Learnings

Outcomes

Project Outcomes:

• Quantification of water consumption rates associated with electrolyser technology types and their required purification: HydroStar determined that the water consumption rates depend primarily on three processes within the hydrogen production chain, electrolytic water requirements, as well as hydrogen compression and hydrogen storage water demands. When considering direct water demand from production this is inherently related to electrolyser type. During this project HydroStar considered four electrolyser types; Proton Exchange Membranes (PEM), Alkaline, Solid Oxide Electrolyser Cell (SOEC), and Membraneless. HydroStar were able to conclude that:
  • Membraneless electrolysers can use the chemical stoichiometric minimum water per kilogram of hydrogen produced (9 Litres per Kilogram of H2).
  • Proton Exchange Membranes (PEM), Alkaline and SOEC electrolysers require the use of ultra-pure water and therefore have considerably higher relative water consumption through the electrolysis process when compared to Membraneless Electrolysers. Water consumption for all of these technologies fall between (135 – 306 Litres per Kilogram of H2). This range of water consumptions directly from electrolysis is a result of the different efficiencies of the Reverse Osmosis process that is required to purify water to the level required for these three technologies.
• As mentioned above cooling towers are often necessary additions to the balance of plant at larger hydrogen production installations for two key reasons (1) some types of electrolysers get exceptionally warm, notably SOEC, and therefore must be cooled, (2) to facilitate efficient condensation of hydrogen post compression (having used mechanical compressors as opposed to metal hydrides). Both of these requirements for cooling towers results in the loss of water to the surrounding environment as the water used within the towers evaporates. Evaporation is the method at which heat is removed in a cooling tower. Water will still evaporate even when left undisturbed, and cooling towers use moving water to capture and remove heat. This results in the following additional water demands within the hydrogen production chain:
  • Cooling equipment for SOECs will likely increase water consumption by 20-40L/kgH2.
  • Cooling for compression would increase water consumption yet again by 20-50L/kgH2, and this applies to all technologies when utilising mechanical compression.
• Changes made to WWU’s Pathfinder Model: HydroStar added the following User Inputs into tab 2.0, ‘Electrolyser Type’, ‘Water Purification Requirement’, and ‘Compression Requirement’, as well as introducing data into the Fixed Inputs Tab (4.0). Specifically, ‘Electrolyser Types’, ‘Stack Direct Demand’ (litres/MWh), ‘Water Purification water demand’, ‘Cooling Compression water demand’ this input impacts tabs, Baseline Hourly Calculation [Tab 8.0], and Scenario Hourly Calculation [Tab 9.0]. These changes built water demands of electrolytic hydrogen under different cooling/compression scenarios into the Pathfinder Model, increasing awareness of the huge water requirements surrounding large-scale electrolytic hydrogen.  
• Relationship between all energy vectors (water, electricity, green hydrogen) when modelling future energy scenarios that are suitable to be integrated into WWU’s Pathfinder Model: HydroStar developed a Python Model that combined all of the energy vectors associated with Green Hydrogen production. This model was also provided with solar variability and estimated water availability values harvested from UKCP18 climate project models that were run up to 2050. This showed how the vectors were likely to change and how that would impact the ability to produce Green Hydrogen. For example, UKCP18 data showed that South Wales was anticipated to see a 0-10% increase in solar availability during Summer months, but a 0-10% decrease in availability during winter months during all of the Representative Concentration Pathways (2.6, 4.0, 6.5, 8.0). This shows that when utilising solar as the primary renewable energy source for powering the electrolytic production of Green Hydrogen in South Wales it is likely that production will tend towards being more seasonal in nature, with higher production capacities in the Summer and vice versa in the Winter. This is something that major gas users / Local Authorities must take into account when using the Pathfinder Model to make value decisions regarding their decarbonisation methodology(s) as greater hydrogen generation capacity will have to be factored in to allow for BAU operation in Winter months which will see lower generation rates over time due to the impact of climate change.

Opportunities for Future Projects/Project Development Identified:

• Extreme Events and Seasonality of Green Hydrogen Potential Project: There is a vast amount of data available for analysis of this area, a further project looking solely into the vulnerability of electrolytic hydrogen due to drought events would render even higher resolution results than were made available through this project. HydroStar have already established a good relationship with the Met Office whose experience would be invaluable in this regard. Furthermore, establishing how extreme events and the inherent seasonality of Green/Electrolytic Hydrogen will impact its relative production through a year/ going further into the future will help build a more resilient plan for roll-out/delivery of this low-carbon energy.
• Building RCPs/Robust Climate Scenarios into the Pathfinder Model: WWU could start to build in climate variables into their Pathfinder Model, this was suggested to the WWU team working with HydroStar and the feedback was very positive. HydroStar have already engaged with Professor of AI at the University of Exeter Ed Keedwell and a Met Office representative Dr. Cyril Morcrette on this project idea, which could be funded through an Innovate UK, EPSRC, or Environment Agency funding stream.
• Further Development of the Pathfinder Model: WWU have an excellent tool in the Pathfinder Model. This tool is a catalyst for clean energy change within Local Authorities, specifically regarding Local Area Energy Plans. Building further functionality, modelling, and scenario development capabilities into this established model would likely be beneficial to those developing LAEPs.  

Lessons Learnt

• Difficulty of contacting Local Authorities/Councils: HydroStar would have benefitted from receiving a rolodex of WWU’s Local Council contacts at the start of the project to leverage WWU’s existing relationships. This would have enabled HydroStar to engage with more Councils than was achieved during this project. Equally important is that HydroStar needs to develop a more effective way of starting discourses with Local Councils rather than relying on emails/LinkedIn.
• Difficult to acquire data from water companies due to red tape: In future projects the possibility of bringing water companies in as project stakeholders could be explored so that they have prior knowledge that information will be required from them and NDAs can be created in advance. Additionally, as WWU is looking at the possibility Green Hydrogen at meso and large scales, it would be to no one’s detriment to engage with water companies that operate within WWU’s coverage as vast amounts of water will be required as a feedstock.

Overall, HydroStar believes that the research conducted as part of this NIA project was effective and led to a successful project outcome where all the success criteria was achieved during the allotted project timeline.