Stillwater Energy Center

Client: Stillwater Utility Authority (SUA)
Location: Stillwater, Oklahoma


Stillwater Utility Authority (SUA) selected Burns & McDonnell to provide full engineering, procurement support and construction management (EPCM), permitting, and gas services for the Stillwater Energy Center. Phase I provides 56 megawatts (MW) using three natural-gas-fired Wärtsilä 18.8-MW reciprocating engine generators.

Burns & McDonnell engineered the installation of the three Wärtsilä 18V50SG natural gas-fired engines and the balance-of-plant equipment to interface with SUA’s 69-kV transmission system. Each engine — chosen for its low heat rate, low emissions and efficiency — provides 18.8 MW of power, allowing SUA to meet its native load and contract commitments. Our scope included: gas procurement services; permitting services; procurement support to SUA for all portions of the project; plant detailed design; T&D detailed design; redesign of the existing distribution 12.47-kV/69-kV substation to accept the new generation; and construction, startup and commissioning services.

Features include outstanding heat rates at all loads and high ambient temperatures while providing rapid response to varying grid conditions. The plant will offer full grid black start capabilities. This plant also employs a closed loop cooling system and therefore will not consume process water or require wastewater treatment or disposal.


  • Permitting
  • Gas procurement
  • Detailed design — plant
  • Detailed design — T&D scope
  • Procurement support 
  • Construction management
  • Startup and commissioning support
  • Southwest Power Pool (SPP) interconnection support


  • 56 MW (Phase I)
  • Natural gas-fired; three Wärtsilä 18V50SG reciprocating engines (Phase I)
  • Designed to add two Wärtsilä 18V50SG reciprocating engines (Phase II)
  • Greenfield site
  • Modular design
  • 25% power in two minutes; full plant output in less than seven minutes
  • Black start capability
  • SCR/CO catalyst for NOx/CO reduction
  • 12.47-kV/69-kV switchyards and substations
  • New high-pressure gas pipeline to serve the energy center

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Vic Ranalletta Manager - Energy 630-724-3318
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