In Texas, Could Geothermal be an “Off Ramp” for Drillers?
January 28, 2023
The Hill:
Four years of drilling for energy deep underground would be enough to build Texas a carbon-free state electric grid, a new study by an alliance of state universities has found.
The state’s flagship universities — including the University of Texas at Austin, Rice University and Texas A&M University — collaborated with the International Energy Agency to produce the landmark report.
It depicts the Texas geothermal industry as a potential partner to the state’s enormous oil and gas sector — or an ultimate escape hatch.
In the best case, the industry represents “an accelerating trend” that could replicate — or surpass — the fracking boom, said Jamie Beard of the Texas Geothermal Entrepreneurship Organization at the University of Texas.
“Instead of aiming for a 2050 moonshot that we have to achieve some scientific breakthrough for — geothermal is deployable now,” Beard said. “We can be building power plants now.”
The authors stressed that the geothermal, oil and gas industries all rely on the same fundamental skillset — interpreting Texas’s unique geology to find valuable underground liquids.
In this case, however, the liquid in question had long been seen as a waste product: superheated water released as drillers sought oil and gas.
About “44 terawatts of energy flow continually out of the earth and into space,” said Ken Wisan, an economic geologist at the University of Texas.
“Rock is a great heat battery, and the upper 10 miles of the core holds an estimated 1,000 years’ worth of our energy needs in the form of stored energy,” Wisan added.
Most of the state’s population lives above potentially usable geothermal heat — as long as there’s a will to drill deep enough.
Superheated trapped steam that is nearly 300 degrees Fahrenheit — the sweet spot for modern geothermal — is accessible about three to five miles below the state capital of Austin and 2 1/2 to 3 miles beneath its most prominent city of Houston, the report found.
The report casts geothermal energy as a possible way out of two energy paradoxes.
The first concerns the state’s beleaguered electric grid. The isolated system has been repeatedly driven nearly to the point of blackouts by extreme heat and cold, as well as the relentless, demanding growth of the state population.
According to the Energy Information Agency, the state’s substantial renewable potential is meeting part of this growth: Texas leads the nation in wind energy and has near-leading solar potential.
But the Republican-dominated legislature has been anxious over how to establish “baseload” power — the minimum demand of the grid — as well as readily “dispatchable” energy resources.
Several state Republican leaders and the state Public Utility Commission have pushed for the construction of new coal, natural gas and nuclear plants to provide round-the-clock power.
Despite their different forms, these “thermal” options rely on the same fundamental trick. Whether powered by coal or uranium, most modern power plants use the fuel boiling water to create steam, which spins an electromagnetic turbine, creating an electric current.
Geothermal offers another cheaper and more climate-friendly solution: start with steam, which exists in superheated pockets miles below the earth’s surface.
Rebuilding the state a power system on a base of geothermal energy would give “the same performance as gas, coal or nuclear” at a lower cost, said Michael Webber, a professor of clean energy at the University of Texas.
But Webber said it would also do so “without the same fuel reliability problems.”
During Texas’s February 2021 winter storm, Webber noted, natural gas and coal supplies froze — which wouldn’t have been a problem with geothermal.
The industry also gives Texas a means of transitioning its flagship industry off planet-heating products like oil and gas.
The International Energy Agency declared in May 2021 that for the world to meet global climate goals, new oil and gas production would have to cease, as The Hill reported.
Since that warning, global oil and gas production has continued to increase — and is on track to hit record levels in 2023. But Tuesday’s report, which the global energy watchdog helped produce, suggested that geothermal energy could be a politically palatable offramp for the industry.
The report found that if the Texas drilling industry drilled as many geothermal wells as it currently does oil and gas, about 15,000 per year, the state could run itself off geothermal power by 2027.
Webber said that would free up natural gas to replace more carbon-intensive coal in other locations, from Indiana and West Virginia to India and China.
With Texas’s needs at home met by cheap geothermal, “oil and gas would have more molecules to sell to other people probably for more money,” Webber added.
Beard said that the oil and gas industry offers a potential model for how the geothermal industry could rapidly expand.
“The very beginnings of oil and gas, they were picking up oil and gas off the surface of the ground and puddles,” she said, in an analogy to the geothermal industries in highly geologically active Iceland, with its frequent eruptions.
But eventually, the fossil fuel industry began to drill and advance. “And then sure enough, now we’re drilling in 5,000 feet of water offshore with billion-dollar, technically complex wells,” Beard said.
“And that is what we could do for geothermal, right?” she said. “We could go for the deepwater of geothermal, and we can do it in the next few decades.”
The Future of Geothermal in Texas:
There are three major areas of technology development in scalable geothermal concepts, otherwise known as ‘Hot Dry Rock’ geothermal, and many of these advancements are happening here in Texas. By scalable, we mean geothermal systems that could feasibly be constructed anywhere in the world, and that are not dependent on the presence of specific subsurface conditions, like rock type, porosity, and the presence of water. (See Chapter 9)
Engineered (or Enhanced) Geothermal Systems (“EGS”) are man-made reservoirs, created by the use of hydraulic fracturing techniques to provide pathways through the rock through which fluids can be pumped. Those pumped fluids become heated while they circulate in the subsurface, and are produced to the surface, where they power turbines to generate electricity.
Closed-Loop Geothermal Systems (“CLGS”), also referred to as Advanced Geothermal Systems (“AGS”), are also man- made geothermal reservoirs like EGS, but they differ in that they operate in a closed loop with no fluid exchange in the subsurface, and they do not utilize hydraulic fracturing.
There are, however, several technology challenges associated with CLGS, including high drilling cost associated with well development, and the need for more advanced and higher temperature drilling technologies to develop the systems in deeper, hotter reservoirs.
The use of CLGS allows for utilization of non-water Working Fluids, such as supercritical CO2, which increase heat harvesting at lower temperatures, a benefit of CLGS.
Finally, there are Multi-System Hybrids, like CLGS/EGS combinations, for instance, that couple multiple geothermal system types and features into one system. Entities are working to test and deploy scalable geothermal concepts such as these in the State currently. (See Chapter 1)
Aside from electricity production, several of these geothermal concepts can be used for “Direct Use” applications, meaning utilization of produced geothermal heat to directly heat and cool buildings, or for applications that utilize low enthalpy heat, such as agriculture, manufacturing, food processing, and industrial processes. These low enthalpy applications offer a significant opportunity for geothermal to contribute to heat decarbonization of the built environment.
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