In 2002, a consulting engineering team was created and charged with the task of developing a pioneering "energy consumption benchmarking" report for the state of Wisconsin. This team, working under the auspices of the "Wisconsin Focus on Energy" group, included Energenecs, a Wisconsin water/wastewater systems integrator. The purpose of this landmark study was to establish a baseline of how Wisconsin's public and private utilities had been consuming energy, as compared to the rest of the world. From this study, it could then be determined where improvements should be made.
During the development of the benchmark report, it became readily apparent that power consumption data in plants, including overall daily and location-specific usage, was for the most part absent. The discovery that the majority of pumps had neither watt nor amp meters, indicated a lack of knowledge of energy costs and the small operational changes which affect energy bills. With this in mind, Energenecs incorporated 25 years of water/wastewater experience with state-of-the-art Control Microsystems SCADA products, and created the Energenecs Sensory Processor (ESP) pump control panel.
The challenge
In the current environment of reduced operational budgets and ever-mounting utility costs, the main challenge for any community is to provide its residents and businesses alike with safe and reliable water/wastewater services, while at the same time maintaining fiscal restraint.
One method of keeping costs down is to reduce electrical energy consumption across the board. This can be accomplished by using energy efficient equipment when replacing aging infrastructure, or when installing new systems. Improving energy efficiency not only saves money by reducing the amount of electrical energy that needs to be purchased, but also results in a number of secondary cost savings including the reduction of fossil fuel dependence and the minimization of the negative impact on the environment.
In the water/wastewater industry, it has been reported by the U.S. Department of Energy that pumping systems account for nearly 20% of the world's energy demand, and that approximately 20% of that could be saved by utilizing proven techniques and technologies. This savings potential was certainly worth further investigation.
When considering the design of the optimum remote pumping station, not only did energy-efficient equipment need to be considered, but also the control of this equipment. The implementation of control techniques such as intelligent pump switching, peak demand period avoidance and automatic maintenance advisories would further increase energy efficiency.
The programmable controller that was to be chosen to provide this intelligent control would have to be powerful, easy to program, flexible to use and maintain and cost-effective.
The solution
In addressing the energy consumption issue, Energenecs designed the ESP by taking a unique approach to how lift stations are controlled.
In addition to the standard control method of at this level, turn pump "A" on, other pump station characteristics that could have an impact, were looked at including:
Automatically forcing an inefficient lead pump to lag;
Monitoring energy usage of each pump; and
Reporting inefficient pump performance to maintenance personnel.
When flow rate and energy demand are plotted against the time of day that utility rates change, operators can take advantage of lower rates, and avoid costly energy spikes, by operating pumps outside of peak demand periods.
The reliable and low-cost controller, programmed using standard open software tools, allowed for the easy implementation of these intelligent pump control features. Flexible communication features, including independently configured serial ports, Modbus and DF1 supported protocols and various communication media such as dial-up and wireless, ensured that even though the ESP is typically used as a stand-alone pump control system, it could be easily integrated into an existing SCADA network. The system can be configured to provide remote controller programming and diagnostics capabilities through the aforementioned connection types.
The operator interface terminal provides an inexpensive method of displaying critical pump performance data as well as an alarm display and control facility.
