Water and energy are deeply connected, and in order to manage one properly, one must properly manage the other. Water and wastewater utilities need a substantial amount of energy to conduct crucial processes and operations. Faced with tightening budgets and increasing energy costs, the U.S. water sector is focusing more on waste-to-energy practices these days and is considering alternative energy options. W&WD Managing Editor Elisabeth Lisican spoke with Danfoss Vice President of Sales John Masters about some recent developments affecting energy in the water sector.
Elisabeth Lisican: What are some recent projects you have come across that demonstrate successful water-energy efficiency?
John Masters: Danfoss has been involved in several water-energy efficiency projects—both in water and wastewater application—that have successfully implemented variable-frequency drive (VFD) technology not only to improve energy and water efficiency but also to optimize the process. This has ranged from the simple speed control of pumps in municipal and commercial swimming pool applications, where we see energy cost improvements that exceed 50%, to full-scale implementation of VFD technology in wastewater facilities, where we, in conjunction with additional technologies, have helped to achieve a net positive energy surplus of as much as 30%, allowing the treatment facility to sell excess power back to the utility.
Lisican: Which technologies will play a key role in achieving sustainable energy goals for the water sector?
Masters: VFD technology is one of the most cost-effective technologies available, and can be used in water, wastewater and irrigation systems to control the speed of water pumps, aeration blowers and other motors depending on the system requirements. VFDs can be retrofitted onto existing motor systems or built with original equipment and can control both standard and high-efficiency motors ranging in size from fractional horsepower motors to units rated at several thousand horsepower. VFDs allow the end user to operate equipment at the precise speed required to optimize the system and reduce energy and water consumption.
Lisican: What do you believe is the most important recent development in water-energy efficiency regulation?
Masters: The ongoing Department of Energy pump efficiency rulemaking is, in my opinion, the most significant development in the past year. The regulation, which has been a joint effort from industry professionals and regulating agencies, will put into effect a new, defined set of standards and testing procedures to regulate the efficiency of clean water pumps. These types of regulations allow end users the opportunity to better determine the benefits of using various technologies to improve efficiency.
Lisican: What are the latest trends and some best practices that facilities can follow in terms of energy efficiency and generation?
Masters: There has been a strong focus recently in wastewater facilities where process optimization has resulted in the facility becoming energy-neutral or, in some cases, producing excess energy that can be used outside of the facility. With wide diurnal changes in a facility’s load, it is imperative to have control strategies in place to adjust for and accommodate these variances. For this reason, we are seeing the use of variable-speed technologies in all phases of the treatment facility, including aeration blowers, pumps and other motorized equipment.
This, in conjunction with other high-efficiency technologies like motors and aeration equipment, allows for much tighter control of the process and improved energy efficiency.
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