Industrial Utility Efficiency

Helping Wisconsin Wastewater Treatment Facilities Save Energy

Wisconsin water treatment plant

Leidos Engineering works with Focus on Energy to help water/wastewater facilities throughout Wisconsin identify and implement methods for reducing energy use.


Leidos Engineering, LLC (Leidos Engineering) is responsible for implementing the Wisconsin Focus on Energy® Large Energy Users (LEU) Program in Wisconsin. Blower & Vacuum Best Practices interviewed Leidos Engineering’s Joseph Cantwell, P.E., Senior Energy Management Professional, Focus on Energy – LEU Program, to learn how the firm works with Focus on Energy to help wastewater treatment facilities in the dairy state reduce energy consumption and save costs.


Good afternoon! Tell us about Leidos Engineering and Focus on Energy

Leidos is a Fortune 500® firm based in Reston, Virginia, with 32,000 employees around the world. We offer information technology, engineering and science solutions with the mission to make the world safer, healthier and more efficient. Since 2014, the work our Leidos Engineering division has done with the LEU customers of Focus on Energy has saved more than 726 million kWh and more than 52 million therms of natural gas.  That’s enough savings to power about 25,000 homes or heat over 5,200 homes for a year.

Leidos Engineering is proud to be working with Focus on Energy (, which is the statewide utilities’ energy efficiency and renewable program funded by Wisconsin’s investor-owned energy utilities and participating municipal and electric cooperative utilities. The goal is to help Wisconsin residents and businesses install cost-effective energy efficiency and renewable energy projects. In fact, the Focus on Energy program was recently recognized in a study conducted by the Lawrence Berkeley National Lab as the most cost effective energy efficiency program in the United States.

Joseph CantwellJoseph Cantwell, P.E., Senior Energy Management Professional, Focus on Energy Large Energy User Program, Leidos Engineering, LLC.

What is your professional background and your role with Focus on Energy?

My work with municipalities and wastewater treatment facilities goes back to my days as an undergraduate student at Marquette University in Milwaukee, Wisconsin, when I worked for a municipality as part of the university’s co-op program.

I also worked for municipalities in various jobs for a few years after earning my bachelor’s degree in civil engineering. I then began to focus on wastewater treatment facility design and water systems. Toward that end, I earned my master’s degree in sanitary engineering and then joined an engineering consulting firm in their wastewater treatment facility design group. After that, I worked for a couple of consulting firms and focused on wastewater treatment and water systems, but basically focused on the wastewater side.

In 2000, I joined Leidos Engineering. Since then, I’ve become extensively involved in the Focus on Energy LEU Program. I was the lead author of Focus on Energy’s Water & Wastewater Industry Energy Best Practices Guidebook, which is a 179-page resource designed to assist water/wastewater systems to identify and implement methods for reducing energy use. I’m currently an energy advisor for the program and my job is to help large water and wastewater systems identify energy-saving opportunities and take advantage of incentives offered by Focus on Energy.


How do you help treatment facilities get involved with Focus on Energy?

Energy advisors like myself visit customers throughout the state to review their operations and processes to identify where they have opportunities to save energy. Once we’ve identified potential opportunities, we conduct baseline energy assessments to determine how much energy a given opportunity can save based on the initiatives involved.

Our discussions include the types of incentives we can offer through Focus on Energy and the potential savings, as well as the payback on the investment. The treatment facilities we work with must have energy utility bills that are consistently over $60,000 per month to qualify for LEU Program incentives.

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What kinds of incentives does Focus on Energy offer Large Energy Users?

The first type of incentive is “prescriptive,” which means a set dollar amount is awarded for replacing equipment with more energy-efficient equipment.

The second is a “custom incentive.” This type of incentive involves more unique projects, such as when equipment is being added or even eliminated. The incentive varies based on the estimated annual energy savings. The incentive amounts are calculated based on estimated first-year savings.

Focus on Energy also helps fund project assessment studies including an incentive to assess applicability of anaerobic treatment.


What are some examples of prescriptive and custom incentives?

A good example of a prescriptive incentive is the installation of a Variable Frequency Drive (VFD) on a constant-speed device. In this case, the plant would receive a predetermined number of dollars per horsepower as long as the equipment operates a minimum of 2,000 hours per year.

I’ll use an aeration project to describe how a custom incentive works. Let’s say the treatment facility replaces its coarse bubble diffusers with fine-bubble diffusers. This means the facility would save energy on an ongoing basis throughout the year. This could result in hundreds of thousands of kilowatt hours (kWhs) saved per year. The estimated annual savings in kWh and kW is multiplied by the per kWh and per kW incentive the program pays in order to determine the total custom incentive.

Since projects involving custom incentives are more sophisticated and require approval before implementation, energy advisors help gather energy savings calculations on the front end. We’ll also submit an application for the incentive on behalf of the customer.


How does a treatment facility verify whether energy conservation measures worked?

On certain projects, a separate team will review the energy consumption of a facility a few months after project implementation and compare it to the energy baseline taken before the energy-savings project started. At times, the team will work with the facility to assess the overall project impact to confirm the project achieved the claimed savings.

At the end of the day, municipalities are most interested in whether the treatment facilities fully understand their electric bills and learn how to keep energy costs in control based on the initiatives implemented. If energy consumption and costs don’t go down, the municipality and facility superintendent will revisit the project to assess what conditions changed.


Where can wastewater treatment facilities realize the most energy savings?

It’s important to note there is no typical wastewater treatment facility. They might have similar processes, but each one functions and operates differently.

That said, the most intensive energy use takes place in the primary and secondary stages of a conventional wastewater treatment process. It’s known that pumping in the primary stage and aeration in the secondary stage of processing together account for about two-thirds or more of a facility’s energy consumption. It’s normally either aeration systems or raw sewage pumping we focus on.

With aeration, the main areas for energy savings opportunities include the use of aeration blowers, diffusers, and control systems. As far as equipment itself, an aeration blower is typically the largest consumer of facility energy.


What can treatment facilities do with blowers to realize energy savings?

The most significant opportunity has to do with machine sizing and selection. The reason is because facility design codes require treatment facilities to select blowers with the intention of meeting peak-flow conditions for a 20-year period. Facilities must also have a redundant unit as a backup safety factor for unforeseen equipment failures, peaks or emergencies.

It started from the EPA in the 1970s and continues now; you look at your treatment facility for 20-year peak conditions and size blowers for that. There are a lot of facilities that have one large blower and then a second one because they need to have redundancy. But low loading conditions were not looked at, which may have been a lot less. Therefore, the blower should have been, or could have been, sized a quarter or a third of its size in order to efficiently meet the low loading conditions. This is where the potential opportunity for energy savings comes in.

Rotary screw blower Atlas Copco

Shown is a rotary screw blower at a Wisconsin wastewater treatment facility.


What should facilities do differently with blower sizing and selection?

Put in three or four blowers, each one a third of what you need, or a quarter of what you need to meet that low-flow condition efficiently. Then you can turn the second or a third unit on as loads increase. Or throughout the day, they go up or they go down with diurnal flow, and you can efficiently meet the changing conditions.

Let me give you an example. Say a treatment facility picked a 100-horsepower (hp) blower based on its need to meet peak conditions. Let’s also say the plant installed a second 100-hp blower for redundancy. On the first day of operation the facility probably only needed 22 to 25 hp. The primary 100-hp blower, however, doesn’t have sufficient turndown to efficiently match the airflow rate for this minimum process need.

So instead of two 100-hp blowers, why not install three 50-hp blowers and use one of them at 50% of capacity to efficiently meet the low-flow conditions? You can then turn on the second, or third blower as loadings increase. This also provides redundancy.

That’s just one example of multiple ways blower sizing and selection can reduce energy use. When the Focus on Energy program started, we reviewed approximately 50 sites. From that, we learned most facilities operate at only 30-35% of their designed condition.


What impact are advances in blower technology having on energy savings?

I think blower sizing and selection is the biggest challenge for wastewater treatment facilities while blower technology is a secondary consideration.

There’s no question advances in blower technology have gained traction in the wastewater world and have helped facilities reduce energy consumption. But different blower technologies are better at meeting different ranges of airflow. I try to get people to focus on the right size selection of the blower and then select the right technology for that airflow rate.


How would you assess a treatment facility’s interest in adoption of energy-conservation measures?

Facility operators openly embrace energy efficiency and seek ways to better manage their energy use. They know more restrictive discharge requirements are coming, but facility operators typically do not just say, “Oh, well. This is something we have to do.” Instead, they ask, “How can we operate our facilities more efficiently when requirements change?’ ”

Operators are environmental stewards. Not only are they cleaning the inflow and discharging good, clean water but they're also doing it with the least amount of energy consumption. They’re managing the use and costs.


Are there water resource recovery facilities that have gone net-zero energy?

We have a couple in Wisconsin that have that capability. We have others that are using renewable energy resources, primarily biogas, to offset a fair amount of their energy.

Wisconsin water treatment plant

A number of Wisconsin wastewater treatment facilities leverage a host of technologies, such as this biogas-fueled generator set, to offset their energy consumption.


What impact do programs like Focus on Energy have on a facility’s decision to implement energy conservation measures?

The vast majority of feedback we’ve received is very positive and I think part of it is because Focus on Energy offers an independent, third-party review of and recommendations for energy-saving opportunities.

What we’re saying is, “This is how you can get the same amount of work done at your facility, but not work as hard to produce the same or better effluent results, all while saving energy and money.”

It makes sense when you consider utility costs are usually a treatment facility’s second highest cost, coming in behind labor costs.


Thank you for these insights.


For more information about Focus on Energy’s Large Energy User Program, contact Joseph Cantwell, email:, tel: 262-786-8221.To obtain a copy of the Focus on Energy’s Water & Wastewater Industry Energy Best Practices Guidebook, visit:

All photos courtesy of Leidos Engineering.

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