UGI Energy Services and Synthica Energy, LLC, jointly developed one of the nation’s most advanced anaerobic digestion facilities, which converts high-strength industrial and food waste into renewable natural gas (RNG). The control systems transform challenging feedstocks — such as high-salt glycerin with total dissolved solids exceeding 200,000 mg/L — into pipeline-quality RNG while reducing industrial pretreatment loads and landfill disposal.
RETTEW served as the lead design engineer for UGI Energy Services and Synthica Energy’s flagship facility in the Village of St. Bernard, adjacent to Cincinnati. The $80 million facility processes approximately 550 wet tons of organic material each day and delivers RNG to a regional natural gas distributor. At full capacity, the plant generates 260,000 MMBTU of RNG each year — enough to power 4,000 homes.
RETTEW developed a pilot testing program to evaluate and optimize dilution strategies for the unique high-strength waste streams, ensuring digester stability and performance reliability for project financing and design. Following the testing, RETTEW led all aspects of the facility design and control systems, and the project finished $2.5 million under budget. Supporting the construction and commissioning activities, our team ensured the successful implementation of this advanced anaerobic digestion system that established the foundation for Synthica’s broader $400 million portfolio of facilities nationwide — representing more than $1 billion in future investment and demonstrating RETTEW’s leadership in scalable, waste-to-energy design.
This project received an Outstanding Achievement Award and the Grand Award from ACEC of OH, as well as a National Recognition Award from ACEC’s Engineering Excellence Awards.