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Nov 18, 2023

Hydrogen

With the injection of hydrogen into the natural gas pipeline, the measurement of

With the injection of hydrogen into the natural gas pipeline, the measurement of what is flowing in the gas grid and through the gas meters will become of more and more fundamental importance, writes Luigi Bernardo of MeteRSit.

As a matter of fact, the flowing gas will have a different composition compared to natural gas, resulting in different physical properties and calorific values.

Even considering the injection of a fixed percentage of hydrogen into the gas grid, there will be no assurance that the same percentage will be available at any single point of delivery, so the composition of the mixture and calorific value might change along the distribution line.

This fact will require much attention to the measurement devices, i.e. the gas meters, which are already installed or will be installed in the field and able to cope with the new renewable gases.

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Most of the gas meters already installed in the field are volumetric gas meters, i.e. diaphragm, ultrasonic, turbine, etc., which means that all can measure the volume of natural gas flowing in the pipe.

On the other hand, none can provide any relevant information on the proportion of the hydrogen and natural gas in the pipeline and consequently on the calorific value of the gas blends, which is the energy that is delivered to the end point, and for this reason the most important as it is directly linked to the end user's bill.

It is becoming clear now that not only the volume of the mixture of gas will increase compared to the volume of natural gas to deliver the same calorific value (up to 20% more), but also the calorific value will change, so that more accurate reading and monitoring, in particular at the endpoints, becomes necessary with the injection of hydrogen in the grid.

Available to help to solve this important problem is thermal mass technology, an advanced static measurement technology that has been gaining popularity in recent years across the installations of millions of gas meters in Europe and Asia.

This technology is well-known and has been widely used in the laboratory and industrial environment for decades. It benefits from the reduced size of the sensitive electronic components (the micro-electro-mechanical system or MEMS) and it is now also widely available and reliable for the application of gas measurement at domestic and industrial sites.

The technology, besides the high performance in the volume measurement of the gas flowing, can intrinsically provide several points of information on the chemical/physical information of the flow. Notably, the reading of gas meters does not need to be converted at standard temperature and pressure.

The possibility of having advanced control of gas physical properties at the endpoint, besides assuring a reliable measure of the gas flow even in the presence of a mixture with variable hydrogen percentage, also assures the possibility to evaluate the real energy distributed at the endpoint.

Already versions of this type of gas meter which can detect the amount of hydrogen in the gas blend and transmit this information to the energy provider's systems are becoming available and are gaining MID certification for blends up to 23%.

Other important points to note but not considered in this article include the tightness of the meter, the gas chamber and the tightness of the shut-off valve inside the meter, due to the different physical and hazardous properties of hydrogen compared to natural gas. These points are strictly related to safety at the point of delivery.

ABOUT THE AUTHOR

Luigi Bernardo is Business Development Manager at MeteRSit (a SIT company).