What we normally think of for geothermal energy
I have long been fascinated by the untapped potential of geothermal energy. As a spelunker in my youth, I became aware that the temperature of the Earth down below 20 or so feet was constant at around mid 50 degrees Fahrenheit. I always found this to be cool (especially in the hot summer when we usually went caving). This was in the late 70’s during the energy crisis. Everyone was talking about alternative energy sources and I decided to write my big class research paper on energy alternatives. Also, the national debate topic for that year was about alternative energy plans for the nation and I did a lot of research on wind, solar, biomass, water (dam/wave), nuclear and geothermal alternatives to oil and gas.
In those days it was more about energy independence from OPEC than it was about clean energy. Maybe it was due to my caving experiences, but I became fascinated with geothermal. It just seemed to make too much sense. Here we were sitting atop a huge furnace in the core of the earth providing all the energy we could ever want and for some reason we hardly took advantage of it.
What is geothermal energy?
Fun fact: The molten core of the Earth, about 4,000 miles down, is roughly as hot as the surface of the sun, over 6,000°C, or 10,800°F. That’s why the geothermal energy industry is fond of calling it “the sun beneath our feet.” The heat is continuously replenished by the decay of naturally occurring radioactive elements, at a flow rate of roughly 30 terawatts, almost double all human energy consumption. That process is expected to continue for billions of years.
The ARPA-E project AltaRock Energy estimates that “just 0.1% of the heat content of Earth could supply humanity’s total energy needs for 2 million years.” There’s enough energy in the Earth’s crust, just a few miles down, to power all of human civilization for generations to come. All we have to do is tap into it.
Tapping into it, though, turns out to be pretty tricky.
It has been a long slow history of geothermal research and advancements. Early development was only for the most obvious and cheapest ways of capturing energy from areas where the earth’s crust wasn’t thick and the heat was escaping as geysers (as pictured in this diary) and warming bodies of water as hot springs. The first commercial plant to take advantage of one of these areas is just up the state from me and just north of Santa Rosa in Geysers, California. There are more than 60 commercial plants in operation today but I have been disappointed that we haven’t done more to advance this technology and take advantage of the potential as it can provide on-demand clean energy without needing large battery storage systems to support it.
While I have maintained my enthusiasm over the decades for geothermal energy, I admit to not having been keeping on eye on the latest goings on in the field, which is why I was pleasantly surprised to come across this Vox article entitled, Geothermal is poised for a big breakout. It is a nice read and provides an overview of geothermal energy along with the historic development and the latest research, technology and demonstration systems being implemented.
I got really excited by the work being done on what is being termed Advanced Geothermal Systems or AGS. It is the latest and greatest technology and the leader in the field seems to be a company called Eavor. From their website which explains the technology better than I could:
Eavor (pronounced “Ever”) is a technology based Energy company led by a team dedicated to creating a clean, reliable and affordable energy future on a global scale. Eavor’s solution (Eavor-Loop™) represents the world’s first truly scalable form of clean baseload power. Eavor achieves this by mitigating or eliminating many of the issues that have hindered traditional geothermal solutions. As a completely closed-loop system, Eavor has the advantage of no fracking, no GHG emissions, no earthquake risk, no water use, no produced brine or solids, and no aquifer contamination. Eavor instead circulates a benign working fluid which is completely isolated from the environment in a closed-loop, much like a massive subsurface radiator. This “radiator” simply collects heat from the natural geothermal gradient of the Earth via conduction, at geologically common and drilling accessible rock temperatures. Unlike traditional geothermal, Eavor isn’t burdened with exploratory risk or limited to niche geographies through the need for highly permeable aquifers at volcanic-like temperatures. Unlike wind and solar, Eavor-Loop™ is not intermittent, but instead produces much-needed reliable baseload power. Unlike other forms of power, Eavor is benign enough to literally fit in someone’s backyard. Eavor is the solution the world has been waiting for.
What I love about this technology and other geothermal projects and research is that it provides a transition path for the big oil and gas companies to leverage their drilling experience into making advances in this field. I know many of my fellow environmentalists may think, “screw the oil and gas companies” to which I agree as they’ve been polluting our land, air and water for decades without concern. However, as we know, these big companies wield lots of political power across the political spectrum and many Americans, towns and small businesses rely on them for employment. They also have the money and skill set to help advance the drilling technology and to refine the processes. It seems like a big win for both environmentalists and those who support the drilling industry.
What does everyone think? I’d love to hear some different perspectives on this especially from anyone who has engineering experience in this or related fields. Is this feasible? Can it be cost effective? Can it scale? What are the limitations?
