Many cities, particularly metros, are increasingly opting to supply natural gas through piped gas distribution systems. As an emerging market, India still has to graduate to the level of matured markets, where gas availability and infrastructure connectivity are not constraints. The key focus areas for improving the functioning of city
gas distribution (CGD) utilities are enhancing operational efficiencies and bringing down costs. Technological advancements in meter-to-cash, distribution, customer service, leakage detection, workforce management and asset management can help in revenue protection and operational efficiency.
To record gas offtake, most CGD utilities use diaphragm meters, which are predominantly based on mechanical measurement techniques. Some advantages of diaphragm meters are their good turndown ratios, high tolerance of installation effects and load characteristics, and low maintenance requirements. However, the size of such meters, particularly at large capacities, is a concern, as is their accuracy specification compared to other meters. Diaphragm meters require manual intervention, thereby being prone to errors in billing practices.
Smart metering has emerged as a vital tool for addressing the aforementioned issues to bring about significant cost savings for gas suppliers and consumers. In addition to providing customers with energy usage information via in-home displays to increase energy efficiency, smart meters enable the elimination of physical meter readings.
Functionality and benefits
Smart gas meters perform the following functions:
- Record consumption with the best possible accuracy
- Report consumption at any interval and excessive consumption, if any
- Determine consumption patterns
- Correlate consumption rates with in-house appliances
- Govern consumption by setting limits (prepayment mode)
- Raise alerts/alarms for tampering
- Can be remotely read and controlled (tariff and supply)
- Enable improved revenue collection with lower overheads.
As per the current practice, gas meters are installed at consumer premises for the purpose of measuring usage. In view of the manifold benefits of advanced metering solutions, CGD operators have gradually started deploying these concepts. Smart meters offer improved readability, reliability and accuracy, and are also less affected by temperature and humidity conditions in comparison with analog devices. Moreover, since they can be replaced with different types of devices, their use also enables inventory reduction.
Smart metering solutions
Rotary meters: These volumetric meters are appropriate for medium-sized loads at lower pressures and have a typical turndown ratio in the range of 35:1 to 50:1. Rotary meters have good turndown, and high tolerance for installation effects and load characteristics. They also have a longer shelf life and are much smaller in size in comparison with diaphragm meters. However, they require lubrication and can result in gas supply disruption in case of a meter failure. They are also comparatively more expensive.
Turbine gas meters: These are inferential meters that are sensitive to gas velocity instead of volume flow. They are capable of processing high pressure steady loads and have a typical turndown ratio of 20:1. These meters are smaller in size, entail lower costs compared to the alternatives and have higher accuracy rates. Unlike rotary meters, their gas supply is not disrupted in case of a turbine gas meter failure. However, these meters are sensitive to installation effects and load behaviour, and require gas filtration to ensure accurate readings. They also require frequent lubrication.
Hybrid smart flow gas meters: Although hybrid gas meters still use mechanical elements for measurement, error compensation is easier as they are electronically computed (with gears). However, these meters are affected by degradation owing to the shrinkage of diaphragm material and the wear and tear of the gear train. Such gas meters require recalibration every five to seven years.
Electronic gas meters: Electronic ultrasonic meters are smaller in size, lighter than hybrid gas meters and have a wide dynamic range. They take electronic measurements and have a natural interface with electronic systems. They also last for longer time periods. Meanwhile, electronic thermal gas meters, which are noiseless and wear-free, have a very low starting flow. Electronic charge flow meters are also highly accurate and small in size.
Prepayment meters: Many energy utilities are encouraging the prepaid mode of energy purchase for consumers as this helps reduce payment collection efforts. The consumer buys energy by paying upfront and the meter is then preconfigured to allow energy supply worth the total amount loaded in it. A prepayment meter disconnects supply at the consumer end when the balance amount falls below the threshold level. This system is currently applicable for electricity but can be deployed for water and gas distribution as well.
AMR gas meters: Automated meter reading (AMR) gas meters are based on four different technologies: radio, telephone, power line carriers, and a hybrid of these technologies. AMR meters collect and transfer gas consumption data from the home meter to the utility (one-way communication). Data from AMR systems is typically gathered only monthly or, at most, daily.
AMI meters: Advanced metering infrastructure (AMI) gas meters have evolved from the foundations of AMR. They enable two-way communication by transmitting pricing and energy information from utility companies to consumers. They record consumption on an hourly or more frequent basis, thereby allowing real-time on-demand interrogation with metering endpoints.
Conclusion
In a scenario where global CGD utilities are investing in smart metering concepts, India needs to scale up newer technology driven by the internet of things, like sensors, smart meters and remote monitors. The successful implementation of smart gas meters will largely depend on factors like market demand, metering infrastructure, client selection timelines and national safety regulations. India has not introduced smart metering on a large scale but has made some progress with regard to its implementation at the pilot level in select utilities. Major infrastructural development is required, along with capacity building solutions, before these metering projects can be adopted on a large scale.
