Pipeline costs

[fvdborre]

The costs of different pipelines can be compared by converting different units to the same unit which refers to the volume of gas that is transported per hour.

Based on this common unit, the costs of hydrogen pipelines seem too low taken into account:

• far less experience with hydrogen pipelines in comparison with NG gas pipelines
• hydrogen needs bigger and more compression stations
• hydrogen is a very small molecule and can leak easily
• hydrogen causes hydrogen embrittlement which requires different materials and will reduce the lifetime

Furthermore, the techno-economic parameters of repurposed pipelines don't seem correct since the cost should be based on the NG pipeline cost combined with the conversion cost.

[fneum]

Thanks for sharing your stance on the pipeline cost assumptions with us. We're happy to improve them continuously based on new publications. Do you have any alternative sources you would like to point us to?

While the conversion to a common unit helps with the comparison, I am not sure it is sufficient to demonstrate that there might be a problem with the assumptions here.

Regarding the cost of the repurposed pipelines, I do not think adding the pipeline cost for new natural gas pipelines would be appropriate, assuming the NG pipelines have amortized. It should, however, be ensured that the potential for repurposed hydrogen pipelines is limited to the extent there are existing natural gas pipelines.

[euronion]

Thanks for sharing your approach:

• I think the energy densities you are using are off. Are you considering the right pressure levels? 3 kWh/Nm³ for H2 seems very close to atmospheric conditions. Pipelines operate at far higher pressures. Could you check again and provide the sources + pressure levels for your assumed energy densities?
• Also H2 works a bit differently in pipelines than CH4: You have lower friction, thus less pressure drop and can operate at either lower pressures or with less booster stations compared to CH4 pipelines. So these are things to keep in mind in addition to your arguments.
• Repurposed pipeline costs as @fneum mentions, only include the costs for repurposing intentionally

[fvdborre]

Thank you for the feedback.

I am indeed using Normal Cubic Meter (Nm3), representing the quantity of gas that, at 0 degrees Celsius and at an absolute pressure of 1.01325 bar, and when free of water vapor, occupies the volume of 1 cubic meter.

In comparing these gases, I assume similar pressure levels, and since they all adhere to the ideal gas law, the pressure level becomes inconsequential. If a lower pressure level is assumed for H2, the transportable gas volume decreases, resulting in a higher relative cost of the pipeline.

The assumption that Natural Gas (NG) pipelines have been fully amortized is unrealistic. At the time of conversion, these pipelines still retain some value in the accounts of the NG Transmission System Operator (TSO), and regulatory measures will ensure adherence to accounting rules, preventing cross subsidies. Furthermore, there is limited experience with the conversion of NG pipelines to hydrogen, likely placing it at a Technology Readiness Level of 6 or 7. Little is known about the remaining lifetime post-conversion, considering the effects of hydrogen embrittlement.

Additionally, there is a time gap between when the first hydrogen user wants to connect and when the last NG user wants to disconnect. In practice, TSOs will likely need to construct new hydrogen pipelines. The number of NG pipelines that can realistically be converted to hydrogen will be limited, taking into account the previously mentioned arguments.

While the cost value of an H2 pipeline may appear low, it becomes realistic when considering that the cost of a pipeline is not fully proportional to the volume that can be transported. The cost of a repurposed pipeline, on the other hand, is deemed unrealistic.