Minimize Pumping Costs and Energy Consumption

Pumping costs account for a high proportion of a water utility’s operating budget, so it’s important that energy consumption is actively managed and minimized as much as possible. With WaterCAD and WaterGEMS, minimizing energy cost is as easy as A-B-C.

WaterCAD/WaterGEMS help water utilities reduce their pumping costs and energy usage in numerous ways, including:

• Identifying old pumps that no longer perform on their pump curves
• Detecting pumps that no longer match well with the distribution system
• Finding pump combinations that do not work well together
• Analyzing when to use variable speed vs. constant speed pumping
• Determining energy costs for different operating rules to find the best operational strategy
• Providing optimal pump operation schedules
• Determining how to take advantage of time-of-day energy pricing
• Purchasing the right pumps

Most utilities can find places where their pumping operation is not optimal and simply changing a pump (or impeller) or modifying operation can have a dramatic payoff. WaterCAD/WaterGEMS energy cost management tools can take the work out of finding and correcting these pumping energy problems.

WaterCAD/WaterGEMS Energy Cost Management Tools

Convenient Energy Cost Manager

In order to estimate what energy costs are going to be in the future or to make design choices that result in energy efficiency, the included Energy Cost Manager:

• Performs multiple energy analyses with alternative pricing for pumping stations in different parts of the system.
• Considers the effects of storage on cost of running the system.
• Returns many results for operational strategy comparisons:
  daily cost, usage cost, overall energy used, overall unit cost, average efficiency, and so forth.

Optimized Pump Scheduling

Darwin Scheduler allows engineers to optimize pump operations. This module is included in WaterGEMS and available for WaterCAD.

Additional benefits include:

• Darwin Scheduler avoids a manual trial and error approach to finding the most efficient operating schedule, using genetic algorithm optimization to control nominated pumps during an extended period simulation (EPS).
• Solutions and costs calculated using Darwin Scheduler can be exported back to the selected scenario
• Darwin Scheduler gives modelers the flexibility to choose from two optimization types:
  • Minimize Energy Use: This type will try to minimize the energy used. The effect of tariffs making energy cheaper at certain times is neglected in this type of optimization.
  • Minimize Energy Cost: This type uses energy tariffs and peak demand charges to calculate the cost of energy used.

Pump Selection With Accurate Determination of the System Head Curve

System head curves in WaterCAD and WaterGEMS can now be created for closed systems using a Pressure Dependent Demand alternative, function, and calculation option. This allows users to produce an accurate system head curve, which enables operators to determine better operating points for pumps.

With this method to determine system head curves, even for closed systems, engineers can more easily evaluate the energy cost of the pumps at many operating points.

Download the Developing System Head Curves for Closed Systems white paper
(as published in AWWA Journal, September 2010)

Accurate Variable Speed Pumping (VSP)

WaterCAD and WaterGEMS are based on the EPANet solver/engine, like most commercial software. The difference is that the solver has been highly improved within WaterCAD and WaterGEMS, so that Variable Speed Pumping (VSP) modeling is more accurate than in any other modeling software, giving operational results that you can trust.

WaterCAD/WaterGEMS provide the flexibility to model VSPs during past events where pump speed is known as well as to model case where pump speed is adjusted to maintain a head somewhere in the system. This allows users to mimic the behavior of VSPs in the field which is very difficult to achieve with other models.

Pump Combinations Analyses

Determining the right pump combinations to run in a complex pumping station can be challenging. The pump combination display now available in WaterCAD and WaterGEMS provides a quick way to identify operating points and their corresponding pump efficiencies to avoid inefficient combinations.