HARNESSING VOLCANOES
It seems like the height of daring to attempt to harness the volcanoes, and yet there is a plant in Italy which utilizes volcanic energy and develops useful power from it. At Volterra, in the province of Tuscany, there is a volcanic region where jets of very hot steam issue from cracks in the ground. These steam jets, known as soffioni, are laden with gases and mineral matter. For many years the boric acid that they contain was abstracted from them, but the steam was allowed to escape. In some few instances it was piped into houses and used for domestic heating. In 1908 an attempt was made to convert the energy of the steam into useful power. Holes were bored into the earth and steam of a temperature of 302 degrees Fahrenheit came up the pipes. This steam was applied directly to a forty horsepower steam engine, and for the first time volcanic heat was set to work. The steam, however, contained so many impurities that it was impracticable to use it directly in the engine. The valves and cylinders were soon clogged with deposits of boric acid. Then instead of trying to obtain power directly from the steam, the latter was used to heat a boiler in which pure steam was generated. This plan proved perfectly practical and a 300 horsepower condensing steam turbine was driven by the energy thus obtained indirectly from volcanic heat. This power was converted into electricity and the power was transmitted to the surrounding villages. After the World War broke out and Italy began to feel the shortage of fuel, the price of coal having risen to $50 per ton, the use of volcanic power was extended. A 3,000 kilowatt plant was installed and electric current was transmitted to Florence, Leghorn, Volterra, and other towns of Tuscany. The exhaust steam from the boilers was utilized in the boric acid industries.
Other projects for utilizing the internal heat of the earth have been given serious consideration in Italy. Near Naples there is the dormant volcano, Solfatara, the crater of which is filled with a sea of very hot mud underlying a cool thin crust of earth. Holes bored into this mud to a depth of a few feet send forth steam hot enough to do useful work and a plan to utilize this store of energy is under way.