NATURAL HEAT

Evening Post, Volume CXVI, Issue 22, 26 July 1933, Page 4

NATURAL HEAT

IX THEPiM'AL DISTRICT

A SOURCE OF ENERGY?

An article, published in the "l^cw Zealand Journal of Agriculture" at the end of last year directed attention to some recent developments in the utilisation of subterranean heat.. - It was shown that in at least three' localities—Tuscany, California, and Iceland •—considerable attention had been, given to the harnessing and developing of natural heat for the needs of mankind. The writers, Mr. J. A. Bruce and Mr. P. B. Shorland, of tho Department of Agriculture, in the last num-

her-of the same journal carry the subject further and suggest that possibly the natural heat to be found in the Dominion's thermal regions could bo utilised.

The possibility of utilising the stupendous heat energy of the interior of the earth has frequently, been considered by scientists, but the technical difficulties involved are such as to hinder any immediate commercial applications.. In point of fact, the writers state, to obtain a continuous heat yield equivalent to 4000 horse-power it would bo necessary to bore into the earth a hole 30 miles, deep and 2ft in diameter In post-volcanic regions, however, the internal heat of the earth is close to the1 surface, and can be satisfactorily harnessed and applied under the- appropriate conditions to the needs of iudustry and agriculture. In this connection it might be supposed that the sinking of tubes into the- hot soil surrounding volcanoes would.'provide a useful means of exploiting natural heat. Experience has shown, however, that heat -transmission, even from incandescent lava,-is exceptionally poor, so that enormous heating surfaces would be required'to be worth utilising for industrial or agricultural purposes. Amoiif tho most important thermal areas of°the world are the Katmai district of Alaska, the Sonoma County of California, Yellowstone-Park-, parts of Arkansas, Oregon, and Nevada (all in the- United States of America), the Tatio region in Chile, and areas in Bolivia and associated countries of the Andes-where there is post-volcanic ac tivity, the volcanic areas of Java, Tuscany (in Italy), Iceland, Greenland, and New Zealand. "Increasing attention has been and is being directed towards the development of the resources in a number _of theso thermal regions, mainly arising from Prince Conti's fundamental achievements in ■ establishing steampower units and boric acid. recovery plants at Larderello, in Italy," the article continues* "It ,is a noteworthy fact that Japanese scientists.and engineers have of recent years, been among the most closely interested .visitors to Prince Conti's geothernial 'plant,' and it is quite possible that these progressive people are already making a beginning in the exploiting of their own extensive thermal areas, although the recent catastrophic earthquakes would doubtless tend to hinder developments. However, the point that should be borne in mind is that the Japanese have become seized with the importance of developing natural heat areas for agriculture and industry at present used as playgrounds for. tourists." After describing the success obtained at Larderello, Tuscany, where a natural steam power plant has been in continuous use since 1916, the writers say that as a result of observations made during a recent visit to Rotorua, it is thought that-the thermal area there, while far more .extensive, and p.erhap.s. more powerful, is not intrinsically different from the" Larderello area. _ If small-scale experiments were organised on a rational basis and a survey made of our thermal regions, it is that large-scale power plants .would ultimately be practicable, as at';:Lardereiio. :;■■•

Tho abundance of hot aridj. boiling pools in and around tho town.-pf'Boto-nia would lead ono to supposejthat the hot water will on© day be satisfactorily tapped and utilised by means of. a suitable system of pipes for thajforeing of glasshouse crops in. additionxto heating homes, offices, etc. i:;..: Chemical tests of typical -warm soil collected from near some of the innumerable warm pools at Kotorua'dudicate that the acidity of the earth iri certain cases is much too great for the production of crops, and beforo satisfactory agricultural utilisation is possible 'it would be necessary to convey the warm water underground to less, acid areas with the aid of a series .of non-c.orrod-able pipes. In this connection;it is interesting to note that in the case of a large pipe-line leading from a largo area of boiling water near the Spout Baths for a distance of nearly two miles to the Ward Baths the temperature drop is 50 degrees C. A recently published statement by Prince Conti regarding the possibilities of natural-heat utilisation in Now Zealand is quoted as follows: —"I consider that the l\evr Zealand steam springs are quite worthy of being carefully studied and compared, with those of Tuscany, and I do not doubt that competent authorities will take thematter up and devote tho-aocessary care and study-to the inv.estjga.tjon of these phenomena,, the importance of which must not be too.lightly.and hastily considered." '