At a recent webinar, experts covered research activities that have formed part of the Offshore Renewable Energy (ORE) Catapult’s Hydrogen Innovation Initiative (HII) Programme.
Presentations covered some of the technical and operational challenges for producing green hydrogen from wind, with the work of the HII striving to create an “investible, globally competitive hydrogen technology services sector” in the UK. Kicking things off, Dr Ines Tunga, Renewable Practice Manager at the Energy Systems Catapult set the scene by highlighting how as the energy transition progresses, the power sources we use will become increasingly weather dependent and less predictable.
This means flexibility is needed, where hydrogen will be a key element.
Tunga went through how Catapult has worked to understand exact demand for hydrogen and where it could be most feasible to deploy. Considering challenges with grid reinforcement, co-location with offshore wind is increasingly appealing, with Catapult finding a greater opportunity for this in areas of the country with lower population densities. Rapid and accelerated grid reinforcement is still needed, however, with there also a requirement to set out how electrolysers can contribute to managing the grid and related business models to ensure there are no unintended consequences.
Michael Walsh, R&D Engineer for Hydrogen Systems at ORE Catapult, ran delegates through the development of the Hyfive system – a lab-scale hydrogen electrolyser and fuel cell rig for green hydrogen research and development. Through this, they have been able to learn how encryption and remote control access with the energy management system impacts site safety and system management; how regulatory planning, utility and health and safety considerations must be explored early in the project lifecycle; how the strategic location of non-return valves, emergency pressure relief valves and process pressure relief systems are essential for site management; and, in instances where regulatory guidance is lacking, how the experience of integrators and health and safety consulting can fill gaps.
Next to speak was Dr Anup Nambiar, Senior R&D Engineer for Electrical Systems Applications at ORE Catapult who explained the different electrical considerations for wind to electrolyser integration. There are three ways of integrating wind and green hydrogen production – onshore centralised, where an offshore wind farm is integrated with an onshore electrolyser; offshore centralised, where an offshore wind farm has a centralised offshore electrolyser; and offshore decentralised, where an offshore wind farm has an offshore electrolyser actually on-turbine. Onshore centralised is the closest to conventional wind farm operation, whereas the two offshore options are still growing mature, with challenges around regulation, control and stability, plus there is the growing need for energy storage.
Nambiar noted wind farms and turbines already have well defined requirements under the grid code but requirements for ‘demand’ – where electrolysers lie – are fewer and less onerous. There are expert working groups across the UK and EU that are exploring how to improve grid codes that could see electrolysers have advanced compliance requirements in the future. While an additional energy vector that can help to get around grid constraints, there is still a need to work out exactly how green hydrogen will fit, with testing continuing to evolve and advance conversations forward.
Finally, Ed Macfarlane, Principal Consultant at Abbott Risk Consulting, spoke about hydrogen safety. Macfarlane began by talking about specific considerations for hydrogen, including its low density, which means it rises at 20 m/s in the air; its low viscosity, which sees it leak easily; its high diffusivity, leading to it migrating through volumes and materials 3.8 times more than natural gas does; and its flammability range and explosion limits, both of which are more than natural gas by some margin – 4-74% versus 5.3-15% and 18.3-59% versus 5.7-14% respectively.
While hydrogen itself is not new, the areas of application now are, with existing legislation, standards and guidance having to be updated in parallel to deployments and the sector doing a lot of learning by doing. Examples of good practice include limiting inventories as far as is practicable, minimising the potential for leaks, segregating between different pressure sections of the power system, optimal location of the system relative to sources of heat and fire, and passive and active pressure protection with routing to safe location for pressure relief as good design steps to avoid overpressure scenarios.
Further steps to take include maximising ventilation, eliminating and minimising ignition sources, minimising congestion and confinement, and secondary protection including fire walls, blast walls and explosion relief in a bid to control and mitigate dangers. Finally, on emergency responses, detection is key. This could include flame detectors appropriate for hydrogen flames and pressure monitoring, a response system such as increased ventilation, and audible and visual alerts and alarms. Emergency plans, including first responder information, and access to systems that have to be protected, including wetting with water, are also recommended.
