Energy Audits

April 15, 2011

About the author: Lee E. Ferrell, P.E., BCEE, CEM, LEED GA, is water/wastewater energy and process consultant for Schneider Electric Industry Business. Ferrell can be reached at [email protected].

undefinedLaying the groundwork for improved efficiency

Knowledge is power when it comes to managing an energy-conscious water or wastewater facility. Collecting consumption data via an energy audit empowers operators to pinpoint and address inefficiencies. In an interview with WWD Managing Editor Caitlin Cunningham, Lee E. Ferrell of Schneider Electric discusses how the process works and why it is important.

Caitlin Cunningham: What makes a water or wastewater treatment plant a good candidate for an energy audit?
Lee E. Ferrell:
Water treatment pumping and wastewater treatment aeration require a majority of a facility’s energy consumption. However, each treatment facility is unique, and although one may have the same output quality requirements as another, its combination of processes may be entirely different than another located just down the road. That said, you cannot apply the same energy-efficiency formula to each plant. The energy requirements for every plant have to be understood completely, and an audit is a critical tool to help gain that understanding.

Cunningham: How does the auditing process work?
The energy audit is a critical piece of a larger strategy to maximize the energy efficiency of a plant. In most audits, a team of energy and process consultants will work with a facility manager to collect the necessary information, such as energy bills dating back several years and plant and equipment drawings. The team will tour the plant to understand its output needs and goals, and also inspect each load individually, looking for energy data collection points and opportunities. Sometimes this process can take days or weeks, depending on the type of facility being audited.

After this data is collected, the consulting team creates and presents an energy action plan. This plan provides detailed information on where the energy is being consumed and how existing equipment can be better utilized to reduce energy consumption. The plan also offers suggestions on upgrades to power management devices and more efficient equipment. A comprehensive plan will also include suggestions for renewable energies, as well as provide information on energy credit opportunities offered by the government.

Cunningham: Are there any facility components, processes or methods that audits repeatedly reveal to be “energy hogs?” If so, how can these be made more energy efficient?
The No. 1 consumer of energy in a plant is typically electric motors, which are used for pumps and blowers. In addition, ultraviolet disinfection is notorious for energy consumption. An increase in reverse osmosis and membrane filtration has also added to energy requirements.

Manufacturers are taking great strides to make these devices more efficient. Standards have been enacted to provide guidance with this, including the international standard IEC 60034-30 for super-premium efficiency class of electric motors. But most plants have legacy equipment and often cannot afford to upgrade everything at once. Additionally, the new efficient motors are still only a part of the larger process-efficiency equation.

Cunningham: What benefits can facilities realize by saving energy?
Besides the obvious benefit of a lower power bill, facilities can win awards from various government programs that will provide credits or other types of awards for carbon footprint reduction and sustainability.

Cunningham: How do you see the role of energy audits developing in the water/wastewater industry in the coming decade?
Facilities will increasingly begin to realize the importance of regularly scheduled energy audits—not only for improving efficiencies, but also for validating and documenting the strides they may have taken already to accomplish carbon footprint reduction.

Equipment manufacturers will continue to improve device efficiencies. The use of built-in, data-collecting devices will continue to increase. Process science and techniques will keep evolving. Each plant will continue to expand its output to meet the requirements of the community it serves. This said, energy audits will continue to play a vital role in understanding the energy consumption of a facility and provide a foundation for improving the facility’s efficiencies.

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