Presentation to South Texas RARE meeting June 9 -10, 2006
There are many things we all have in common.
But did you know that one of them is that we are over an area of the Earth with unusually high
amounts of pressure and high temperatures? The high pressure is Geopressure and the high
temperatures are included in Geothermal Energy.
I am Maria Richards and I work in the Southern Methodist University Geothermal Lab in Dallas,
Today I’m going to discuss with you how the people of the region of Texas can use the
geothermal energy resources it has.
There are 3 types of Geothermal Usage possible here:
1. GSHP - commonly used in homes and schools
2. Direct Use of shallow well water for agriculture and aquaculture
3. Electrical Production from high temperature fluids and pressure being produced by o/g
The surface of the Earth varies in temperature according to the climate. Here in South Texas the
temperature of the Earth at 3 - 9’ below the ground is about 75-77?F, year round. The climate
varies between 40 - 100 ?F, but every day the ground temperature is 75-77?F.
That constant temperature can be used for cooling or heating the air in a home, school, or small
business using ground source heat pumps or geoexchange units. GSHP are units which
exchange the Earth’s temperature through a series of pipes in the ground with a building’s air system using fluids. It’s a renewable energy system that let’s the Earth help to heat and cool
your building. Notice that I said help. Here in S.TX there would need to be an additional need
for cooling if a building is going to be less than 77?F. But it is still much easier to start with 77?F than with the outside air of 98?F or 40?F in the winter.
Its an exciting time for installers of these systems. With energy prices rising, many homes and
schools are installing GSHP. In 2006 they are estimating 70,000 units will be installed in the US. There are already over 1,000,000 units installed in the US. The GSHP are a way to reduce
electrical needs and that energy savings this year will be about 7000 MW, which is comparable
to the energy consumption for an entire need for the state of Nebraska.
Many people who install these systems see them as a way to become energy independent or “off
grid” from the major utilities. It reduces our US needs for power plant production and thus
makes the US have increased energy security.
Because the systems have been installed in the US from 30 - 50 years, depending on where you
live, the concept and knowledge base have made systems much more risk free. It is still
important to find yourself a good installer to get it right.
So here in S. TX GSHPs are a bridging technology - one more piece of the renewable puzzle.
Because they use the ground, and luckily the Earth is a constant always “on” 24 hours a day, 7
days a week, 365 days a year, it works well with other intermittent renewables - solar, wind, fuel cells, etc.
S.TX has a long agricultural background. Direct use of geothermal energy can be incorporated into the industry through shallow wells, reducing the cost and improving the crop. Jim Witcher of NM works closely with the AG business in NM and AZ developing systems. Its an economic boost because of the energy savings, and it helps to develop and maintain rural communities by keeping them thriving.
In Agriculture the working fluids can be directly used if between 75 - 195?F. Here in S TX the temperatures are already 75?F right below our feet. Wells are drilled and water is pumped through systems to heat/cool greenhouses. Also lines running along the ground in fields are one way to increase specialty crops in the winter. The hot water can also be used for in related industries such as drying and processing that use high amounts of energy.
NM is finding about a 25% decrease in operating costs from using geothermal fluids in Agriculture. They are also reporting a better environment for humidity control, decreasing the amount of diseases and fungus.
Another growing use of geothermal direct use is in aquaculture. For fish farming they tend to need temperatures from 100 - 150?F. I noticed that here in S. Texas are multiple shrimp farms. There are many other types of fish that can be grown using geothermal fluids. As the natural areas decrease for fish growth, aquaculture will continue to be a growing industry. Idaho is one state that seems to be taking off in fish farming using geothermal fluids. It seems very exotic to be growing alligators in Idaho.
Geopressure & high temperature = Electrical Production
The third type of geothermal use to discuss is the electrical capacity from geopressure and high temperature fluids. Geothermal energy is a HUGE resource! The Earth has 50,000 times more geothermal energy than all the known oil and gas reserves known today. Most people think of geothermal energy with volcanoes and places like Yellowstone National Park, but its basically everywhere, and as long as the Earth is here, so is geothermal energy.
Geothermal Energy is clean - steam is the main released pollutant.
In the US there is 2800 MW of electrical production from geothermal energy power plants. They are all in the Western US - CA, NV, UT, ID.
Texas has never really been known for its geothermal energy, but that is about to change. Back in the 1970’s and early 1980’s there was a geothermal - geopressure resource assessment done.
From those studies it was determined that there were bands of higher temperatures in shallow aquifers following the geologic fault trends and geopressure existed in the gulf coast region.
The data was from city water wells, some oil and gas wells, and spring locations. What we know now is that the deeper resource is much bigger then what they predicted. The deep Oil and Gas drilling then is now considered shallow. Wells are drilled today to 20,000 ft in some area. Plus the numbers of wells drilled is enormous - into the hundreds of thousands.
What we know today is that places without specific geopressure or high temperatures, most likely have booth here in S. TX. (Explain the pink, blue dots, brown area on map). But from the study done in the 1970’s, the Department of Energy (DOE) was enthused enough to build a geopressure plant in Brazoria County (North of Corpus Christi). It was the only geopressure plant ever built in the US. The plant ran for 6 months in 1989-1990, was deemed successful, produced about 1 MW of electricity from the geopressure and natural gas, and shut down. They let the geopressure well run for a couple more years to see if the pressure would diminish, but it did not.
The cost of oil and gas was so low then that the geopressure could not compete at about 11cent/kw hour. Today, that is different. There is still plenty of geopressure and high temperatures still in the Earth waiting to be turned into electricity.
In S. TX oil and gas wells are reaching temperatures in the 300 - 400 ?F range as they pump waste fluids up with the oil and gas. As shallow as ~10,000 ft the temperatures here are over 200?F. As you can see on this map of Texas, in other areas, they reach that temperature at twice the depth. You are sitting in an area prime for geothermal development.
So what can you do with 200?F waste fluid from oil and gas wells? Right now it gets trucked off or reinjected into a well and considered a waste fluid … much to the dismay and cost of the
producer. Using this chart showing the MW capacity for 1000 gpm of waste fluid with various temperatures, at 210?F input it becomes about .5 MW of electricity. If the input temperature is 325?F - much more common for this area - the output is about 2.5 MW of electricity. Now this can vary with the amount of fluid flow into the system, and it can also increase if there is geopressure and along with that natural gas. Thus here in South Texas a high flowing well may be capable or producing between 4 - 10 MW of electricity!
Using just the current 2004 levels of waste water produced in wells in Texas, there was over 12,000,000,000 barrels of waste water produced. Using that same chart, if on average the fluid was 210?F then Texas is capable of generating over 400 MW of electricity. If the average temperature is closer to 325?F then Texas can produce over 2000 MW of electricity. Combining the entire Gulf Coast the amount varies from 1000 - 5000 MW depending on temperature and flow rates. You can imagine how excited the Department of Energy is when we show them numbers like this. Remember that the entire US Geothermal power plant production is currently 2800 MW. Texas alone could also most double that amount.
If we look at produced fluids across the Country, Texas and Oklahoma have some of the highest amounts of waste fluids being produced. Wind power in Texas has over taken California as the highest producer, Texas could potentially become the highest geothermal producer, over taking California in this also.
What are the actual Texas field conditions?
? We have wells with >300?F at 15,000ft or less
? There are hundreds of 1000s of wells, many of them close together so the fluids could be
combined into a central production site.
? We have existing infrastructure of powerlines, roads, pipelines, well knowledge from
? We have off shore platforms that could also be using similar technology.
Direct costs for Development
? Build a mini power plant - 250kw is about the smallest currently available.
? Refacture some of the wells to increase fluid production (oil and gas wells are designed
to limit fluid flow of water.
? Drill a reinjection well if not already using one.
? Connect multiple wells with a pipeline if low flow.
? Chemicals added to fluid to prevent precipitates forming when temperatures are dropped.
If wells are producing high volumes of fluid flow, then oil/gas companies will usually shut down
the well even though there are still resources in the ground to extract. Thus this would extend
the life of a field.
It is expected that a conversion to a geothermal electrical production could keep a well flowing
for an additional 20 - 40 years. The original systems in California were thought to last 30 years.
They are now into 40 years. The Geothermal Industry has many years of knowledge to share.
The geothermal binary plants look something like this. This is a 5 MW system in Nevada.
Notice the lack of pollution from it. The new smaller systems can be transported on the back of
a truck and moved from well to well as needed.
So what does it take to make this happen?
? Temperature, pressure, and flow rate of wells
? Owner of Geothermal-Geopressure Mineral Rights
? USDA Rural Renewable Project
? GeoPowering the West Grant for Pilot Project
? Renewable Energy Investment Companies
? Choose company – ORMAT, United Technologies – Carrier, Encore Clean Energy,
Deluge, or ACES -= a middle man company.
? Negotiate a power purchase agreement with the utility
? Determine REC (Renewable Energy Credits) As I mentioned in the beginning of the talk, Geothermal is a good bridging technology because it
is always on. The power plants in Western US have a 90 - 95% production rate with down time
only for maintenance. This makes it comparable to a wind farm of ? bigger.
The SMU Geothermal Lab is responsible for outreach and networking with those interested and
working in geothermal in Texas. We are a group who does not want to be just a research -
computer lab. We are here to work with others to get geothermal up and going in Texas.
Now take a minute and think about people you know who could use geothermal energy, and plan
to talk with them this week. Let them know about our SMU Geothermal Lab program.