Rico geothermal research project Phase 1: map subsurface hydrothermal resource, create district heating preliminary design

Rico Geothermal Coalition hosted a "community outreach" brunch at Rico Town Hall in the Courthouse building Saturday, December 14, 2024 to explain geology, geothermal energy technologies and plans for the Rico project. The presentation was also available via video-conference.

     
by Allyn Svoboda
Publisher

Western Colorado University lecturer Holly Brunkal explains geothermal geology at a December 14, 2024 community outreach presentation, while Teal Stetson-Lee directs the slideshow.
Photo by Todd Gillman

Contents

1. Presenters
2. Community engagement
3. Geothermal 101
4. Phase 1 scoping study: synthesize past results into new model to predict drilling site
5. Boise ID thermal energy network is an example for Rico
6. More info

1) Presenters

Teal Stetson-Lee
Rico Geothermal Coalition chairwoman and community liaison for the Rico geothermal project

Holly Brunkal
Lecturer in Engineering and Geology and Senior Professor of Geology and Engineering - Western Colorado University at Gunnison

Emilie Gentry
Senior Geothermal Geoscientist at Teverra

Kevin Kitz
Independent consultant at Boise, Idaho specializing in geothermal powerplants development and operations, geothermal heat pumps and district heating.

2) Community engagement

presentation by
Teal Stetson-Lee

Teal is Community Liaison for Rico Geothermal Project.

Rico has some of the highest hydrothermal potential in the state. Colorado School of Mines professor Masami Nakagawa and students studied the resource from 2009 - 2018.

Teal formed the Rico Geothermal Coalition consisting of six local residents, Teverra LLC, and Western Colorado University. "We're build on all of the data that's already been collected , and continuing to move this process forward to find out if geothermal solutions is something the town of Rico may be interested in."

Transparency. "It's 100% grassroots, community-lead. Our intention is to make use of our hydrothermal resource for the benefit of the community. The Rico Geothermal Coalition is folded under the Rico Land Collaborative nonprofit. The nonprofit structure allows us to apply for grants and funds, and also to build a more expansive network. We will be interacting directly with the community for your input and your feedback. We would like to know how the community wants to utilize this resource that we have."

Funding: Rico selected in May 2024 by the Colorado Energy Office receive a $100,000 grant consisting of federal Inflation Reduction Act funds for "infrastructure." The Rico Center provided a small grant to assist with creating the Rico Geothermal Coalition website.

Phase 1 "scoping study" began October 2024. Duration is 18 months. Scope of work is to map the subsurface hydrothermal resource and assess the potential to create a district heating thermal energy network (TEN) for supplying buildings and residences with hot water and heat. A hybrid TEN may include heat pumps at buildings and residences.

Geothermal is a "cascading resource" which may be used for multiple scenarios. First application is a closed loop system to heat buildings. If geothermal resource heat capacity is sufficient, other uses such as heat for a greenhouse, hot springs pool, or snowmelting.

Scientific research by Teverra by to map the reservoir, which has never been done before, will provide a more comprehensive picture compared to previous research, and designate where to access it.

Phase 1 scoping study will calculate a thermal energy network and provide a preliminary design for geothermal heat distribution in Rico.

Community engagement by Rico Geothermal Coalition and Teal will include educational events and materials, presentations to Rico Board of Trustees, and a community survey with intent to include everybody. "My job is to connect with all of you and hear your voice and make sure that's engaged in the whole process."

"Localized energy" goals and benefits - reduced heating costs, employment opportunities, greenhouse gas emissions reduction, cleaner air.

3) Geothermal 101

presentation by
Holly Brunkal

Precipitation falls on higher-elevation recharge area and flows down geologic faults (black lines) to geothermal heat source. Steam pressure caused by heating may force hot water or steam to rise along fault lines and escape as hot springs, steam vents or geysers such as Old Faithful in Yellowstone National Park.

diagram source:
Rico Geothermal Coalition
Community Outreach
December 14, 2024

"Why is geothermal important? Geothermal is a low carbon form of energy and it can be used in a lot of ways. Geothermal power production can fill in the gaps for other areas like solar, which is obviously peaking in the middle of the day, and wind which has its peaks at either end of the day. Geothermal energy can fill-in where the variable energy sources fluctuate down.

"We're not getting heat from the Earth's core, it's too far. We're using heat that is stored in the Earth's crust, within the top kilometers, 10 kilometers would probably be the max. As you go down in the Earth's crust, it gets hotter. There is a general geothermal gradient of about two degrees centigrade per kilometer average for the Earth's crust. We're looking for places where that geothermal gradient is steeper, where we have more heat per kilometer of depth than the average.

Holly displayed a Colorado geothermal heat gradient map. "High gradient right around Rico. How about that?"

Note - link to map provided because image may be subject to copyright. See also Colorado Interpretive heat flow map of Colorado, which also shows Rico's high potential.

Three kinds of geothermal energy production and distribution systems. "Conventional hydrothermal, enhanced geothermal, and direct-use which is more shallow and more attainable because the temperatures don't have to be as hot." Example uses of each:

• hydrothermal: "High temperature systems (such as electric power generation,) hot springs, Yellowstone geysers."
• direct use: "Heat pumps, low-temperature applications that are accessible in more applications."
• enhanced geothermal systems: "Larger projects that are, rather than having the hydrothermal system in place, are enhancing the heat transfer."

Geothermal electricity generation: "The places where you have the heat, the water, and the "plumbing" all together . . . those spots have all been identified and developed if they can be developed. Geothermal power is concentrated right now in the western United States, because that's where we have the active geology, where we have the water and where we have the systems in place for electricity generation.

"There are a lot of places under development for enhanced geothermal power. The Geysers power plant in California is the largest geothermal field in the world. . . . It's been cranking out the same amount of power since 1960."

Part of The Geysers electric generating complex. U.S. Department of Energy photo at flickr.com.

Located in Sonoma and Lake Counties in California, The Geysers complex produces over 900,000 kilowatts of electricity to provide power to about one million residential customers in northern and central California. Pacific Gas and Electric Company builds and operates the generating plants while several other companies provide the steam by drilling geothermal wells 7000 feet to 10,000 feet below the surface. - U.S Department of Energy

Faulted geology allows surface water to penetrate down to a hot hydrothermal reservoir. Water boils at 100° C (Celsius, 212° Fahrenheit). Water deep underground is pressurized so it can attain higher temperatures without boiling and changing to steam.

Lower-temperature hydrothermal is less than 150° Celsius (C). Water boils at 100° C (212° Fahrenheit). "Water at depth in the Earth's crust is under pressure, so is prevented from flashing to steam. You wanna' trap that liquid water when it's at high temperature as a liquid and bring it to the surface and then let it flash to steam to make the electricity."

"District heating is also considered direct use." Examples: geothermal heat pumps, hot springs resort pools, district heating, greenhouses, aquaculture."

"Here in Rico the hot water is coming to the surface because it was given a pathway by drilling holes . . . in the 70'sand 80's. They were looking for something else, and they found hot water. That's a hydrothermal system that was 'blind'. We didn't know it existed until it was drilled into.

In some geothermal electric generating locations, subsurface hydrothermal water, "heats-up a secondary fluid, and that secondary fluid has a lower boiling temperature. The hot water comes out of the ground, goes through a heat exchanger, and goes back underground ground. It never interacts on the surface with anything else, It's just going in a circle. And then that heat gets transferred to a secondary fluid that goes through and drives the turbine" (to generate electricity.) This closed loop system conserves water and prevents hydrothermal water from contaminating the surface.
> see video at end of this report

Binary-cycle hydrothermal electric generating system with heat exchanger.

source:
Rico Geothermal Coalition
Community Outreach
December 14, 2024

Lower-temperature hydrothermal is less than 150° C. This resource may be used directly as a heat source for ground-source heat pumps, hot springs, district heating, greenhouses, aquaculture.

Ground source heat pumps could complement a Rico thermal energy network geothermal resource.

Enhanced geothermal systems (EGS) are used when the subsurface heat resource has no water. Drilling, fracturing and injecting water creates an artificial hydrothermal reservoir.

4) Phase 1 scoping study: synthesize past results into new model to predict drilling site

presentation by
Emilie Gentry

Teverra is a subsurface geoscience and engineering company ". . . looking at turning reliable clean energy into reality by providing innovative subsurface solutions."

Current understanding of Rico resource includes research reports from 1976 - 2018 of mining boreholes and water geochemistry which predicts the temperature of the subsurface hydrothermal reservoir. Previous geophysics research at Rico by Colorado School of Mines consists of ". . . imaging of the subsurface to help us understand where there's faults, where there might be a reservoir, where there's fluids flowing."

The geochemistry results predict the Rico geothermal reservoir is about 120 - 140 degrees Celsius (248 - 284 degrees Fahrenheit) down in the reservoir, not at the surface.

Rico heat gradient is about 101 degrees Celsius per kilometer. "Geothermal gradient at Rico stands out to be higher than anywhere else in the state. Continental average is about 30 degrees Celsius per kilometer, the Rico average is about 101. . . . Geothermal heat flow for Rico is also among the highest in the state."

"Data from 2011 up through 2024 is still showing more and more that Rico is in a 'hot spot,' for lack of a better term."

"We have an understanding of what the geology looks like and what exists in Rico."

"The geophysics helps us get an idea of what the geometry could be. In 2010, 2016 and 2018 Colorado School of Mines came out and took different geophysical studies." Purposes of this previous Rico research:

• understand the location of faults.
• identify location of the hydrothermal reservoir.
• identify location of permeability - fluid pathways where the water flows.
• measure the reservoir extent - east/west and north/south - and reservoir depth.

"Resistivity results in 2010 and 2016 gave an understanding of the geometry of the reservoir. . . What faults serve as fluid pathways and what faults serve as barriers or boundaries. With that is also an understanding of hydrology, where the water flows and how it flows through the system and how that regenerates within the subsurface, from the surface to the subsurface, cycling through that."

"In 2018 they did an MT - magnetotelluric - study . . . to get an idea of how deep the reservoir is. The results of that is the reservoir is less than 1000 meters deep at the hot springs location."

"The study and the grant that Teal talked about (phase 1 scoping) is to continue to piece together so that we know where to drill and where to put in the best location of the well."

"The geophysics that was done are indirect measurements of the permeability and water flow. . . . This gives us a good picture of what the resource looks like and what the reservoir is and to say that there is high potential, but it's not good enough to hang your hat on, is not good enough to understand the depth and the breadth of the geothermal reservoir, and it's not good enough to say 'let's put a well in right here.'"

"What we're doing is to integrate all of the existing data. We're not collecting any new data currently. We are bringing all that into a model and then synthesizing what that means together. What does the temperature data mean, what does the fault data mean, what does the geophysical data mean. And if we put all that together, what kind of story and understanding can we get of the subsurface?"

"The work is still ongoing right now so I can't give too much of a conclusion or analysis. We just started two months ago. I will have results hopefully at the next town hall meeting. Current idea is to create a model that brings all of these components together with the idea to select a target location for a well. With that, we want to select the most optimal location based on the geometry of the reservoir, Its extents and depth, as well the characteristics of the reservoir, meaning he permeability and the water flow."

Emilie displayed 3-dimensional computer-generated Teverra images of geology and characteristics of the Rico geothermal reservoir.

5) Boise ID thermal energy network is an example for Rico

presentation by
Kevin Kitz

Geothermal district heating and cooling consulting engineer Kevin Kitz describes existing community projects and Rico options via video-conference connection. Teal Stetson-Lee directs the slideshow. Photo by Todd Gillman

"High temperature geothermal is 250 degrees F or greater, it's used for power generation. Low temperature is where Rico falls, it's not what I would consider to be an economical grade for power generation."

"At Boise the geothermal water comes out of the ground at about 170 to 190 degrees Fahrenheit."

The Boise geothermal heating project began in 1890, consisting of the Warm Springs district in the downtown area. It has expanded to 4 geothermal heating districts including Boise State University, the VA, and the state capitol building.

"The lesson there is that you can start with something and grow it over time."

"Cold climate with a very strong heating dominant, this is often a more challenging location to do this sort of thing because you're extracting heat from the ground for a long time period. But this is most likely the strategy we will pursue in some form or another for Rico, in my opinion, Is using (electric-powered) geothermal heat pumps."

"We could use hot water circulating through town, or we could use more tepid water in combination with the geothermal heat pumps."

Adding a heat pump is 2.6 X more efficient compared to geothermal-heated fluid alone, and extends the heat avaliable from the geothermal reservoir to more buildings.

Boise, Idaho district heating pipes
image source:
National Renewable Energy Laboratory
"2021 U.S. Geothermal Power
Production and District Heating Report"

Today, the city of Boise is home to the largest municipally operated geothermal heating utility in the country, with more than 20 miles of pipeline warming over six million square feet of building space throughout the city. The system delivers naturally heated water at a toasty 177 degrees through this extensive network of pipes, providing heat to buildings like City Hall and the local YMCA, melting snow from sidewalks—and, yes, heating what is now a city recreation pool at the former Natatorium.

source:
Geothermal District Heating & Cooling
U.S. Department of Energy
Geothermal Technologies Office

Geothermal community district heating concept diagram (above). Pumps at "ENERGY STATION" (left) circulate fluid or refrigerant gas to and from a subsurface geothermal heat reservoir. Pumps push heated fluid through a pipe network to buildings and homes. Fluid may be pumped directly from the geothermal reservoir to the distribution pipes, or heat from the reservoir may be transfered through a heat exchanger to the distribution network. Heat extraction and distribution pipes are "closed loop" . . . cooled fluid is returned to the heat source for re-heating.

image source:
Rico Geothermal Coalition
Community Outreach
December 14, 2024

Heat pumps
U.S Department of Energy photo

6) More info

Think Geoenergy Brief description of Colorado Energy and Carbon Management Commission (CEMC) published 2024 report on Colorado's geothermal resources and potential utilization models, titled Geothermal in Colorado: Resources, Use Strategies, and Impact Considerations. Report prepared by Teverra with the Colorado Geological Survey and Colorado School of Mines. ". . . a comprehensive report on the geothermal resources and history of Colorado, a utilization and market analysis, and an environmental and regulatory evaluation of the state’s geothermal opportunities."

U.S Department of Energy

GeoVision

Low Temperature & Coproduced Resources
Low-temperature geothermal resources are generally considered those below 300°F (150°C). Low-temperature geothermal uses include geothermal heat pumps (GHPs) for individual homes and businesses, district heating and cooling, and direct-use applications, where water from the geothermal resource is piped through heat exchangers or directly into commercial or residential buildings to meet heating and hot water demands. These resources can meet many energy needs, from heating and cooling to industrial processes like paper drying, greenhouses, and even beer brewing.

Geothermal Technologies Office
The U.S. Department of Energy’s (DOE) Geothermal Technologies Office (GTO) works to reduce costs and risks associated with geothermal development by supporting innovative technologies that address key exploration and operational challenges.

Energy 101: Geothermal Energy
Geothermal electrid power generation.

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