I examine Google and Voltus’s announced expansion of their distributed energy collaboration to build a 1,070 MW Virtual Power Plant (VPP) in PJM. I break down the mechanics of the "Bring Your Own Capacity" model, how tech companies are using capacity arbitrage to access scarce grid capacity, and why industry transparency is critical if this commercial framework is going to be replicated at scale.

Here are the key points covered in today's analysis:

The Capacity Arbitrage Premise: Data center developers operate in a world where connecting new load quickly is worth immense sums of money, while traditional demand response programs have often struggled due to modest economic incentives. If end-use customers are offered sufficient financial incentives—recalling former utility CEO John Rowe’s famous phrase, "the rat must smell the cheese"—they may deliver substantial flexible capacity to the table.

The "Bring Your Own Capacity" Mechanism: Data centers finance distributed capacity, which is registered with the regional transmission organization (RTO/grid operator) and then delivered to the load-serving entity that supplies power to the data center load.

From 100 MW Pilot to 1,070 MW Scale: Following an oversubscribed 100 MW pilot announced in June, Google and Voltus announced plans to scale the initiative across PJM. In subsequent interviews, Voltus CEO Dana Guernsey confirmed the target is 1,070 MW, ramping up over three to four years, with Voltus managing the capacity under contract with Google through 2040.

Aggregated Assets & The Role of Batteries: While the program encompasses flexible demand across multiple customer classes—including smart thermostats, industrial assets, and batteries—CEO Guernsey indicated that a large portion of the capacity is expected to come from commercial-scale onsite batteries, which offer large, predictable blocks of capacity compared to shifting complex commercial or industrial operations.

The Need for Transparency: For this deal to fulfill its stated goal of catalyzing the market and establishing a durable commercial structure that others can emulate, grid planners, utilities, and regulators need greater visibility into delivery timelines, technology breakdowns, and progress benchmarks.

If you find this analysis helpful, please like, subscribe, and share your perspective in the comments on how data centers and distributed capacity should interact on the grid.

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🎙️ About Energy Future: Powering Tomorrow’s Cleaner World

Hosted by Peter Kelly-Detwiler, Energy Future explores the trends, technologies, and policies driving the global clean-energy transition — from the U.S. grid and renewable markets to advanced nuclear, fusion, and EV innovation.

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In this episode, I break down AEP’s major announcement to purchase up to 1.6 gigawatts (1,600 MW) of Mainspring linear generators through 2034, moving this technology into gigawatt-scale power generation. I explain how linear generators work, compare their efficiency and fuel agility to traditional gas turbines, and look back at how far this technology has come since I first saw a bench prototype over a decade ago.

Here are the key points and technical details covered in today's video:

• The 1.6 GW AEP Procurement: On October 13th, AEP announced the largest linear generator procurement to date—up to 1,600 MW through 2034, starting with a 190 MW initial tranche delivered in 2027. This provides a rapidly deployable alternative to traditional gas turbines, which currently face up to five-year acquisition backlogs.
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• How a Linear Generator Works: Often described as a "horizontal pogo stick," the machine uses air springs, a central reaction chamber, magnetic oscillators (pistons with magnets), and surrounding copper coils. A mixture of air and fuel undergoes a low-temperature, non-combustible reaction 13 times per second, driving magnetic oscillators horizontally through copper coils to induce electric current without spinning turbines or complex mechanical linkages.
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• Efficiency & Environmental Profile: Delivers a 46% electrical conversion efficiency rate on natural gas (compared to ~40% for aeroderivative turbines without heat recovery) and greater than 80% efficiency in Combined Heat and Power (CHP) applications. The system operates with low NOx emissions, quiet operation, and zero water usage across temperatures ranging from -22°F to 122°F (-30°C to 50°C).
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• Fuel Flexibility: Systems are software-programmable to switch between natural gas, renewable natural gas (RNG), biogas, propane, and hydrogen.
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• Standardized Packaging & Deployment: Delivered in standardized 2.5 MW configurations bundling ten 250 kW generators with skid-mounted inverters and transformers.
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• Commercial Track Record: Commercial adoption includes Kroger (clusters up to 230 MW supported by NextEra Energy since 2020), Lineage Logistics, FedEx, Amazon, and the U.S. Department of Defense.
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• Capital & Manufacturing Scale: Supported by an $87 million U.S. Department of Energy grant to expand Mainspring's Pennsylvania facility to produce up to 1,000 units (~250 MW) annually, alongside a $242 million Round F financing that brings total fundraising to over $1 billion.
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• Personal Reflection: A look back to 2013, when Mainspring co-founder and CEO Shannon Miller brought me into their Menlo Park headquarters to deliver an educational session on competitive power markets when the machine was still a working lab prototype.
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If you find this analysis helpful, please like, subscribe, and leave a comment with your thoughts on onsite generation and linear generators.

Support the show

🎙️ About Energy Future: Powering Tomorrow’s Cleaner World

Hosted by Peter Kelly-Detwiler, Energy Future explores the trends, technologies, and policies driving the global clean-energy transition — from the U.S. grid and renewable markets to advanced nuclear, fusion, and EV innovation.

💡 Stay Connected
Subscribe wherever you listen — including Spotify, Apple Podcasts, Amazon Music, and YouTube.

🌎 Learn More
Visit peterkellydetwiler.com
for weekly market insights, in-depth articles, and energy analysis.

In my latest episode, I break down the following key details from the project updates and industry filings:

Fervo's 33 MW Launch at Cape Station: Fervo Energy has begun producing 33 MW from its first commercial project in Cape Station, Utah under a Power Purchase Agreement (PPA) with Shell Energy. Phase one consists of three 33 MW "GeoBlocks" (with the remaining two expected by year-end), an additional 400 MW under construction for 2028, and environmental permits allowing expansion up to 2,000 MW.

Hydrothermal vs. Hot Dry Rock: Traditional hydrothermal systems (such as The Geysers in Northern California, which dropped from 1,875 MW to ~900 MW due to steam depletion) rely on rare natural underground water reservoirs. Next-gen geothermal drills 3 to 4 miles deep into 400°F–450°F granite lacking natural water.

Advanced (Closed-Loop) vs. Enhanced (Fracked) Systems: Advanced geothermal (such as Eavor’s project in Geretsried, Germany) uses closed-loop underground pipe "radiators," but faces complex lateral drilling challenges (connecting 6 of 12 planned lateral pairs). Enhanced geothermal (used by Fervo) utilizes parallel well pairs, cemented steel casing, perforating guns, and multistage hydraulic fracturing to open micro-fissures directly in the granite.

Water Recapture & Heat Exchange: Fervo circulates degraded water (such as saline or agricultural runoff) through rock micro-fissures to absorb heat, bringing superheated water to the surface to vaporize a secondary working fluid in a closed loop. Fervo reports an 80% to 90% water recapture rate.

Commercial Offtake & Pricing: Major PPA deals include Fervo’s 396 MW contract with Google, 320 MW with Southern California Edison, and a publicly filed 115 MW Clean Transition Tariff contract with NV Energy priced at $107 per megawatt-hour.

Houston Geothermal Ecosystem: Over a dozen advanced and enhanced geothermal startups are leveraging Houston's oil and gas fracking expertise, including Sage Geosystems (partnering with Ormat on a 150 MW deal with Meta) and XGS Energy.

Geographic Constraints: U.S. Geological Survey mapping shows suitable hot rock at 1.5 to 3 miles depth in the Western U.S. versus 5 to 8 miles depth in the Eastern U.S., meaning near-term development will remain concentrated west of the Continental Divide.

Support the show

🎙️ About Energy Future: Powering Tomorrow’s Cleaner World

Hosted by Peter Kelly-Detwiler, Energy Future explores the trends, technologies, and policies driving the global clean-energy transition — from the U.S. grid and renewable markets to advanced nuclear, fusion, and EV innovation.

💡 Stay Connected
Subscribe wherever you listen — including Spotify, Apple Podcasts, Amazon Music, and YouTube.

🌎 Learn More
Visit peterkellydetwiler.com
for weekly market insights, in-depth articles, and energy analysis.