Calorific value: fiscal measurement in the multi-gas era
Today’s state-of-the-art gas meters measure the volume of gas that has been consumed. Consumers, on the other hand, are billed based on the energy they consume. Utility companies convert the measured volume of gas into consumed energy by determining the gas’ calorific value when it enters the municipality and combining this value with a simple distribution model.
Calorific value
This approach has traditionally been accurate enough for fair billing. With the trend towards decarbonization, this simplistic approach may be revised due to two main developments.
First, the variability in the gas composition will significantly increase due to the blending of natural gas with liquid natural gas (LNG), hydrogen, and biogas. Second, there is a clear trend toward decentralized injection into the utility grid. This imposes the need for a measurement of the gas’s calorific value at or close to the point of consumption to achieve fair billing.
This report shows that it is already possible to determine a gas’s calorific value at the meter level by relying on a modified thermal-mass flow measurement principle, a technology that has already been used for over a decade in millions of gas meters worldwide.
The current trend in the global energy supply is to replace fossil fuels with renewable energy.
In the context of natural gas, this transition is expected to take the form of gradually replacing natural gas with biomethane and hydrogen, before potentially switching to pure hydrogen. Consequently, many countries are now publishing their hydrogen strategies and adapting policies to prepare for this transition; hence the requirement for all boilers sold in the UK from 2025 to be hydrogen-ready. At the same time, multiple pilot projects are being launched around the world to test the readiness of networks for the arrival of renewable gases – especially hydrogen, whose properties significantly differ from those of natural gas.
Renewable gases
The production of renewable gases is set to be much more decentralized than the current gas supply. Biomethane can be produced from biomass at wastewater treatment plants, landfills or large farms.
Hydrogen can be produced at renewable power plants as an energy storage medium, from biomass or even by small electricity producers, who convert excess energy into hydrogen by means of water electrolysis.
The introduction of these renewable gases into the grid is predicted to greatly multiply the number of injection points and lead to diverse CVs of the gas distributed to the end-users.
Owing to the homogeneous quality of gas in networks to date, the separation of measuring CV (at injection points) and volume (at each consumer) has yielded satisfactory results in the past. With the multiplication of renewable gas injection points, the cost-benefit ratio of scaling the current approach is likely to become unfavorable.
While class A and B accuracy are currently used for measuring CV away from the end-point, the technology exists to measure CV closer to the customer at a fraction of the cost. One future solution could be to use direct energy meters based on Sensirion gas metering technology with OIML R140 class B (1 %) or C (2 %) accuracy in CV measurement and class 1.5 accuracy in volume flow measurement.
Once the regulations permit direct energy metering with class B or C accuracy in CV measurement, Sensirion will offer an economic solution that is compatible with hydrogen and biomethane to combine volume and CV measurement in one gas meter.
Authors:
About Sensirion
Lead the energy transition with Sensirion – Headquartered in Stäfa, Switzerland, Sensirion is a leading manufacturer of sensor solutions for the multi-gas future. Its product range includes environmental and flow sensors such as microthermal gas meter modules or gas analyzers.
Website: Calorific value: fiscal measurement in the multi-gas era (sensirion.com)
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