Cerro Prieto, twenty miles south of the United States border, is a large geothermal energy field likely to produce 1,000 megawatts of electricity annually by the early 1990's. This will be well above its initial' 1973 capacity of 75 megawatts, which was doubled in 5 1979, with a further 30 megawatts added two years later to bring it up to its present capacity. However, in addition to the primary purpose of producing electricity, scientists at Cerro Prieto have developed several other uses for the geothermal heat and fluid, including some in acquaculture and hydroponics. In relation to the former, 10 crayfish are raised in water kept at about 85F. They feed on the minute crustaceans and algae occurring naturally in the geothermal fluid while special strains of bacteria have been introduced to clean the water along with small local crayfish that absorb salts harmful to the commercial variety. This variety's metabolism is speeded up 15 by the controlled environment, which reduces growing time.

The salt-rich geothermal fluid also produces sticking results through the use of hydroponics, which yields of crops such as tomatoes and cucumbers as much as 300 per cent higher than in normal soil. Meanwhile, 20 a ten-meter-long enclosed shed produces half a ton of barley grass per day, the grass reaching a height of five inches in only seven days from seed.