Across the globe, a number of dynamics, such as new technology, financial pressures and changing community outlooks, are impacting businesses large and small. The demand to do more with less has never been greater. This new operating reality also holds true for water utilities around much of the world. To balance these competing forces, water utilities are working to improve energy efficiency via new approaches to decades-old business practices.
According to Black & Veatch’s 2013 “Strategic Directions in the U.S. Water Industry” report, roughly 90 percent of respondents indicate their organizations are implementing or are interested in launching energy efficiency programs.
To this end, gains can be found in treatment facilities and in water conveyance systems. Treatment plants include complex processes in which power costs are a major factor along with labor and chemical costs. In a water conveyance system, pump stations often represent the largest power cost, but regulating valves can also be a cause of lost energy (poor settings) or a potential source of energy recovery (hydro generation).
Two key factors impacting aging water and wastewater systems are the population and load projections made during the design phase. For years, treatment plants were designed with growth in mind. Given the typical lifespan of these facilities, a plant developed in 1970 for a community of 100,000 people might in fact have been designed and built to serve double that amount in the future.
While this foresight proved wise in many instances, other communities were saddled with oversized assets when growth did not occur or when populations declined.
“Frequently, the capacity-driven design practices of the past resulted in systems that now operate inefficiently, in terms of energy performance,” said Steve Tarallo, North American Business Lead, Sustainable Solutions with Black & Veatch. “While it goes against our sense of bigger is better, sometimes too much capacity can be too much of a good thing.”
Pumps and Aeration Systems
Pumping and aeration systems are the highest energy users in a water treatment plant. Typically aeration systems are responsible for 50 to 60 percent of total wastewater treatment plant energy use. In some areas, pumping within a water distribution system can use as much as 80 percent of total energy for municipal water supply. As a result, systems not tuned or unable to reduce excess aeration blower or pump capacity can waste energy and money for decades. This waste can also result in greater greenhouse gas emissions over the life of the plant.
Tarallo added, “When energy was less costly and national grants made for easy access to capital, water utilities were less concerned with the cost of operations. But rising energy costs and more stringent effluent standards that require more energy and capital for compliance are making efficiency critical.”
Besides generational trends, periods of crisis can also impact system design. For example, systems built to respond to extreme climate events, like the major drought in Australia of the mid-2000s, can also face challenges when operations return to historic norms.
“These very substantial capital investments in Australia’s water sector came during a time of crisis. Today, the challenge is for utilities to reduce operational overheads without passing on the cost to their customers,” said James Currie, Managing Director of Black & Veatch, Australia.
Pathways to Energy Efficiency
There are several pathways to increase energy savings, improve efficiency and decrease greenhouse gas emissions, ranging from small-scale projects to major “right-sizing” of capital investments.
“Building in efficiency and whole-life costs into planning and design has been driven by higher energy costs and competing demands for capital in many places around the world,” said Ahmet Ozman, a Planning and Asset Management expert with Black & Veatch’s water business. “For example, in the UK, asset management plans by water companies incorporate carbon reduction targets and customer willingness-to-pay into their formulas. This reflects that the sizing of assets has to satisfy other objectives in addition to providing capacity.”
In transmission and distribution systems, an evaluation of pressure zones and the operation of pumping stations and storage facilities can uncover many opportunities for efficiency gains.
“Advances in technology, design, modeling and more are now making their way around the globe,” added Ozman. “We are helping many water utilities and agencies discover savings and system optimization opportunities by using advanced hydraulic modeling techniques.”
Operations management evaluations can play a role as the starting point of many energy efficiency plans. Program elements can include:
- Evaluations that can allow operators to focus on areas of energy efficiency and prepare for more active programs, including the automation of certain functions and off-peak power purchases.
- Automation and the use of new controls that are often low-cost, high-return approaches to reducing energy consumption while improving system response. Advanced sensors and software can help optimize existing equipment while quickening responses to changing conditions.
Once efficiency measures become integrated into operations, plants seeking greater energy savings should examine the outright replacement of major energy consuming equipment. Though a more costly option, new aerators can typically reduce overall energy consumption of a plant by 15 to 30 percent. New motor, drive, and pump technologies have also created very significant gains in efficiency.
“Effective equipment replacement requires an integrated systems approach,” noted Tarallo. “Band-Aid type solutions often wind up costing more than they save.”
ESCOs Help with Plant Evaluations and Implementation
A more recent development in this era of tight financing is the use of performance contracting arrangements.
While the shift to right-sizing began about 10 years ago, spikes in energy costs and limited access to capital have curbed water utilities’ ability to undertake needed projects. This conflict has led to opportunities in the fast-rising performance contracting market.
Water utilities lacking traditional funding options can turn to energy service companies (ESCOs) that will evaluate a plant and implement operational and capital-focused projects. Projects are then financed through savings guaranteed by the ESCO to exceed the debt service on the cost of the project. Should the savings not be realized, the ESCO pays the balance.
Currie concluded, “We need a fresh look at how to maintain, manage and automate facilities, as well as how we use energy. The good news is that around the world we’re seeing the water industry adapt operations and introduce new practices that are saving energy and, therefore, money.”
Published originally on Black & Veatch Solutions