By Don Schlenger
Interest in advanced metering infrastructure (AMI) among North American water utilities is turning toward systems that can deliver short-interval consumption data. Depending on the region and the utility, this interest is driven by conservation requirements, the need to reduce non-revenue water, and efforts to improve customer service while reducing operating costs. This trend toward more detailed consumption information has enabled utilities to change their customer service relationships.
AMI and Self-Service
Customer service representatives can often answer questions about high consumption by simply reviewing AMI-derived consumption data. Some utilities have gone beyond this, commonly notifying some customers of consumption anomalies before they get a high bill. The utilities collect customer phone numbers and email addresses to facilitate proactive outbound notification.
Providing customers direct access to detailed consumption data as a customer service and conservation tool has come to be regarded as a fundamental adjunct of AMI systems. In a trend toward self-service, customers are encouraged to access their own information online. Many utilities have reported major improvements in customer service efficiency and high bill complaint resolution by providing graphs of even one read per day.
In many parts of the country, water supply issues are chronic; in other areas, recent droughts have created new sensitivities. Managers of utilities that have installed AMI consider it a particularly effective tool to help their customers conserve water. For example, AMI facilitates monitoring outdoor watering restrictions much more effectively than having utility personnel patrolling the streets or relying on reports from neighbors.
AMI and Individual Water Budgeting
Another important new trend is individualized water budgeting. In a typical scenario, an average daily water budget is created for a customer based on household characteristics (number of occupants, lot size, size of irrigable areas, swimming pool, etc.) On an individualized web page, the customer can see on a frequent (e.g., daily) basis how he is performing against budget and in comparison to others. The utility can provide an automated warning to customers when they are consuming more water than the budget suggests. The ability to provide this information prior to billing is enabled by AMI.
As a logical extension of this trend, several water utilities in water short areas like California and other western states are implementing rate structures based on individual water budgets. Water budget-based water rates, also known as individualized, goal-based, and customer-specific rates, are increasing block rates where the blocks are defined by an efficient level of water use based on one or more customer characteristics, such as lot size. If a household is using water under its budget, it will be charged a lower rate per thousand gallons. If the household uses between 100 percent and 140 percent of budget, for example, it will be charged a higher per gallon rate; and if it uses more than 140 percent of budget, it will be charged an even higher penalty rate.
Individual budget rates have been enabled by utility billing systems that can incorporate customer-specific information into a billing calculation. Many of the utilities that have implemented water budget-based rates have experienced substantial conservation savings attributable to the rate structure coupled with customer outreach. By providing timely reads and detailed consumption information, AMI can enhance the effectiveness of these programs.
Eventually, customers may be provided a choice of budget rate plans, similar to cell phone service plans.
Customization and Enhanced Services
As utilities become comfortable with managing detailed customer information and massive quantities of consumption data, as well as the ability to individualize budgets and rates, some are exploring new service enhancements, including flexible billing dates (with a reading every day, the customer could be billed any time), and tailored conservation and leak detection information. For example, the amount of water needed can be suggested to customers with outdoor irrigation systems based on local evapotranspiration rates. Also, leak notification thresholds can be established for individual customers.
Almost every AMI system being marketed to water utilities is capable of reading the meters at least hourly, and requests for proposals now commonly require this reading frequency. Some manufacturers are marketing devices that can be converted from mobile automatic meter reading (AMR) to fixed AMI. Most AMI manufacturers tout the ability to deliver time-synchronized readings, which generally require some sort of two-way communication with the transmitter. (For the most part, the need for true two-way systems has much more relevance at this time in the electric industry than for water utilities.)
This level of granularity may exceed the capability of the utility's existing water meters, and what is necessary to support a benefit area. For example, if the resolution of a meter is 10 gallons, a running toilet wasting about 200 gallons per day would readily be detectable by the AMI system. However, a toilet with a flapper leak wasting 10 gallons per day would create a series of 0 and 1 incremental unit registrations on the meter. A leak (characterized as a period of non-zero consumption) might be hard to identify.
If the meter had a transmitted resolution of 1 gallon, then the ability to identify a leak would be somewhat greater. However, increases in precision may have diminishing incremental benefits. In fact, some utilities with AMI find it sufficient to use only daily reads to indicate potential leaks to customers.
Similarly, in calculating water loss in a pressure zone using mass balance, the precision gained by reading all the meters at the top of the hour (say the stroke of midnight) may not be much more valuable than reading all meters sometime between 11:30 P.M. and 12:30 A.M., or even once in six hours, particularly if the meters have only 10 gallon resolution or if the number of meters in a pressure zone was large.
Utility managers need to compare the incremental cost of greater precision to the incremental benefit to the application. While the incremental cost of the AMI equipment to provide it is diminishing, this may require replacing all of the meters.
New Meters Support Increased Precision
The drive to increased precision persists among meter manufacturers and utilities. Many small inference or positive displacement water meters are capable of readings down to one gallon or 0.1 cubic foot. Meanwhile, the advent of no moving part (NMP) meters (principally ultrasonic, electromagnetic, and fluid oscillating) in small sizes will likely change the industry in a few years.
Based on the Doppler shift principle, ultrasonic meters continually calculate flow rate and consumption based on the measurement of signals sent in rapid succession in both forward and reverse directions. Frequency shifts of the signals caused by the moving fluid can be used to calculate the flow rate.
Based on Faraday's principle, magnetic flow meters measure the flow of water through a magnetic field surrounding the flow tube. Electrodes mounted in the pipe wall detect the induced voltage, which is directly proportional to the flow rate, and the meter's electronics convert the raw signal into a digital output.
Fluid oscillation has been available to the small water meter market for several years. In this design, small portions of the flow are diverted through feedback passages, pushing the stream of water from one sidewall of the fluid chamber to the other. The frequency of oscillations is proportional to the volumetric flow rate.
NMP meter manufacturers promise unprecedented wide-range accuracy and greater precision over longer service lives. These meters incorporate solid state electronics and long-life batteries. Since ultrasonic and electromagnetic meters have no restrictions in the flow tube, head loss is lower than for mechanical meters, so they may be more suitable for residential fire service applications. Simplified construction should eventually result in higher reliability and lower costs. NMP meters will change the retrofit-versus-replace equation and the timing of meter replacement, impacting AMI business cases.
While interest in AMI is very high among utilities that have not yet undertaken it, current financial conditions make it difficult for some utilities to afford new metering systems. Unlike the grants for energy smart grid initiatives, there are fewer opportunities for assistance in funding water AMI systems.
Faced with significant capital requirements in other areas that do not generate savings, many utilities are looking for innovative ways to finance their AMI systems. Interest in performance contracting, in which the contractor takes a share of the savings generated by the system over a period of time, outsourcing (in which a third party deploys the system and the utility pays for meter readings), and public-private partnerships has increased.
Where utility staff resources to manage a complex project such as AMI are limited, public-private partnerships may be attractive. Some utilities have recently solicited AMI systems under a "design-build" scenario. A recent request for proposal from the Puerto Rico Aqueduct and Sewer Authority, for example, required "planning, design, installation, and operation of AMR/AMI systems."
Increasing Business Case Sophistication
It is not always easy to quantify the benefits of AMI for conservation, non-revenue water recovery, or enhanced customer service. Incorporating these elements into AMI business cases has sometimes been challenging. However, some water utilities that have not heretofore justified an advanced metering system are developing more sophisticated business cases, and a Water Research Foundation project entitled 'Advanced Metering Infrastructure-Best Practices for Selection, Acquisition and Implementation' (in press) has endeavored to provide improved business case tools.
Some water utility managers are now thinking in terms of AMI-enabled demand management and capital efficiency. In a few cases, utility managers have accepted in principle the savings in interest costs related to postponing some capital projects because of lower peak-to-average ratios engendered by AMI-based consumption information and conservation programs.
As AMI technology becomes more accessible and business case tools become more sophisticated, AMI will continue to change the face of today's water utilities.
Study Examines Water Conservation, Customer Behavior
A new study released by the Water Research Foundation found the top reason consumers conserve water is to save money. Researchers surveyed 6,000 residential customers, interviewed water agencies, analyzed billing, and reviewed utility literature to measure the effectiveness of conservation communications campaigns in changing customer behavior.
The report Water Conservation: Customer Behavior and Effective Communication (project/order #4012) also found that many customers feel they are already conserving as much water as they can.
Key findings include:
The top reasons customers conserve are to save money, followed closely by the idea that it's the right thing to do, and then by concern about water availability.
Many customers believed they are already doing all they can to conserve water.
Only 9 percent of customers participate in utility rebate programs, but 60 percent said they would participate if they knew about them.
Customers say they prefer getting information from bill inserts and television ads.
Customers found water supply managers are the most credible source of information about water conservation. Customers distrusted elected officials, the media and retail outlet sales associates.
"These findings will help utilities promote their conservation programs and encourage more people to participate in water conservation," said Robert C. Renner, executive director of the Water Research Foundation.
The study found few customers were aware of conservation rebate programs, yet their desire for such programs was high. This provides an opportunity for utilities to promote cost-effective measures that are underutilized, such as repairing leaking plumbing and appliances and replacing water fixtures. WW
About the Author: Don Schlenger, Ph.D., is a vice president with R. W. Beck, an SAIC company. He has more than 30 years of experience as a utility executive and consultant in technology implementation and process design and was the founder and first president and executive director of Utilimetrics (formerly Automatic Meter Reading Association).