From Underperforming to Unmatched
What repowering Lightning Dock means for the future of geothermal power
Photo by Nils Caliandro / Zanskar
May 28, 2025
By 2024, most of the industry had given up on the Lightning Dock Geothermal field in southwest New Mexico. But we saw an opportunity to prove a big idea: that even declining conventional geothermal fields still hold enormous potential.
Today, less than a year from Zanskar’s acquisition, Lightning Dock is home to the most productive pumped geothermal well in the U.S. and quite possibly the world. With just one well, we’re now powering the entire 15 MW plant and setting a new bar for conventional geothermal in the U.S.
This isn’t just a comeback story for one plant; It’s a glimpse into the future of geothermal.
We believe Lightning Dock is one of hundreds to thousands of overlooked geothermal fields sitting on enormous latent potential.
What we achieved here wasn’t a one-off. It was the result of a repeatable, deliberate, data-driven approach that we’re now applying to the next sites, and the next after that.
In part one, we explained why we bought the Lightning Dock Geothermal field and how we hoped to deliver more power at cost using today’s best drilling technologies and next-gen computational geoscience models. This post is about what happened next.
Having since completed construction of the pipeline and auxiliary equipment, we are now pushing new electrons to the grid—less than 12 months from acquisition—and putting Zanskar into a category of its own as the only geothermal startup to be operating a utility-scale geothermal power plant in the USA today.
The numbers speak for themselves:
35% faster drilling than even the fastest of all prior wells drilled on site
75% reduction in surface infrastructure costs
3x net output and restoring gross generation back to plant nameplate ~15 MWe
Record-breaking flow rates and heat content that outperform comparable wells in the Western U.S.
Let’s dive into the details.
1. Drilling >35% faster using oil and gas drilling best practices
To cut through 8,000+ feet of hard and complex geology, we utilized polycrystalline diamond compact (PDC) drill bits—bits widely deployed in the oil and gas industry but originally developed for hard-rock, geothermal drilling. PDC bits are made of synthetic diamond – think, incredibly durable and thermally stable – making them ideal for the extreme conditions of deep drilling.
While common in oil and gas and increasingly so in enhanced geothermal systems (i.e., where the reservoir is created artificially), these bits are more rarely used in conventional geothermal due to higher upfront costs. At Lightning Dock (LDG), we targeted ~8000 ft, much deeper than average conventional geothermal wells (~2000-4000 ft), so we thought the reduction in drilling time should offset the higher upfront costs. And they did. The PDC bits proved to drill faster through both soft sedimentary and hard volcanic zones—cutting many days off our spud-to-depth timeline compared to legacy wells drilled at the same site without PDC bits (Figure 1). We saw improvements on the order ~130% faster drilling versus average drilling times without PDC bits at LDG, with fewer bit trips and faster drilling speeds. Note that the number of non-drilling days (the horizontal parts of the drilling days plot) has a major impact on total drilling days too, and that’s less related to PDC bits and more related to drilling and mitigation plans (e.g., lost circulation zones, casing and cement runs, etc.). Also note that consumable costs (drill bits, muds, cement, and steel) are a major cost component of geothermal wells, too.
Figure 1. Spud to measured depth (MD) for production or injection wells at Lightning Dock greater than 1000 ft deep. Well drilled without PDC bits are shown in grey, while the new production well drilled with PDC bits is shown in red. Note that the Eavor “Deep” test well is not included per confidentiality.
This wasn’t just about drilling efficiency—it was about enabling deeper, hotter wells that were previously not economically accessible. For geothermal to scale, especially in conventional geothermal fields that have been written off as “depleted,” going deeper is critical, and so are these kinds of cost reductions that enable that.
2. Precision steering: Why one degree of deviation changes everything
Low to moderate enthalpy geothermal production wells depend on mechanical pumps to lift hot brine to the surface at very high flow rates. Because of the high temperature of the fluids and the need to prevent premature flashing, the pumps need to live inside the well, typically within the first 500-1500 ft of the well. At Lightning Dock, that means using line-shaft pumps, which requires a near perfectly vertical near-surface section of the well to operate reliably. A small deviation in this near-surface section of the well can cause the pump shaft to rub on the sides of the well and to accelerate wear and tear; shortening the operating life of the pump itself.
So we did something rarely done in geothermal: we actively steered the well even while drilling straight down, using mud motors and directional drilling assemblies designed to keep the bit perfectly vertical without sacrificing speed. Our vertical section stayed within ~1 degree of deviation from vertical over the first 1,800 feet—well within tolerances for optimal line shaft pump performance (Figure 2), while being one of the fastest sections of our well drilled (Figure 1).
Figure 2. At left, is a plot of the “dogleg severity” (DLS), which is a measure of how sharply a wellbore is changing direction over a specific length — essentially, how “bent” the well is, of the first 1800 ft of our well (where our line shaft pump lives). The directional DLS data show that we kept the well from deviating more than ~1 degree per 100 ft, within our line shaft pump specifications. At right, is a plot of the cumulative deviation from vertical over the first 1800 ft of the well. Note that deviation is less than 15 ft south and 5 ft east.
Drilling this near-surface section of the well vertical but fast allowed us to keep our drilling costs down while keeping the home of our line shaft pump optimal for a long pump life.
3. We steered sideways to cut costs and shrink our footprint
Most geothermal developers follow a simple but expensive playbook: drill where the heat is, then build roads, pipelines, and power lines to connect everything. It works, but it's costly and environmentally disruptive. We flipped the script.
At Lightning Dock, we used modern directional drilling assemblies to deviate from vertical and “steer” the well over the course of ~5000 feet underground to our reservoir targets ~2000 ft away, enabling us to keep the wellhead within ~500 ft of the existing plant. That allowed us to hit high-potential target zones without needing to build out new surface infrastructure far from our existing surface infrastructure, saving us significant topside capital costs (CapEx; Figure 3).
Figure 3. Pipeline tie-in cost comparison between a theoretical vertical well located above our reservoir target that is more distal from the plant (“distal well”) and a deviated well located closer to the plant (“near well”). Note that the “near well” is our newly completed production well, while the distal well was not drilled.
The results are great: we estimate a ~75% reduction in surface CapEx for gathering pipelines (Figure 3), as well as a similar reduction in land disturbance compared to a traditional layout. This kind of directional flexibility has been standard in oil and gas for years, but now, we’re showing its impact in geothermal, too.
4. Predicting the unpredictable: Next-gen subsurface modeling
Subsurface geology is inherently uncertain. Even with detailed maps and temperature data, in geothermal fields, no two wells are exactly alike. That’s why we use stochastic resource modeling—a probabilistic approach that simulates thousands of possible subsurface scenarios, each honoring available data but reflecting a different “version” of reality that can fit those data (Figure 4).
This novel modeling framework, developed in-house by our geoscience and data teams, helped us plan for a wider range of drilling conditions we might encounter: including lost circulation zones (where drilling fluid disappears into fractures). We used these simulations to improve our drilling program—all before breaking ground.
Figure 4. One of thousands of simulations of the Lightning Dock geothermal reservoir that honors the geologic and well field data. Arrows denote flow paths and colored planes denote constant temperature isotherms. Note the red arrows denoting upwelling geothermal brines.
This is the first time such advanced modeling has been applied to a U.S. geothermal resource at this depth and scale. And the results were undeniable: fewer slowdowns, greater confidence in our approach, and improvements to our overall drilling program.
5. We designed for the industry’s largest pump, unlocking world-class flow
The final piece of the puzzle was matching the well design to new, bigger, high-efficiency geothermal pumps. Advances in line-shaft pump design now allow for larger diameters, deeper installation depths, and higher flow rates—all of which improve the economics of geothermal well fields, especially those relying on pumped production (low to moderate enthalpy reservoirs).
We engineered our well to accommodate these new, larger pumps, but we also needed the reservoir to be able to support that much production. Luckily, our gamble to oversize the intermediate casing (where the pump lives) paid off. After drilling into a network of open fractures within the reservoir and conducting a brief flow test, we measured a productivity index of ~50 gallons per minute per psi—enough to justify the installation of the largest geothermal line-shaft pump on the market, and to support the full capacity of the 15 MW-nameplate plant from just one well.
Our 14-inch line-shaft pump is now installed and running, and our new well is now piped into our power plant, and it has already ~tripled our plants output, alone. With this operating data, we can now compare our new wells production to production data across 18 operating geothermal well fields in Nevada (nearly all such well fields utilize pumps for production). Assuming a brine outlet temperature of 50 C (note that every plant has a slightly different brine outlet temp, depending on plant and brine conditions), we can model how many MWth are delivered to and utilized by these Nevada geothermal power plants, and compare them to our new well. This simple comparison shows just how exceptional our new LDG production well really is; providing more MWth than any operating well in Nevada (Figure 5). For pumped geothermal wells, it is the most productive geothermal well in the USA today.
Figure 5. Histogram of MWth delivered to geothermal power plants by geothermal production wells in Nevada, assuming a brine outlet temperature of 50 C. Data are from operating production wells during 2024 from the Nevada Division of Minerals. Shown in cyan is the new LDG production well as it is operating today.
This result not only confirms that Lightning Dock has untapped potential, it validates the second half of our thesis: that conventional geothermal has much more to give as we get deeper into their systems (remember that fault-hosted reservoirs are steeply dipping and not horizontal (!), therefore the deeper we drill, the farther into the belly of the system we get, and the closer to the hotter and more productive source).
Why this matters—for Lightning Dock and beyond
Lightning Dock is more than a one-off success. It’s a playbook we are ready to run again and again.
It’s a demonstration of what becomes possible when you apply today’s best drilling methods with a model-driven, data-rich targeting approach. Our five technical improvements added up to a single well that not only repowers an underperforming power plant, but moves the site’s limiting factor from subsurface resource to surface equipment, setting the stage for a likely expansion. That’s an incredible place to be.
The U.S. has hundreds of conventional geothermal sites that are overlooked, underutilized, or undervalued by the market. Lightning Dock is a signal to the entire energy industry that conventional geothermal is full of untapped promise and “forgotten” sites. With the right team, the right tools, and the right strategy, we can unlock gigawatts of clean, firm power quickly, cost-effectively, and sustainably.
