Down a drift in the former gold mine a mile beneath Lead, South Dakota, a young scientist from Stanford University pulls water from thick granite walls, looking for a tracer.
"You can see it with a microscope," said Adam Hawkins, a postdoctoral scholar.
His purple gloves held up a vial of what appears to be normal water — a little rusty maybe — that could hold a clue to mapping the inside of the mountain. "This is the first nano-particle that can travel through the ground without getting stuck," he said.
The SIGMA-V experiment is part of a larger project out of the Lawrence Berkeley National Lab that began Oct. 1 in the Sanford Underground Research Facility, or SURF, that seeks to find out how geothermal fracking impacts rock in deep underground wells.
Typically, fracking is not considered a clean energy. Engineers push water and fluids into shallow wells to extract hydrocarbons, such as natural gas, but the byproducts are the stuff of headlines: water from faucets in Appalachia able to be lit on fire or seismic tremors in Oklahoma near wells. But geothermal fracking is much deeper and involves only water.
"We're talking green energy here," said Bill Roggenthen, a seismologist with South Dakota School of Mines and Technology in Rapid City, South Dakota. "No CO2, no methane. Geothermal energy is, well, pretty cool, but really we're talking about utilizing heat that is coming out of the earth in a responsible manner."
The underground mine in Lead is popular for physics experiments seeking the origins of the molecular universe. A trip down to the 4,850-foot-level — a 10-minute ride down a wooden shaft that once hauled miners to and fro for a day's pay — reveals plenty of physics going on.
A doctoral student from the School of Mines monitors a particle accelerator that can create stars. Another researcher from the school discusses the world's purest copper, grown in the sterile environment free of cosmic radiation. (Visitors need to remove coveralls and place blue booty wraps over steel-toed boots.)
But a new experiment has attracted new scientists to the lab — geologists.
Throughout a drift that looks a lot like a gold mine, a makeshift laboratory is operating on the crushed dolomite and old rails. Hoses run into holes in the wall. Dusty laptops run numbers. The machines and gadgets fill the narrow workspace with a constant hum, and scientists are, basically, mapping fractures in the rock. Under a mountain of rock dating back 2 billion years, the four or five bores drilled by scientists are being studied by the research team.
They pump a pint of water a minute into the hole, which seeps into the fissures and around 20 minutes later exits the rock through a tube 30 yards down the drift, where Hawkins stands ready with a vial. Occasionally, the team injects a microscopic "tracer" into the rock wall and back down the drift. Another Stanford University researcher collects the water samples, searching for the tracer. The time that tracer takes to navigate its crushed terrain helps the team know what those fractures look like.
Understanding these rock fissures can help scientists develop bigger and better experiments that might someday mean power plants on the surface run by water are heated by hot rocks thousands of feet underground.
By 2025, the Western Governors Association projects around 13,000 megawatts of energy could be produced in the western United States (it takes roughly 14,000 solar panels to produce a single megawatt of power).
The information gleaned deep below Lead will also help scientists make better models to predict how fracking might go in a deep hole to be drilled soon in Utah, which can help engineers get closer to extracting geothermal energy that might heat houses, businesses and even whole towns.
"It's all a bench test that we'll scale up to bigger and bigger levels," Roggenthen said. "Geothermal heat is everywhere. It's just a matter of how you get to it."
Standing at a computer terminal, geologist Vince Vermeul monitors numbers.
"There's probably 20 people across the country watching what we're doing right now," said Vermeul, of Pacific Northwest National Laboratory in Washington state.
It's just the latest chapter in the 10-year-old underground research facility retrofitted into the 100-year-old gold mine. But remnants of the old mine aren't gone. Down the drift from the geologists, near a hammer with an American flag pattern on the handle and a lunch pail, Rick Tinnell stands repairing a rusty trolley — underground mass transit.
"I'm the rope man," he said. "I was hired in '78, and I still come up here about once a week."
Officials say about 30 workers from Homestake Mine still work there, and many take the shaft back up the mine, which still runs on a schedule inherited from the gold mining days.
"There is no personal space on the shaft," one worker said, causing the scientists and maintenance men to laugh. Tinnell recounted the day last weekend when friends and family of the current SURF team were invited down to the facility for a tour.
"It's been many years since I've pulled that many people on the cart," Tinnell said.
And the cage began to slow as it reached the surface, natural light creeping back between the bars and lighting the faces of the riders.