How much energy do water and wastewater companies use to treat and distribute water? Thus far, the issue has been relatively undocumented, according to the American Council for an Energy-Efficient Economy (ACEEE). But the ACEEE and the National Association of Water Companies (NAWC) recently conducted a survey to find out.
In addition to helping the two organizations expand their understanding of the energy involved in water sourcing and conveyance, treatment, and distribution, as well as wastewater treatment and discharge, the survey also sought to help NAWC members better understand their energy use and bring attention to possible opportunities for reducing it.
Overall, the survey found that energy costs can represent 25 to 30 percent of total operation costs for water and wastewater utilities. However, the size of the water systems, pumping requirements between geographic locations and raw water characteristics all impact the energy intensity of the water system.
“Our findings indicate that energy intensity is impacted by a variety of factors, including the distance water has to travel, the elevation, the type of water itself, etc.,” said Dave Ribeiro, senior analyst for ACEEE’s Utilities, State and Local Policy Program.
For example, brackish groundwater or seawater desalination require much more treatment, so their energy intensity is significantly higher.
The report also found that some water and wastewater companies are making substantial progress in improving their energy and water efficiency, and suggests water and wastewater facilities leverage things like energy audits, capital investments, operational improvements and energy utility incentives to help reduce energy use (water efficiency programs save energy because energy is embedded in water through the water system).
Efforts such as leak detection, conservation programs, the use of cooling towers, water conservation incentives and installation of water-saving technology can all help, the report states. For example, most residences and commercial buildings use treated, potable water for activities that do not require potable water use, such as landscaping.
“This means that every gallon of water used in homes and offices is treated and includes all the energy to process that water,” the report stated. “In addition, there is a huge amount of energy embedded in hot water. Water conservation programs aimed at reducing hot-water use can save billions of kilowatt-hours of electricity.”
Meanwhile, approximately 38 percent of fresh water withdrawals are used for irrigation, but in common watering practices, a large portion of the water applied to lawns and gardens is lost through evaporation, runoff or by watering too quickly or too much. The use of water-saving technology can improve the efficiency of irrigation systems and reduce those losses by applying only as much water as is needed to keep plants and lawns healthy. The report suggests that water companies offer qualifying customers assistance installing high-performance technology and water-efficient appliances, fixtures, water systems and accessories that help reduce water use.
“This report is helping us to start answering relevant questions about energy use by water and wastewater companies so that long-term we can get an idea of the concrete opportunities for increased energy efficiency throughout our water systems,” said Ribeiro.