sure Of Steam For 100 Years

“The Press” Special Service

WELLINGTON, March 14. Steam at Wairakei may not come from a deep reservoir of hot water under the area but from an underground horizontal body of water fed by Lake Taupo. If this is so, the geothermal power station is almost certainly assured a constant supply of steam. The suggestion is made in a paper published in the latest New Zealand Journal of Science and written by Messrs T. A. Rafter. S. H. Wilson and B. W. Shilton, of the Department of Scientific and Industrial Research. They say that “it seems hard to conceive a very large reservoir of water undp the limited active area at Wairakei, as it must be so deep that it would reach into depths where the porosity of the strata is very low. It seems more feasible to suppose that the mixing of ground water with magmatic steam (steam from molten rocks) does not occur under Wairakei but elsewhere, nearer to Lake Taupo, and that the flow has been horizontally through porous or fissured beds.” The authors’ conclusion follows a study of the gas escaping from the geothermal bores. From this they deduce that either the reservoir of water is very deep or it is lateral and some miles in extent. Their paper supports the second theory, though Mr Wilson yesterday said there was no evidence yet for a firm decision. Asked if the theory meant that

Wairakei was almost guaranteed no shortage of steam, Mr Wilson said that it seemed possible there would be no shortage if the supply was lateral. He said there had been no sign yet of any falling off and that “the life of the supply might be 100 years if it is lateral.” The investigation outlined in the paper was primarily concerned with the gases coming off with the steam. The paper shows that 90 per cent, of the gas is lost before it reaches the surface. The practical result will be that less power will be required at Wairakei to pump off gases than is required at Lardarello, the Italian geothermal station, where 10 per cent, of the power produced is used for this.