Best Practices and Emerging Technologies

Liquid Hydrogen Storage is complex, owing to the extremely low temperature and permeability. The company reported that their liquid hydrogen storage tanks are made of stainless steel, with cryogenic rated valve procurement presenting the greatest challenge. The liquid hydrogen tanks manufactured in the UK utilise multi-layer insulation and vacuum insulation in tandem, which, according to the company, is the most advanced insulation method currently available. Yet, boil-off is inevitable, and the company indicated that they currently do not employ any boil-off management techniques, and levy the responsibility of boil-off management to the client. They reported that re-condensers and cold heads are the emerging boil-off techniques, but present as an added complexity to system design. The company stated that they had experience in delivering several successful liquid hydrogen storage tanks, ranging from 50 – 20,000 litres. For their largest tanks, they reported a gross mass of 9400 kg, with only 15 % being accounted for the liquid hydrogen, at a cost of approximately £ 360 per kg of liquid hydrogen stored. In terms of product delivery challenges, it was found that significant delays were faced because of the client’s inability to specify requirements due to lack of knowledge and standardisation. Whilst standards and regulations around liquid hydrogen storage are being actively developed, the company utilises standard pressure vessel testing guidelines such as radiography, pressure tests, helium leak tests, road transport suitability, drop and racking test, dimensional check, and frame di-penetrant testing based on the PED, TPED, TPR, ADR, ASME, CSC, IMDG standards. Adhering to these standards and the safety measures described in the Cryogenic Safety Manual, BCGA & EIGA codes of practice, and PSSR, the company ensures that strict health and safety criteria are met before tank commissioning. While having an established cryogenic liquid storage business, the company still ensures constant research and development through academic collaborations, most recently with Durham University, mainly identifying and solving critical challenges within the liquid hydrogen value chain. Although keen to collaborate with academia, the company reported that academic research projects are burdensome for SMEs, taking years to achieve meaningful outputs, and diverting focus from profit generating activities. Furthermore, grant funded academic research collaborations are only cost funded, and generally, the IP generated as a result of the collaboration are not commercialised.

Proton Exchange Membrane Fuel Cell (PEMFC) systems are culmination of many individual components and layers, normally divided into electrodes, electrolyte, and interconnects (GDLs and BPPs). The company reported that, in their PEMFCs, electrodes are comprised of Platinum and Platinum based alloys (Pt-Co, Pt-Ni), while the electrolyte is normally a variant of H₂SO₄, with only five high volume manufacturers globally. The Bi-Polar Plates (BPPs) are normally metallic, especially for automotive applications, and supplied by Plugpower and Nuvera. Ballard exclusively provides carbon-based BPPs, although the company reported that polypropylene-based BPPs require further research to evidence lifetime exceeding 20,000 hours. Further material research is ongoing, focusing on increasing power density and lifetime, while reducing costs. High volume manufacturing is essential for widespread PEMFC adoption, with the company reporting that their current manufacturing is highly labour intensive, but they are transitioning towards volume manufacturing through batch processing. The company believes that the PEMFC market should take heed from the lithium-ion battery industry and move towards automated manufacturing. The company stated that they have demonstrated, through previous projects, their capability in automated manufacturing, achieving cell manufacturing times of less than 10 seconds. Similarly, other major PEMFC OEMs are demonstrating improvements in automated cell and stack assembly utilising robots. One of the key challenges experiences in the scaleup of PEMFC systems in the supply chain unreliability of certain critical components (such as compressors) and the lack of testing environments to support certification and regulatory requirements. In terms of PEMFC performance, the company reported a cell and stack degradation of 3 – 10 mV/hour, with efficiencies ranging from 45 – 55 %, and product lifetime up to 10,000 hours (working towards 20,000 hours). The thermal management strategy of PEMFC systems depends on the size, with less than 20 kW systems being air cooled and larger systems being liquid cooled. The companies’ clients have expressed interest in combining MW scale systems with CHP applications to increase the overall system efficiency. PEMFC systems are ideally suited for applications at environmental temperatures of -20 – 45 °C. Higher ambient temperatures bring about humidity changes, affecting membrane hydration, but the desired power output can still be achieved, albeit with a 10 % lifespan reduction trade-off. To combat these limitations, HT-PEMFCs have emerged, but the company believes they require further development in terms of critical issues such as acid leaching and corrosion. In terms of hydrogen storage for PEMFCs, high-pressure gaseous hydrogen tanks are utilised, with a capacity of up to 7 kg. Specifically for UAV applications, the company reported having successfully demonstrated compact liquid hydrogen tanks. For light automotive applications, a battery up to 4 kWh is sufficient for range extension, while HGVs require 10 kWh batteries. In terms of cost, the company is aiming for $30/kW, at an annual production rate of 500,000 units, by 2030, with current PEMFC systems costing over $100/kW. Reporting on the maintenance of their PEMFC systems, the company reported providing a full warranty for all products and retaining a dedicated remote and on-site technical support team, offering repair and service options. To aid with troubleshooting, all PEMFC systems have on-board data logging and fault code display, which the company has access to via the cloud. Early fault identification is an area of research interest to the company, focusing on AI and digital twinning research collaborations with academic partners. Additionally, research is also being conducted in cost reduction and longevity of PEMFC systems with the Loughborough University, University College London, University of Birmingham, and the University of Nottingham. Reporting on the issues of academic collaborations, the company reported that academics lack understanding of commercial profit driven goals, with collaborations taking years to produce meaningful outputs. With lack of funding surrounding fundamental fuel cell research, it would be beneficial to ensure commercialisation of generated IP. Although a relatively mature technology, PEMFC systems still require development to address critical challenges for performance enhancement. These include low-platinum construction, high stability catalyst engineering, and quality control for Membrane Electrode Assemblies (MEAs), catalyst poisoning, non-noble metal catalyst activity, and uniform platinum catalyst production for catalyst layers, and performance optimisation, cost-effective manufacturing, and high-flux preparation of Gas Diffusion Layers (GDLs).

Solid Oxide Fuel Cells (SOFCs) and Solid Oxide Electrolyser Cells (SOECs) utilise Pervoskites for air electrodes, Nickel Ceria for fuel electrodes, and Ceria for the solid oxide electrolyte, with materials sourced globally. The company is continuously researching new materials to reduce cost and increase system lifetime, while simultaneously looking into derisking the supply chain through procurement of new materials from multiple suppliers. Since the SOFC and SOEC technology is licensed to experienced manufacturers, high-volume manufacturing processes, such as screen printing, is being utilised with an aim to reduce manufacturing and assembly costs while introducing automation for kW to MW scaleup. The attractiveness of SOFC and SOEC technology lies in their high performance, with cell and stack efficiencies exceeding 70 % and 65 %, respectively. However, the long cold start-up duration of solid oxide technology remains an issue, normally requiring up to 1000 thermal cycles (a few hours for MW scale) to reach ideal conditions, although this can be reduced by providing external heat. In terms of degradation of SOFCs, the company reported a cell and stack degradation of 0.2 % and 0.25 % per 1000 hours, respectively. For SOECs, the company employs thermal cycling to limit degradation, wherein the SOEC runs at thermoneutral, and the temperature is slowly increased over the lifetime of the product, resulting in minimal system level degradation. Although the company reported commercialisation of 600 kW SOFC and 2 MW SOEC systems, cost remains a major hurdle for widespread adoption, with SOFCs and SOECs currently priced at $500/kW and $200/kW, respectively. Since the technology is licensed, the licensee carries out the necessary certification and testing procedures, although the company supports the process. In terms of fault identification, onboard data logging is present in all SOFC and SOEC systems, although end-user support is required for access. Hence, the company is rapidly researching AI and digital twinning techniques for rapid fault identification and troubleshooting, along with fundamental research into the state-of-the-art material characterisation, through academic collaborations with Imperial College London, University of Liverpool, University of Manchester, University of Saint Andrews, and the University of Surrey. The biggest component level challenges that need to be addressed for rapid commercialisation is robustness to poisons for extending life for next generation products, improving layer interfaces, and high-volume low-cost component manufacturing.