May 31, 2012
Earlier this year, the World Bank, through its Energy Sector Management Assistance Program (ESMAP) published “A Primer on Energy Efficiency for Municipal Water and Wastewater Utilities.” While principal ESMAP efforts are focused on infrastructure in developing nations, this report applies equally well to energy efficiency for many US medium and small urban and rural water and wastewater systems. The ESMAP Primer makes its energy efficiency for water case very clearly through the following statements:
- Electricity is a critical input for delivering municipal water and wastewater services.
- Electricity costs are usually between 5 to 30 percent of total operating costs among water and wastewater utilities (WWUs) worldwide.
- Improving energy efficiency (EE) is at the core of measures to reduce operational cost at WWUs.
- Since energy represents the largest controllable operational expenditure of most WWUs, and many EE measures have a payback period of less than five years, investing in EE supports quicker and greater expansion of clean water access for the poor by making the system cheaper to operate.
The ESMAP Primer goes on to share some interesting data about surface water v. groundwater energy use. “With the exception of gravity-fed systems, pumping for distribution of treated water dominates the energy use of surface water-based supply systems, usually accounting for 70 to 80 percent or more of the overall electricity consumption. The remaining electricity usage is split between raw water pumping and the treatment process. Groundwater-based supply systems are generally more energy intensive than surface water-based systems because of higher pumping needs for water extraction (on average, about 30 percent difference in the United States). On the other hand, groundwater usually requires much less treatment than surface water, often only for the chlorination of raw water, which requires very little electricity.”
To view or download the complete World Bank ESMAP Primer, click here.