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Idaho's Geothermal Potential Faces
Barriers to Large-scale Production

by Laura Lundquist
Times-News, February 14, 2011

Idaho's push for renewable energy is gaining strength.

Since 2008, federal stimulus dollars have combined with tax incentives to bring more renewable energy projects online as rising fuel prices made the ventures more lucrative.

Enough companies rushed to build wind projects in Idaho that in December, Idaho Power petitioned the Idaho Public Utilities Commission to severely cap the amount of intermittent renewable power it's required to buy. This week, the petition was granted.

The rapid random proliferation of wind power projects across Idaho's high desert prompted calls to regulate where the projects could be placed.

This week, U.S. Interior Secretary Ken Salazar held a two-day conference to address the administration's efforts encouraging renewable energy projects on federal land while emphasizing responsible project siting. Not surprisingly, much of the focus was on wind energy.

Barely scoring a mention was geothermal energy.

With more obstacles to development, geothermal plants have spread more slowly and their siting hasn't triggered as much public concern.

But figuring out where to drill is a big concern to the developers themselves.

Drilling blind

On the surface, geothermal energy appears to be one of the best green energy alternatives.

Geothermal plants release no greenhouse gases and, unlike solar and wind projects, produce energy continuously. They don't dominate the landscape like wind turbines. Geothermal development isn't hampered by the radioactive waste issues associated with nuclear energy.

But similar to nuclear energy, it has high up-front costs. Drilling deep into the earth to find a suitable heat source is labor-intensive, expensive and without guarantee of success.

"An engineer told me it was like having a coal-powered plant but having to buy all the coal upfront," said Chris Harriman, president of Boise-based U.S. Geothermal Services. "Put drilling in front of anything and you're talking bucks."

To bore a mile into the earth, crews may drill for weeks using dozens of $2,000 diamond bits to chew through everything from sediment to granite. But a project's potential for success most relies on finding a good site.

Two traits are desirable for geothermal development: an area with subterranean heat that's close to the surface and a relatively unhindered flow of underground water.

The hottest sites allow for the simplest, and thus the cheapest, technology: geothermal steam-driven turbines. So initially, developers focused on areas with obvious indicators of high underground heat and water: geysers.

Developers descended upon California's geyser area in the 1960s and 18 plants built in that era remain in operation. The famous geysers of Yellowstone National Park were preserved from development by their park status.

"That's how it goes; you always go for the lowest-hanging fruit because it's the cheapest," said Harriman. "But now it's more challenging."

Last year, 77 geothermal plants were online in the U.S. with 188 projects in development, according to a Geothermal Energy Association report.

With many known hot sites developed, developers are researching secondary sites. But even in areas of hot spring activity, no one is quite sure where is best to drill.

Although organizations such as the Idaho National Laboratory's Geothermal Program have developed maps showing regions of likely activity, geothermal drilling still resembles wildcat drilling: There's a great deal of risk. If one well doesn't yield, developers have to start over.

Methods exist to compensate for less optimal sites, but they cost more money.

"Every site is different and we never know what we're going to run into," said Chris Delahunty, operations director of the Snake River Geothermal Drilling Project.

For that reason, geothermal energy supporters have lobbied for help from the federal government.

"We need a geothermal endowment," said Dan Kunz, U.S. Geothermal CEO. "We have the geology here in Idaho but need to have people willing to take the risk to drill."

U.S. Sen. Mike Crapo, R-Idaho, co-sponsored the Geothermal

Energy Investment Act in September, which would have increased the investment tax credit for geothermal producers. A similar bill was introduced in the House in July.

Neither made it out of committee.

Crapo spokeswoman Susan Wheeler said the bills suffered from being introduced late in the 2010 session with little active support. She said Crapo plans to reintroduce the bill early this session to give it a better chance of passing, but it will battle for support in a Congress that already has its hands full with weightier issues.

Four bills were recently introduced in the Idaho Legislature to reduce leasing restrictions for geothermal projects on state land and give the land board more flexibility to negotiate royalties collected from projects on state land.

State royalties are currently set at 10 percent of the value of the project's product -- electricity in this case -- which is far greater than the 2 percent charged by the federal government.

While supportive of geothermal power, little in these bills helps defray a geothermal company's upfront cost. They'd only help projects once they're underway.

A Cassia County pioneer

In a mostly uninhabited region of sagebrush just east of the Jim Sage Mountains in Cassia County, steam rises in the cold air from a small tributary of the Raft River. Hot springs may indicate hot water below, but it may not be hot enough to produce steam.

Such is the case at U.S. Geothermal's Raft River plant, Idaho's only such plant and the first in the Northwest.

In the mid-1970s, the U.S. Department of Energy chose this site for its geothermal demonstration project, which operated until 1982.

The Raft River valley sits atop a fault that serves as a chimney for the earth's heat below. The DOE dug four wells along the fault more than a mile deep as part of its $40 million project.

That's partly why U.S. Geothermal bought the Raft River site: The company saved money because most of the wells it needed were already drilled.

"And we got to learn from their mistakes," Harriman said.

The catch was that, even more than a mile down, the water isn't hot enough to produce steam. Water comes up from the Raft River wells about 20 degrees shy of the 300 required to turn a turbine.

In this case, and in most future plants, energy producers have to use two-step technology that wasn't available when the DOE owned the plant. The well water surrenders half its heat to another chemical fluid -- isopentane -- that turns to gas at a lower temperature than water. The force of the gas turns the turbines.

It is then chilled back to a fluid and reused.

In 2006, Raft River was one of the first U.S. plants to use the process, opening the doors for others. In 2009, every U.S. plant that went online used the process.

While it increases geothermal possibilities, the process has a drawback. Along with high upfront cost, the efficiency of this two-step process is only around 10 percent. For every 10 units of heat energy brought from below, the plant produces one unit of electricity.

That's less efficient than solar energy, which has slowly crept its way into the 20- to 30-percent efficiency range.

"You could extract more if the technology improves but we're in our infancy," Harriman said.

The Raft River plant has a 20-year agreement with Idaho Power, in which Idaho Power pays for 10 megawatts a month at a rate equivalent to what it would pay for natural gas. Even with its efficiency issues, the rate is enough that the plant comes out ahead on its day-to-day operations.

As Western water users are learning, groundwater flows at a far slower rate than people can extract it. So, geothermal plants are now designed to return the water from whence it came to keep the resource going.

For every production well, an injection well must be drilled nearby, although they aren't usually as deep. They can't be too close to the injection wells because the cool return water could reduce the underground heat the system depends on.

Harriman said even with optimal well placement, most geothermal sites eventually cool off to the point where plants can no longer produce power using available technology. He hopes the Raft River site is good for 30 years. Other sites have lasted longer.

"It's built into our business model to replace wells with time but we'd need to do more drilling," Harriman said. "We need more modeling."

Looking below the surface

One research group is trying to help Idaho developers reduce the guesswork and risks associated with drilling.

The DOE awarded around $4 million of stimulus funding to Utah State University for its Snake River Geothermal Drilling Project. In addition, the project participants, which include Boise State University and the U.S. Geological Survey, will ante up around $2 million to fund the drilling of three mile-deep exploration wells in southern Idaho.

The project will generate and measure seismic waves sent throughout the region and use the information to design detailed underground maps of rock composition. Different rock types affect the speed of shockwaves.

They'll be able to match the rock type because the cores bored at the three sites are being carefully collected and taken to Utah to map the geology of each site, inch by inch. Little information of such detail at such depth has been collected, said principal investigator John Shervais of Utah State.

"The traditional method of finding geothermal resources was find a hot springs and dig," Shervais said. "We want to get beyond that so we can better develop the resource."

The three sites are in a region of predicted geothermal potential but they represent different situations: the porous Snake River plain around Kimama north of Paul, the northwestern faults running under Kimberly, and Mountain Home's fault-bounded system.

The first well is complete near Kimama and crews are just setting up to drill near Kimberly.

"Once you get below the aquifer, there's high heat flow," Shervais said of the Kimama well. "Our preliminary temperature readings got up to 176 (degrees) Fahrenheit but our tools stopped working because it got too hot."

It will be a couple years before Shervais' data can be used to fill in a picture of south-central Idaho's underground world. In the meantime, without other financial incentives, geothermal companies may not develop much, despite the good will.

U.S. Geothermal had originally planned a second phase involving construction of a second plant, but Harriman said that would require drilling more wells at $3 million each.

"If we had a 350 Fahrenheit resource, it would be worth it," Harriman said. "Knowing where to find those resources would be worth it because there will never be cheap drilling."

Laura Lundquist
Idaho's Geothermal Potential Faces Barriers to Large-scale Production
Times-News, February 14, 2011

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