Decarbonisation Technology - August 2023 Issue

hydrogen plants range in size from 25 to 100+ MMSCFD), around 275 MW of power would be required. Furthermore, based on current projections and these usage levels, achieving the target 2050 green hydrogen production goals would require all the power generated globally in 2018. Combining this power demand with the drive for EV vehicles and further electrification of growing economies in Asia and Africa, the power generation requirements and associated infrastructure will have to grow by orders of magnitude and utilise renewable sources rather than fossil fuel-based power generation. Hence, the application of electrolysis for hydrogen generation with carbon-based power sources will not achieve decarbonisation targets – substantial power generation and distribution within wind, solar, biomass, hydro, and even nuclear is needed to meet renewable power growth as well as being sources of power for green hydrogen. In addition, water requirements are substantially higher for electrolysis hydrogen compared to conventional SMR hydrogen with carbon capture (around 6 kg H₂O/kg H₂ for SMR with carbon capture vs 9 kg H₂O/kg H₂ for electrolysis). Using the same 50 MMSCFD hydrogen plant above would require 200 gpm of high-purity water. Though efficiencies will help these applications and research is being done to use lower quality water, electrolysis hydrogen facilities will require substantial amounts of water, which will impact the possible location of a given facility and the water availability for other residential and commercial users in that location. The current leading electrolyser technology is polymer electrolyte membrane (PEM), and one of the key raw materials is iridium. Based on just the projected US demand for PEM electrolysers, around 15-30% of the global iridium supply would be required. In addition, the US EPA and the EU may designate several perfluoroalkyl and polyfluoroalkyl substances (PFAS) chemicals as hazardous, and many of these ionomers are required for PEM electrolysers. Therefore, this decision could impact the supply chain and availability of these specific PFAS, which could slow the adoption of green hydrogen projects. These points are being made not

to dismiss the potential of green hydrogen but to help provide a frame of reference on the scale of requirements for using hydrogen as a decarbonisation mechanism. To meet these challenges, significant investment in infrastructure and research and development is required. Distribution and logistics No matter the form of energy utilised within our economies, the focus is typically on the production and consumption sides, with the distribution and logistics systems often taken for granted, under-invested in, or even forgotten. Yet, such infrastructure will ‘make or break’ the adoption of hydrogen as a viable decarbonised energy source. Based on a recent US Department of Energy study, between $85 and $215 billion of investment is required to meet the forecasted demand of 10 MmT per annum of domestic clean hydrogen, with 25-40% of that investment required in the midstream distribution infrastructure. This high percentage is due to the lack of current investment in logistics systems with more focus on production assets. Therefore, getting the right infrastructure in place is critical for the long-term viability of the hydrogen supply chain. The key issue with hydrogen distribution is that the hydrogen must be transported in gaseous form via compression, in liquid form via liquefaction, or via a liquid carrier (such as a liquid organic hydrogen carrier, LOHC). While hydrogen compressors and pipelines have existed and been used for decades, these systems are typically concentrated within industrial zones or focused regions. To meet the consumption options outlined previously, significant expansion of hydrogen pipelines and compression would be required, which is counterbalanced by the lack of desire of many landowners to provide right-of-way access for further installation of pipelines on their land. Most hydrogen pipelines operate between 1,200 and 1,800 psig, and most electrolysers produce hydrogen at 100-200 psig, with newer technologies being near atmospheric pressure and SMRs producing hydrogen at 250-350 psig. Therefore, multistage centrifugal compressors or reciprocating compressors will be required to get the product to distribution system pressure.