3.7 What is the Energy Use of My Assets?

In addition to the information considered thus far, it is important to consider the energy use of your assets. This question involves a consideration of the asset's overall energy consumption, the type of energy used, and whether the energy consumption contributes to greenhouse gases. This assessment is important because energy usage is a significant portion of a utility's expenses, sometimes accounting for as much as 50 to 75% of the total operating costs. Therefore, optimizing energy consumption can have a significant impact on the cost of operating a water or wastewater facility. In order to determine the potential to reduce energy use, energy usage data should be collected for the assets in the inventory. As the assets are being inventoried, data on energy use, such as the following should be collected, to the extent possible:
  • Type of energy used
  • Horsepower
  • Variable or constant speed
  • Design specifications
  • Operating status and practices
  • Hours of operation per year
  • Average equipment run times
  • Measured power consumption
  • Peak energy demands
  • Total kilowatt-hours (kWh) of electrical consumption
The best method of gathering information about energy use by an individual asset is actual metered energy usage. However, most utilities don't have energy meters on each piece of equipment that uses energy and some utilities may only have one master energy meter that indicates overall energy use. In these cases, estimates will have to be made of asset energy use based on load, performance factors, equipment efficiencies, operator experiences, manufacturer's data, and reference guides. A particular reference guide that may be helpful is EPA's Energy Star Program.

... one of the things we've found is a limitation....at the water plant, there is one master meter.
--Barry Kirchhoff, Columbia, MO


In considering overall energy use, it is important to look beyond those assets that are easy to identify as energy consumers, such as pumps, motors, blowers, and drives, to those assets that have a less obvious effect on energy use. For example, leaking pipes have an impact on energy use because they result in more water being pumped and treated than is needed by the customers. Other energy use may come from "assets" that are not included in the inventory, such as light fixtures or heating units in buildings or pump stations or the gasoline or diesel usage of the utility's fleet of vehicles. It is important to have a method of capturing this type of energy use in your overall baseline assessment of total energy usage.

There are multiple areas of energy use.
--Russell Batzel, St. Peters, MO


Appendix A contains forms that can be used to gather information of energy usage of assets.