Early on in his role as Plant Superintendent, Dale Doerr recognized that while he could not control the cost of energy, he certainly could control its usage. The facility in Sheboygan is a primary and secondary waste treatment facility built 30 years ago with continuous need for improvement. Beginning with a study focused on the energy efficiency and renewable energy potential at its facility conducted in 2002, Sheboygan Wastewater Treatment Plant (WWTP) has closely focused on energy usage at its facility with the goal of eventually becoming energy self-sufficient. Sheboygan WWTP has undertaken numerous initiatives to reduce energy consumption and produce energy on-site. The “unwritten policy” at Sheboygan WWTP is to consider energy use whenever an equipment or process upgrade is needed. The plant now uses 20% less energy compared to a baseline figure in 2003 and ranges from 70-90% energy self-sufficient due to the energy produced on-site.
Capital investment recommendations for Sheboygan’s WWTP made by Mr. Doerr must be approved by the Director or Deputy Director of Wastewater and, at times, the Director of the City of Sheboygan Department of Public Works, the Mayor, or City Council. Sheboygan’s initiative to save energy and produce it on-site derived mostly from his leadership and the staff at the plant level. Funding for these investments is provided mostly by the city. Wisconsin Focus on Energy (
Most of the credit for the energy efficiency measures undertaken in Sheboygan rests with the Plant personnel and city officials, who have leveraged resources from the local utility,
Aside from stakeholders at the plant and in local government, Alliant Energy (AE), the electric utility serving Sheboygan WWTP, has also been an important partner for the plant’s combined heat and power (
Sheboygan WWTP has also replaced many of its motors with efficient models installed with variable frequency drives. A replacement of two motors with two 200 horsepower (hp) NEMA Premium™ motors at its influent pump station in 2006 cost $170,000. As with many of the Plant’s other energy-efficiency efforts, Focus on Energy provided technical assistance and for this particular project, along with a grant for $3,861. The new motors reduce energy use by 157,000 kWh (over $5,300 in energy cost savings) per year.
Another project that replaced motors with two new 125 hp NEMA Premium™ Motors in 2004 cost $150,000. The project received a Focus on Energy grant of $6,142, offsetting the higher costs for the higher efficiency motors. The energy savings for the first year exceeded $12,000. The average monthly reduction in kilowatt hours consumed for the first 10 months of operation was 6,595 kWh (Focus on Energy 2006).
Another major upgrade, featured in an EPA best practice document (2010), was the replacement of four older, less efficient blowers with more efficient units. After realizing that without control valves, dissolved oxygen levels in the individual aeration basins could not be controlled, the plant installed control valves in 2009. Details of the costs and savings from these two investments are described in the tables below.
Staff commitment to measurement and optimization has been critical for the success of energy initiatives at Sheboygan WWTP. A key component of the staff engagement has been the easy display and monitoring of energy usage in the plant. Sheboygan WWTP greatly benefits from nine power meters that feed information into the plant SCADA (Supervisory Control and Data Acquisition) system, which is capable of monitoring performance of equipment and processes throughout the entire plant. While many facilities use SCADA, Sheboygan uses the tool innovatively by connecting the system to its DO controls to improve feedback of energy usage information. The SCADA system allows plant operators to monitor status and make process adjustments from various terminals located throughout the plant, as well as from one central location at the wastewater treatment plant. Critical to its success, Sheboygan has not only made investments in high-efficiency technologies, but has paired the investments with continuous engagement and commitment to measurement and optimization, enabled by control technologies.
Staff evaluates the lifecycle cost of all projects, instead of implementing the least capital cost fix for replacing failing equipment. The proactive approach taken by the staff—engaging numerous stakeholders including utilities, equipment vendors, and energy efficiency service providers such as
Sheboygan Regional Wastewater Treatment Plant
3333 Lakeshore Drive
Sheboygan, WI 53081
 Replacement of 250 hp positive displacement blowers with two single-stage centrifugal blowers equipped with 350 HP NEMA Premium™ motors.