Prometheus plans a 1.5 GW islanded data center campus in Texas featuring onsite generation, requiring a new customer, modular construction, and a dedicated power plant to meet its 2027 target.
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.
Data center developer Prometheus Hyperscale is betting that the fastest path to deploying AI compute in West Texas is bypassing an initial ERCOT grid connection entirely. The company plans a 1.5 GW data center campus in Pecos, Texas, powered by an islanded generation system. While the project’s development path extends to 2.5 GW, initial generation will rely on pipeline natural gas, with a planned co-located fractionation facility later providing ethane fuel flexibility once it enters service.
This approach removes the campus from the initial ERCOT interconnection queue, but it does not eliminate the complexities of power supply. Prometheus and its eventual tenant will jointly manage generation, firm fuel supplies, air permitting, maintenance, redundancy, and financing—responsibilities typically borne by a utility in a grid-connected model. Adam Mirick, Prometheus’ chief energy and business officer, told Data Center Knowledge that the company has already held discussions with several prospective customers.
However, the project remains contingent on a firm customer commitment. Prometheus states that a modular deployment could deliver 100–150 MW of compute capacity by 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.”
The 1.5 GW figure denotes planned IT load rather than generation capacity. For initial generation blocks, Prometheus favors rich-burn reciprocating engines due to their incremental deployability and ability to accommodate fuel variability. As the campus expands, larger turbine units may prove more economical.
“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 noted that an initial reciprocating-engine configuration could require approximately 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 place 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.
Mirick added that the company intends to deploy best available control technology and secure all required air permits for the generation facilities. Achieving the initial power target hinges on more than generation equipment. According to Mirick, a customer targeting 2027 compute must accept modular data center construction; a conventional stick-built facility would extend timelines.
“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 to be completed. A customer commitment would also trigger orders for the modular data centers and generation equipment, firm gas transportation contracts, 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 a Pecos tenant. Mirick said there is strong early interest but declined to characterize the discussions further.
The Reeves County 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 currently 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 a baseline mix of 85% natural gas and 15% ethane. 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 on-site ethane storage and, potentially, propane storage. The company plans two separate methane pipeline connections with firm transportation agreements. 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.”
Located in Reeves County, 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.
While this strategy directly addresses uncertainties surrounding Texas’ large-load interconnection process, it does not exempt the project from state regulation. The generation facilities will still require environmental permits and robust fuel infrastructure, and the project must secure financing while constructing a power system capable of continuous operation. Prometheus could eventually connect the campus to the grid, but Mirick said that decision 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.
The harder question is whether private generation can deliver hyperscale reliability without simply shifting the risks elsewhere. Prometheus expects to use N+1 generation for the initial reciprocating-engine fleet, with the exact level 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 necessitate 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, noted that operating generation continuously creates mechanical challenges distinct 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 suggested that battery storage could serve as a buffer between volatile AI loads and onsite generation, thereby reducing mechanical stress on the engines.
This 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 the broader power-supply ecosystem.
Prometheus also views private generation as a mechanism 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, assuming $3.50/MMBtu for natural gas. 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 is therefore 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.”
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