"Green Pumps" Program: Refurbishing Pumps to Improve Energy Efficiency
Industrial Pump Servicing: Refurbishing for Improved Efficiency vs. Repair and Maintenance Only
A program for refurbishing old, large pumps to increase efficiency.
Item ID: 430
Commercial, Industrial, Agricultural
Process Loads & Appliances--Industrial Processes
The Green Pumps program provides services to owners of large, typically industrial, pumps. Refurbishing a pump would typically include replacing wear rings, bearings and shaft sleeves, and inspecting and replacing the impeller if necessary. Pump casings may be sent out for sandblasting and to apply a slick, NSF-approved, brushable-type, ceramic-filled epoxy coating on the inside of the volute (interior casing) of the pump to reduce friction losses in the system and increase pump efficiency.
It is important to choose appropriate applications for pump refurbishment and the applying of coatings as the pump is one component of a pumping system. In many constant-speed pump applications, reducing friction losses by coating the volute will increase the efficiency of the pump but can actually increase total energy use. An Electrical Apparatus Service Association (EASA) report (see below under Additional Information) discusses conditions under which coatings make sense from an energy efficiency standpoint. Pumps that operate at full-flow and cycle as needed will produce energy savings. Those with high heads and low flows will not benefit from a coating upgrade, nor would oversized pumps that use a modulating discharge valve to achieve a specific flow. In the latter instance, the discharge valve would close to compensate for any friction reduction provided by the coating, with the valve recreating the friction that the coating eliminated. Circulating water pumps would run at increased flow and pressure and with increased energy consumption. If the increased flow and pressure provide no additional benefits, operating costs would increase, not decrease. Reduced-friction coatings are beneficial in systems with adjustable speed drives.
Baseline Description: Refurbish pump without application of an internal coating
Baseline Energy Use: 336900 kWh per year per unit
The baseline energy use is due to operation of a 70% loaded 75 hp pump with a refurbished (without internal coating) efficiency of 70%. Drive motor efficiency is taken as 93% with 8,000 hours of annual operation. This would correspond to an industrial application, irrigation pumping, pumps at wastewater treatment plants or used for water supply, or a large circulating water pump (like a cooling tower pump).
Manufacturer's Energy Savings Claims:
"Typical" Savings: 7%
Savings Range: From 1% to 17%
Industry reported efficiency improvements for a centrifugal pump show a potential efficiency improvement of 5% due to an impeller surface finish and 12% for an interior surface finish (application of a smooth coating). It is likely that the pumps that have undergone refurbishment are those that offer the highest savings potential. Examination of a database of of 1790 refurbishment service records indicates an average gain in efficiency of 6.6% of original pumping annual energy use (Green Motor's Practices Group, 2011).
Best Estimate of Energy Savings:
"Typical" Savings: 7%
Low and High Energy Savings: 1% to 17%
Energy Savings Reliability: 6 - Approved Measure
Savings are dependent upon pump size. They are also dependent upon annual operating hours---thus pump refurbishments in the industrial sector will likely have much greater savings than those in the agricultural sector. Energy savings estimates for both sectors as a function of pump drive motor hp rating are (Green Motor's Practices Group, 2011):
Size, hp Industrial Agricultural
5 524 kWh/yr 387 kWh/yr
10 1,310 726
25 3,816 1,763
50 8,435 3,745
100 22,053 8,862
200 39,309 17,556
Note that these assumptions are for pumps that take do not use throttling valve flow control. Savings would also be diminished for pumps that are controlled by an adjustable speed drive.
Note: This is a deemed measure under the October 1, 2014 BPA "Energy Efficiency Implementation Manual". The deemed amount is $2.00/hp.
Energy Use of Emerging Technology:
313,317 kWh per unit per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
The emerging technology energy use is due to operation of a 70% loaded 75 hp pump with a refurbished (with internal coating) efficiency of 77%. Drive motor efficiency is taken as 93% with 8,000 hours of annual operation. This would correspond to an industrial application without throttling valve flow control.
Potential number of units replaced by this technology:
The U.S. Department of Energy estimated (in the United States Industrial Electric Motor Systems Market Opportunities Assessment) that national industrial pumping system loads amount to 142 billion kWh annually. Assuming that 4% of this industrial load occurs in the Northwest region (prorating industrial loads by population) indicates a regional industrial pumping load of about 5.8 billion kWh/year. Actual pumping energy use might be much greater due to agricultural irrigation pumping.
With an annual energy use of 313,900 kWh per 75 hp pump, this translates into the energy use of 18,477 equivalent 75 hp pumping units. This number will be used as the units to be replaced for the purposes of displaying potential energy savings due to pump coatings.
Regional Technical Potential:
0.44 TWh per year
Regional Technical Potential of an Emerging Technology is calculated as follows:
Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)
Installed first cost per: unit
Emerging Technology Unit Cost (Equipment Only): $1598.00
Emerging Technology Installation Cost (Labor, Disposal, Etc.): $0.00
Baseline Technology Unit Cost (Equipment Only): $0.00
Values given above are for a 75 hp pump. The cost of applying a ceramic filled epoxy coating onto a pumps interior surfaces is dependent upon pump size. Incremental costs of a refurbishment including application of a coating are given below(Green Motor's Practices Group, 2011):
Pump size, hp Average Incremental Cost, $
Simple payback, new construction (years): 0.8
Simple payback, retrofit (years): 0.8
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
Simple payback is dependent upon pump size, load point, control type, whether the pump is serving a static lift or circulating water application, and annual operating hours. For a 75 hp pump in an industrial setting, if savings are equal to 13,748 kWh/year and the incremental cost is equal to $1,598, the simple payback is only 1.3 years (at $0.09/kWh). The simple payback increases to 3.6 years for an agricultural or irrigation district pump due to reduced run times. It is likely that free ridership would be a substantial issue with the offering of an incentive for this technology as many pumps would be refurbished with smooth coatings anyway.