In factory and manufacturing environments, electricity costs account for 40% of the total cost of ownership (TCO) of a pump. By following energy management best practices, a manufacturer can decrease the electrical consumption of its pumping systems by at least 30%, yielding a 20% reduction in TCO and a return on investment within 24 months.
Graphic 1: Typical pump life-cycle cost profile (Courtesy of Hydraulic Institute and Pump Systems Matter)
If improving the energy efficiency of a pumping system can result in significant savings, why do operations teams find it difficult to initiate changes? Typically, pumping system performance ratings aren’t tied to energy efficiency, making it difficult to justify resources for energy improvements. But with a limited investment, following three basic energy management steps can help manufacturers meet their sustainability objectives and reduce ownership costs.
Step 1: Manage your energy efficiency Most efficiency problems result from a mismatch between pump operations and the actual system requirements, and from improper use of throttling valves and damper technologies to control the flow of liquids. One simple solution is to deploy variable speed drives (VSDs), which enable high efficiency performance and can save 20% of energy at 100% flow and 36% at 60% flow.
- Replace fixed drives with variable speed drives to control speed, pressure, and flow.
- Monitor data for production and energy consumption via control system software for cost-effective decision making.
- Monitor the operating point of a pump and its efficiency to observe trends as a basis for efficiency actions.
- Use metrics to mark changes in efficiency and to compare performance of pumps.
Step 2: Maintain your assets Maintenance costs represent 25% of TCO for a pumping system, and maintenance practices contribute to energy-influenced savings. Proper maintenance of motors, drives, pumps, and associated pipes is crucial, as efficiency drops by 10 to 15% for an unmaintained pump.
Graphic 2: Cost curves of the different maintenance approaches (Courtesy of Penn State University / Applied Research Laboratory - “Open systems architecture for condition-based maintenance”)
- Establish preventive maintenance plans for conducting systematic inspection and detecting potential failures before they occur.
- Monitor the pumping system and combine energy- and process-related data to enable condition-based maintenance – the most cost-effective approach. Condition-based maintenance tracks system data over time, and, as a result of this monitoring, provides an accurate status assessment and helps to predict when downtime will occur.
- Deploy corrective maintenance measures as needed in response to an unanticipated problem or emergency. Incorporating preventive and condition-based maintenance practices can help minimize the need for corrective maintenance.
Step 3: Understand your energy costs In order to cut additional costs, industrial site owners and facilities teams for water/wastewater and oil and gas operations must decipher their utility bills and understand common billing terms. Customer charge is a fixed charge based on an anticipated power consumption range and the price of the actual power consumed. Actual energy charge is for the active energy consumed over a set time and whether usage was during “peak” or “off-peak” hours. Demand charge is for the highest average power consumed within any 15-minute time period over the span of a month. Power factor penalty is the ratio between “active power” that generates work and “apparent power” that could potentially be used to generate work. If the power factor is less than the given value stated in the utility contract, then the penalties are invoiced for the power factor. The following actions are recommended:
- Review the utility contract to understand the billing charges.
- Adjust the timing of energy usage from the peak rate period to off-peak periods as much as possible.
- Reduce the monthly peak demand number to reduce the demand charge.
- Reduce the amount of energy consumption that does not generate revenue.
By adopting energy-efficient technologies, implementing reliable maintenance practices, and optimizing cost control of the utility bill, industries that operate pumping systems can establish an effective energy management plan, reduce TCO by 20%, and achieve their operational sustainability goals.