To serve 16.2 million customers across 32 US states, American Water Works Company, Inc. maintains 5,000 separate electrical accounts. The majority of the electricity consumed through those accounts, “somewhere in excess of 90 to 95%,” powers the company’s pumps, according to Brett Bower, Senior Energy Specialist at American Water.
In a 2010 push to save energy and money on pumping operations, American Water focused on its 50 largest electrical accounts. Bower says the company chose to look at just those 50 accounts, because they collectively represented more than half of the company’s electricity costs.
Once American Water identified its target facilities, the company continued its efficiency efforts by determining each facility’s “wire-to-water” ratio. This ratio measures how much electricity a given facility needs to deliver water. It is sometimes defined as the horsepower provided by a pumping plant divided by the electricity (converted to horsepower) required to run the plant’s pump drive motor. Under this version of the calculation, the ratio is expressed as a percentage.
American Water’s research found that the average wire-to-water ratio of existing, in-field utility pumps was about 55%. Studies performed by American Water showed that the company could increase pump efficiency by as much as 20% by making upgrades to older pumps. As the company updated and upgraded equipment in 2011, engineers designed all new installations to achieve wire-to-water ratios of 76% to 82%.
Water utilities should begin energy efficiency programs with this kind of measurement. Upgrading motors, pumps, and filtration equipment, as well as optimizing pipe networks, will almost certainly save energy.
According to Terry Brueck, president of consultancy EMA, Inc., it’s “not uncommon for water utilities that implement new efficiency regimes to reduce their energy use by 25%.”
When energy costs represent as much as 30% of a water utility’s budget, those savings can have a serious impact on the bottom line. But those energy- (and cost-) saving efforts will be blunted if utility managers don’t know where or how they use electricity.
In addition to giving utility managers the tools they need to install the most effective energy-saving techniques for their situation, properly understanding and managing a water utility’s power usage can disproportionately save the utility money; clever managers can find financial savings on maintenance costs and time-of-day use by carefully crafting the utility’s energy strategy. But it all begins with properly monitoring power usage.
The Nitty Gritty
While a given facility’s electricity bill will help a water utility understand how much energy it has used historically, utilities can enhance their monitoring and savings opportunities by tracking finer data.
“All water utilities closely track their energy consumption, but the tools that they use and the depth to which they integrate those tools vary widely,” says Greg Dixon, senior vice president for marketing and sales at energy management company, EnerNOC, Inc. His and other companies provide services like real-time metering of every pump within a system–including the quantity and phase of energy each pump consumes.
Dixon says this kind of service is worth the investment for water systems with as few as 10 pumps. Monitoring a pump network through EnerNOC costs a utility between $100 and $300 per meter per month, and should enable savings in excess of that.
For the best results, utility managers should feed the data from such monitoring systems into a SCADA (supervisory control and data acquisition) system. These systems allow utility managers to monitor energy use in real time and gives them a better understanding of what pumps are drawing power when. Simply understanding this data allows managers to make minor changes that produce energy savings.
“There may be situations where it is less costly and more efficient to use water from a certain plant,” says Brueck.
One plant may have been updated more recently than others; one may draw from a reservoir closer to the surface; or one may draw from a water source that requires less filtration. Regardless of the reason, smart utility managers can prioritize their pumps such that more efficient facilities run to full capacity before less efficient ones come online.
Shifting Energy Usage
Being aware and in control of each individual pump’s energy usage can also help water utilities reduce their energy costs–if not their use of energy itself.
For most water utilities, any time the utility’s demand for electricity exceeds its previous peak, its electricity provider permanently raises the utility’s electric rate. Utility managers can mitigate new peaks and avoid paying higher electricity rates by keeping abreast of the system’s current usage.
When water use spikes and a utility’s power demand climbs, managers can employ several tactics to avoid new peaks. They can reduce their pumps’ output and sacrifice water pressure to curtail electricity usage. Utility managers who planned ahead by filling storage tanks or water towers can release that capacity to reduce pumping temporarily. When neither of those approaches can prevent a demand-induced rate hike, the utility manager may be able to use backup generators. Generators need to be run occasionally for maintenance purposes anyway, Brueck notes. If those occasionally necessary runs can be synched to peak electricity usage hours, utility managers can fulfill two needs at once.
While generator use and pressure reduction work as temporary spot tactics, use of storage capacity can reduce a utility’s electricity costs on a regular basis. Utility managers with sufficient storage capacity in their system can shift some of their most expensive electricity usage to lower-demand hours when electricity rates are cheaper.
According to Dixon at EnerNOC, electricity rates during the day during a heat wave can climb to 30 times the rates incurred during a night with minimal demand. By using pumps to fill storage tanks and water towers overnight, the utility can save stored water to release during peak hours each day.
“Essentially, you’re filling up the battery and draining it down,” says Brueck.
In addition to saving costs, Dixon says, water utilities that contract with demand response firms like EnerNOC can even make money by using less energy at key times. During times of especially high electricity usage, many electricity utilities offer financial incentives to its largest customers if they can temporarily cut their power use.
Knowing which equipment needs to be replaced most urgently will help improve the energy efficiency of the whole system.
Saving Energy and Maintenance
Monitoring every pump within a system in real time can help utility managers spot which pumps are operating the least efficiently–especially when compared to their own historical performance. Any pump drawing significantly more energy than it has before may be suffering a mechanical problem. Spotting and following those cues can help crews address maintenance issues while they’re still inexpensive to fix–and can also save the energy costs associated with allowing continued degradation.
“Broken pumps can become a big energy suck on the system,” says Dixon.
The addition of multi-phase monitoring can help maintenance managers spot additional leading indicators of degrading equipment–or even mildly defective equipment. For example, if installation crews fail to notice a pump has been wired backward, it may be left running in that state, which could lead to a catastrophic failure. But anyone looking at the multiphase electricity usage data for the installation would instantly spot that something was wrong–allowing utility managers to shut down the pump and correct its wiring before it becomes a costly disaster.
While this kind of approach can help save energy by helping to ensure that all equipment runs optimally, it can also save time and fuel energy on equipment that’s running well. Most water utilities today still monitor the condition of their pump sites by sending crews to fill out checklists on routine walkarounds.
“The fact of the matter is a lot of those walkarounds and drive-arounds are just not necessary,” says Dixon. “These are systems that run pretty well most of the time. What you’re trying to do is manage the exceptions.”
He adds that by employing proper energy monitoring tools, maintenance managers can reduce or eliminate routine maintenance checks–and doing so doesn’t mean that the utility must dedicate an employee to scour data constantly. A water utility would have to be a “massive, massive consumer of energy” for such an arrangement to make sense, he says. Instead, companies like EnerNOC can “push” notifications about noteworthy conditions to a utility worker’s e-mail or smartphone in the form of text message.
“When you push that information out to them where they are,” says Dixon, “they’re going to read it, and they’re going to address it.”
While such a system may require some getting used to, it may also come with significant support. EnerNOC, in particular, offers telephone technical support at every hour of the day, he says. As utility workers get new alerts they haven’t seen before, they can call the helpline for clarification.
New Equipment
Beyond minor repairs, closely monitoring electricity usage data can help water utilities prioritize the replacement of their pumps and motors. Most utility managers’ capital budgets will provide for regular equipment replacement, and knowing exactly which equipment needs to be replaced
most urgently will help improve the energy efficiency of the whole system.
In the past few decades, water pump technology has drastically improved. Variable speed motors, Brueck says, replaced variable speed pumps as the state of the art for controlling an installation’s flow rate. Variable speed pumps, in turn, replaced now-ancient throttling valves–though some of that old, inefficient equipment may still be in use.
“There are definitely units out there that have been in service for more than 20 years,” says Brueck.
Individual pumps or motors may also have other reasons for falling behind the efficiency curve. Unexpected events may have damaged surface level equipment in a manner not repairable by routine maintenance, or running a station at a higher capacity may have shortened its useful lifespan. Regardless of the reason, repairing or replacing the worst-performing installations within a system will typically increase the effectiveness of the system as a whole.
Upgrading water filtration equipment may also yield meaningful savings. While water filtration represents a small portion of a given utility’s electricity usage, new membrane technology has significantly improved the energy efficiency of filtration.
“There’s kind of been an evolution of improvements in reverse osmosis,” says Jeff Peeters, a senior product manager for GE. “We have realized about a 20% reduction in energy consumption with these products.”
Ultrafilters, like GE’s ZeeWeed hollow fiber membranes, only require a small amount of vacuum to pull water through the filter and leave impurities behind. Should a water system have aging filters that are demonstrating decreased efficiency, managers there should be able to install or retrofit new, more efficient filters with little difficulty.
Additionally, newer filtration systems allow administrators to set alerts for when the machines need to be cleaned. As material builds up behind the filter, it causes the system to expend more energy to clean the same volume of water. But cleaning the system also requires energy that will not transport water to customers, and taking a filter out of commission temporarily reduces the plant’s capacity. By understanding the system’s water demand dynamics, a utility manager can optimize when his filters should be cleaned and set alerts appropriately.
Utility managers can also improve their systems by transitioning from old-style standpipes to more modern pulsation dampeners. New pulsation dampeners take the form of flexible reservoirs that absorb extra pressure within a system and feed the water back in as pressure drops.
“It acts as a sacrificial lamb to make sure you’re protecting the whole system,” says Andrew Yeghnazar, president of Blacoh Fluid Control.
Such dampeners are intended to reduce the negative impact of the “water hammer” effect on fluid systems, but may have energy-saving benefits.
Yeghnazar says his company has not yet conducted specific study on whether pulsation dampners save electricity, but he believes they improve the overall efficiency of fluid systems. And increased fluid efficiency likely translates to improved electrical efficiency.
Water = Energy
Beyond improving the efficiency of a utility’s pumping and filtration process through finely monitoring energy usage, utility managers can make sure that as much of their water as possible makes it to customers.
“Certainly part of the overall strategy of American Water . . . [is] reducing our non-revenue water,” says Bower with American Water.
Non-revenue water, Bower clarified, is any water pumped that doesn’t reach a customer–typically because it is lost through a leak in the system. Patching a utility’s leaks–starting with the most egregious–can save the utility from pumping non-revenue water, and, therefore, save the associated energy use.
“A kilowatt-hour saved for that purpose is worth as much as a kilowatt-hour that was saved by efficiency,” says Bower.
Utility managers can compare their pump data to customer water usage data as a starting point for finding leaks in the system. That data can often show utility managers what regions of their systems are experiencing the most water losses.
Once the portions of the system most likely to show losses have been identified, utility managers can examine the pipes there more closely. According to Brueck, the technology for this task has evolved to include sensors that can be affixed to hydrants and valves. The sensors send acoustic signals through nearby pipes to check their flow. When the sensors find the flow to be less than what a computer model of the system says it should be, workers can search the preceding pipe for leaks.
Utility managers can further investigate pipes by using devices like Pure Technologies’ “SmartBalls.” These spherical sensors travel pipes for as long as 12 hours, according to Pure’s promotional materials, collecting data on the condition of the pipes by sending constant sonar pulses. Such devices can narrow the location of a leak to within 10 feet, according to Pulse.
Once workers find the leak, they can repair it. These days, those repairs can often be performed with the use of “trenchless technology.” This field, which has rapidly developed in recent years, allows utilities to avoid digging up roads and disrupting traffic or water service. New pipes can be slotted into place, and old pipes can be improved with new liners.
Trenchless technology also yields another energy-saving opportunity, Brueck says, eliminating frictional losses. As pipes age, pit, and rust, their roughened surface can increase the force required to move water through the pipe. By using a liner to smooth the internal surface of problem pipes–or by replacing them altogether–utility managers can achieve additional energy savings.
The Human Element
While every gallon lost to a leak represents energy the water utility didn’t need to use, the same logic applies to water that customers didn’t need to request. Water utilities can further reduce their water demands–and therefore energy demands–by offering customers tips and incentives to use less water. In most jurisdictions where water is scarce, water districts have the authority to institute a variety of water conservation efforts such as sprinkler bans. Districts that don’t suffer from historical water scarcity can still send customers suggestions on how to save water–such as watering lawns early in the morning–and may see some reduction in demand from those efforts.
American Water offers such tips to customers–including advice on how to conserve water by purchasing water efficient appliances. Consumers, Brueck says, may see water reduction efforts in a positive light like they do recycling efforts: adhering to the utility’s suggestions may make them feel as though they’re acting responsibly.
Utility managers in all districts can incent water conservation through rate structures, but Brueck calls this a “double-edged sword.”
Reducing water demand may save energy for a water utility, but it also reduces revenue. Because most water utility costs are fixed, a sharp drop in demand triggered by a conservation-focused rate restructuring may damage the bottom line by reducing revenues faster than it reduces costs.
System Design
Properly designing a pipe network can challenge modern engineers–particularly when they are dealing with legacy pipes and pumps. In these cases, subsequent generations of pipe system expansions can create counter-productive tangles. In the worst cases, Brueck says, utility managers may unknowingly pump their water in a circle, expending energy for no meaningful gain. Sometimes, changing the orientation of one or more valves can solve a problem of this nature. In less egregious cases of inefficient system routing, utility managers may pump water up a hill, only to pump it back down to serve customers on the other side. A utility manager who discovers this kind of inefficiency in his system design may be well served by adjusting valves to instead route the water around the hill.
To identify these flaws, Brueck says, utility managers should invest in creating accurate computer models of their systems. Many flaws, once identified, can be easily fixed, but such inefficiencies–even infinite loops–may occasionally be necessary.
“If you do your most efficient energy operation, you may violate your water quality regulations,” says Brueck. Water that remains stagnant in the name of efficiency may become unsuitable for drinking. “It is a balancing act. It’s an optimization of multiple constraints.”
Where new pipes are necessary, Brueck suggests building the flattest possible network. In the past, this might have required creative digging techniques, but can be accomplished today with recently developed horizontal boring techniques.
Ongoing Efforts
American Water started its energy efficiency program by auditing its 50 largest electricity accounts, but that’s not where the company ended its efforts. According to Bower, American Water is holding itself to company-wide sustainability goals that include smaller programs within each state in which the company operates. In 2011, the company collectively aimed to reduce the carbon intensity of delivering water to its customers by 16%.
