Fresh off the heels of our successful repowering of Lightning Dock Geothermal, we’re excited to announce another geothermal discovery, this time at a greenfield site in northern Nevada called “Pumpernickel”. This is a site long known to the industry, but which has been written off for not being capable of generating utility-scale power. But by leveraging AI-augmented well targeting, we discovered ~280°F heat at just ~2500 ft depth, surpassing prior estimates and confirming viability for a conventional well field power development. Advanced well field targeting with custom AI tools is the exact same playbook that repowered Lightning Dock earlier this year, and is our pathway forward for scaling conventional geothermal power. Read on to learn more about our Pumpernickel discovery.
Zanskar was founded with the belief that the U.S. has far more geothermal potential than currently utilized, but that we didn’t yet have the tools to systematically, and not accidentally, uncover them. Zanskar is showing how porting over modern geoscience and machine learning into geothermal will make up a core toolkit needed to make geothermal power predictable and scalable. For the last 5 years, we have done the hard work of building integrated geology, AI, and exploration tools, making predictions, and testing those predictions in the field. In the early days, we focused on shallow predictions that we were able to cheaply and quickly test. But this year, we started to make deeper predictions, and started taking million dollar drilling bets.
We first tested this theory with deep drilling at Lightning Dock Geothermal (LDG), where we used data-first, AI-enabled modeling to help target the deeper resource to revive a legacy field that industry insiders had written off and to deliver utility-scale power quickly and cost-effectively.
Next up, applying our deeper targeting models to a greenfield site, one with a known potential resource that had been written off. Located in Humboldt County, Nevada, the site has been called a few names over the years, “Hot Springs Ranch”, “Tipton Ranch”, and “Pumpernickel”. And for now, we’re sticking with the name Pumpernickel (named after its location in Pumpernickel Valley, Nevada).
Zanskar has just finished a drilling campaign at Pumpernickel, a site with sparse data, a spotty exploration history, and a lot more uncertainty than LDG. And we’re happy to announce that once again, we struck steam.
Pumpernickel isn’t just hot. It is hot and has permeability (the other equally important ingredient for conventional well fields). Permeability is equally as important because it saves you all the costs associated with unconventional well fields (e.g., drilling and completing long horizontal laterals and then fracking). And based on this first drilling campaign, we’ve proven Pumpernickel can support a low-cost, conventional well field. And importantly, our models led us straight into the resource, without spending tens of millions in exploratory drilling costs to find it or prove it.
Expedient and accurate exploration is what geothermal needs to reach its potential. In the last 10 years, only 1-3 greenfield sites in the U.S. have had discovery wells of this caliber (hard to know exact number as info is not public, but it is a very small number), and only 1 greenfield power plant has been built and put online (Tungsten Mountain). The industry has to move faster and Zanskar is on a mission to do just that. Accuracy means lower costs, shorter timelines, and more confidence going into development. And while we love to see all the innovation happening in how to access deeper or hotter rock (advanced drilling methods), geothermal energy can’t scale if we don’t solve the equally critical challenge of knowing exactly where to drill.
LDG demonstrated that we can increase the net generation at already operating geothermal power plants. Pumpernickel proves that we can open up entirely new greenfield sites to power development, even those with a few skeletons in their closets (Pumpernickel has had a few explorers come its way prior to Zanskar). Together, they are part of a repeatable, high confidence approach to finding and scaling geothermal. And with dozens more similar geothermal anomalies already found and in the queue, LDG and Pumpernickel are just the beginning. Let’s dig into what we discovered and how we did it (again) at Pumpernickel.
Below is a brief memo on finding temperature, finding permeability, and testing our stochastic reservoir modeling approach at Pumpernickel. A few key highlights before diving in:
maximum equilibrated temperature of ~280 F at ~2500 ft measured depth
multiple loss zones and artesian flow zones correlated to highly fractured damage zones (telltale signs of exceptional permeability)
enough heat-in-place at <2 km depths to support a phase I 20 MWe development (minimal size needed to economically justify development)
Proving temperature
In the world of thermal power plants, plant inlet temperature is a key physical property that controls both the thermal-to-electric efficiency and net power generated. Geothermal power plants are indeed thermal power plants, but they generally operate at lower plant inlet temperatures than their thermal power plants peers (coal, nat gas, and nuclear). For what are called “moderate enthalpy” geothermal fields, like those that exist at shallow depths (1000-5000 ft) in the intermountain west (e.g., Nevada), the median production well delivers ~292 F inlet brines to geothermal power plants (NDOM, 2024; Figure 1).
Figure 1. Histogram of the average inlet brine temperatures per production well in Nevada during 2024 (NDOM, 2024).
At Pumpernickel, we first targeted <3000 ft depths, and therefore needed to encounter >230 F, to assure ourselves that Pumpernickel could produce close to average Nevada inlet brine temperatures (~290 F) with initial phase 1 production well field depths (<8000 ft). Our mean stochastic model predictions suggested we’d encounter ~240 F temps at ~3000 ft, and so we were optimistic heading into the drilling campaign.
In our first exploratory hole we encountered difficult drilling conditions that prevented us from reaching our target and also prohibited us from even getting logging tools to the bottom of the hole (hot, unstable drilling conditions can be a great sign of a big geothermal reservoir but make drilling difficult!). Our second exploratory hole, however, did reach its target despite encountering multiple total loss circulation zones and proved a maximum equilibrated temperature of ~280 F at ~2500 ft (Figure 2). What is most promising about this well is that these electric-grade temperatures are correlated with one of several, thick, heavily fractured damage zones.
As you can imagine, proving ~280 F at only ~2500 ft is a very exciting moment for Pumpernickel and for our team. These results mean we can find at least the same reservoir brine temperatures that the median (~290 F) Nevada geothermal production wells produce by targeting future production wells >2500 ft into the resource (fault-hosted geothermal systems cool off as they convect upwards from greater depths). Already finding ~280 F brines at such shallow depths is really, really exciting, and it easily unlocks an initial 20 MWe phase development.
Figure 2. Lithologic and temperature logs from the second of our two exploration holes. Note the ~280 F measured temp at ~2500 ft depth.
Proving permeability
Permeability is a geologic term that defines a rock's ability to facilitate fluid flow. In the world of fluid minerals (e.g., oil and gas and geothermal), permeability dictates whether a well flows, and therefore, is commercial. This is especially true in geothermal, where at ~290 F, our fluids are much less energy dense than hydrocarbons. Since they’re less energy dense, we need to flow more to access equivalent amounts of energy. At ~290 F, that gap is almost two orders of magnitude (~700 kJ / kg vs ~40,000-50,000 kJ / kg), meaning that for every unit of flow of hydrocarbon, geothermal has to flow almost ~100 times more volume to get a similar amount of energy. In conventional geothermal reservoirs, this is very doable, but for enhanced geothermal reservoirs (EGS), this is the great challenge– artificially making otherwise impermeable rocks flow at commercial rates!
Conventional geothermal reservoirs are almost always hosted in heavily fractured rocks with inherently high permeability. Therefore, fractured rocks are our drilling targets. This is what makes drilling great conventional geothermal wells such a tricky thing, the bigger and badder a geothermal resource, the thicker and more heavily fractured its reservoir rocks are, and the more technical the drilling.
At Pumpernickel, we encountered multiple lost circulation zones and artesian flow zones that correlated with thick (>60 ft) damage zones (Figure 3) that made our drilling teams work hard!
Figure 3. At right is an image log with a flat and 3D wellbore representation revealing fracture zones along the wellbore wall and at left is the rock core from the same depth interval.
Encountering total drilling losses that correlate with heavily fractured intervals documented by image logs, rock core, and equilibrated temperatures of ~280 F proves reservoir-grade permeability and temperature in one beautiful geothermal bundle.
Testing stochastic reservoir modeling
We talked about our probabilistic modeling approach in our last blog post on Lightning Dock and how it helped us better plan our well’s trajectory and design. We took the same approach at Pumpernickel, but with much less prior well field data, as Pumpernickel only has a few legacy geologic datasets and shallow exploration holes in and around it. How would our stochastic modeling approach work at a more data sparse geothermal site?
Using a similar workflow as Lightning Dock, we modeled a range of geological scenarios that fit prior data and then recommended drilling targets based on maximizing the likelihood of two key criteria: temperature and permeability (Figure 4). This is a perfect problem for large compute, exploring a large, but bounded search space for two parameters. In the end, we drilled two of our best recommendations considering surface constraints. The first encountered difficult downhole conditions (hot and very unstable formations associated with intense fracturing) such that we couldn’t reach our target. The second hole reached our target and encountered electric-grade brine temperatures and permeability.
Figure 4. Schematic of how our models explore the search space for maximum temperatures and permeability.
Why this matters – for Pumpernickel and beyond
As we said about Lightning Dock, we’re not looking for one-off successes. We build tools to make conventional geothermal a repeatable, predictable, and financeable energy source, unlocking a path forward to reduce the levelized costs of geothermal and make it competitive with other forms of less clean firm energy. We find value in sites that are brand new, neglected, or underdeveloped, to get geothermal megawatts on the grid today, next month, and next year. That means building and using tools that make otherwise stranded or overlooked geothermal sites commercially viable. Pumpernickel is the next data point showing that our approach is viable and working.