Pumped for Efficiency
Water pumps remain key to efficiency gains.
Doug Potts calls it a daunting, but doable, goal: American Water, a utility that provides drinking and wastewater to more than 15 million people in 30 states and in Canada, wants to reduce its annual energy consumption by 8% by the end of 2016.
Doing so would make a big impact on both the environment and the utility’s bottom line. Voorhees, NJ-based American Water is no small company. It maintains treatment plants, storage facilities, pumping stations, and 45,000 miles of main and connector pipes across the country. It also employs more than 7,000 people. Reducing energy usage by 8% a year would be a big boon.
And Potts, senior design engineer at American Water, says it all starts with the pumps upon which the utility’s state subsidiaries rely. According to his data, about 95% of the energy that water companies consume comes from the pumps that utilities use to push water through their systems.
“The energy that we use for the lights in our buildings is a tiny percent of the amount we use to pump water,” says Potts. “We have firm goals in place to improve our energy efficiency across the company. Pumps are the biggest piece of that. The real effort in improving our energy efficiency has to go toward improving the efficiency of our pumps. In the last couple of years, American Water has paid a lot more attention to its pumps. Now we have real tangible goals for ourselves.”
American Water is far from the only utility across the country looking at the efficiency of its pumps. As water utilities struggle with tighter budgets, and a mandate to provide their services while spending fewer dollars, a growing number are taking steps to reduce the energy they consume each month. By doing so, utilities can realize significant savings.
And this is a trend that few in the water industry see slowing any time soon.
“I’m sure many utilities are paying more attention to their energy efficiency with the reduced tax income that most of them are experiencing today,” says Craig Redmond, director of engineering with Mansfield, OH-based Gorman-Rupp Company, which designs, manufactures, and sells pumps and related equipment to municipalities and other end users.
“Utilities are watching their budgets more closely,” says Redmond. “Many have had to make difficult choices when it comes to manpower reduction. They are working to control expenses in other areas, too. By minimizing the amount of energy consumed throughout their service areas, and in the pump stations in particular, utilities can realize some sizable savings.”
An Increasing Area of Concern
Many water districts have long been concerned about the amount of energy they consume. But these concerns tend to be magnified today, says David Robinson, director of marketing for Morristown, NJ-based Honeywell, a company that provides several products designed to improve the energy efficiency of utilities both large and small. The reason is simple: the economy.
In tough economic times—such as the economic slump that the United States is still suffering through—governments and utilities are forced to look more carefully at all of their costs. Today’s sluggish economy is no exception, Robinson says.
“Municipalities and utilities today are faced with the lingering effects of the economic downturn,” says Robinson. “A lot are looking at ways to reduce the money they spend on providing water to residents. It’s an area of increasing concern.”
And many water utilities still face a long haul before their bottom lines improve, Robinson says. That’s the result of a simple formula that Robinson employs: There’s a two-year lag from when the general US economy bottoms out and when economic problems hit municipal government. There’s also a two-year lag between the time when the country’s economy starts to rebound and when municipalities’ coffers start to recover.
This means that even those taking the most optimistic view—that the nation’s economy is in a solid recovery phase now—have to accept that utilities will still face a lag of at least two years before they start to experience their own recoveries.
Unfortunately, while water utilities recognize that they need to boost their energy efficiency levels, many are struggling to take the right steps to do so.
This might be because some water districts have few simple solutions for boosting their water system’s efficiencies.
Robinson points to the large number of districts that are designed to pump out more water than they ever need to actually distribute. Many water districts built their distribution systems based on predictions of how fast and large their populations and business districts would grow.
In many cases, these predictions oversold the number of residents who actually moved into a community. They also overestimated the number of businesses that would serve these residents. The economic downturn has also meant that many businesses are no more, even large ones. This means that many water districts are built to handle an ultimate load that they never have to actually deliver.
This results in inefficient pumps, which cause these utilities to consume more energy than necessary in a year, Robinson says.
At the same time, end users have a much greater awareness of the importance of drinking and wastewater today, Robinson says. Residential users, in particular, are more frequently turning to low-flow toilets and aerators on their faucets. They are now consuming less water each day than they were five years ago.
“Municipalities have to plan for population and business growth sometimes 20 years out,” says Robinson. “So some systems are far over-designed. These systems are inherently inefficient. What you have often is a water grid that is sized for an ultimate load that it is hardly ever using. This presents an excellent opportunity for progressive utilities to really fine tune their water-distribution systems and optimize them for both the short and the long terms. Pumps, of course, are a great way to do that.”
The most progressive utilities today are increasing the efficiency of their pumps in a wide variety of ways, Robinson says. Some are relying more on nighttime storage to leverage off-peak energy rates instead of letting their systems pump whenever they sense the need to pump.
Other utilities are embracing the demand-response method of making sure that their pumps work as efficiently as possible, Robinson says.
Under this system, utilities send e-mail messages to customers who have signed on to their demand-response programs. Customers then have a limited amount of time, usually two to 12 hours, to take a specific action. The utility might want its end users to modify the control settings on their SCADA systems to increase their water storage for a short period of time. This allows the utilities serving these customers to avoid using their normal high-pressure high-service pumps during a period in which to do so would consume the most energy.
The demand-response model is growing in popularity because utilities have discovered that there are a certain number of hours each month during which their water-delivery grid faces operating constraints that make delivering water to their end users a more costly task. The goal of demand-response programs is to enlist end users in the effort to reduce their water distribution needs during these hours.
Robinson says that Honeywell is now working to equip 10 water utilities with the communications and control infrastructure to allow them to participate in demand-response programs.
“These systems can save utilities tens of thousands of dollars a year,” says Robinson. “We have one of those photos of an oversized check being presented to a utility, and the number on that check is in the six figures. That’s a significant amount of savings for a program that is relatively simple to institute.”
Convincing water utilities to sign up for a demand-response program remains the real challenge, Robinson says. But the arguments in favor of such programs are becoming stronger every day, thanks largely to the nation’s weak economy.
With utilities being forced to come up with more savings each year, a demand-response program—especially because it requires little new equipment and boasts a reasonable upfront payment—is a fairly easy sell to city councils and boards, Robinson says.
Honeywell officials present their end users with a clear formula showing them how much participation in the demand-response program will cost them and how much in savings it will generate each year. The numbers usually make the case.
“As utilities are seeing reduced water usage, there is pressure on them to increase their rates. This is one additional way of putting off rate increases as long as possible,” says Robinson. “We are seeing more participation now in these programs. Utilities are reassured when they see their peers successfully using demand-response to cut their costs. No one wants to be the first adopter for technology or a new approach to doing business. Once they see it as being a successful program, once they see the magnitude of savings by their peers, they are quick to jump on the bandwagon.”
Spending Big for Savings Later
Instituting programs that enlist end users aren’t the only steps that utilities are taking to improve their overall efficiency levels. Many are replacing antiquated water facilities, and their inefficient pumps, with new models.
This requires a huge upfront cost. But, those municipalities that can afford the millions it takes to open new water treatment, and distribution plants can see big energy savings each year, thanks to the new, more efficient pumps they’ll be employing.
Just ask Emmett Autrey, director of utilities with the city of Amarillo, TX.
In December, the city opened its new $18 million pump station to more efficiently move water to its business and residential customers. The station has been designed to move 87 million of gallons of water a day, a significant increase from the 73 million daily gallons of water that the station it replaced had struggled to distribute.
But, while the new plant will move more water, it will actually cost the city less to do so. The pumps at the station are 20% more efficient than they were at the old one, Autrey says. This will bring more than $220,000 a year in energy savings, he adds.
The new plant boasts six pumps driven by 1,500-horsepower motors. It replaces a pump station that first went into service about five decades ago.
“The old water plant was becoming inefficient,” says Autrey. “We were putting more and more of a hydraulic load on the pumps as the community grew. For efficiency and capacity reasons, we went with a plan to design this new pump station.”
The new plant relies on variable frequency drives, better known as VFDs, to run at least 50% of its pumps, Autrey says. This means that plant operators don’t have to turn these pumps on and off, saving wear and tear on the devices. Pumps powered by VFDs also consume less energy to operate.
The designers of the pump station made sure, too, that the pipes and valves connected to its water pumps were designed to provide as little restriction as possible on the flow of water as it leaves the pumps. Such a seemingly small step can actually result in sizable energy savings as pumps have to exert less strain to move water through a water distribution system.
The projected efficiency gains from the new plant’s water pumps were important. The predicted yearly energy savings allowed Amarillo to qualify for stimulus funds from the American Recovery and Reinvestment Act.
“Being able to show that we were going to be saving about $220,000 a year made all the difference in the success or failure in getting that funding,” says Autrey. “Our old pumps were becoming very inefficient. Being able to boost our efficiency by so much made a real difference in our efforts to secure those stimulus funds.”
Amarillo isn’t alone in seeing sizable efficiency gains by updating aging water pumps. A large number of water districts across the country are delivering water while relying on old water pumps. As pumps age, their efficiency levels naturally drop.
New models of water pumps also tend to be more efficient than their predecessors. At Gorman-Rupp, that certainly is the case. Redmond says that the company is constantly working on new pump designs that are more efficient than are previous generations.
“Efficiency is becoming a more important requirement on our products now,” he adds.
The challenge remains convincing water utilities to make the upfront investment in the new pumps that will bring them significant energy savings each year, Redmond says.
“It’s always been a battle with the customer perception of upfront costs versus the long-term savings they can realize,” he says. “It’s a cost of ownership discussion.”
Redmond says that utilities should consider several factors before deciding to replace their aging pumps. Most important, of course, is the cost of a new pump and the amount of energy savings this new pump will bring each year. Many new pumps will be so much more efficient, a water utility might be able to recover its upfront investment in a relatively short period of time.
But utilities won’t always have to replace an entire pump to realize significant efficiency boosts, Redmond says. Often, a pump might need a single new part to increase its efficiency. Other times, the cost of tearing apart an aging pump and installing new components is so high that it makes more financial sense to start over with a new, more efficient pump model, Redmond says.
“Utilities need to perform a cost-benefit analysis. And they need to include the time and effort that they have to put into retrofitting a pump versus replacing it,” says Redmond. “If a pump’s impellers are wearing out, they will wear out the pump’s housing at some point in the future. The pump, though, doesn’t necessarily have to be replaced every time the impeller is.”
Boosting Pump Efficiency Across the Country
At American Water, increasing pump efficiency has become a priority. Starting two years ago, the utility enlisted its maintenance services group to measure the efficiencies of the pumps in American Water’s largest 50 treatment plants across the country. That testing was nearly done at the end of 2011.
The next step is for American Water’s individual state subsidiaries to look closely at the pumps at these treatment plants to make efficiency decisions. The officials at these subsidiaries will have to determine which pumps are operating at efficiency levels that are low enough to warrant either replacing the pumps or rehabbing them.
According to the plan, once the state subsidiaries make these decisions and then take the steps necessary to repair or replace inefficient pumps, overall efficiency will jump 8% at American Water subsidiaries by the end of 2016.
Potts says that the message has gotten out to state subsidiaries about the importance of pump efficiency. American Water is putting its money behind the idea, too, budgeting $70 million out of its normal operating budget for its efficiency project.
“The message has been going out,” says Potts. “The vice president and president have been getting the message out there over the last year. At first, the idea took a little while to catch on. But we are now seeing more commitment to it, because it’s become a higher-level initiative. Of course, we are still very early in the process. Our state subsidiaries are still trying to figure out what to do in their states. A lot of this project is still in the evaluation stage.”
Potts points to a water utility that recently tested the efficiency of its pumps. It found that more than 10% of its pumps where operating at lower efficiencies than when they were new.
The next step for this utility is to have its engineers evaluate the pumps that are losing efficiency to determine how many need to be replaced. That is not always a simple decision.
For instance, maybe two of the pumps with efficiency drops are rarely used. It wouldn’t make financial sense to replace them. Other pumps that are used on a regular basis, though, might consume enough energy to make replacing them with more efficient models a wiser financial choice, Potts says.
Water district officials must also decide whether to replace a pump in its entirety or to replace certain parts of it. A pump might just need a new impeller, for instance, to once again operate near its peak efficiency levels. And replacing an impeller is a lot less costly than installing a new water pump.
The American Water efficiency program, though, isn’t only about repairing or replacing pumps. Some state subsidiaries might discover that though they’ve done a good job maintaining their pumps, the equipment still isn’t operating at top efficiency levels. The problem might be that a large industry in the utility’s service area, which once required a huge amount of water, has gone out of business. Perhaps the utility never adjusted its water pump needs after that large business left town.
Other utilities might decide that variable frequency drives would boost the efficiency of their pumps sufficiently so that they won’t need to replace or repair any of their pumping equipment.
Other times utilities might discover that many of their valves may have been throttled over the years. This practice—one that’s not all that uncommon—can cause pumps to work harder than necessary, again lowering their efficiency levels.
The problems and solutions that each state subsidiary finds at American Water will vary. But that, Potts says, is the point of the company’s efficiency program.
“The goal we have is a real one,” says Potts. “We think we can make a real difference with the efficiency of the water systems throughout our network. And so much of that has to do with making sure that the water pumps throughout our system are working as efficiently as possible.”
Author's Bio: Dan Rafter is a technical writer and frequent contributor.