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Finding the heat — Small drone ’copters conduct geothermal survey, at less cost

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Drone helicopter

Bryan Stueve, left, and Matthew Lavin, project engineers with the Dewhurst Group LLC based in Montana City say drone helicopters cut geothermal survey costs nearly in half.

WARM SPRINGS — A new method of mapping geothermal energy is taking flight in Montana.

Dewhurst Group LLC, a geothermal exploration company with offices in Montana City, is developing sensors fixed aboard small drone helicopters to survey geothermal sources from the air.

Project engineers led a demonstration Tuesday behind Montana State Hospital at Warm Springs, joined by officials from the Montana Department of Environmental Quality and Department of Commerce.

The remote-controlled drones buzzed like giant bumblebees over knee-high grass, fitted underneath with both a conventional and infrared camera to detect differences in heat coming off the ground.

By September, the team hopes to fully develop sensors that would allow the drones to measure a site’s magnetic field and pinpoint what, if any, underground geothermic features are present up to several kilometers deep.

The process, known as magnetotellurics, is done by crews on the ground. But if successful, the aerial surveys could provide a faster, cheaper way for developers to locate and ultimately use geothermal energy to generate electricity.

Kerry McCallum, project manager, said a typical magnetotellurics survey costs about $300,000, but with the drones they could cut that cost by as much as one-third to one-half.

“Nobody else in the industry is doing anything like this,” McCallum said. “We just need to figure out the process, and make it efficient.”

Geothermal sources include hot springs and bubbling pools beneath the Earth’s surface. Dewhurst Group spent about two years looking into “aeromagnetotellurics” to find potential new sources for commercial development.

The state donated a test site at Warm Springs about one month ago. Engineers started with a traditional ground survey, and will spend the next two months comparing that with data from the battery-powered drones.

The Maryland-based Dewhurst Group, owned by geophysicist Warren Dewhurst, believes the aerial surveys can mitigate the risks of investing in geothermal exploration and open the door for future development of power plants.

Aerial surveys are also safer, Dewhurst said, and would avoid putting workers in dangerous areas. They plan to test the drones next over the Nevado del Ruiz, an active volcano in Colombia.

The flights over Warm Springs were the group’s first over an actual test site, Dewhurst said, and a landmark day for the project.

“Ideally, I’d like to perform a survey through this entire valley,” he said. “It would be too expensive with a ground survey, but you put a few of these (drones) in the air, and we could get that done.”

Montana does not have a geothermal power plant. David LeMieux, engineer with DEQ, attended the demonstration and said the project is a neat approach to geothermal development.

“Obviously part of this testing is to see whether it will actually provide the data they need,” LeMieux said. “It would be pretty impressive.”

Geothermal energy is a clean, renewable energy source that still offers base load power to meet the minimum demands of energy customers, LeMieux said. The combination is tough to beat.

Geothermal plants can generate between 50 and hundreds of megawatts, McCallum said, and the Dewhurst Group’s innovation locating sources could lead to greater use of the green energy.

“The energy is clean, and there’s such great potential for it,” McCallum said. “We’re confident we can make this work. Nobody else has the type of equipment we have.”

— Reporter George Plaven may be reached at 496-5597, or via email at Follow him at


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