Energy transitions are often talked about in terms of infrastructure, new technologies, and ambitious climate goals. But for the people living in the neighborhoods where these changes happen, the transition feels much more personal. It shows up in monthly energy bills, comfort at home, job opportunities, and the chance to have a voice in decisions that shape their future. Meaningful community engagement is not optional; it is essential to making energy transitions successful.

In Sonoma and Mendocino counties, this transition is taking shape through the GeoZone, an initiative led by Sonoma Clean Power (SCP) to develop up to 600 MW of geothermal energy. As a community-owned, not-for-profit power provider governed by a board of local elected officials, SCP answers directly to the people it serves. That accountability fundamentally shapes how the agency approaches engagement. The goal is not simply to secure permits, but to ensure projects reflect community priorities and help residents understand why energy choices matter. For example, regional outreach has helped build understanding of why solar alone cannot provide around-the-clock reliability, and why geothermal plays a critical role in a resilient clean energy system.

Geothermal development offers long-term benefits for the region, including reliable clean power, local workforce opportunities, new tax revenue, and protection against rising energy costs. Keeping those benefits local is a core reason why SCP has entered the geothermal space. Achieving that outcome requires early and ongoing public involvement so communities can help guide how projects evolve. For many customers, engagement also starts with understanding who Sonoma Clean Power is and why its name appears on their electricity bill. 

Public presentations and town halls have created space for transparency and dialogue with residents, local leaders, partners, and industry experts. Events in Santa Rosa, the largest city in SCP’s service area, and Cloverdale, near the GeoZone’s original interest area, drew strong participation and surfaced a range of perspectives and questions, from construction impacts to seismic monitoring. Beyond large public forums, SCP continues smaller, focused conversations with local organizations and community leaders, where consistent priorities have emerged: affordability, local jobs, and long-term reliability.

Community input has also helped shape SCP’s policy advocacy for responsible geothermal development. Two SCP-sponsored bills, AB 1359 and AB 531, have been signed into law, supporting more efficient and cost-effective development of new geothermal resources. Ongoing efforts focus on improving permitting, strengthening transmission planning, and lowering costs for customers. At the same time, SCP is working with technology developers, local agencies, and research partners to advance geothermal solutions that align technical innovation with community needs. 

As the GeoZone advances, it highlights a broader lesson for energy transitions everywhere: progress depends not only on technology, but also on trust, accountability, and collaboration. By grounding innovation in community priorities, policy alignment, and strong partnerships, Sonoma Clean Power aims to demonstrate how local solutions can build a more reliable, affordable, and resilient energy future. 

Enhanced geothermal systems deliver firm, always-on power by turning hot, low-permeability rock into a controlled heat exchanger. Instead of tapping a rare natural hydrothermal reservoir, developers create permeability through stimulation, then circulate water through the engineered fracture network.

In that model, it is imperative that the system is built to last. The fractures and their ability to stay open and conductive become the heart of the asset. If the fracture network closes or degrades, the well’s productivity falls. If it remains open and conductive for decades, the same capital investment can support decades of baseload energy.

That is why the quality of the engineered reservoir “system” is an overlooked variable in EGS success. It determines not only how the well performs in the first few years, but also how it behaves over twenty or thirty years of thermal cycling and flow.

For CARBO, this is where the company’s role starts. CARBO positions itself not as a commodity supplier, but as a subsurface technology partner focused on the performance and longevity of the engineered reservoir.

Within an EGS reservoir, proppant often looks like a detail. It is not as visible as the drilling rig or the stimulation pumps. Yet it plays a decisive role. Proppant grains keep fractures open once pressure is released. They are the skeleton and ultimately the backbone of the heat exchanger.

If the proppant crushes, dissolves, or migrates, fractures close, and effective flow paths can narrow or even cease to exist. That leads to higher pressure drop, lower flow rates, and a shrinking thermal sweep. In economic terms, it shortens the productive life of the well.

More importantly, in an EGS development, the propped fracture network is not just a subsurface detail. It is a direct extension of the power plant infrastructure. The efficiency and long-term output of the surface facility are fundamentally tied to the reservoir’s ability to deliver consistent, high-conductivity flow over time. If conductivity degrades, the plant does not operate at its design capacity. If it is preserved, the entire system, from reservoir to turbine, performs as intended for decades.

Several factors make EGS more demanding than typical oil and gas environments:

• Temperatures can reach 300°C or higher in some advanced EGS and superhot rock concepts.
• Closure stresses can be high as the rock responds to stimulation and thermal cycling.
• Geothermal brines can be chemically aggressive, with scaling and corrosion tendencies.

Conventional silica sand was never designed for that combination. Under high temperature and stress, sand will crush into fines, partially dissolve in hot fluids, or chemically react in ways that narrow or block flow paths. Research on proppant reactivity in EGS environments has highlighted that long-term fracture conductivity can decline sharply when proppant is mismatched to the reservoir conditions.

By contrast, high-performance ceramic proppants are engineered from the start for strength, thermal stability, and chemical resistance. CARBO’s geothermal line, for example, is built specifically for EGS and other extreme subsurface environments. Products like GEOPROP and GEOPROP MAX are designed to withstand high temperatures, high closure stresses, and aggressive brines while maintaining conductivity and mechanical integrity.

The core idea is simple: if proppant is the skeleton of the engineered heat exchanger, then proppant selection is a strategic design decision, not a line-item commodity.

Ceramic proppants bring several characteristics that are directly relevant to enhanced geothermal systems:

• Strength under stress. Engineered ceramic grains are manufactured to high, consistent strength, so they resist crushing under elevated closure and thermal stress cycles.
• Thermal stability. Ceramic proppants such as GEOPROPare fired at temperatures above 1500°C. That thermal history helps them retain structure and conductivity in geothermal reservoirs where formation temperatures can exceed 300°C.
• Chemical durability. Ceramic compositions and patented pelletization techniques can be refined to resist dissolution and chemical attack in geothermal brines, reducing fines generation and preserving flow paths over time.
• Optimized conductivity. Uniform grain size and shape help create higher-conductivity packs, reducing tortuosity and pressure drop across the fracture.

For geothermal developers, the economics of these properties are straightforward. EGS wells require high upfront capital for drilling and stimulation. Once that money is spent, there are only two ways to improve returns: increase the heat produced over the life of the project, or extend its productive life. Long-term fracture conductivity serves both goals.

Ceramic proppants are designed to maintain that conductivity under conditions that would quickly degrade sand. 

In other words, proppant is directly tied to improving lifecycle economics. Getting it wrong can shorten the reservoir's life. Getting it right can protect the capital invested in the well and support truly infrastructure-grade geothermal assets.

Supply certainty is another, often overlooked, variable in geothermal project risk. EGS developments are capital-intensive and schedule-driven. Delays in critical materials can cascade into rig standby costs, missed grid connection windows, or contract penalties.

CARBO manufactures its ceramic proppant in the United States, building on a forty-five-year manufacturing base in high-quality advanced ceramics. That U.S. footprint provides several advantages for geothermal projects operating on tight timelines:

• No exposure to overseas tariffs on core proppant volumes.
• Shorter and more predictable logistics chains for North American projects.
• The ability to coordinate delivery schedules with drilling and completion programs.

For developers, that supply-chain reliability translates into one less source of uncertainty. It also supports domestic content goals where they apply, which is relevant for projects seeking certain forms of U.S. federal support.

In a market where EGS wells are often drilled in frontier conditions and testing new designs, reducing supply-chain risk around critical materials helps keep attention on the subsurface learning curve, not on whether the next proppant shipment will arrive.

Since 1979, CARBO has built a global business around engineered ceramic solutions for demanding environments: high-pressure completions, complex unconventional reservoirs, industrial processes, and now geothermal.

Over more than four decades, CARBO has:

• Pioneered high-strength ceramic proppants that became widely used in oil and gas for maximizing  EUR and return on investment.
• Invested in research and development centers to characterize fracture conductivity, proppant transport, and long-term performance under stress.
• Developed diagnostic and modeling tools that link proppant selection, fracture design, and economic outcomes in complex reservoirs.

In the geothermal space, that experience is now being applied to enhanced geothermal systems and superhot rock concepts, working with developers to design fracture systems that will remain conductive under the thermal, mechanical, and chemical realities of each project.

For Geothermal Rising’s member community, this kind of cross-sector transfer is part of the broader story of how subsurface expertise from oil and gas can accelerate the geothermal learning curve.

The geothermal sector is moving from pilots toward large-scale, infrastructure-grade deployment. EGS and related technologies are central to that transition, and as that shift happens, expectations around asset life and reliability will tighten. Power purchasers, regulators, and investors will question how long a deployment can sustain output. That question leads directly back to the engineered reservoir and to the materials that support it.

Ceramic proppants are not a silver bullet, but they are one part of an integrated EGS design that includes stimulation strategy, well architecture, and thermal management. They are part of what directly touches the “overlooked variable” this article began with: the quality and durability of the fracture network.

By combining advanced ceramic proppant technology, subsurface engineering expertise, and U.S.-based manufacturing, CARBO is uniquely positioned as a solutions-based partner for developers who want to de-risk EGS performance and protect the long-term value of their assets. For investors and operators betting heavily on infrastructure-grade geothermal, the focus on the longevity of the underground heat exchanger is a necessity.

For Geothermal Rising members, the main lesson is simple: in enhanced geothermal systems, fracture network quality is something you design. Proppant selection is a critical component in a successful development.

Treating proppant as a strategic choice rather than a commodity can:

• Improve long-term fracture conductivity and connectivity in extreme temperature and stress environments.
• Support better lifecycle economics by protecting early capital investments.
• Reduce some of the operational and supply-chain risk associated with EGS development.
• Reinforce power plant efficiency and long-term reliability by ensuring the reservoir consistently delivers the flow needed to sustain design capacity and revenue generation.

As enhanced geothermal systems scale up, the operators and developers will be judged not just on drilling deeper or hotter, but on building systems that last. Advanced ceramic proppants, applied thoughtfully and supported by subsurface expertise, are one tool that can help make that longevity real.

Most BHA components in high-temperature wells are designed for a maximum operating temperature around 149°C (300°F). In contrast, formation temperatures in some shale and geothermal wells already exceed 177°C (350°F). As the circulation loop runs, the relatively cool mud that is pumped down the drillpipe absorbs heat from the hot rock around the wellbore. At the bit, the mud turns and returns toward the surface in the annulus as hotter circulating mud. Because the well is drilled overbalanced, native formation fluids stay in the rock, and it is the drilling mud that picks up and carries the heat. By the time mud reaches the bottom hole assembly, its temperature is much closer to the formation temperature, which is the temperature the tools actually have to withstand.

Elevated temperatures do more than stress electronics. They accelerate corrosion, erosion, and fatigue in steels and elastomers and degrade mud rheology, thinning the fluid and reducing its ability to clean the hole. The result is familiar to drilling engineers: more unplanned trips, more tool failures, and more non-productive time.

Whether the well is chasing gas in the Eagle Ford or heat in a geothermal project, the central question is the same. How do we keep the circulating system cool enough for the tools to survive, without sacrificing performance?

NOV’s Tuboscope business unit has spent decades developing internal coatings that extend tubular life by resisting corrosion, wear, and deposit buildup while maintaining hydraulic efficiency. As operators in oil and gas and geothermal began seeking a coating that could also serve as a thermal barrier, the research team focused on one key property: thermal conductivity.

Carbon steel drillpipe has a thermal conductivity of roughly 45 W/m·K, so it readily conducts heat from hot rock and annular fluids into the cooler mud inside the pipe. Legacy internal coatings improved corrosion resistance but did relatively little to slow heat flow.

Using a heat flow meter, NOV tested candidate coatings across a wide temperature range. 

Earlier coatings averaged about 0.84 W/m²K. Through multiple iterations, the team developed TK Drakōn with an average thermal conductivity of 0.162 watts per meter Kelvin, more than five times lower than that of previous coatings and nearly 280 times lower than that of steel. The inside of the pipe becomes a significantly cooler pathway for drilling fluid.

TK Drakōn was also subjected to high temperature, high-pressure exposure, immersion in corrosive solutions, and physical tests for abrasion, impact, and flexibility. The coating is applied in a thin 20 to 30 mil (0.5 to 0.75 millimeter) layer that preserves a smooth internal surface, supports efficient flow, and limits the buildup of scale and solids.

With more than 1.0 million feet (about 305,000 meters) of TK Drakōn-coated pipe in service, the coating has moved from concept to a standard option for high-temperature drilling. For geothermal developers, it offers a qualified way to manage heat along the drillstring while also protecting tubulars from aggressive brines.

Managing temperature inside the well starts at the surface. Once hot mud returns from the hole, it passes through shakers and solids-control equipment, then becomes a candidate for cooling before being pumped back downhole. 

Conventional mud cooling often relies on evaporative or air-based systems that struggle in hot, humid environments and may require large volumes of water. Chillers use a closed refrigeration loop to remove heat from the fluid and can maintain precise temperature control without external water.

NOV’s Tundra Max mud chiller combines air cooling and chiller technologies in a two-stage, closed-loop package. In the first stage, an air cooling unit removes heat from the drilling fluid by transferring it into a circulating water loop. In the second stage, a refrigeration unit removes additional heat from the same water loop, allowing it to continue pulling heat from the mud. Both stages use plate and frame heat exchangers in a counter-flow configuration, where the drilling fluid flows in one direction, and the cooling water flows in the other, which increases contact and improves heat transfer from the hot drilling fluid to the cooling medium.

The trailer-mounted unit can handle oil-based, synthetic-based, and water-based muds. In the first stage, an air-cooling unit removes heat from the water loop. In the second stage, a refrigeration unit chills that loop further. Both stages use plate-and-frame heat exchangers in a counterflow configuration to transfer heat between the mud and the cooling medium.

At the rig site, Tundra Max draws relatively clean fluid from the suction tank, chills it, and returns it to the solids control tank, typically the hottest point in the surface system. The result is a continuous heat sink that pulls the overall system temperature downward before the mud is pumped back into the well.

In long, high-temperature laterals in South Texas, this integrated approach delivered measurable gains. In one case study, Tundra Max lowered the active mud temperature at the surface by an average of 29.5°C, from 61.7°C at the inlet to 32.2°C at the outlet. With the mud chiller alone, the bottom hole temperatures were reduced to about 186°C, even though the undisturbed formation temperature was close to 196°C. When the chiller was combined with TK Drakōn-coated drillpipe, the bottom-hole circulating temperatures in the wellbore dropped further to an average of 159°C. That additional margin improved the operating environment for downhole electronics and elastomers and reduced heat-related risks for personnel at the surface.

As lateral lengths approach 8 kilometers and geothermal concepts push toward supercritical and superhot conditions, drilling will increasingly be limited by the tools that can tolerate them, not just by rock mechanics. Temperature in the circulation system is something operators can actively design around.

For geothermal projects, whether conventional hydrothermal, enhanced geothermal systems, closed-loop designs, or superhot pilots, the path is similar. Assume active temperature management from the earliest phases of well design. Pair downhole insulation, such as TK Drakōn, with surface cooling, such as Tundra Max, as standard practice in high temperature campaigns. Use early wells in a field to tune bit selection, trajectory, hydraulics, and the thermal profile of the circulation system.

NOV is already extending its coating and cooling expertise into geothermal projects. These cross-sector lessons are relevant to a community experimenting with new well architectures and resource types while still relying on many of the same drilling fundamentals.

The story behind TK Drakōn and Tundra Max is less about individual products and more about a systems approach to heat. By reducing heat transfer into the drilling fluid and removing heat at the surface, NOV’s integrated system keeps BHAs operating closer to their rated lifespans, reduces non-productive time due to temperature-driven failures, stabilizes mud properties, and improves rig safety. Across multi-well campaigns, those gains compound and drive down cost per meter drilled.

As a participant in the Geothermal Rising community, NOV brings high-temperature drilling experience and a coatings and fluids portfolio that can be adapted for geothermal. In an industry-driven organisation that exists to connect subsurface innovators, this kind of technology transfer supports a shared goal: making clean, always on geothermal energy a practical choice in more places around the world.