Water treatment plants and several critical remote pumping and storage facilities are electrically-intense operations. Water utilities are generally considered large customers to the electric utility. A failure to keep treatment plants and critical pumping stations in operation at all times could lead to water quality problems within the water distribution system as a depressurized water distribution system is susceptible to intrusion from groundwater or other contaminants. To ensure that these sites have electrical power at all times, emergency power generation systems have been made a part of these facilities.
In the event of a power outage, these systems automatically start and apply electrical power to the facility to restore operations. When stable electric power from the electric utility returns, the source of electric power for the facility is transferred from the emergency power generation system back to the electric utility. The emergency power generation systems are capable of running for just a few minutes to several weeks if necessary. Historically, power outages are rare and are generally short in duration (less than a few hours).
Des Moines Water Works (DMWW) like many other water utilities, also uses the same emergency power generation systems to participate in curtailment programs offered by Mid-American Energy Company. Mid-American Energy allows their larger electrical customers to self-generate electricity on days when electrical usage is peaking. This allows Mid-American Energy to better manage their peak demands. In exchange for the self-generation effort, Mid-American Energy compensates DMWW approximately $180,000 per year to participate. The curtailment season is limited to sixteen events, with each no longer than six hours in length.
Integration of emergency power generation systems into critical facilities is clearly in the best interest of the customer. Participation in the curtailment program from Mid-American Energy also provides an opportunity to offset operating expenses associated with the operation and maintenance of the emergency power generation systems.