Energy policy — geothermal: Colorado Geothermal Working Group seminar

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Here’s a recap of a recent seminar on geothermal potential up in Chaffee County, from Ron Sering reporting for The Mountain Mail. From the article:

The seminar gathered public and private entities from throughout the state – including a variety of local officials and leaders to learn about issues and prospects for abundant area geothermal resources. Joani Matranga, western regional representative for the Governor’s Energy Office, outlined broad goals for the group. “We want to identify our geothermal resources for economic development and expand direct use of heat energy,” she said. The group also wants to start the first electricity production in Colorado.

Geothermal energy is roughly divided into three applications: geoexchange, which uses the natural temperature increase beneath the surface of the earth, direct use and electric power generation.

Geoexchange takes advantage of warm subsurface temperature with ground source heat pumps that pipe liquid through the ground and back to the surface to heat buildings in winter. The same temperature differentials permit cooling in the summer.

“Direct use,” John , professor emeritus of civil engineering at the Oregon Institute of Technology, said, “is providing heat, or cooling directly to buildings, greenhouses, aquaculture ponds, and industrial processes.” Colorado has at least 40 types of direct use geothermal applications. Locally, these include several hot spring spas and the Colorado Gator Farm aquaculture operation in the San Luis Valley…

Geothermal electricity production takes advantage of a new generation of technology to produce electricity using hot water cooler than 300 degrees, officials said. Past application required steam resources, which are fewer than hot water. The water is piped out of a geothermal well and through a reservoir of fluid that boils at a temperature lower than water. Resulting steam drives turbines to produce electricity. The water is subsequently reinjected to the aquifer. A cold water source cools the binary fluid for reuse and the cycle begins again. Although not without potential water resource issues, the process is considered a nonconsumptive use of water resources.

Although some western states such as Utah regard geothermal as a mineral resource, Colorado governs it under water law. Key to permitting geothermal ground water in Colorado is to prove the resource is “nontributary” – it has limited or no connection with surface streams.

Here’s an article about the recent test drilling up in Chaffee County, from Ron Sering writing for The Mountain Mail. From the article:

Mount Princeton Geothermal has gained permission for first exploration of geothermal resources in the area since the 1970s. The process is similar to drilling a water well, except the goal is to measure heat. “These holes,” [Fred Henderson III, of Mount Princeton Geothermal, LLC] said, “are nonconsumptive and will be used to measure the temperature change by depth to determine heat flow in each well. We measure the temperature gradient every three feet.” The project is the first of its kind in decades. “The goal with these six holes is to complete the western side of the high heat flow anomaly drilled by AMAX Exploration Co. from 1973-75,” Henderson said.

A drill site on a plateau south of the Mount Princeton chalk cliffs, resembles a water well. ASAP Drilling of Buena Vista planned to penetrate 600 feet. “Test holes will be capped,” Henderson said, “but left open for later temperature measurements to serve as monitoring holes to detect changes as we proceed with our program.” “We will set up a monitoring network,” Henderson said, “to understand how much we are adding to or changing the water table.”

Thermal gradient testing is the second part of a four-phase program by Henderson and Mount Princeton Geothermal. Additional wells are planned during May and possibly June. “We have to learn about the resource,” said Joani Matranga of the Governor’s Energy Office, “and what we can do with it.”

The next phase will be deep slim hole drilling and pump tests, scheduled this year. “That is critical for a whole bunch of reasons,” Henderson said. “One is to prove we won’t be interfering with anyone’s water table. There are a lot of people’s homes up there – second cabins – and they don’t want us to harm their water. It’s critical for us to do it right.” The goal is to begin production and injection drilling to begin developing a geothermal electrical generation facility next year. “We don’t yet know where the plant would go, because we don’t know where the hot water is,” Henderson said…

The Mount Princeton group must pass a number of other permitting and regulatory tests, including assurances the water resources used are nonconsumptive and, in the case of geothermal ground water, nontributary to more senior water rights. “We don’t want to be connected to the water table. We want it to be nontributary. We will check this by well testing,” Henderson said.

More Coyote Gulch coverage here and here.

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