The UK government has made significant investments in the deep decarbonisation of various key sectors, such as transportation, industry, built environment, agriculture, and heating. Robust and harmonised collaboration between the government, stakeholders, and the wider community is critical for a smooth and efficient transition towards a clean carbon-neutral UK economy. The UK government has invested generously in renewable energy, with the UK now producing 43 % of its electricity demand from renewable energy sources (such as wind and solar). This investment is fortified by the commitment to ban new fossil fuel cars by 2035 and promoting electric vehicles. Indeed, the UK is well placed to meet these targets, exemplified by various low carbon technology deployments across all major emission intensive sectors.
Hydrogen has been hailed as a versatile energy vector, with the potential of long-term deep decarbonisation of hard-to-decarbonise sectors. Indeed, a pivotal moment in the UK Net Zero goals was the UK government’s ambition in utilising hydrogen and alternative hydrogen carrying fuels as the fuels of the future, subsequently releasing the UK Hydrogen Strategy in 2021. The Department of Business, Energy, and Industrial Strategy estimates that 30 % of the UK’s total energy consumption would be met by hydrogen by 2050, amounting to 460 TWh of hydrogen. Yet, hydrogen is only carbon-neutral when produced by low-carbon energy sources. This has led to ambitious targets being set by the UK government, committing 10 GW of low-carbon hydrogen production by 2030, out of which 6 GW is dedicated to green hydrogen processes. The UK Net Zero Hydrogen Fund and Industrial Energy Transformation Fund are examples of many UK government investments towards establishing a nationwide hydrogen energy network. UK research organisations have always been held in high regard world-wide, and the UK government has emphasised the importance of UK universities in leading the charge in hydrogen innovation. Subsequently, UK Research and Innovation has funded HI-ACT (Hydrogen Integration for Accelerated Energy Transitions), which is one of two national hydrogen research hubs (the other being the UK hub for research challenges in hydrogen and alternative liquid fuels-HyRES) to help ensure hydrogen is appropriately integrated in future energy systems through a holistic multi-disciplinary approach encompassing end-to-end hydrogen value chain. One of the main deliverables of HI-ACT is to generate a shared vision of all stakeholders on a holistic hydrogen technology roadmap, which encapsulates promising hydrogen technologies across production, transport and storage network, and ‘end-use’ applications within the main hydrogen value chain.
Hydrogen production makes up the basis of the hydrogen economy, and green hydrogen is the key to a clean and sustainable energy economy. Green hydrogen production can be broadly classified into electrolytic and thermo-chemical water splitting processes, with the condition that renewable energy sources (such as wind and solar) are utilised as energy inputs. In terms of electrolytic hydrogen production, an electro-chemical process is utilised which requires an electric current source. Different hydrogen electrolyser technologies have been developed, with some still in their nascent stages, and each characterised by the type of electrolyte being used. Alkaline, Proton Exchange Membrane, and Solid Oxide electrolysers are the most promising electrolytic hydrogen production technologies, each presenting unique challenges and opportunities across various applications. Thermo-chemical water splitting is the latest innovation in hydrogen production, where different catalytic chemicals are introduced to water, which when presented with high heat input facilitate the splitting of water into hydrogen and oxygen. These energy requirements are usually met through solar concentrators, or integration with nuclear power. Yet, questions about cost-effectiveness and efficiency need to be answered before widespread deployment and commercialisation may occur. A coalition of different green hydrogen production processes might be required in tandem to realise the required hydrogen production estimates, and a combination of cost-effectiveness, technology performance and maturity, government incentives, stakeholder engagement, and public perception is critical for a nationwide hydrogen production network.
Transport and Storage (T&S) networks and related infrastructure is the backbone of the fossil fuel-based economy, and the same will be true when hydrogen takes its place as the future clean fuel. Encompassing a variety of technologies, hydrogen T&S networks allow safe, efficient, and reliable pathways to connect hydrogen production sites with diverse ‘end-use’ applications. The pathways are usually divided into storage, conditioning, and distribution. Hydrogen storage includes various technologies, allowing for short- and long-term hydrogen storage. Gaseous hydrogen storage may involve high-pressure vessel-based storage solutions or long-term underground cavernous storage. Cryogenic liquid hydrogen storage involves compression, heat rejection, and rapid expansion to convert gaseous hydrogen to liquid, effectively increasing the density. Hydrogen may also be stored in solid materials, either through hydride formation (involving chemical reactions between hydrogen and metals) or physical adsorption (where hydrogen is stored in the surface of the material). The latest development in hydrogen storage is Liquid Organic Hydrogen Carrier, where hydrogen is transported as a derivative within an organic compound (toluene etc.) using a process called hydrogenation and is released at the ‘end-use’ application back to hydrogen through a process called dehydrogenation. All these hydrogen storage processes require conditioning, such as pressure increasing devices, hydrogen purification, and liquefiers for liquid hydrogen conversion. Conditioning is an integral part of the hydrogen T&S network, as various applications have unique hydrogen pressure and purity requirements which need to be met to ensure durability and reliability of hydrogen-based systems. The pressure needs are usually met by compressors (gaseous) and pumps (liquid), while hydrogen purification processes ensure purity such that no contamination (during production, storage, and transportation) affects end use system performance. Current fossil fuel T&S network relies on pipelines and shipping for long distance transport, and hydrogen must utilise similar infrastructures if it is to compete with fossil fuels. Hydrogen distribution must include a variety of different distribution techniques (pipeline, pressure-vessels), accompanied by suitable control measures. A robust, reliable, and efficient T&S network ensures a steady supply to hydrogen ‘end-use’ applications.
‘End-use’ applications of hydrogen involve either combustion or electrochemical conversion to produce power and heat (if needed). Electrochemical conversion of hydrogen is realised through utilisation of fuel cells, each of which is characterised by its unique electrolyte, to facilitate the production of electricity. Alkaline, Proton Exchange Membrane (PEM), and Solid oxide fuel cells have been developed to leverage the emission reduction potential of hydrogen without producing localised emissions. All fuel cells work on the same principle of electrochemical conversion through ion-exchange between the electrodes through the electrolyte but are differentiated based on the type of electrolyte used. Alkaline fuel cells utilise an alkaline electrolyte, PEM fuel cells utilise a proton-conducting polymer membrane electrolyte, and solid oxide fuel cells utilise a solid oxide electrolyte, facilitating ion exchange and generating an electric current which passes through an external circuit producing power. In terms of combustion, hydrogen may be utilised as an alternative fuel in traditional (with modifications) internal combustion engines, gas turbines, and industrial burners. The utilisation of hydrogen necessitates retrofit or modification in traditional combustion devices but provides the advantage of transferability of some infrastructure and skills, which is rare in hydrogen technologies, known for their innovativeness and uniqueness.
With rampant ongoing efforts to establish hydrogen as the replacement for traditional fossil fuels, it must be kept in mind that hydrogen presents with unique challenges and safety risks, some of which are universal to hydrogen usage, while some may be technology specific. Hydrogen, known for its high flammability and explosiveness, necessitates stringent safety protocols and comprehensive policies prior to national deployment. Ensuring material compatibility, leak detection, and monitoring is critical for safe hydrogen-systems deployment. Hydrogen’s propensity to accumulate and its asphyxiation risks, particularly in confined spaces, underscore the need for proper ventilation. To mitigate these risks, robust health and safety policies and regulations, emergency response measures, and public education initiatives are essential. With the growing demand for hydrogen, international and national regulatory bodies are establishing guidelines for its safe handling and use. Adherence to rigorous safety standards is vital for the secure integration of hydrogen into national energy systems, most certainly starting out as localised clusters across the UK. These clusters are likely to elicit varied reactions from communities regarding the social, economic, and environmental impacts. Local populations may perceive hydrogen projects as threats to local safety, landscapes, and long-established domestic routines. Concerns about the costs of transitioning to hydrogen technologies, supply chain disruptions, and fuel poverty may also arise, potentially limiting government and stakeholder actions. On the other hand, these projects may be viewed as economic opportunities for self-sufficiency, particularly in niche applications like transport hubs, which are less disruptive compared to large-scale projects such as gas pipelines. Community risk perception is often shaped by public views and situational control rather than informed decision-making. The diverse responses to hydrogen infrastructure highlight the challenges of regional deployment, exemplified by some cancelled village-scale hydrogen trials due to public opposition, while trials in Tees Valley continue. Limited public knowledge about hydrogen technologies underscores the need for education on their environmental benefits to foster positive perceptions. Effective deployment necessitates intricate navigation of diverse socio-economic and cultural backgrounds, with potential opposition where technologies impact community relations, identities, and practices.
HI-ACT’s mission is to deliver impactful research on integrating hydrogen into the energy sector and the broader UK economy. A key task of HI-ACT is to generate a new UK hydrogen roadmap, which will strongly support the co-creation of a national strategy with stakeholders. This new roadmap necessitates a comprehensive review of all existing and emerging hydrogen technologies. HI-ACT’s vision is to ensure hydrogen is seamlessly integrated into the UK energy system through holistic, multidisciplinary collaboration. This report aims to provide a technological framework across the entire hydrogen value chain, establishing a clear hydrogen technology roadmap. It will assist the UK government in making informed, investment-driven policy decisions that enable scaling and rapid deployment of hydrogen technologies nationwide. This effort will position the UK at the forefront of hydrogen innovation, enabling it to lead the global hydrogen economy.
