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Looking for ways to tap our geothermal sources

Article by Allen Best

Energy – February 2008 – Colorado Central Magazine

SOUTHWEST OF ASPEN, at the head of the Conundrum Creek Valley, are hot springs. At 11,200 feet, just below timberline, they are among the highest hot springs in the nation.

But the Conundrum Hot Springs are also distinguished by what is in the water, helium isotopes consistent with rocks found in the Earth’s mantle, instead of its crust, according to research by Karl Karlstrom of the New Mexico Institute of Mining and Technology.

Why this is, scientists can’t say for sure. But it is a tantalizing fact that folds into a broader phenomenon that they call the Aspen Anomaly. Extending roughly from Paonia to Leadville, the Aspen Anomaly has been identified by geophysicists as suggestive of increased subsurface heat somewhere along the same order as Yellowstone.

“I don’t know if scientifically we can say exactly what is happening there,” says Matt Sares, deputy director of the Colorado Geological Survey. The Earth’s crust may be thinner around Aspen, he says. Then again, there may be a pathway through the crust that allows transmission of heat from the interior to the surface.

But whatever the geological explanation, scientists and engineers are intrigued by the potential that wells –particularly those more than 10,000 feet deep –could ultimately be used to tap heat of 400 to 500 degrees Fahrenheit that could then be used to produce electricity.

The federal energy bill signed into law late last year by President George Walker Bush gives a strong push for this deep geothermal drilling, often called enhanced geothermal systems. Congress authorized — but has not yet funded — $95 million annually for five years to sponsor a broad and aggressive research program.

Already, California gets 5 percent of its electricity from geothermal plants, although from shallower, hot-water sources. Tapping the more shallow hot-water sources also plays a key role in Nevada’s ambitious goal of quadrupling the electricity it derives from alternative energy in the next three to five years. A new power plant using hot water resources is also coming on line in Idaho. Existing geothermal plants also operate in Utah, Hawaii and Alaska.

The technology for converting this underground heat into electricity was first deployed in Italy in 1904. In the United States it has been used for 40 years. Iceland gets nearly all of its heat and electricity from geothermal sources.

But what excites many scientists is the much broader heat located somewhat deeper in the country. Such deep-geothermal system pilot projects are already in place in France and Australia.

A 2006 Massachusetts Institute of Technology-led report called “The Future of Geothermal Energy” concluded that up to 10 percent of U.S. electrical production could come from deeper geothermal sources by the mid-century, with even higher percentages in the West.

In the study, Colorado is considered to have the best geothermal resource among all the states at depths between 10,000 to 13,000 feet (3 to 4 kilometers) and the sixth best potential at depths greater than about 10,000 feet (3 kilometers). Within the state, the most promising concentrations of heat are in and near the San Juan Mountains and the San Luis Valley. And natural gas fields, such as those found north of Denver, may be exploited for geothermal heat, too.

Because the federal government controls so much surface land in the West, as well as the subsurface, it is a major decision-maker in where, and how, geothermal resources will get developed. Currently, a programmatic environmental impact statement is being prepared. That document is expected to be completed late next year, opening the door for leases of public land in early 2009.

Interest in geothermal energy in Colorado is increasing, and a large conference focusing on the subject was held in Montrose in October 2007. Whether any wells get drilled anytime soon is yet another matter. Sares said commercial exploration in Colorado may happen soon, but likely remains some years away.

Because of the depths and expense of drilling for hot water, it’s not the sort of thing that homeowners would pursue for heating, he noted. Geo-exchange, or ground-source heat pumps, is another matter, though, and is already being widely employed in many backyards of Western Colorado.

Plenty of upside

Denver-based alternative energy analyst Tom Konrad sees plenty of upside to geothermal.

In a posting at, he says stocks in geothermal companies that he has followed since 2003 have, as a group, more than tripled in value.

Geothermal is attractive to utilities, he explains, because it can generate electricity continuously, similar to coal-fired plants, for what is called base-load generation. It’s also relatively inexpensive, with costs comparable to wind, biomass, or even new coal-fired plants, and cheaper than so-called clean coal, solar photovoltaic, or nuclear power.

Electricity from existing coal-fired plants may be 2 to 3 cents per kilowatt hour, while new coal-fired plants will deliver it at a cost of 5 cents. Geothermal from the shallow wells typically comes in at 4 to 6 cents.

“Financially, it’s absolutely comparable,” said Konrad of geothermal electricity, “and when you consider the environmental costs of coal, geothermal is a much better deal,”

Unlike solar or wind, which require larger spaces, geothermal has a small environmental footprint, he notes. And once the infrastructure is installed, costs are low and yield is high — net margins often exceed 60 percent.

Konrad also points out that technology is currently improving to take advantage of lower-temperature resources, and the federal government’s Energy Policy Act of 2005 simplified lease structures and royalty payments. The new energy bill, he adds, “is big news.”

R&D nudge needed

Enhanced geothermal — the deeper drilling — was one of the few types of renewable energy to get significant support in the federal government’s new energy bill. Colorado is named as one of four priority states.

“It gives new life for the geothermal efforts within the federal government,” said Curtis Framel, of the U.S. Department of Energy.

However, it did not extend the production tax credit, which is due to expire late next year.

The federal government in recent years has devoted $5 million annually. Estimates are that Congress in future months will allocate $25 to $30 million, said Sares.

For people like Jefferson W. Tester, a professor of chemical engineering at the Massachusetts Institute of Technology, it’s about time. “Geothermal has been on a starvation diet for the last 15 to 20 years in the United States, and it’s time we changed that,” Tester said at a conference about geothermal held during October in Montrose.

Tester chaired a task force of 18 researchers from universities, federal laboratories and private oil and other companies that issued “The Future of Geothermal Energy.” That report calls for $800 million to $1 billion investment in research and development to improve drilling technology and other aspects of enhanced geothermal. Detailed study by Tester’s group found no “major barriers or limitations to the technology.”

Tester said he sees the need for federal aid to establish locations of greatest potential for tapping underground heat. As in oil exploration, determining the resource spots is the most risky. Later, as field sites are proven, the private sector will assume a greater role, the team predicted.

In Colorado, most areas with known potential have been identified, and the next work is to begin leasing.

Difficult energy choices

Geothermal advocates say it’s only fair that the federal government bankroll development of enhanced geothermal. The U.S. government subsidized development of both hydroelectricity and nuclear plants, says Tester. The federal interest in advancing geothermal is energy security, which is now being redefined as national security.

Allowing free markets to lead the past choices which favored fossil fuels has “put us in what I think is a very precarious state as we move forward,” he said.

Electrical generating capacity has increased 40 percent in the last decade, with most of that increase coming from the burning of natural gas, the MIT report notes. But prices of natural gas are expected to escalate substantially during the next 25 years. Much of that supply is expected to come from foreign countries, “further compromising U.S. security beyond just importing the majority of our oil for meeting transportation needs.”

Solar and wind energy cannot provide 24-hour- a-day base load without mega-size energy storage systems. Coal is plentiful, but the technology for burning it without causing greenhouse gas emissions and other pollution is far from clear. The transition to so-called clean coal is fraught with “costs and uncertainties,” the report notes.

Finally, the report notes uncertainty about whether the American public is ready to embrace increased nuclear power capacity.

A 2005 study by the Western Governors’Association projected total production of 12,558 megawatts of electricity from enhanced geothermal by 2025. Taking a longer view, the MIT report, however, foresees potential for 100,000 megawatts of base-load generating capacity by mid-century.

In contrast, the hotly contested Desert Rock coal-fired plant proposed on the Navajo Nation within New Mexico would deliver 1,000 megawatts.

A pair of power plants in Kansas that have drawn national attention would be 700 megawatts each. Kansas officials have vetoed them because of carbon dioxide emissions (although the basis for that veto is being challenged in court).

Colorado’s hot springs

Most people think of geothermal in terms of its surface manifestations — hot springs. Colorado has 59 recorded hot springs. Many are developed commercially, particularly for bathing. There are also several greenhouses located near the foot of Mt. Princeton, near Buena Vista, and even an alligator farm in the San Luis Valley.

In addition, several communities in Colorado have tried to take advantage of nearby hot springs. In Pagosa Springs, 13 businesses and 2 homes are heated with a geothermal system installed in 1982.

Ouray has year-round public baths as well as several private baths in lodges. Some years ago the town government there attempted to tap the same heat source for broader public benefit, but was forced to retreat when lodge operators complained that their hot springs were becoming merely warm.

Owners of the world’s largest commercial hot springs, at Glenwood Springs, have been protective that the source of their hot water is not diminished by wells dug by others.

Much of what is known about Colorado’s geothermal resources comes from studies in the 1970s and early 1980s, when energy was a hot topic, so to speak. Now, geothermal potential is being studied again — with some promise.

“The more we look, the better the prospects,” said Sares, of the Colorado Geological Survey.

Aside from the hot springs, the potentially much larger payoff will be in the deep wells — wells that have yet to be drilled. Although more costly to drill, the temperatures deeper into the Earth’s interior are higher and more uniform, which accommodates easier production of electricity. Conventional geothermal wells in the United States today are generally less than 10,000 feet deep, whereas deep, or enhanced geothermal wells are deeper than 10,000 feet.

The fundamental geology of Colorado favors the potential for underground heat that can be exploited. From the Rocky Mountains to the Sierra Nevada the crust is breaking up, providing pathways for fluids to migrate to the surface.

Where the Aspen Anomaly fits into this is still unclear. Sares, who cautions that he is not a geophysicist, says the anomaly became evident because of the way that seismic energy waves resulting from earthquakes travel through the earth. Those patterns suggest an interior composition of rock similar to that of Yellowstone, but confirming evidence awaits additional research.

Could heat in the mountains someday provide electrical production? Possibly, says Sares. “It will take a little more coaxing, a little more research and data to get people to spend money to drill deeper for geothermal resources,” he says.

Whether this will happen anytime soon is a guessing game. But given the uncertainties about new coal plants and nuclear waste storage, and the growing concern about greenhouse gases, things are beginning to look up for those intent on digging deep into the Earth for heat.

Allen Best writes from greater Denver, although he spends a lot of time on the road.