Pumps & Systems, October 2008
To achieve a sustainable future, the green movement demands increased energy efficiency and conservation. Here is a look at how these changes will impact the water industry and its use of pumps and controls.
The Green Movement and the Water Industry
The water industry has experienced the green movement since environmental activism gained strength in the 1960s. The 1990s introduced new green concepts like "sustainable development," "green cities," "low-impact development" and "Leadership in Energy and Environmental Design." These concepts all focus on conserving resources and cutting pollution.
Another concept in the green movement that has recently gained momentum is the fight against climate change, caused by a rise in greenhouse gases that increase global temperatures. Climate change will have wide-ranging consequences for the water industry. In addition to changing temperatures and rain and snow, climate change could affect sea levels, floods and droughts, and wet and dry seasons-all of which affect the water industry.
Additional Water Industry Pressures
The water industry must simultaneously respond to additional external and internal pressures. Customers expect water utilities to deliver reliable supplies and environmental protection, while these utilities grapple internally with cost pressures, tighter regulations and aging infrastructure.
The water industry also feels pressure stemming from public health concerns over water quality. These concerns focus on treatment processes and materials used in water systems. The water industry has responded recently to specific concerns about water distributions with research on controls that prevent harmful disinfection byproducts, lead in drinking water and bacteria that grow in stagnant zones.
Affordability is an often-neglected aspect of sustainability, but the water industry's ability to pay for system operations, maintenance and upgrades must also be sustained. Fixing aging infrastructure will sap our ability to mount sustainable systems in the future.
Reduced use of resources and lower impacts on natural systems are related to water efficiency, a term that encompasses conserving, valuing, allocating and measuring water use. Water efficiency means allocating water to uses with the highest value, which is not always an easy task. For example, a farmer may have the right to pump irrigation water, but the water could be reallocated to higher-value uses for cities or landscapes. Valuing[EU1] water will require that it be measured and managed carefully, and these tasks will require advances in instrumentation, controls and management systems.
Water Industry Response
To address these numerous challenges, the water industry is conducting ongoing research. As part of this research, the water industry has investigated topics including how water and wastewater utility infrastructures can adapt to changing climate conditions. For example, what happens if a reservoir and a treatment plant are based on a utility's "reliable" water source, but the supply suddenly changes? Similarly, what do you do if your wastewater plant has a permit to discharge into streams that can handle the releases, but the stream flows diminish?
This research explores ways to use energy, funds, water and workforces efficiently. While research on these topics is just beginning, some of the potential problems must be solved on a local basis. For example, if the sea level rises and floods a community's wastewater treatment plant, a big response will be required for that local area.
The following are specific solutions the water industry has explored:
Pumps
EPA's Energy Star Program estimates that approximately 3 percent of all energy use in the United States is for water supply and wastewater management. Water and wastewater utilities use pumps throughout their systems, from pumping raw water, to treatment, to booster pumping in distribution and collection systems. They are also used in wastewater lifting, flood control and movement of raw water for irrigation, energy and industrial purposes. Pump systems are found in public and private sector applications and in system sizes that range from small-scale plumbing systems to giant conduits that can be 10-ft in diameter and more. Because of this widespread pump use in the water industry, going green requires more efficient pumps.
As in the case of automobile efficiency, pump efficiency is less significant with low energy costs. Thus, a small improvement in efficiency would be a minor consideration to a water or wastewater utility. With high energy costs, a small gain in pump efficiency becomes more attractive and potentially worth the investment. Adding in the cost of energy, the need to reduce the carbon footprint and invest in cost-effective infrastructures means that smaller, more efficient and more flexible pumps and systems look attractive for the future.
Systems
On the systems side, using smaller, more flexible systems as a response to the green movement can also improve security and responsiveness to change. Small, local water and wastewater systems can replace large, centralized ones. According to E.F. Schumacher's 1973 book Small is Beautiful, trends toward large, industrialized systems are counter to human needs, which focus more on local, manageable technologies.
Consider drip irrigation, which is common in the landscape industry. Large irrigation systems once dominated the industry, but the need to use water better and save energy and labor have created new opportunities for small scale components.
For water systems, point-of-entry (POE) or point-of-use (POU) water treatment systems can replace large remote centralized treatment plants. For localized wastewater systems, recycling capabilities can minimize the need to move water from one zone to another.
In control systems, utilities are downsizing operations staffs and focusing more on their SCADA (Supervisory Control and Data Acquisition) and AMR (Automatic Meter Reading) systems. For infrastructures, asset management efficiently automates data-driven management systems to inventory, assess and plan replacement of infrastructure components.
To supplement these systems, the water industry has also turned to instrumentation, including various meters and water quality monitors. Controls include valves, weirs and other hydraulic structures. Management systems include monitoring, telemetry and automated, computer-based decision systems.
Conclusion
The search for energy efficiency in the water industry will take several directions. More efficient hydromachinery will be one avenue, as will conserving the amount of water pumped.
A sustainable future will require the water industry to use resources better, cut pollution and adapt to climate change, while simultaneously improving lives through better service and protection of health. Future water-handling systems will need to be more efficient, flexible, reliable and affordable.