GEO-THERMAL POWER

Taupo Times, Volume II, Issue 83, 19 August 1953, Page 1

GEO-THERMAL POWER

THE ITALIAN SCHEME An interesting study entitled "The Steam Vents of Tuscany and The Larderello Plant," written by Alfredo Mazzoni, and published in Bologna in 1948, is of special local interest today in vew of the work being carried on at Wairakei by the Ministry of Works Geo-thermal Power Project. The steam vents of Tuscany, which have aroused great interest over a long period, are distributed over an area south of Voiterra covering more than 80 square miles. Manifestations of geo-thermal steam can be observed at Larderello and other centres where the Larderello Company has its undertaking, situated along an irregular ellipse about 9 miles long by 5 miles. The first historical reference to the Tuscan thermal area occurs in a poem of the first century B.C. Parchments of the seventh century, and old documents of the eleventh century, give accounts of the phenomena. and it is considered that in view of the known age of the thermal area, and the continuity of its activity through the centuries, there is every possibility for the manifestations continuing for many hundreds of years. The ancients obtained alum, vitriol and sulphur from the steam vents, and following the discovery of boric acid in 1777 at Monterotondo the industrial exploitation of chemicai products began. In 1818, Lardarel and Co., having absorbed their competitors, began to develop under the guidance of Francesco de Larderel, after wliom the Larderello is named. Search for Steam The first researches into the exploitation of underground steam started in 1832, carried out with drilling outfits as used for artesian wells, but no real results were obtained until 1856. The problems of drilling in country with active chemicai agents in the steam and incidental to the presence of steam under great pressure, were carefully studied in the years 1904-1932. In 1939, when the Second World War broke out, >- more than 140 wells, or bores, were active. The first to experiment in the direct mechanical use of steam vents was Dr Ferdinando Raynaut, who in 1894 used steam to heat water in a multitubular boiler, the steam from which was used to run a 9 h.p. reciprocating engine. This experiment proved the error of the theory of some scientists, that if the flow of steam from a vent was restricted by a pipeline the steam would find an easier way to the surface. Difficulties due to corrosion were overcome, and in 1905 a Cail reciprocating engine of 35-40 h.p. actuated by direct steam was installed. _ which operated a dynamo producing electric power for the whole Larderello plant. By 1914 a much more poWerful installation was in use, consisting of three turbines fed by steam produced by multitubular vertical boilers with condensers and driving an alternator of 2750 kilowatts. Generation of Power Early in the year 1944 the capacities of the turbo-generator units installed in the various power stations of the Larderello scheme totalled 135,800 kilowatts. The associated chemicai plants had, as a minimum, a yearly production of several thousand tons of raw boric acid. Several drilling machimli were used "that could reach a depth of 5000 feet with a starting diameter of 231 inches. But in June, 1944, extr^mely serious damage was done by the retreating German Army. All steam pipe connections were mined and destroyed, many pipe lines were injured, the machines of six big drilling rigs were destroyed, all the generator units of the various power stations together with the transformers, the greater part of the boilers, and the buildings of the power stations, were blown up with systematic and scientific preeision. Following the liberation, work started on clearing up the debris. A small turbo dynamo unit of 15 kilowatts was discovered among the ruins and with this it was possible to begin the first electrical welding of the steam pipes. By 1946, seven turbo-generator units were producing 57,500 kilo-

watts, ;and in Augusi^, 1948, fcome fifteen units, in five power stations, had a total capacity of 136,500 kilowatts, and it was expected that within the third quarter of the year 1948 the total power of the various stations would be 150,500 kilow^atts. The mere recital of these details of the Larderello geo-thermal power undertaking is sufficient to throw into relief the obvious importance of the work being carried out by the Geothermal Power Project at Wairakei. There can be no doubt that the New Zealand engineers will achieve similar success in the production pf electrical power from our geo-thermal sources.