Des Moines Water Works: Coupling Real-Time Energy Data Use with Enhanced Staff Training
Founded in 1871, Des Moines Water Works (DMWW) provides water to the residents of greater Des Moines, Iowa. This is accomplished via 3 water treatment plants, which feed into the overall water distribution system. Changes at one plant affect the total dynamic head (the total equivalent height that a fluid is to be pumped, taking into account friction losses in the pipe) on pumps at the other two plants. If operators know when certain pump combinations are yielding inefficient operation, they can make changes to the pump operating scheme to ensure that the optimal combination of pumps are online. Additionally, as normal pump wear occurs, the efficiency drops, so trending this data over long periods can help maintenance, repair, and operations (MRO) personnel better schedule pump rebuilds and investigations.
Two issues were impairing the ability of employees at Des Moines Water Works to understand when their pumps were not operating efficiently. First was an absence of electric submeters, and second was MRO’s lack of knowledge regarding energy management, electrical use, and how pump efficiency can impact energy use. MRO staff are directly responsible for operations that account for nearly 80% of the organization’s total energy use yet did not have the information or training they needed to make informed energy related decisions. To address these shortcomings, the partner established an action plan to install submeters throughout their system, and to train critical staff.
Des Moines Water Works is seeking to reduce overall energy intensity by 25% over a 10-year period. Because nearly 80% of the organization’s energy is used to pump water, the steps outlined in this case study were needed to help the agency stay on track to achieving its goal.
The following steps were taken to install and program the submeters, and also to enhance staff capabilities:
- A contractor was hired to install 60 submeters, while internal technicians programmed and added them to the agency’s existing supervisory control and data acquisition system (SCADA).
- Internal control systems specialists installed and configured programmable logic controllers (PLCs) to calculate/display:
- Pump Wire-to-water efficiency in real time;
- Month-to-date electric consumption and consumption cost;
- Peak demand and demand cost;
- Real-time demand;
- Instantaneous kW rate; and
- MOR’s Energy performance indicator (EnPI) real-time kW/million gallon (MG).
- Training was held on energy management, select electrical terminology and theory, and pump wire-to-water efficiency for the MRO staff.
- Three big screen monitors dedicated to displaying energy information were installed along with the submeters of critical significant energy users (SEUs). The graphical display of electrical data and pump efficiency made it easy for operators to see how operational changes at one plant affect efficiencies at the other two plants.
- To ensure full utilization of the monitors the company provided the authority to staff to utilize the new energy information in their decision making.
To ensure this process ran smoothly, DMWW outlined a 4-step roll-out process:
- Obtain top management support and approval. This was obtained by directly communicating with the CEO, who was provided with biweekly update reports which kept the project moving at a steady pace.
- Develop implementation plan and staff feedback. The planning and execution of the implementation required the cooperation and coordination of top management, MRO supervisors, engineering, energy manager, internal technicians and contractors. Because the CEO fully supported and publicized the initiative, and all stakeholders had a common goal, cooperation was easily achieved.
- Obtain funding for the plan. Funding was made possible through direction from the CEO to the finance team.
- Execute the plan. The project took 3 months to implement and the total installed project cost was $204,700, as shown in the Summary of Costs table.
Summary of Costs
Contractor labor & materials
Thin-client, monitors, network switches
To properly evaluate the success of the implementation, the company utilized Average kWh/MG as their primary metric. DMWW tracks each plant individually and all plants combined. This tracking showed a 9.2% improvement in kWh/MG from 2016-2018, as shown by Figure 1 below.
Figure 1 - Average Site kWh/MG
As an example of the results produced by the new monitors, Figure 2 displays a real-time energy performance indicator used by staff.
Figure 2 - Energy Monitor Screen Shot
From 2016 to 2018, Des Moines Water Works saw a 9.2% improvement in kWh/MG as a direct result of improved operations (a product of new energy monitors). In just 2018, energy monitors contributed to energy savings of more than 36,000 MMBtu and a CO2 reduction of 5,650 metric tons. Cost savings subsequently amounted to $185,000 per year making the payback period 1.1 years. The 5-year ROI is shown in Figure 3.
Figure 3 - Simple ROI
On a qualitative level, new employees are now trained on the energy management system along with additional focused training on pumping system efficiency, electric terminology, and their role in energy efficiency. Maintenance and repair technicians are also given additional training on maintaining pump efficiency and associated instrumentation.
Top management has recognized the significant impact these monitors have made, not only on the bottom-line, but on the MRO staff’s enthusiasm and continual interest in running the treatment plants as efficiently as possible while still providing customers with reliable, high quality water. Plans are under way to develop similar energy monitors for twelve pumping and booster stations throughout the distribution system and add / upgrade instrumentation.
Given these tools and results, MRO staff are much more engaged and excited to see how they can improve energy intensity of the systems they operate and maintain. The energy monitors are also proving to be a great educational tool for the staff. Maintenance/repair staff are pleased with the additional equipment condition monitoring the energy monitors provide, and their increased ability to plan and budget for major overhauls.
DMWW improved energy efficiency and staff expertise by installing "energy monitor" systems fed by electric submeters to track pump efficiency, paired with increased training for maintenance, repair, and operations personnel.
Water and Wastewater Treatment Agency
An absence of real-time data on processes that are significant energy users, and staff untrained to leverage such energy data effectively
Installation of "energy monitor" systems fed by electric submeters tracking pump efficiency, paired with increased training for maintenance, repair, and operations personnel
Upgrades resulted in more than 36,000 MMBtu of electrical savings in 2018, and a 9.2% improvement in kWh/MG between 2016 and 2018