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Geothermal Potential Touted

American Association of Petroleum Geologists (AAPG)

Seemingly endless images and slogans, from both industry supporters and critics, remind us almost daily that the public conversation about energy these days is about the future.

Paul Morgan
Paul Morgan

But no future conversation about energy is complete without talk of geothermal energy, says AAPG member Paul Morgan, a senior geothermal geologist with the Colorado Geological Survey.

“What makes this a practical consideration to pursue at the present time,” Morgan says,“is state energy portfolios.”

Morgan, who presented the paper“New Horizons for Geothermal Energy in Sedimentary Basins in Colorado” at the recent AAPG Annual Convention and Exhibition in Houston, has conducted geothermal studies in Cyprus and Kenya, but today he mentions by example the case of Colorado, which is planning for 20 percent alternative energy by 2020.

But that will take some doing – both for the state and, ultimately, the nation.

“Wind and solar are coming on line,” Morgan said,“but there is only so much of these intermittent resources that can be absorbed by the grid.”

And that’s why geothermal, to him, is so promising: Once it’s up and running, he maintains, it’s really up and running.

“Geothermal is very desirable because it is 24/7/365,” he said.“Geothermal is a heavy investment up front, but it is easily competitive once on-line.”

By comparison, other alternative energy sources, such as solar and wind, are and will continue to be heavily subsidized, even after they’re operational.

Moreover, his excitement is enhanced by what’s on the horizon: the huge potential in sedimentary basins, which may offer hundreds of square miles of resources.

Being able to tap more energy from more areas could mean more energy for the nation’s supply of frost-free refrigerators and George Foreman grills.

Slow Starts

In fact, such projects in Europe have demonstrated the feasibility of generating electricity from these low-temperature fields. Iceland, Morgan noted, because of its concentration of volcanoes, produces 24 percent of its energy needs already from these traditional sources. Specifically, geothermal heating meets the heating and hot water requirements of approximately 87 percent of all buildings in Iceland.

Where, then, are we in America in terms of the development of geothermal – both from traditional and sedimentary basins?

“Nationally, geothermal is on an upswing, together with other alternative energy resources,” he said,“but since it has been producing on a significant scale in the United States since the 1950s its recent growth is not proportionately as rapid as solar and wind.”

Still, of late, there has been increased growth due to a review by the Bureau of Land Management, which clarified the process for geothermal leasing on land owned by it and U.S. Forest Service. In that review, much of the western states region experienced a renewed interest.

“Since the earlier exploration, technology has changed – so lower temperature resources are of interest for electricity generation.”

The process is slow.

Morgan points to 2009 and 2010 where the funding opportunities mostly focused on exploration and development techniques, rather than specific on-the-ground geothermal projects. One project, however, was National Geothermal Data System.

“Almost all states are compiling geothermal data for this project,” he said.

Hydrofracking Concerns

No talk about geothermal, however, is complete without discussion of its environmental impact.

“There are two basic environmental issues – induced earthquakes and water contamination associated with hydrofracking.”

To the first, he admits; to the second, not so much.

“Induced earthquakes have definitely occurred during the deep injection of fluids at high pressure, especially into crystalline basement rocks,” he said.“I think that the Rocky Mountain arsenal near Denver was the first observation of induced earthquakes, with one magnitude 5.0 event and many smaller events associated with waste disposal in a 12,000 foot well. High-pressure fluid injection in the foothills of the Alps near Basel, Switzerland, recently induced a few magnitude 3 earthquakes in an attempt to hydrofrack crystalline rocks for an EGS system.

“However, there is no record of significant seismicity being recorded during hydrofracking operations or geothermal operations outside zones of known seismicity,” he said.

And the point, he adds, is that when found in sedimentary basins, there is no possibility of geothermal exploration causing such seismic activity.

“The type of geothermal system described does not operate by the injection of high pressure fluids, especially if run under pressure,” he said.“In terms of aquifer contamination during hydrofracturing, these operations would be carried out at great depths compared to aquifer depths.”

And there’s proof.

“In these hydrocarbon fields tens of thousand of wells have already been hydrofractured with no aquifer contamination,” he said.“There is no reason why contamination should start now.”

In Colorado, specifically, there is due diligence on this very issue.

“Geothermal wells are permitted by the Division of Water Resources in Colorado, but plans for all wells projected to be over 2,500 feet in depth and/or 212 degrees Fahrenheit in temperature must also be approved by the Oil and Gas Conservation Commission, and are subject to the same rigorous standards as oil and gas.”

Is any of this producing dividends, though?

Sort of.

“In Colorado we have a long history of direct use of geothermal resources, but no geothermal electricity production to date,” he said.

Morgan says that is because much of the hydrocarbon production in Colorado is from low-permeability formations.

“In terms of extracting heat, therefore, the hydrocarbon-producing horizons are unlikely to be good candidates,” he said.“The alternative is to either find good natural aquifers above or below the hydrocarbon units, or to create artificial fracture aquifers through hydrofracturing.”

Raton’s Potential

And he has found a place: Colorado’s Raton Basin.

“The Raton Basin would be the location for initial experiments because it is a hot basin, and 300 degrees Fahrenheit is attained at perhaps two-thirds the depth of most other basins in Colorado.”

He says if electricity generation is successful in the Raton Basin, a large portion of the Denver, San Luis, San Juan and Piceance basins probably would also be suitable for power generation.

“In these basins, power would be generated from depths of 10,000 to 12,000 feet, or shallower if the temperature can be dropped below 300 degrees. Most other basins in the Mid-continent and Gulf Coast region also become prospective at these depths or a little deeper.

“The Colorado Geological Survey (CGS) has been compiling geothermal data and publishing it in reports since the early 1970s,” he continued.“The more recently formed Colorado Governor’s Energy Office has obtained some funding to give grants to municipalities, companies and individuals to develop geothermal in the state. CGS is providing scientific support for a number of geothermal prospects for geothermal electricity production, including the Raton Basin.

“If sedimentary basin geothermal can be developed,” he says in conclusion,“a lot of the uncertainty of geothermal should be removed.”

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