November 2004 Newsletter

Digging Deep for Energy Solutions

September 2, 2004
By Chip Thompson, Twin Falls Times-News

It's green, it possesses enormous power, and it comes from deep below the Earth's surface.

No, it's not the latest monster to come out of Hollywood. It's geothermal energy, and it's poised to be a blockbuster in eastern Cassia County.

Daniel Kunz, president of Boise-based U.S. Geothermal, has spent three years securing energy rights and leasing and buying property, and he expects to put a proposed 10-megawatt geothermal generation plant in Raft River on line by 2006.

One reason the project can move so fast is that much of the work was done by the US. Department of Energy, which operated the site as a geothermal demonstration project from 1974 to 1982.

"A lot of the nitty gritty stuff is already done," Kunz said Tuesday before a tour of the site with U.S. Rep. Mike Simpson. "Many of the risks have been taken care of -- the risk of discovering the resource, for one."

Kunz said a resource nearly a mile underground can be difficult to locate -- usually requiring drilling exploratory wells on a massive scale, because surface features offer little evidence of geothermal potential.

In a nation often accused of burying its head in the sand when it comes to finding energy solutions, the strategy has paid off with geothermal.

"A rancher was drilling for stock water and kept coming up with hot water," Kunz said.

The rancher had tapped into an aquifer warmed by a rift of magma below that extends all the way to Yellowstone National Park and heats deeper water to 300 degrees.

The Department of Energy drilled wells through two water tables in the early '70s to reach the superheated water. When the demonstration project was shut down in 1982, the wells were capped and the facility sold to an Oregon-based company that never developed it for energy production, Kunz said.

U.S. Geothermal bought the facility and one square mile of land from the company and has negotiated leases and energy rights for another five square miles, Kunz said, meaning the plant will have more than 3,700 acres of geothermal potential to tap. Kunz said he expects the plant to eventually have a capacity of 90 megawatts.

But the plant isn't a done deal.

"We're still in a high-risk stage of our life," Kunz said, adding that a power purchase agreement with Idaho Power Co. currently being negotiated will be a key step forward.

Viability of the facility may also depend on the passage of legislation to provide production tax credits to geothermal producers.

"In production tax credit, wind gets a huge advantage compared to the rest of us," Kunz said.

Simpson asked Kunz what level of tax credit would make the project viable.

"Wind gets 1.8 cents per kilowatt hour, and that would make it more than viable," Kunz responded.

Kunz said legislators need to examine the advantages of geothermal as a renewable, non-consumptive and environmentally friendly energy source that's both quiet and has minimal visual impact. And, once the plant is built, geothermal energy is inexpensive to produce.

"The more they look at geothermal, they'll realize that this is the cheap power of the future," Kunz said.

Construction of phase one of the plant, which could begin in 2005, would employ about 100 workers for a year, and plant operation would require 15 workers, Kunz said.

How geothermal energy production works

Water, nearly a mile beneath the Earth's surface and superheated to 300 degrees by magma rifts, is brought to the surface via deep wells. Heat exchangers transfer heat from the water to a secondary, or binary, liquid with a low vapor temperature. The Raft River project is expected to use butane, like you'd find in a disposable lighter, as a binary liquid because it vaporizes at about 80 degrees.

Turbines are powered by the binary fluid as it vaporizes and expands. The turbines generate electricity. Closed systems are used for both the superheated water and the binary liquid. Water is returned to the rift to be heated again, and the binary fluid condenses and returns to be vaporized again.

Potential power generation at the Raft River facility is expected to be about 15 megawatts per square mile.