Donohue & Associates and the City of Sheboygan, Wisconsin, received the Grand Conceptor Award - the top prize - in the 2013 ACEC Wisconsin Engineering Excellence competition. The award recognizes an ambitious energy production and recovery project, making the City’s wastewater treatment facility the first in the state to achieve energy net-zero status. Donohue led the planning and design of this project.

Donohue has been working with the City of Sheboygan since 2000 to improve energy efficiency, reducing the utility’s dependence on grid electricity. The latest project included two elements: (1) anaerobic digestion improvements to increase effective digestion capacity and biogas production, and (2) 400-kW of additional microturbine capacity to convert biogas to heat and electricity. For the former, the City elected to install energy efficient linear-motion mixers and became the state to use this technology.

With the substantial increase in biogas and the additional microturbine capacity the facility now converts nearly all of its biogas to heat and electricity. The Sheboygan facility is one of only a handful of wastewater facilities in the world that can regularly produce all of its energy on-site using a renewable fuel source. Combined with revenues from its high-strength waste program, the combined bottom-line benefit is roughly $1 million annually.