ENGINEERS SEEK THERMAL POWER AT WAIRAKEI

Bay of Plenty Beacon, Volume 15, Issue 97, 18 September 1950, Page 3

ENGINEERS SEEK THERMAL POWER AT WAIRAKEI

With a rumbling rush and a growing roar a spout of steam leapt from the earth in a remote valley near Wairakei last week. As a workman opened a valve, the spout of vapour increased in volume and violence until its sound could be felt rather than heard. The steam roared 200 feet into the air with the noise of many locomotives. The man-made geyser was one of the seven test bores being sunk in the Wairakei district as part of the Government’s current long-range geothermal project. The end is in sight for the developmenl of hydroelectric power in the North Island and it is conservatively estimated that within 20 years alternative means of generation must be found Many factors are involved in the generation of electricity from thermal power. The fact of steam being readily found at relatively high pressure close to the earth’s surface does not mean that it is suitable for conversion into terms of units and kilowatts of power. To this end exhaustive tests are being made by officers of the Department of Scientific and Industrial Research. Involved technical data is being collated and examined, and many months may elapse before the outcome of the experiments is known.

Steam rushing from the earth is not enough. It must be constant in pressure; it must be “dry”, and it must be in volume sufficient to spin the giant turbines. Several departments are taking part in the exhaustive tests at Wairakei. First, the Geological Department in conjunction with the D.S.I.R. is deciding upon localities for the test bores.

The actual work of drilling is being carried out by the Works Department and, when steam is found, the Geological Department and D.S.I.R. again combine in analysing the results. All departments are working under the direction of the State Hydro Department.

Nearby Karapiti Blowhole to regarded as symbolic of the constancy of Wairakei’s latent thermal forces. Maori legend tells of the spirits of the departed maiden which can be seen dancing ;within the rushing vapour of the geyser, said to be at least 600 years old. It is certain from scientific observation that Karapiti has remained unchanged in the past 50 years. Thermal power is put to practical use in the heating of Wairakei Hotel. “Wet” steam from a bore specially sunk for the purpose is run through a heat-exchanger which raises the temperature of fresh water to near boiling point This is circulated through the hotel and, apart from maintenance of the plant, heating the large building costs nothing.

It would not be practicable to use for heating steam direct from the bore, as the minerals would soon corrode the pipes. Accurate Picture In the test bores steam has been ‘found at pressures of up to 901 b to the square inch at depths ranging from 600 ft. to 900 ft. Some of the bores have blocked quickly after “blowing”, and it has been necessary to re-open them by further drilling. Sample cores are retained and reconstructed to give an accurate picture of the terrain. At Lardarello, near Siena, Italy, is the only plant in the world operating on volcanic energy. Wells have been drilled to some depth, and super-heated steam is led through insulated pipes to two power stations where it turns turbines that run huge generators. The steam then passes through spool-shaped condensation towers to a chemical plant where it yields. Western Europe’s only supply of boric acid and borax.

Word that another bore has yielded steam no longer creates interest around Taupo and Wairakei. The methodical work of drilling, testing, taking temperatures and capping the wells goes on steadily. Will the bores of Wairakei provide for the North Island’s power needs of the future? One day the D.S.I.R. will know the answer.