Southern California Edison’s free pump-testing program has always been about helping its agricultural and industrial customers thrive, but now it’s also about the intimate relationship between water and energy efficiency.
The snow pack may be shrinking and the rains may be getting sparser in California. But Southern California Edison’s (SCE’s) pump testing program was created while the effects of the Industrial Revolution were still young in 1911, and before these changes began being noticed. Such changes in our environment do highlight the importance of water management, and SCE’s program is doing that these days.
The State of California is now recognizing the intimate relationship between water and energy efficiency. In a study commissioned by the California Energy Commission, Lon House found that electrical demands of delivering and treating water in the state exceed 2,000 MW on summer peak days. Studies have shown that agricultural-groundwater and surface-water pumping represent 60% of that peak demand.
Twenty percent of the electricity used to pump water is consumed in SCE’s service territory. SCE’s percentage is exceeded only by water users in Pacific Gas & Electric’s service territory (32%) and the State Department of Water Resources (44%). Daily peak electrical demand by SCE’s agricultural customers in 2005 varied between 200 MW and 300 MW, according to House’s report.
SCE’s free pump-testing program has always been about helping its agricultural and industrial customers thrive, but now it’s also about improving their energy efficiency. Danny Johnson, manager of the pump-testing program in the Business Customer Division at SCE, says, “If I can keep us competitive [through energy efficiency], farmers are more competitive and consumers benefit. ...This impacts everybody.” With more efficient use of water, less is used and water rates can be reduced impacting residential water users, golf courses, and even hotel rates, he argues.
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Photo: Courtesy of Southern California Edison |
| Improved pump efficiency can decrease energy costs. |
The Key to Costs
SCE’s pump testing program is all about energy efficiency. Starting with new pumps, a baseline performance is established to compare with future performance and to verify that equipment is operating as designed. Thereafter, the frequency of tests is dependent on many factors, including annual operating hours, energy consumption, and changes in pumping conditions. These operating characteristics are specific to a pump’s location and the results of the pump test are specific to the location. As a general rule, SCE recommends that a well pump with average to high usage be tested every one or two years. Booster pumps can be tested every two to three years.
If an existing pump is operating in a sub-par manner, it is probable that energy is being wasted. Inefficiency is caused by wear, perhaps by particulates in the water such as sand. Even if the pump appears to be operating properly, if it is not able to produce the required flow and pressure needed, a repair, retrofit, or replacement may be needed.
So how is sub-par performance measured? The pump tester measures a pump’s rate of flow, total head or pressure, and power input to the pumping plant to determine overall pumping plant efficiency (OPE). The OPE is the relationship between the power consumed (in kilowatts) and the amount of water delivered (in gallons per minute) at a given pumping head (in feet).
Going into the test, the pump tester will need to know about the pump’s management and design to do a complete cost analysis. For example, he will need to know the pump’s hours of operation, its normal operating conditions, the required flow rate, the discharge pressure, and where the water is going.
An OPE in the low to fair range will suggest that a pump may need a retrofit, repair, or adjustment, or that the pump is not matched to the current operating conditions. For example, the water table may have dropped significantly over time, increasing the total lift above the original specifications.
The table lists plant efficiency rating guidelines established by the California Public Utilities Commission for all pumps. For example, a 3-horsepower (hp) to 5-hp pump has a low OPE if it tests 41.9% or lower. However, a 75-hp pump has a low OPE if its efficiency is 55.9% or less. Brand-new pumps should test in the 70% range.
Testing the Pump
One bright and warm morning, this reporter met Rick Koch, an SCE technical specialist, in Santa Clarita, CA, north of Los Angeles, to witness tests on two new pumps in a booster station that had been built for the Newhall County Water District to serve a new residential development at Stetson Ranch. While this was not an agriculture pumping plant being tested, Koch says the procedure is the same in all cases.
The two pumps being tested were 60-hp Peerless pumps matched with US Motor premium-efficiency motors. Before he began, Koch had to drill permanent test holes into the pipe midway down from the pump. In addition to a calculator, his testing equipment included a Pitot tube used in conjunction with a manometer to measure velocity head. The differential reading on the manometer multiplied by the inside area of the pipe determined the water flow.
After turning on the pump, Koch let it run to stabilize and then moved the discharge pressure to 128 psi. It produced a total head of 193 feet—the amount of work it takes to lift the water to the reservoir some distance away from the booster station. Koch’s calculations revealed the pump had an OPE of 75%, and was using 263 kWh per acre-foot. At $0.10 per kilowatt-hour, it will cost the water district $26.30 per acre-foot to operate.
Koch then changed the pressure in a second test, increasing it to 141 psi. Total head increased to 224 feet, and increased the cost to 300 kWh per acre-foot, but it also increased the pump efficiency to 76.3%. Increased efficiency doesn’t necessarily mean lowering costs, Koch says, and depends on pump design, further complicating the issue for a layman. On the third test, he again increased pressure that produced a total head of 246 feet. This time, efficiency went down to 70%, and the cost increased to 358 kWh per acre-foot. If the operator throttles down the flow to lower the total head, he will cut costs, Koch says.
With the results of these tests in hand, both SCE and the water district will be able to follow the future performance of these two pumps.
Designing the System Right
One of the biggest challenges pump testers face is finding an adequate test location on a pipe behind the pump. The optimum location is a straight length of pipe eight diameters in length between the pump and the test port and two diameters after the test port. For example, an 8-inch pipe should have 80 inches between the pump and the test location. The distance is needed to eliminate testing in the midst of turbulence. For example, the installer may be tempted to save the farmer a few capital dollars by cutting back on a few feet of pipe, but he ends up with a system that does not have an adequate test location on the pipe to measure water flow.
In another instance, Johnson says, a system may be mis-designed because the farmer doesn’t know what his pumps are producing. For example, an almond grower changes his flood irrigation system to a drip system without taking efficiency into account. Using an existing pump in an application different from what it was designed for produces a mismatch that decreases efficiency while increasing pumping costs.
An example of the financial impact a poorly performing pump might have is reflected in the following example: If total pump head is 600 feet, the cost to pump an acre-foot of water using $0.11 cents per kilowatt-hour with a pump at 45% OPE is $150. The cost to pump an acre-foot of water at 75% OPE is $90. If the annual water requirement were 200 acre feet, the cost of operating the lower-efficiency pump would be $30,000 while the cost of operating the high-efficiency pump would be $18,000.
Once a test is completed, the farmer receives a letter detailing the results, including data gathered, as well as what financial and energy savings will be available if improvements or repairs are made. He is then free to meet with his pump contractor to decide on the improvements. The test information serves as a roadmap, allowing the contractor to properly match the new pump or repair to the pumping site.
Johnson further explains that a pump’s efficiency should be coupled with the right tariff. A time-of-use rate has the potential to reduce electric pumping costs, and it will also give SCE more flexibility in distributing power through the system when the load on the grid gets tight.
Studying History to Manage Costs
Mark Merritt is one of the owners of EW Merritt Farms in Porterville and Pixley in Tulare County, CA. He grows row crops—wheat, corn, alfalfa, and cotton, plus walnuts, grapes, and olives on the family-owned farms started in the 1930s by his grandfather. More than 70 deep-well turbine pumps irrigate a little over 11,500 acres.
SCE has been testing the pumps on Merritt’s farms for 20 years, and he has a history of pump-efficiency performance going back to 1986. A pump contractor uses this information to determine if efficiencies are declining due to a changing water table, for example, if the pumps need to be repaired, or if they are operating outside of their design parameters. Merritt currently has three pumps being replaced, and seven or eight are scheduled for replacement, at a cost of $15,000 to $25,000 each.
When the electricity bills hit $1 million annually 10 years ago, Merritt built a reservoir and went on a super off-peak electricity rate, reducing his bills to $600,000. His contractor used SCE’s pump test analysis to determine the best location for the reservoir by determining how close the pump and pipeline needed to be to it. By filling the reservoir at night and using that water during the day to irrigate about 10% of his acreage, he was able to avoid operating seven pumps during peak periods after going on the time-of-use tariff and using time management load controllers. Moreover, he was able to irrigate during super off-peak hours when rates are cheaper.
More recently, in consultation with SCE, the farm switched to a TOU-PA-7 rate, which, Merritt says, created flexibility and allowed the farm to irrigate around the clock, including peak periods, although it increased electricity bills. This tariff was created to encourage farmers not to switch to natural gas– or diesel-fueled engines. However, it is no longer being offered and customers currently on it will have to switch over to another tariff at some point in the future.
Merritt admitted his options to manage costs are limited at this point. Given that his farms are in separate locations, he buys water from several agencies and these costs vary. On some of his ranch land, the water costs $35 per acre-foot, while water rates at another of the ranches may be $50 per acre-foot. By studying the test history of his pumps he can manage costs by turning off his less-efficient, higher-energy-consuming pumps when it’s extremely hot. His other options may be to plant less or drill more wells.
Solving Pumping Problems
Jim Lloyd-Butler has been growing lemons and avocados for 24 years on a small ranch, near Oxnard, CA, about 7 miles from the ocean. He has 600 acres under cultivation and irrigates his lemons, on average, once every three weeks. During the summer months he irrigates his avocados once a week.
The farm has rights to water from the Santa Clara River and the United Water Conservation District. Lloyd-Butler spent about $26,000 last year on electricity. He calculates his total cost of production is $3,000 per acre-foot for avocados, and a little less for lemons.
Lloyd-Butler says he tries to have SCE test his four turbine pumps annually. Right now, he says, a pump is being pulled to take videos of the well. The pump has been pumping sand, which is not good for the pump or for the water containing the sand. The video pictures of the hole will tell whether the orifices in the casing that lines the well are plugged. If some are plugged, there are fewer orifices through which water can be drawn by the pump, making it work harder, cutting its efficiency, and costing more to operate.
Bob Ereth, with Layne Christensen in Fontana, CA, is the pump contractor who video logged the well to determine the integrity of the well casing. He says there are multiple problems. The purpose of gravel pack around the casing is to filter out sand and other particles. Gravel in the pack normally falls due to consolidation. A hole may form if the gravel on top doesn’t descend with the lower pack, allowing the sand to get into the water stream.
In this case, the gravel pack has to be redeveloped. A new casing may have to be installed inside the old casing, and then the gravel pack between the two casings has to be installed. Ereth says the right size of gravel is needed to create a properly designed filter pack. This is determined by a sieve analysis.
Ereth says it will take about four weeks to determine the correct size of the gravel pack, install it and a new casing, then test the pump and well, and determine if it is producing gallons per minute at its normal level.
Another common problem seen, Ereth says, is when water drawdown decreases, indicating the well needs to be cleaned. Here, the perforations in the well casing plug up due to biofouling and mineral deposits.
Lloyd Butler had another problem that surfaced when a pump tester from an independent service company found two holes—one the size of a $0.50 piece—in a column pipe. If that hole hadn’t been found, the water would have eventually squirted out into the casing. The force of water against the casing would have eventually ruined the well. Drilling a new well now would cost close to $200,000, he added.
The Competition for Water
Ed Lorenzi manages one of nine farms owned by Sun Pacific, a large citrus grower. His 2,700-acre farm is located in Lindsey in the northern tip of SCE’s service territory in the San Joaquin Valley. The Naval and Valencia oranges, tangelos, and murcots he grows are drip-irrigated with micro sprinklers—one per tree, he says. Pumps supply water to the fields.
SCE has been testing his five- to six-dozen pumps since the mid-1980s. He pays $725,000 annually for electricity. When efficiency goes down, he says, water distribution is affected. Too much water increases costs. You can judge by the lower pressure if there is a problem, he explains.
Lorenzi is concerned about the bigger picture and the changes that are occurring. “It’s been some years since we’ve had drenching rain and heavy snow pack,” he says. The drying weather pattern requires deepening wells and lowering pumps further into the wells. Furthermore, the new home developments in the San Joaquin Valley are creating more demand for water. “We used to furrow ditches [to carry water]. Now that’s considered an ancient practice,” he says.
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Photo: Courtesy of Southern California Edison |
| Matching electrical rates to pump activity saves money. |
Finding the Right Electrical Rate
Casey Alesso has owned Alesso Farms in the Antelope Valley for seven years. He grows alfalfa and green crops on three different farms totaling 640 acres. The crops need constant irrigating. Some of the five 100-hp turbine pumps operate 24 hours per day, seven days per week.
By matching electrical rates to pump activities Alesso has saved money. But in spite of his economies, Alesso’s electrical rates went up 40% last year while he was on the TOU-PA-7 tariff mentioned earlier. It included an exponential increase in on-peak charges. His annual electrical bill in 2006 was $170,000, the number-one cost for alfalfa farmers.
Of the alternative tariff rates available, Alesso has elected the utility’s time-of-use super off-peak tariff using time management load controls to prevent peak penalties. He’s already paid for the lock boxes, at $2,671 per box per well, which will turn off his pumps for four hours each day during peak periods. He could have chosen to dig more wells, at great expense, and pump water only at night. Instead, he has chosen to reduce acreage being planted because he doesn’t have enough irrigating capacity to meet the actual land demand.
SCE’s pump testing program has been extremely valuable, Alesso says. Having the numbers right there helps him make a decision. SCE is the “farmer’s best friend when usually farmers and utilities don’t get along,” he concludes.
Rick Koch, the SCE technical specialist who tested Alesso’s wells for pump efficiencies last fall, says the pumps are not running at high efficiencies. Alesso will have to weigh the costs to repair worn pump impellers and/or rehabilitate wells, which are not producing enough capacity to meet his needs, against operating costs, he explains.
Koch says there are 12 agriculture rates and all have different applications. One of a pump tester’s jobs is to help a farmer reduce costs by assisting him in choosing the right tariff for the site. Alesso’s TOU super off-peak tariff has a rate of $0.09 per kilowatt-hour. If he operates a pump any time between 1:00 p.m. and 5:00 p.m. he will be penalized. Koch describes a 75-hp pump on another farm that had run more than 15 minutes during an on-peak period. The owner received an extra charge of $1,500 based on a penalty of $43.00 per kilowatt-hour.
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Photo: Courtesy of Southern California Edison |
| Testing pumps can prevent costly leaks. |
Alesso could have chosen the TOU-PA-B rate at $0.1267 per kilowatt-hour, allowing him to operate during peak periods without penalty, but at a higher cost than it would if the pumps could operate in the middle of the night. Instead, Alesso may choose the AP-I rider for interruptible service which will give him a year-round discount of $0.00933 per kilowatt-hour off his TOU super off-peak rate ($0.08464 on-peak, $0.01723 off-peak). The AP-I rider allows the utility to turn off his pumps without advance notice for a limited number of times throughout the year if the power is needed.
Rebates Are Available
SCE’s agriculture energy-efficiency pump replacement program with rebates is the most popular program that pump testers deal with, says Koch. It provides rebates based on individual projects up to a maximum of 50% of a customer’s costs. It is designed to reduce the cost of pulling the pump and making the repairs. The increased efficiency should show up in the next pump test, and on reduced electricity bills.
SCE also has a motor replacement program to promote premium-efficiency motor installations. Furthermore, the utility has a special discounted rate, PA-ICE, to replace gas-fired internal combustion engines.
Johnson, SCE’s hydraulic project and services program manager, says 4,000 to 5,000 pumps were tested in 2006. Thousands more were not tested because of the lack of knowledge about the program and because there are not a large number of trained, experienced pump testers in the marketplace that Johnson could hire. To supplement the program’s reach, SCE has contracted with the Center for Irrigation Technology at California State University–Fresno to add independent pump test contractors.
All requests for testing are customer generated—mostly from word of mouth, educational seminars, or previous experiences. There are no bill inserts or TV ads for the program. The program could not handle an instantaneous increase in demand, Johnson says, since it takes a minimum of one year to train a technical specialist. Additional steps are being taken to train specialists in preparation for future expansion, he states.
Should the reader be interested in a pump test, he or she can call SCE at 1-800-634-9175.