geothermal energy

Arizona Geology e-magazine for summer 2013 now online

The Arizona Geology Survey has just released its summer, 2013, issue of Arizona Geology which features seven articles.  See the whole issue at

Most interesting to me is the article: Ground-Source Geothermal Heating and Cooling: Sustainable and Affordable Energy for Arizona and the U.S.  The article begins:

“This past August 12th was the first day of the new school year for ~ 1,000 students at Lookout Mountain Elementary School in Phoenix, Arizona. The high temperature that day was a torrid 109 degrees Fahrenheit while inside the newly constructed 50,000 square foot wing of the school, temperatures were a balmy 76 degrees Fahrenheit, thanks to a new ground-source geothermal system that exchanges heat with the cooler earth hundreds of feet below the ground surface.”

The other articles:

Arizona Seismic Update – January – July 2013

“The Arizona Broadband Seismic Network documented over 50 earthquakes in Arizona from January to July 2013. The quakes were mostly located in northern Arizona and were at depths ranging from 1.4 to 26 km (0.9 to 16.25 miles depth)”

Earthquake Shakes North Rim Area

“On July 7that 1:38 MST, a magnitude 3.5 earthquake shook the towns of Fredonia, Jacobs Lake, and Havasu . The earthquake was followed by a series of aftershocks, with two registering Md ~ 2.0 and several in the 1.0 range.”

Digitizing, Cataloging, and Publishing Arizona’s Mining Legacy Online: Mine Maps, Reports, and Photographs

“In 2011, the financially troubled Arizona Department of Mines and Mineral Resources (ADMMR) and the Arizona Mining and Minerals Museum shuttered their doors. The Arizona Geological Survey (AZGS) received the Department’s maps, photos and manuscript collections. That year, AZGS began a comprehensive inventory of the 30 archival collections, creating finding aids1 for the more than 10,000 folders, 6,000 maps, and 7,000 photographs.”

Update on the STATEMAP mapping program in Arizona

“The STATEMAP program is a component of the National Geologic Mapping Act of 1992. STATEMAP is a matching fund program whereby State general funds are matched one-to-one by federal funds to support geologic mapping by the states. The Arizona Geological Survey (AZGS) has participated in the STATEMAP program since its inception, and has produced 1:24,000-scale geologic maps of a large fraction of the State with funding from this program.”

Making Geologic Maps with GIS

“Geologic map production begins in the field. Geologists spend several months traversing pre-defined areas of Arizona’s landscape to collect geologic information about that area. Geologists collect qualitative and quantitative information in the form of observations in a field notebook or on a topographic map. Geologists use a GPS (global positioning system receiver) to identify observation locations.”

Summary of oil and gas activity in Arizona – January to June 2013

Besides oil & gas, this article provides brief information on drilling for carbon dioxide, CO2 sequestration, geothermal energy, and potash exploration.

Check it out.

State of geothermal resources in the US

The Department of Energy (DOE) has just released its 2012 update on the state of geothermal in the U.S. You can download the report here (9.7Mb):                                                                                                                                                                                                                                                                  

The report discusses the state of the U.S. geothermal potential and highlights several projects. The Arizona Geological Survey is a lead agency in coordinating the information. The DOE report also points to another website: “A significant amount of information on exploration techniques, geothermal regions, and related publications has been made available through the National Renewable Energy Laboratory’s OpenEI website.” That site does contain interesting information, but I found its production figures a few years out of date.

The U.S. leads the world in geothermal production. The Geysers plant in California is the largest geothermal plant in the world generating 875 MW. I had thought that volcanic Iceland would have a large geothermal potential, but upon checking found that the five Icelandic plants have a combined capacity of 660 MW, smaller than California’s Geyser operation. However, besides electricity, Iceland’s geothermal plants also provide about 87% of heating and hot water requirements to buildings in the country. Iceland gets 74% of its electricity from hydropower.

The DOE report features a section on Enhanced Geothermal Systems (EGS). They say:

“Enhanced Geothermal Systems are man-made reservoirs, created where there is hot rock but insufficient or little natural permeability or fluid saturation. In an EGS project, fluid is injected into the subsurface under carefully controlled conditions, which cause pre-existing fractures to re-open. Increased permeability allows fluid to circulate throughout the now-fractured rock and to transport heat to the surface via a production well where electricity can be generated. While advanced EGS technologies are young and still under development, EGS has been successfully realized on a pilot scale in Europe and now at a new DOE-funded demonstration project at The Geysers.”

This technique is similar to “fracking” in oil and gas fields. It allows exploitation of areas lower in temperature than the Geysers and also exploitation where there is much less groundwater.

Research is also underway to recover lithium, manganese, and zinc from geothermal brines during the power production process. The map below shows the relative geothermal potential of the U.S.


See also:

Arizona Geological Survey Leads Geothermal Energy Study

New Source of Geothermal Energy in Western US.

National Geothermal Data System, free online

National Geothermal Data System, free online

The Arizona Geological Survey has announced that the National Geothermal Data System (NDGS) has reached a milestone with data from over one million wells now online and available for free to anyone ( ).

The database contains information from a network of academic researchers, private industry, and state and federal agencies. It includes more than 717,000 oil and gas wells, 414,000 water wells, and 9,300 geothermal wells spread broadly across the nation. The data are all free for online viewing or downloading, funded by a number of grants from the US Department of Energy. The system is still growing and AZGS expects there to be an additional 2-3 million wells in the database within a year.

These wells are critical resources to aid in the exploration and development of the nation’s geothermal energy resources. They also represent an invaluable resource for a wide variety of environmental, hydrological, and other natural resource uses.

Each well is accompanied by geographical coordinates, county and state location, well status, total depth, and spud and end-of-drilling dates. Some wells include some or all of the following: bore hole temperature, aqueous geochemistry, drillers log, and geophysical logs – typically porosity, resistivity and temperature logs.

To serve the geothermal exploration and research communities, the NDGS catalog portal provides fast and efficient data discovery via an interactive geographic map tool, ready data access, and analysis. NGDS uses open standards and protocols to encourage developers to build custom applications for accessing and displaying data. The site also includes a frequently asked questions section and tutorials for use of the system. The system can accommodate common GIS applications, including GoogleEarth, ArcGIS Online, ArcGIS Explorer, NREL Geothermal Prospector, Microsoft Layerscape, and the USGS’ National Map Viewer. Give it a try.

See also:

Geothermal potential in Arizona

New Source of Geothermal Energy in Western US.

New Source of Geothermal Energy in Western US

The Arizona Geological Survey announced that exploration work in Utah has discovered geothermal resources that could represent a new type of target. These targets can be exploited with a binary cycle plant (see illustration below).

The AZGZ announcement reads as follows:

Discovery of a new type of geothermal energy resource in Utah offers hope for significantly more potential across the western U.S., and a boost in geothermal power production.

 In 2011 and 2012, Utah Geological Survey geoscientists, in partnership with a U.S. Geological Survey research drilling crew, drilled nine temperature gradient holes in Utah’s Black Rock Desert basin south of Delta to test a new concept that high temperature geothermal resources might exist beneath young sedimentary basins. Preliminary results show that near-surface temperature gradients in the basin vary from about 60° C/km (33° F/1000 feet) to 100° C/km (55° F/1000 feet). This implies temperatures of 150- to 250° C (300- to 500° F) at 3 – 4 km depth (10,000 to 13,000 feet) beneath the basin. An abandoned oil exploration well drilled near Pavant Butte in the central part of the basin in 1981 confirms these exceptionally high temperatures. Seven of the drill holes were funded by the U.S. Department of Energy as part of a National Geothermal Data System project, managed by the Arizona Geological Survey. The new holes also confirm the results from three other research holes that were drilled in the basin over the past few years; these were funded by the Utah State Energy Program and the Utah Division of Wildlife Resources.

 The 1,000 square kilometer Black Rock Desert basin is filled with unconsolidated sediments to a depth of 3 km, while the underlying basin floor comprises a variety of Paleozoic and older bedrock. In some parts of the basin, porous and permeable carbonates (limestone and dolomite) are known to be present and these would be natural hosts for a geothermal reservoir. Using the drilling results, a reservoir modeling team at the University of Utah estimates a basin-wide power density of about 3- to 10 MWe/km2, (megawatts of power per square kilometer) depending on reservoir temperature and permeability. Given the large area of this basin, the power potential is conservatively estimated to be hundreds of megawatts, and preliminary economic modeling suggests a cost of electricity of about 10c per kilowatt-hour over the life of a geothermal power project. The modeling assumes air-cooled binary power generation with all produced water injected back to the reservoir so that there would be no emissions or consumption of water. The heat in the produced water would be exchanged at the surface in an air-cooled binary power plant. Such power plants are common these days in geothermal power developments. The cool, injected water would move laterally in the reservoir between injection and production wells, and can be considered as heat-farming at depth.

 This basin is especially attractive for geothermal development because of the existing nearby infrastructure it is next to a large coal-fired power plant, a 300 MWe wind farm, and a major electrical transmission line to California.

Geothermal exploration in the Basin and Range Province of western Utah and Nevada has traditionally focused on narrow, hydrothermal upwelling zones along bounding faults of mountain ranges. Most current power developments have reservoir areas of less than 5 km2 (2 square miles). However basins within the Basin and Range usually have areas of many hundreds of square kilometers. Although the depth to potential reservoirs beneath these basins is deeper than the geothermal industry is used to, the large reservoir area offers economies of scale. Drilling to depths of 3 – 4 km is not unusual in oil and gas developments.

 Dr. Rick Allis, Director of the Utah Geological Survey and joint lead scientist of the sedimentary basin geothermal research project, said that existing heat flow maps of the Basin and Range don’t have the resolution to identify this type of geothermal energy resource. “There are other potentially hot basins across the Basin and Range province that need to be investigated using this exploration model. We have identified the Steptoe Valley and Mary’s River –Toano basins in northeast Nevada as obvious geothermal targets. There may also be hot basins across the western U.S. that have similar unrecognized geothermal energy potential.”

 The National Geothermal Data System is in operational test mode, integrating large amounts of information from all 50 states to enhance the nation’s ability to discover and develop geothermal energy. Visit the State Contributions site at

See also:

Arizona Geological Survey Leads Geothermal Energy Study

The future of the Arizona Geological Survey

The Arizona Geological Survey is facing a normal sunset review in the Arizona legislature Monday, Oct. 17.  I urge the legislators to continue the survey because is provides many valuable services and maintains a repository of scientific knowledge about Arizona.

The statutory mission of AZGS is:

1. Serve as a primary source of geologic information in this state to enhance public understanding of the state’s geologic character, geologic hazards and limitations and mineral resources.

2. Inform, advise and assist the public in matters concerning the geological processes, materials and landscapes and the development and use of the mineral resources of this state.

3. Encourage the wise use of the lands and mineral resources of this state toward its development.

4. Provide technical advice and assistance in geology to other state and local governmental agencies engaged in projects in which the geologic setting, character or mineral resources of the state are involved.

5. Provide technical advice and assistance in geology to industry toward the wise development and use of the mineral and land resources of this state.

The Arizona Geological Survey is a leader among state surveys.  For instance, last year the Arizona Geological Survey received an $18 million grant from the Department of Energy to lead a coalition of 46 state geologic surveys and universities to study the geothermal resources of the United States.

In April of this year, the Arizona Department of Mines and Mineral Resources was deactivated and its duties transferred to the Arizona Geological Survey.  These duties include maintaining a repository of mineral and mining information, including databases, books, periodicals, individual mine files, mine map repository files, mining district data and an archive of mine data; and providing quality mining data, evaluation, and assistance relating to mineral development to the legislature, federal, state and local governmental agencies, industry, and the public.

An example of the Arizona Geological Survey’s direct value to citizens is its brochure: A home buyer’s guide to geologic hazards.  The Survey has published warnings to the public of the additional  consequences of our devastating forest fires: Forest fires create increased danger of destructive debris flows.  The Survey provides expertise in the realm of geology as applied to water law and regulation, for instance: San Pedro River Geology – Implications for water law.

You can voice your opinion by sending emails to the co-chairs of the hearing committee: John Nelson, and Kate Brophy-McGee, as well as to your own state representatives.

The Yellowstone Super Volcano

Yellowstone National Park in northwest Wyoming is a picturesque land of geysers, hot springs, waterfalls, mountains, and lakes. But just in case you don’t have enough to worry about, it is also the largest supervolcano in North America and among the top three largest in the world. The term “supervolcano” refers to a measure of volume of material erupted and explosiveness. See comparison charts for volume here and the volcanic explosivity index here. You will see that the Yellowstone supervolcano is at the maximum end of both scales.

The U.S. Geological Survey (USGS) map below shows the general setting of the Yellowstone volcano and caldera. Calderas are created following an eruption when the volcano collapses in on itself.


According to the Yellowstone Volcano Observatory, run by the USGS and the University of Utah, during the past 2 million years the Yellowstone super volcano has had three of the world’s largest volcanic eruptions:

Eruption of the >2450 cu km Huckleberry Ridge Tuff about 2.1 million years ago created the more than 75-km-long Island Park caldera.

The second cycle concluded with the eruption of the Mesa Falls Tuff around 1.3 million years ago, forming the 16-km-wide Henrys Fork caldera at the western end of the first caldera.

Activity subsequently shifted to the present Yellowstone Plateau and culminated 640,000 years ago with the eruption of the >1000 cu km Lava Creek Tuff and the formation of the present 45 x 85 km caldera. Resurgent doming subsequently occurred at both the NE and SW sides of the caldera and voluminous (1000 cu km) intracaldera rhyolitic lava flows were erupted between 150,000 and 70,000 years ago.

Yellowstone is presently the site of one of the world’s largest hydrothermal systems including Earth’s largest concentration of geysers. As such, it could be one of the largest sources of geothermal-produced electricity, but that’s not likely to happen.

The USGS map below shows the coverage of ash deposits from the three major eruptions, compared to the 1980 eruption of Mount St. Helens. The map also shows the extent of the Bishop Tuff which erupted from the Long Valley volcano in California 760,000 years ago.

Yellowstone map 2

The Yellowstone super volcano is the youngest of a series of such volcanoes that have erupted over the past 17 million years. The older volcanoes trace a line running up the Snake River Plain. The graphic below shows the location and age of these volcanoes. Notice also the parabolic shape of earthquake epicenters (red dots).

Yellowstone map 3

The theory of this volcanic region is that there is a stationary “hot spot” in the mantle that periodically breaks the surface with an eruption. Eruptions occur in a linear pattern showing that the continental crust is moving over the hot spot at about 2.8 cm/yr at an azimuth of about 247 degrees according to Smith et al. “The Yellowstone hotspot has been the source of voluminous rhyolite tuffs and lavas with eruptions often having volumes of hundreds to thousands of cubic kilometers and representing some of the largest Quaternary eruptions on Earth.”

A similar hot spot occurs under Hawaii. In Hawaii, the magma is basaltic which is very fluid so eruptions are relatively tame: volcanic explosivity index (VEI) 0 to 1. In Yellowstone, however, the magma is rhyolitic, very thick and viscous. That makes for violent explosions (VEI 8, the maximum) which produces ash rather than lava flows.

Geophysical investigations show that the Yellowstone magma chamber is 6- to 16 km deep beneath the caldera. Under that, the feeder zone to the magma chamber extends 660 km into the mantle transition zone.

What is happening now?

The National Park Service assures us, “There is no evidence that a catastrophic eruption at Yellowstone National Park (YNP) is imminent. Current geologic activity at Yellowstone has remained relatively constant since earth scientists first started monitoring some 30 years ago. Though another caldera-forming eruption is theoretically possible, it is very unlikely to occur in the next thousand or even 10,000 years. Scientists have also found no indication of an imminent smaller eruption of lava.”

On the other hand, National Geographic news of January 19, 2011 reports:

Yellowstone National Park’s supervolcano just took a deep “breath,” causing miles of ground to rise dramatically, scientists report.

But beginning in 2004, scientists saw the ground above the caldera rise upward at rates as high as 2.8 inches (7 centimeters) a year.

The rate slowed between 2007 and 2010 to a centimeter a year or less. Still, since the start of the swelling, ground levels over the volcano have been raised by as much as 10 inches (25 centimeters) in places.

“It’s an extraordinary uplift, because it covers such a large area and the rates are so high,” said the University of Utah’s Bob Smith, a longtime expert in Yellowstone’s volcanism.

Scientists think a swelling magma reservoir four to six miles (seven to ten kilometers) below the surface is driving the uplift. Fortunately, the surge doesn’t seem to herald an imminent catastrophe, Smith said.

(Related story with 3D model of magma chamber: “Under Yellowstone, Magma Pocket 20 Percent Larger Than Thought.”)

“At the beginning we were concerned it could be leading up to an eruption,” said Smith, who co-authored a paper on the surge published in the December 3, 2010, edition of Geophysical Research Letters.

“But once we saw [the magma] was at a depth of ten kilometers, we weren’t so concerned. If it had been at depths of two or three kilometers [one or two miles], we’d have been a lot more concerned.”

Here is a graphic from Smith, showing topographic swelling caused by magma pressure at Yellowstone; rather impressive:

Yellowstone map 4

Apparently, all is (relatively) quiet on the western front, but who knows when the pimple will pop.


Smith, R.B., et al., 2009, Geodynamics of the Yellowstone hotspot and mantle plume: Seismic and GPS imaging, kinematics, and mantle flow, Journal of Volcanology and Geothermal Research 188 (2009) 26–56.

See update: 

Arizona Geological Survey Leads Geothermal Energy Study

The Arizona Geological Survey has just received an $18 million grant from the Department of Energy to lead a coalition of 46 state geologic surveys and universities to study the geothermal resources of the United States. The study is scheduled to last three years.

According to a press release by AZGS, “Over the next 3 years, data relevant to geothermal exploration and development will be digitized and published online from 46 states in a web-based, distributed, interoperable National Geothermal Data System (NGDS).

The Arizona Geological Survey was chosen as lead agency because it was already working toward the goal of collation and integration of spacial data, in conjunction with the U.S. Geological survey. The AZGS is a national leader in constructing a framework for geo- spacial data integration. Such a geo-spacial framework will be a valuable tool for other sciences also. It can, for instance, help integrate information on mineral deposits, vegetation patterns, wildlife occurrence and habitats, groundwater supply, and land use. It will allow scientists of many states and countries to share data. The AZGS program is also partnering with 21 European countries for spacial integration of scientific data.

There is already quite a bit of information about Arizona geothermal potential available online from the Arizona Geological Survey: Most of the geothermal research in Arizona was done in the late 1970s and early 1980s when there was an oil shortage.

The survey says “Geothermal energy abounds in the US, ranging from low-temperature, ground-source heat that can be extracted to cool homes in the summer and heat them in the winter; to direct use of low- to moderate-temperature water (68 F to 302 F) for homes, industry and commercial uses; to high-temperature systems capable of driving turbines and generating electricity.”

This program will give us a good assessment of the potential for geothermal energy as an alternative energy source, and provide a framework for integration of other resource studies.