Geothermal Energy Exploration: Deep Drilling For 'Black Smoker' Clues

As part of the Iceland Deep Drilling Project, researchers from UC Davis, UC Riverside, Stanford University and the University of Oregon plan to sink a deep borehole into a site on land where seawater circulates through deep, hot rock. Most such sites on land have circulating fresh water, with very different chemistry.

"It's the dry land version of a deep sea hydrothermal vent," said Robert Zierenberg, professor of geology at UC Davis. Zierenberg and another geology professor, Peter Schiffman, are the UC Davis members of the research team. "It's the first opportunity to look at rocks and fluid together and in situ."

Deep ocean hydrothermal vents support unique communities of living things that, unlike most ecosystems on Earth, draw no energy from the sun. The vents also generate unusual, and possibly valuable, deposits of copper, zinc and other minerals.

Zierenberg said it is technically challenging to drill into rocks that are under high pressure and bathed in corrosive fluids at 450 degrees Celsius (840 degrees Fahrenheit), but it is easier than trying to drill deep below the sea floor in the deepest parts of the ocean.

"We hope to understand the process of heat transfer when water reacts with hot volcanic rocks and how that changes the chemistry of fluids circulating at depth," Zierenberg said. "We know very little about materials under these conditions."

The Iceland Deep Drilling Project is supported by the Icelandic power industry and government, in collaboration with U.S. government agencies. It aims to drill deep boreholes to learn more about processes in deep, hot rocks, with the goal of producing more energy from a single geothermal well. Iceland already gets half of its electrical power and meets much of its needs for space heating and hot water from geothermal energy.

In Iceland, geothermal heating is used at a community level: hot water is pumped up and circulated around a town or neighborhood. The island nation generates more than half of its electrical power from geothermal energy. Hot water and steam from boreholes can be used to run turbines for electricity or directly to heat homes and businesses. Iceland meets the rest of its electricity needs from hydroelectric power, and imports fossil fuels only for transportation.

The university research project is supported by grants from the National Science Foundation and the International Continental Drilling Program. The researchers expect to start drilling in the summer of 2008.