Episode Summary
Executive Summary: This episode introduces Cindy Taft of Sage Geosystems and explains how the company is using oil-and-gas drilling know-how to build next-generation geothermal power and “upside-down” pumped hydro storage. The conversation centers on the technical concept, rapid 13-month build, grid interconnection delays, the role of long-duration storage in replacing coal, and Sage’s partnership with Ormat to scale the technology.
Main Topics: Sage’s “pressure geothermal” concept (Priority: 5/5): Cindy explains how Sage stores energy by pumping water into deep engineered fractures, then releasing pressure to drive water back up through a Pelton turbine. The system combines geothermal generation with long-duration mechanical storage. From oil and gas to clean geothermal (Priority: 5/5): The discussion highlights how Cindy’s background at Shell and Sage’s founders’ oil-and-gas expertise translate directly into geothermal drilling, completions, project management, and cost control. Building and commissioning the first commercial facility (Priority: 4/5): Sage built and commissioned its first commercial-scale facility in 13 months, with most field work completed in about seven months after months of pre-engineering and equipment procurement. Grid interconnection as the bottleneck (Priority: 5/5): Despite finishing the facility early, Sage is still waiting for interconnection. Cindy argues that the process is too linear, too slow, and worsened by speculative queue congestion. Why long-duration storage matters for replacing coal (Priority: 4/5): The episode frames Sage’s storage as a solution for turning variable solar into 24-hour power, especially for utilities like SMECI transitioning away from 24/7 coal generation. Partnership with Ormat to scale next-generation geothermal (Priority: 4/5): Sage’s collaboration with Ormat is presented as a strategic bridge between conventional geothermal expertise and next-generation hot-dry-rock geothermal and storage.
Key Arguments: Long-duration storage is essential if solar and wind are to replace round-the-clock fossil generation; 2-4 hour batteries are insufficient for many coal-replacement use cases. Sage’s underground pressure-based storage is structurally similar to pumped hydro, but does not require mountains or large surface water reservoirs. Greater depth increases energy density because the system leverages subsurface pressure; Sage drills 8,000-12,000 feet, deeper than traditional pumped hydro height. Low-permeability rock can hold stored energy for weeks or months, making the system potentially suitable for seasonal or very long-duration storage. Oil and gas engineering practices are highly transferable to geothermal and are helping accelerate commercialization. Grid interconnection reform is necessary because the current process is slow, sequential, and clogged by projects that may never be built. A partnership with a large incumbent like Ormat helps Sage scale faster by leveraging established subsurface, contracting, and manufacturing capabilities.
Data Points: Time to build and commission first commercial facility: 13 months - Sage completed its first commercial-scale energy facility from funding to readiness for storage in 13 months. Field work duration: About 7 months - After funding, Sage says the dirt work, well drilling, fracking, and facility construction were completed in roughly seven months. Pre-engineering duration: 6-9 months - Cindy said the company spent roughly six to nine months designing before construction began. Pelton turbine pressure rating: 5,000 PSI - Sage’s turbine had to be re-engineered because standard pumped-storage Pelton turbines are not rated for Sage’s deeper, higher-pressure system. Typical pumped hydro share of global storage: About 90% - Cindy referenced pumped hydro as the dominant global storage technology. Depth of Sage wells: 8,000 to 12,000 feet - The company drills deep wells to access pressure and heat for storage and geothermal generation. Depth of tallest pumped hydro: About 3,000 feet - Used as a comparison point to show Sage’s higher depth and energy density. Target permeability: 50 millidarsies or less - Sage targets low-permeability rock to limit leakage and enable long-duration storage. Potential storage duration: Weeks to months - Cindy said water can be stored long-term depending on formation permeability, with seasonal storage possible if the market supports it. Coal plant capacity at SMECI: 410 megawatts - The San Miguel coal plant being replaced is described as a 410 MW facility. Initial solar tranche size: 400 megawatts - SMECI’s first phase of solar is described as 400 MW under a USDA loan with batteries for storage. Typical lithium-ion discharge duration: 2 to 4 hours - Cindy contrasted battery duration with the 16-hour requirement for turning solar into 24-hour power. Target discharge duration for coal replacement: 16 hours - Used to explain the storage duration needed to bridge overnight hours for solar replacement of coal. SMECI USDA grant: $1.4 billion - The utility received a large USDA grant to transition from coal toward solar and storage. SMECI land size: 12,000 acres - Sage’s leased site sits within SMECI’s broader landholdings for future solar expansion. Oil and gas drilling scale: 20,000 to 30,000 wells/year - Cindy contrasted oil and gas drilling volume with geothermal’s much smaller annual well count. Conventional geothermal drilling scale: 30 to 50 wells/year - Used to show why oil and gas learnings were historically not shared effectively with geothermal.
Pivotal Quotes: "It was during that testing that we also recognized that we had the perfect energy storage solution, which is like pumped storage, but upside down." — Cindy Taft: Explaining how Sage realized its geothermal test work also revealed a long-duration storage application. "We were actually able to build and commission that facility in 13 months." — Cindy Taft: Describing the speed of Sage’s first commercial-scale build and commissioning timeline. "I do think it is the age of geothermal." — Cindy Taft: Cindy’s view that geothermal is entering a new growth phase due to improving technology and market need.
Implications: The episode signals that geothermal is moving from niche resource to scalable infrastructure, especially when paired with storage. If interconnection and permitting improve, oil-and-gas-derived techniques could help deliver firm, low-carbon power at scale.
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The energy transition, decoded. Every week, three industry veterans explore the business models, tech breakthroughs, and market shakeups that are driving the biggest industrial transformation in history.