MOTHER EARTH ENERGY

Some of the usable heat in the earth's interior is closer to the surface than the oil and gas that is now being drilled for in African and Malaysian waters, and even Barry Commoner would have to admit (or would he?) that there is no threat of depletion for a few hundred million years, so what's the trouble?

There are several ways of dealing with the problem. The only one now in use commercially is not to fight it. Power plants in California, Mexico, Italy, New Zealand, and a few other places use only the steam, not the brine, available from geothermal sources. There are two things wrong with that: First, the number of places with ready-made geothermal steam is limited; and second, the discarded hot brine contains more than a third of the total energy. Compared with fuel-burning energy converters, this amounts to throwing away one third of the fuel before one even starts to tackle conversion efficiencies - like drilling a hole in a car's gas tank or using a third of a power plant's coal for a land fill.

A better way is to develop machinery that will run on a mixture of steam and hot brine. That is a tall order, but it is being researched, among others, at the Los Alamos Scientific Labs and the Lawrence Livermore Laboratory. The nozzles and turbines must be tailored not only to harness the energy of the combined steam-liquid flow, but to withstand the corrosion by the hot brine as well.

Two facilities will begin operations this month at the LLL. One will develop advanced measuring techniques to determine droplet size, fluid quality, flow rate, and other characteristics of geothermal brines and steam. The other is designed to test the efficiencies of various presently available turbines for different mixtures, temperatures and pressures of the liquid-vapor mixture.