The existing pipelines used for natural gas are not suitable for high % content due to embrittlement. I have seen the 10% H2 added is possible, beyond that comes with larger risks

Depending on what materials are used in each network (pipelines and additional equipment), existing system can be used for anything ranging from 10% to 100% H2 concentration, Each TSO / DSO should study its own network to be able to make an assessment of how appropriate their networks are. However, it is not the materials used in the network that is the largest bottleneck for introduction of h2, it is end-user equipment, which is calibrated on the basis of consumption of natural gas, with some uses mandating very small % of h2 (e.g. CNG vehicles). A general assessment is that 20% H2 blending would be possible without much adaptation in terms of equipment and end-use, but beyond that would be difficult to achieve.

The solution to this issue is the creation of a dedicated 100% H2 network that services H2 consumers. This can be a mix of both fully re-purposed infrastructure and newly built.

What are the factors which make Liquid Hydrogen less suitable (as compared with Ammonia) for the largest ships?

The Volumetric density of the two means that transporting the same amount of energy in the form of ammonia will take less space on the ship, this translates in a loss of space to carry cargo / passengers, this would be the main factor leaning the balance towards ammonia as a fuel for certain ships, however the energy required for liquefaction and for maintaining the liquid hydrogen at low temperatures for long periods of time also plays a role.

What about the cost of all this? to meet the large demand huge production is needed, storage, transport and conversion on the consumer side – it will cost an enormous amount of money – some subsidies by EU is far from enough

There is much to be said about the cost of transitioning to a net-zero economy, and I think there is no denying that such costs exists (although, in my view, they should be seen as investments rather than costs)!

However, when talking about H2, we should also talk about the overall cost-efficiency of the entire shift (as a system). From a system perspective, an all-electric scenario (based on renewable electricity) would be significantly more expensive that a system which complements higher electrification with the introduction of renewable and low-carbon hydrogen as a second carbon-free energy carrier. (So the introduction of H2 actually leads to cost reductions when viewed from the perspective of ensuring carbon-neutrality). This is due to cost-efficiency gained from storage, transportation, the re-purposing of existing gas and refuelling infrastructure (and much more) which more than offsets energy conversion loses that occur in the production of hydrogen.

I agree that H2 has benefits when coupled to a grid, but what about the energy input to make the H2?

The transformation of electricity into hydrogen does carry a conversion loss. Depending on how hydrogen is used (e.g. in a fuel cell, hydrogen boiler, combined heat and power (CHP) unit or as chemical feedstock), another energy conversion loss may occur at the point of use. However, from an energy system efficiency perspective, the benefits of transforming renewable energy into hydrogen far outweigh the disadvantages in many situations where delivery of renewable energy to final consumers in the form of electricity is either not feasible, impractical, prohibitively expensive, difficult due to scale-up or simply undesired by certain consumers.

From an ”Energy System Efficiency” perspective”, the use of hydrogen, in complementarity with electrification is, in fact, more efficient than electrification only. In other words, as an enabler of energy system integration, hydrogen provides a mechanism to flexibility transfer energy across sectors, time and place in a more circular energy system. The advantages of the production of Hydrogen, in complement to electrification, can be found across the entire value chain of renewable energy, from production, to its storage and transport and it’s end-use in multiple consuming sectors. These are summarized below:

1. Production: Hydrogen allows for the installation of more renewable energy generation capacity as you will no longer be constrained by the capacity limitations of electricity grids.

2. Storage: By utilising hydrogen as a storage solution, flexibility is brought to the energy system via seasonal storage and furthermore, renewable energy can be stored thus avoiding costly and inefficient curtailment. In other words, hydrogen allows the production of more renewable energy with the capacity that is already installed.

3. Transport: Hydrogen allows the production of more renewable energy with the same resources by enabling its production in ideal locations and at times when it is most efficient to do so. This is made possible because of the immense cost-efficiency of transporting renewable energy in the form of Hydrogen.

4. End-Use: Hydrogen contributes to the growth in the use of renewable energy sources by unlocking new business and commercial opportunities for renewable power producers. By producing hydrogen, renewable power producers can tap into hard-to-electrify sectors such as heavy industry and heavy-duty transport as well as any other sectors for which electrification is impossible, impractical, prohibitively expensive, difficult due to scale-up or simply undesired by the consumer.

Are storage facilities, as they are today for fossil fuels, suitable for Hydrogen storage?

While the locations of such storage facilities is often well suited for the storage of h2 (e.g. in ports, major industrial and logistic hubs, etc.) a number of adaptations will be necessary to make them suitable for both compressed hydrogen as well as liquid (at very low storage), as they are both very different than most traditional fossil fuels (including natural gas, with whom H2 shares many physical similarities)

The cheapest way to transport H2 is by pipeline, using the overcomplete (as H2 will replace gas) natural gas pipeline network in Europe and between Europe and Africa. In which case ports would not be required?

The IEA as far back as 2018, identified ports as central elements for the development of H2 market, not just due to their role as international trade hubs (which may diminish as pipeline trade develops, as you rightly point out) but also given their role as industrial hubs and shipping centres (for which massive amounts of h2 and/or hydrogen made fuels will be required).

As regards to their role simply as trade hubs, it should be said that (a) while Europe may have alternatives (North Africa, Middle East, etc.) where H2 transport via pipeline will be in competition with h2 transport via ships, other parts of the world (Japan, Australia, South Africa) are not so lucky. – Even in the case of Europe, it should not be excluded that renewable rich areas (e.g. Chile) may still be able to compete with H2 produced in the vicinity of Europe. However, we believe it is a bit too early to speculate on who the final “winner” of this market will be.

Are you working with ITER? And have you heard of Hysoplasm?

Unfortunately, I must admit that I have not 😊