Hydrogen plays an important role in the energy transition and has an impact on production, transmission, storage, utilization up to district heating and the integration of electric and gas transmission systems. By converting the electric energy into hydrogen, it can be easily transported with (and stored in) parts of the existing natural gas transmission network.
However, it is well known that hydrogen only contains roughly 1/3 of the energy of natural gas per unit of volume. Currently, there is no authoritative documentation about the differences in the capacity for energy of the existing grid when hydrogen is transmitted instead of natural gas. Thus, with the intention of determining and documenting the impact of using an existing natural gas transmission network for transporting hydrogen with the same energy capacity as for natural gas, this project was launched within GERG beginning 2022. Specifically, the team investigated issues related to the increase in flow or gas velocity to compensate for the mentioned lower energy value per cubic meter.
The scope of the project is focused on gas transmission pipelines with a design pressure ≥ 4bar. The stations involved in the assessment are valve stations, pressure reducing stations and metering stations in the transmission networks. The impact of the increased velocity was assessed for the following mixed H2NG scenarios’ 5%, 10%, 25% and 50% H2. The impact of a full conversion towards 100% hydrogen was also included.
The project finished by the end of 2022, with constant updates towards the Steering Committee composed of GERG and the project partners: DNV, Gasunie, Fluxys, Enagás, GRTgaz, Storengy, DGC and National Grid. DNV produced a final report for distribution among participating members after some reviews and feedback, and a public version for publication on the GERG-website has been planned.