Washington, Nov.30: Two American geochemists have claimed that they have discovered a new tool for identifying potential geothermal energy resources.

Berkeley Lab geochemist B. Mack Kennedy and Matthijs van Soest of Arizona State University said they made their discovery while determining helium isotope ratios in samples of surface fluids from the northern Basin and Range.

They surveyed parts of California, Nevada, Oregon, Idaho, and Utah, and mapped the steady progression from low helium ratios in the east to high ratios in the west.

Currently, most developed geothermal energy comes from regions of volcanic activity, such as The Geysers in Northern California.

Kennedy and van Soest claimed that the potential resources arise not from volcanism but from the flow of surface fluids through deep fractures that penetrate the earth's lower crust, in regions far from current or recent volcanic activity.

"A good geothermal energy source has three basic requirements: a high thermal gradient — which means accessible hot rock — plus a rechargeable reservoir fluid, usually water, and finally, deep permeable pathways for the fluid to circulate through the hot rock," said Kennedy, a staff scientist in Berkeley Lab's Earth Sciences Division.

"We believe we have found a way to map and quantify zones of permeability deep in the lower crust that result not from volcanic activity but from tectonic activity, the movement of pieces of the Earth's crust," he added.

"We have never seen such a clear correlation of surface geo-chemical signals with tectonic activity, nor have we ever been able to quantify deep permeability from surface measurements of any kind," said Kennedy.

With the urgent need to find energy sources that are renewable and don't emit greenhouse gases, geothermal energy is ideal, and according to Kennedy, the “best renewable energy source besides the sun."

Their findings appear in today’s issue of the journal Science. (ANI)