Prometheus’ 1.5 GW Pecos Plan Tests Private Power

Prometheus Hyperscale plans a 1.5 GW data center campus in Reeves County, Texas, powered by an islanded generation system to avoid initial ERCOT grid connection, with a development path to 2.5 GW. The project, contingent on a customer commitment, could deliver 100 MW to 150 MW of compute in 2027 using modular construction, according to chief energy and business officer Adam Mirick. The company favors rich-burn reciprocating engines for initial generation blocks, which may require about 30% more installed capacity for redundancy.

Prometheus’ 1.5 GW Pecos Plan Tests Private Power The developer plans an islanded campus with onsite generation, but reaching its 2027 target will require a customer, modular construction and a new power plant. Prometheus Hyperscale is betting that the fastest way to put AI compute in West Texas is to avoid an initial ERCOT grid connection altogether. The company plans a 1.5 GW data center campus in Reeves County, Texas, powered by an islanded generation system. The project has a development path to 2.5 GW, with pipeline natural gas supplying the initial generation and a planned co-located fractionation facility providing ethane fuel flexibility after it enters service. That approach removes the campus from the initial ERCOT interconnection process /build-design/texas-creates-a-credibility-test-for-gigawatt-scale-data-center-demand , but it does not remove the difficult work of supplying power. Prometheus and its eventual customer will have to address generation, firm fuel supplies, air permitting, maintenance, redundancy and financing that a conventional grid-connected project would obtain through a broader utility and power-supply system. Adam Mirick, Prometheus’ chief energy and business officer, told Data Center Knowledge in an interview that the company has already spoken with several prospective customers. The project, however, remains contingent on a customer commitment. Prometheus says a modular deployment could deliver 100 MW to 150 MW of compute in 2027. “If we had a commitment, I’d say in October, perhaps we can bring on 100 to 150 megawatts of compute in 2027,” Mirick said. “It’s very challenging to bring anything to market in ’27 right now between the generation, between the MDCs … the contractors, all of it.” A Power Plant Behind the Data Center The 1.5 GW figure represents planned IT load, not generation capacity. Prometheus favors rich-burn reciprocating engines for the initial generation blocks because they can be deployed incrementally and accommodate fuel variability. Larger turbine units could become more attractive as the campus expands. “We’re leaning towards a rich-burn reciprocating engine for the initial blocks, just because the rich-burn engines accommodate the different fuels better than the lean burns,” Mirick said. The final generation fleet will depend on the tenant’s reliability requirements and data center design. Mirick said an initial reciprocating-engine configuration could require about 30% more installed generation than the underlying facility load to provide redundancy. At a preliminary PUE assumption of 1.3, a 1.5 GW IT load would produce roughly 1.95 GW of facility demand. Applying the illustrative 30% overbuild would put potential installed generation at about 2.5 GW. That is not a final project design. Prometheus has not disclosed the final generation configuration or installed capacity for Phase 1. The company expects to use best available control technology and obtain the required air permits for the generation facilities, Mirick said. The 2027 Test The first power target depends on more than generation equipment. A customer seeking 2027 compute would need to accept modular data center construction, according to Mirick. A conventional custom-built facility would take longer. “Stick-built, custom design, it’s not possible in our view in 2027,” Mirick said. “You’re probably looking at middle of 2028 at this point.” Modular construction would allow Prometheus to bring smaller blocks online as equipment arrives rather than waiting for an entire conventional data hall. A customer commitment would also trigger orders for the modular data centers and generation equipment, firm gas transportation and project financing. “The tenant commitment is really the magic that unlocks the capital and gets everything moving,” Mirick said. Prometheus has not signed a binding customer agreement for Pecos. Mirick said there is strong early interest but declined to characterize the discussions beyond that. Natural Gas First The project’s planned fuel system is designed around pipeline natural gas, with ethane providing additional fuel flexibility. Istmo Energy’s co-located fractionation facility is under construction and is expected to enter service in the first quarter of 2028. Until then, the data center’s planned generation would run on pipeline natural gas. Once the fractionation facility is operating, Prometheus expects an 85% natural gas and 15% ethane baseline. Fractionation separates components of a mixed natural gas liquids stream, allowing Istmo to recover ethane for use by the adjacent power system. “Once you get into ’28 and you’ve got the fractionation, then you’re going to have the ethane backup,” Mirick said. The precise operating profile of the fuel mix remains dependent on the final generation design. Prometheus also expects onsite ethane storage and potentially propane storage. The company plans two separate methane pipeline connections and firm transportation. If one fuel supply is interrupted, the generators could operate on the other. “Our base case is 85/15,” Mirick said. “If there’s something wrong with methane pipelines, our checkdown is go full ethane. If there’s something wrong with ethane, you go full methane.” What Islanding Changes The Pecos data center will initially have no physical connection to the ERCOT grid, Mirick said. “We’re building an island because the island is what allows us to deliver the speed, the reliability that’s required,” he said. The strategy is a direct response to uncertainty around Texas’ large-load interconnection process. It does not, however, put the project outside Texas regulation /regulations/texas-pushes-ai-data-centers-to-pay-their-own-grid-costs . The generation facilities will still require environmental permits and fuel infrastructure, while the project must secure financing and construct a power system capable of operating continuously. Prometheus could eventually connect the campus to the grid, but Mirick said that would be driven by the tenant. “We’re not against being grid-connected in the future, but it has to make sense, and it’ll be tenant-directed,” he said. For now, the company is focused on operating independently of ERCOT. “We are solely focused on hitting the timetables and reliability metrics through islanding,” Mirick said. Taking On Utility-Like Risks The harder question is whether private generation can deliver hyperscale reliability without simply moving the risks elsewhere. Prometheus expects to use N+1 generation for the initial reciprocating-engine fleet, with the amount of redundancy determined by the customer’s reliability requirements. “We’re letting them define the number of nines that they want,” Mirick said. Higher reliability requirements require more generation and electrical infrastructure, he said. “The more nines, it’s not a linear cost,” Mirick said. “It starts to go up in nonlinear fashion.” Joshua D. Rhodes, a research scientist at the University of Texas at Austin and a non-resident fellow at Columbia University, said operating generation continuously creates mechanical challenges that are different from the traditional role of standby generators. “One of the things we’ve seen with running what used to be back up generation full-time is that it increases mechanical stress, and the systems can wear out two to three times as fast,” Rhodes said. Rhodes said battery storage could serve as a buffer between volatile AI loads and onsite generation, reducing mechanical stress on the engines. The model shifts more of the operational and commercial risk associated with power infrastructure into the developer-customer relationship. Prometheus and its eventual customer will have to allocate responsibility for the generation fleet, fuel system and electrical infrastructure that a grid-connected data center would ordinarily obtain through a utility and broader power-supply ecosystem. The Cost of Going It Alone Prometheus also sees private generation as a way to give customers greater certainty over long-term electricity costs. Mirick estimated the cost of islanded generation at roughly $100 to $125 per megawatt-hour, using a $3.50/MMBtu natural gas assumption. The company did not provide a detailed breakdown of that estimate, including the treatment of generation capital costs, financing, fuel transportation, emissions controls, maintenance and redundancy. It therefore is not a direct comparison with a utility tariff. “Putting in behind-the-meter, you know what your capex is going to be for power,” Mirick said. “You know what your rate’s going to be for power for 15 years.” The trade-off is greater responsibility for the infrastructure supplying that power. “Grid is easy,” Mirick said. “You basically toss the problems over the fence to the utility.” Little Water, More Power Infrastructure The Pecos campus will use closed-loop cooling rather than evaporative cooling. Mirick said the cooling system would initially contain about 75% water and 25% food-grade propylene glycol. The loop would be filled initially, with limited makeup water expected during normal operation. Prometheus does not yet have a final design and cannot provide a firm water-consumption figure. Mirick estimated that combined water use for the power and data hall operations could be below the equivalent of roughly 100 households, but said that estimate is preliminary. The company does not expect the campus to discharge water during normal operations. The Real Test Pecos is part of Prometheus’ broader strategy of developing data centers around dedicated power systems rather than relying on conventional utility service. The company is also pursuing a Dallas-area project targeting 2027 compute and Wyoming projects targeting 2028. The strategy can remove one major variable from a data center development schedule: the initial grid interconnection. But it replaces that variable with a much larger set of responsibilities. Whether Pecos reaches even its initial 100 MW to 150 MW target in 2027 will depend not on an ERCOT interconnection date, but on whether Prometheus can secure a tenant and prove it can build, fuel, permit, finance and continuously operate its own utility-scale power system.