The Geothermal Energy Podcast

In this episode, we’re diving into the world of subsurface energy storage and geothermal power with Mike Eros, Chief Geoscientist at Sage Geosystems, where he’s pioneering geo-pressured geothermal and long-duration energy storage solutions. A former ExxonMobil subsurface expert, he’s now helping reshape how we tap into and store Earth’s heat.We explore how Mike transitioned from oil and gas into geothermal, the potential of geo-pressured systems for grid-scale power and storage, and Sage Geosystems’ groundbreaking projects reshaping the future of energy.Episode At-a-Glance* Storage + Geothermal: Sage merges long-duration pressure storage with geothermal heat extraction — delivering baseload + peaking power from the same well.* From O&G to Geo: Subsurface and drilling skills transition directly into geothermal; the biggest bottleneck is industry awareness, not ability.* EarthStore Pilot: First 3 MW project in Texas test results showing 70–75% storage efficiency with * DoD + Meta: Early customers want resilience (military bases) and 24/7 clean power (data centers).* Ormat Partnership: Taps into existing interconnections and Ormat’s equipment procuring capabilities — potentially reducing geothermal timelines from years to months.* Superhot Roadmap: Drill to ~16,000 ft, then frack deep to access 300°C rock for 10× power density using mostly standard oil & gas gear.* The Big Blockers: Organic-Rankine Cycle (ORC) turbine and broader equipment delays, interconnection queues, and lack of drilled pilots — not geology.⏱️ Timestamps (Notes below)[1:04] What got Mike into Geothermal? What was his career?[6:14] How do Sage’s Pressured Geothermal Systems work?[16:59] Why do we push the working fluid lung-like “huff-n-puff” operations in fractures?[21:06] What are the variables affecting the economics on your projects and the efficiencies on your storage projects? How can we make geothermal scale faster?[29:55] How does your team measure success? What are the longer term goals?[33:57] How is your team exploring using super critical CO2 as a working fluid?[36:15] What does it look like to build out a Sage site from ideation to creation?[40:59] How is your team engaging with different partners to get things done? [43:07] What are the risks and challenges your team is facing?[45:58] How does financing these different projects look?[49:54] How does your team work with different locales to help integrate projects with the community? What about other regulatory frameworks and environmental risks your team has to handle?[59:31] How are the steps back in supporting certain renewables like wind and solar impacting your team?[1:04:49] Lessons from working with San Miguel Electric Cooperative and ERCOT[1:11:07] How is your team approaching permitting in regards to your work in Altascosa County?[1:13:50] How has your team been approaching the grid interconnection process?[1:15:22] Digging in on the project with the US Air Force in Starr County.[1:19:07] How is your team developing and navigating partnerships with other military branches and the broader US military?[1:22:31] Sage and Meta’s partnership and how the team is approaching it.[1:25:59] Partnership with Ormat in the west.[1:29:29] Where do you see this partnership with Ormat going?[1:31:50] How have technological advancements in energy and drilling contributed to geothermal today?[1:40:08] How can we get communities and the government more excited about geothermal? What can they do to help?[1:45:18] What’s coming up for Sage?[1:48:23] If you had a magic wand, what problem in geothermal would you solve today?Additional Notes* Regarding 10 to 20% dilation - As an additional note, the larger the volume put in the ground compared to the percent that is brought out/smaller volumes allows the system to stay above fracture opening pressure. This maintains sufficient presssure in the fracture to keep the system open without proppant.* Regarding the mention of $0.065/kWh - Mike misspoke on the 10-12 cents. He meant that the costs would fall to the lower side with scale with a target of 6 to 7 cents per kWh. Additionally, for energy storage, the team is targetting Long-duration CAPEX of $2.25M/MW.🔬 Sage’s Tech: What Makes “Geo-Pressured Geothermal” Unique?If you’re new to Sage, their system is: part geothermal, part inverted pumped hydro.Instead of just drilling into hot dry rock and circulating water, they:* Drill mostly vertical wells, with a short deviation.* Create a lung-shaped fracture network beneath the surface.* Cycle fluid in a “huff-and-puff” pattern—injecting to build pressure, then releasing it to run a surface turbine. Where it fits in:* 8-12 hour duration long-term storage* Ideal for solar-heavy regions like Texas & California, as well as Australia* Cheaper + higher energy density than lithium-ion beyond 4 hour discharge durationsSo far, this has led to:* Round-trip storage efficiencies of ~70–75% (on par with lithium-ion and pumped hydro).* Low fluid loss (—critical for long-term operation and environmental confidence.This is different from some of the other well-known players as well:* Fervo Energy: Prioritizes inter-well fracture connectivity for heat extraction (not pressure cycling).* Quidnet: Works at shallower depths with “pancake fractures” for subsurface storage, not geothermal heat.* Exceed GeoEnergy: Aims for closed-loop systems using CO₂ as the working fluid. (Check out our episode with the founder, Tim Tarver, here)* Mazama Energy (and DOE superhot initiatives): Pursue ultra-deep drilling into 300+°C rock—potentially ≥10x power output. A future goal for Sage as well.Sage, in contrast, is finding a viable bridge: using standard drilling tech and tools from oil and gas to unlock deep baseload power and grid-scale storage.🧪 Project Highlights — More Than Just Pilot TalkOne of the most exciting things to note is how quickly Sage has moved from theory to real projects:✅ EarthStore #1 – San Miguel Electric Coop (South Texas)* 3 MW energy storage pilot project co-located with a coal plant with plans for 400 MW solar expansion* Targeting Q1 2026 grid interconnection with ERCOT* First-of-its-kind subsurface storage system using off-the-shelf turbines* 12-month delivery from drilling to facility commissioningWith this built, Sage now has a pad that could support 10+ wells and >50 MW of long-duration storage—all without the need for mountainous terrain, vast water imoundment, and long permitting times that traditional pumped hydro requires.🛡️ Department of Defense PartnershipsSage has leveraged their existing work to further build projects with the DoD.* Sage has completed geothermal feasibility study with UT Austin’s Bureau of Economic Geology (BEG) at Joint Base Ellington. (Hear more about the Bureau of Economic Geology wiht our episode with Ken Wisian (Part 1, Part 2)* They’ve been awarded $1.9M toward a real geothermal power demonstration.* Parallel work is now happening at Fort Bliss (Army) and Naval Air Station Corpus Christi (Navy).* Priority: “behind-the-fence” power resilience to ensure bases can operate even if the external grid fails.Thank you for reading The Geothermal Energy Newsletter! Subscribe for free to receive new posts and support our work.🧠 Meta & Ormat: Strategic Scale, Not Just ExperimentsSage isn’t just proving the tech—they’re anchoring it with serious partners:* Meta (Facebook)* Target: 4–8 MW geothermal by 2027, with paths to scale to 150 MW and beyond.* Location: east of the Rockies (think grid-challenged, heat-rich regions).* Goal: 24/7 clean power for hyperscale AI data centers.* Ormat Technologies* Why this matters: Ormat owns dozens of operating geothermal plants already connected to the grid.* This deal enables Sage to deploy their subsurface system into existing power sites—bypassing long lead times for interconnection and key equipment procurement.* Mike thinks this could cut their first full-scale geothermal project timeline from several years to as little as 12–18 months.🌱 Risk, Regulation & Water: How They’re Meeting Community ExpectationsGeothermal always raises good questions about water use and induced seismicity.Here’s how Sage is addressing those:* Water sourcing: Using non-potable sources, including ranch and industrial water; modeling even wastewater use in future systems.* Seismic transparency: Partnered with UT’s TexNet seismic network, run by the Bureau of Economic Geology to ensure independent monitoring.* Fluid loss: Maintaining 📊 Economics: What Moves the NeedleThe biggest costs in geothermal are:* Drilling and stimulation* ORC procurement (18+ month lead times)* Interconnection delaysBut Mike made it clear:✅ Pair geothermal + storage with solar → competitive LCOE: $60–70/MWh✅ Scale from a single-well pad to multi-well → drive down cost/kW✅ Bundle into confirmed PPAs → unlock project finance instead of venture equity🪄 Mike’s Magic Wand: More Drilling, Less ModelingMike’s #1 concern for geothermal right now? Funding.“You know, if I could instantly give all of the companies that have a brilliant idea, the money that they need to test, I would do it. There aren’t that many players on the field who actually [have] a drill ready proposal. I would do that immediately. Why beat around the bush? Let’s learn together quickly.”What’s missing:* Fast, catalytic funding to drill and prove commercial viability* Public support stalled since the 1970s (For a broader history of geothermal, read more here)* Most investors need to see more commercial successesBright spots:* Rising demand from data centers and utilities for 24/7 clean power* New Energy Secretary showing interest* A few successful pilots could unlock a wave of private capital🔗 Recommended Episodes* Tim Tarver (Exceed GeoEnergy) — Advanced geothermal drilling, fracking challenges, and water reuse.* Jen Wakeland (Beaver County, Utah) — Community engagement, rural development, and transmission planning.* Bill Heins (Getech) — Insurance products and de-risking geothermal projects in Europe.* Eric Bosworth (Eversource) (Part 1, Part 2) — Utility-led networked geothermal and lessons from the Framingham pilot.* Ken Wisian (Bureau of Economic Geology, Texas) (Part 1, Part 2)— Military applications of geothermal and energy security. This is a public episode. If you would like to discuss this with other subscribers or get access to bonus episodes, visit geothermalweekly.substack.com

Hello folks,Welcome back to Part 2 of our conversation with Eric Bosworth (watch part 1 here).Eric is the Manager of Clean Technology at Eversource, his journey spanning oilfield engineering, utility infrastructure, and emerging decarbonization technologies. Currently, Eric leads efforts to pilot and scale alternatives to fossil gas - including hydrogen, carbon capture, and (most relevant) community-scale geothermal.He draws on field experience in oil and gas, system planning expertise from utility engineering, and a customer-first approach to identify and deploy the best-fit solutions across Eversource’s portfolio. Most notably, Eric led the development and execution of the Framingham geothermal pilot - one of the first utility-owned thermal energy networks in the United States.🧠 Highlights* Framingham's real-world data shows strong winter performance and customer satisfaction, even in extreme cold.* Scaling = viability: Networked geothermal shows falling marginal costs with larger customer bases.* Magic wand wish? Eric would create more drilling firms in the Northeast tomorrow; workforce gaps are the biggest blocker to scale.* Beyond boreholes: A future “thermal marketplace” could trade heat between buildings, pools, wastewater, and more.🔍 Where to Learn More* Project updates & background: eversource.com/geothermal* Find Eric on LinkedIn to connect and collaborate* Industry groups: Heat pump alliances, geothermal networks, utility decarbonization forums This is a public episode. If you would like to discuss this with other subscribers or get access to bonus episodes, visit geothermalweekly.substack.com

In this episode, I sit down with Michael Brookman, a seasoned physicist whose career has spanned from nuclear fusion research to pioneering advancements in geothermal energy. Currently serving as a Senior Radio-Frequency (RF) Engineer at Quaise Energy, Michael focuses on leveraging RF technology to revolutionize geothermal energy production.Episode Highlights:* Michael's Journey: From his early days studying physics at the University of Wisconsin to his pivotal roles in nuclear fusion projects across the U.S., including his tenure at General Atomics and Commonwealth Fusion Systems.​* Transition to Geothermal: The motivations and insights that led Michael to shift from fusion to geothermal energy, emphasizing the potential for immediate impact, reduced cost, and scalability.​* Innovative Drilling Techniques: An exploration of how Quaise Energy is adapting gyrotron technology—originally used in fusion reactors—to drill deep into the Earth's crust using millimeter waves, enabling access to superhot geothermal resources. ​* Overcoming Challenges: A discussion on the technical and regulatory hurdles in advancing geothermal technology and how Michael's team is addressing them.​Join us as we delve into the intersection of fusion and geothermal technologies and discover how innovations in one field can catalyze breakthroughs in another.Thanks for reading The Geothermal Energy Newsletter! Subscribe for free to receive our new posts and podcast weekly!🧭 Michael’s Journey: From Shotgun Accident to Fusion Physicist* Survived a childhood hunting accident, discovered fusion through video games like MechWarrior and Civilization.* Studied physics at University of Wisconsin (working on the Madison Symmetric Torus), then UT Austin for PhD (with Ken Gentle’s group)* Specialized in RF systems and gyrotrons at General Atomics (working on their tokamak, DIII-D) and Commonwealth Fusion Systems.🔁 Why the Leap from Fusion to Geothermal?* Quase’s 2030 timeline is half that of fusion’s long timelines (2035+).* Geothermal works now, and Quaise aims for $75/MWh vs. fusion’s projected $140–$500/MWh.* Inspired by How Big Things Get Done—modularity is key to scaling - many gyrotrons making many wells.💡 What is Quaise Doing?Goal: Unlock superhot geothermal by drilling with millimeter waves.The Tech:* Gyrotrons generate high-power millimeter waves that can drill through rock; basically they’re laser beams.* Current testing shows drilling to be at a rate of a meter per hour.* Power is transmitted through corrugated waveguides to vaporize rock—no conventional drill bits needed, avoiding typical wear and tear, bit trucking.* Uses compressed air to cool and clear debris from the hole.* See a video of the drilling in action here. Learn more about the research here.If you’ve read this far, you’ll like our future posts too : )🔬 Tech Challenges and Evolution* Managing arcing (essentially current hopping about the system in potentially damaging ways) in high-power systems (shutoff within 10 microseconds).* System resilience: Quaise’s protection systems and control software allow for long, stable runtimes—orders of magnitude longer than fusion pulses.* Powering the system: Needs ~3 MW input for 1 MW output (~40% efficiency). Can use diesel generators or grid, all containerized on trucks.* Manufacturing bottleneck: Gyrotrons are custom-built. Quaise works with Microwave Power Products to scale production.⚙️ Why Superhot Rock?* Electricity generated by heating water, putting it through a turbine, extracting power from the temperature & pressure drop - Higher input temperatures and lower output temperatures → higher thermodynamic efficiency* More energy per well = higher power density = more competitive with fossil and nuclear.🧱 Barriers to Scale* Permitting takes 12+ months—slower than oil & gas (* Goal: modernize geothermal permitting to match its competitors.📈 What’s Next?* Near-term: Field deployment west of Austin, TX using 1 MW gyrotrons in truck-mounted systems.* Target: Delivering power in 5 years on the West Coast at scale; global expansion beyond that.* Long-term goals:* Scaling 1 MW gyrotrons (faster, deeper drilling) and drilling into hot basement rock (granite, basalt).* Lower cost per megawatt-hour to compete with all major energy sources✨ Magic Wand Wish:Fix permitting. It’s the single biggest blocker to faster geothermal deployment.📚 Learn More🔗 https://www.quaise.energyRemember to:And follow us on your favorite platforms in addition to sharing your thoughts, questions, and recommendations for future guests on:* Substack* Spotify* Apple Music* Amazon This is a public episode. If you would like to discuss this with other subscribers or get access to bonus episodes, visit geothermalweekly.substack.com

In Part 2 of my conversation with Dr. Ken Wisian, we discuss the challenges and opportunities facing geothermal development in the U.S.We cover why geothermal has historically lagged behind wind and solar, how federal and state programs are changing the economics, and what it will take to move from exploration to execution. Topics include Department of Defense projects, geothermal storage, long-term technical risks, and how public funding is shaping the next wave of deployment.🔍 Topics covered:* Why geothermal investment has lagged wind and solar — and what’s changing now* The importance of derisking early-stage projects through mapping and modeling* The Department of Defense’s evolving role in geothermal:* Feasibility studies at Ellington Field, Corpus Christi, and Fort Bliss* Behind-the-meter models and long-term resilience* Tradewinds geothermal portal (see more on recent developments here) and SBIR/STTR pathways* Subsurface energy storage:* The Sage–San Miguel project in Texas* How shallow systems store pressure/heat and complement renewables* Use cases for turning intermittent generation into baseload* Long-term technical risks and research priorities:* Cycling effects on fractures and elastic rock behavior* Geochemistry, mineral scaling, and fluid/rock interactions* Materials science and thermoelectric research* Mentioned Researchers/Research:* Ken Wisian* FORGE Initiative* Eric van Oort* Mohamed Shafik Khaled* Shuvajit Bhattacharya* The role of machine learning in geothermal:* Merging disparate subsurface datasets* Downhole diagnostics and predictive modeling* How aerospace, high-temp electronics, and defense R&D could transfer into geothermal* Ken’s advice for navigating SBIR, STTR, and federal grant programs* Why interdisciplinary teams — blending engineering, geology, economics, and policy — are key to project executionIf you’re building geothermal solutions or considering a project, this episode offers a practical look at what’s working, what’s coming next, and where developers can plug in.PS - if you’d like to check out Part 1, see below: This is a public episode. If you would like to discuss this with other subscribers or get access to bonus episodes, visit geothermalweekly.substack.com

Geothermal energy is poised for a revolution, and it all starts beneath our feet. Bill Heins, a licensed professional geologist with over 35 years of experience, joins the show to break down the challenges and opportunities in geothermal drilling and exploration. From his time at ExxonMobil to his current work at Getech and Ammonite Resources, Bill has tackled complex subsurface problems across the energy sector.In this episode, we explore the role of advanced modeling, geophysical techniques, and risk analysis in unlocking geothermal potential, how lessons from oil and gas are driving innovation, and why deep drilling and data-driven exploration could be the key to scaling geothermal as a reliable energy source. This is a public episode. If you would like to discuss this with other subscribers or get access to bonus episodes, visit geothermalweekly.substack.com