IT WAS approximately two years ago when I last wrote about hydrogen as part of our cleaner, greener, more sustainable and safe energy future1. Then the UK had a target of reducing greenhouse gas emissions by 80% by 2050, compared to 1990 levels, as set by the Climate Change Act 2008.
Since then, global warming has risen still further on the international agenda and in the public psyche, following weather extremes observed in Australia, the US and other countries and with consequences described in the Intergovernmental Panel for Climate Change (IPCC) Global Warming 1.5 degrees special report2.
In June 2019 the UK then became the first major economy in the world to pass laws to end its contribution to global warming by 20503. This was a significant milestone. We will have to utilise every trick in the book to help us achieve it – which means getting to grips with a huge range of new and novel energy innovation and technologies, safely and very quickly.
Specifically, for hydrogen, the UK’s Climate Change Committee recommends the development of a hydrogen economy to service demands for some industrial processes, for energy-dense applications in long-distance HGVs and ships, and for electricity and heating in peak periods. By 2050, a new low carbon industry is needed with UK hydrogen production capacity comparable in size to the UK’s current fleet of gas-fired power stations.
With the emphasis on targets and timescales, it is very important to maintain our focus on safety. In 2019 there were three significant incidents involving hydrogen (US, Norway and South Korea), relating to refuelling of a pressurised hydrogen tube trailer, a hydrogen vehicle refuelling station, and a renewable energy recovery demonstration plant employing electrolysis.
The last of these was the most significant and sadly resulted in two deaths and several injuries.
It is clearly essential at an early stage to understand the underpinning safety assumptions and risk profiles for new technology, retrofitted infrastructure and combined systems planned to deliver the low carbon economy. There is potential for risks, both new and old, to emerge as the energy systems become more complex, but there are also opportunities, with smart systems, to utilise operational data to optimise safety and to introduce safety in design concepts early. It is therefore vital to be proactive when considering safety during the innovation and demonstration phases.
As an enabling regulator, HSE is playing an active role in the safe development of hydrogen as an energy vector across the energy system. In addition to its role as the regulator, it is also using its ability to provide scientific research and consultancy services to other government departments and industry to enable the safe deployment of a number of key hydrogen projects. Helping operators to understand the risks associated with hydrogen use by combining evidence-based theory with real-world experimentation provides a pathway to safe innovation and has resulted in HSE partnering with industry in high profile projects relating to the use of hydrogen as an alternative energy solution.
HSE first started working in hydrogen technology participating in various EU projects investigating fuel cell applications, especially the storage and associated infrastructure. These were not typical of the well-established industrial environments, where hydrogen had been used safely for over 100 years. The drivers for the work at the outset were, and still are, around understanding the unique properties of hydrogen, including its: low ignition energy; wide flammable range; high flame speed and increased tendency for deflagration events to transition to detonation; high diffusivity; and high buoyancy.
Specialising in the safety considerations, HSE’s role was to undertake exploratory research on the behaviour of hydrogen on its 223 ha Science and Research Centre in Buxton, Derbyshire, often working in collaboration with partners in Europe, the US and the Far East. Through these activities a good knowledge base has been established within HSE which is now being developed, and applied to a wider range of sectors, such as heating and power.
A key principle of our current work is understanding how hydrogen differs from incumbent technologies and when those differences really matter. When behaviour differences are understood, engineering or procedural solutions can be applied to maintain safety. We are increasingly involved in advising on safety for a range of hydrogen technologies, including production at scale, and demonstration of potential applications in power, heat and transport. Areas where the HSE has been particularly involved are listed in Table 1.
These projects and demonstrations are providing critical evidence to inform strategic decisions which need to take place soon if we are to meet Net Zero by 2050.
In the UK, the sale of new internal combustion engine vehicles will now end in 2035, if not before.
"Decarbonised transport” therefore needs to see a rapid shift. Vehicles using battery and hydrogen energy storage both currently exist and are operating in the UK. For hydrogen, the sparse refuelling infrastructure, as well as the limited supply of vehicles, has slowed takeup. Nevertheless, hydrogen-powered cars, vans and buses have been operating safely on the UK roads for a number of years. The main safety challenges involve the high pressure (up to 700 bar) on-board storage, and the infrastructure to support them.
For light duty vehicles this safety challenge has been overcome through the use of incredibly strong, highly engineered composite tanks. In Japan and California, thousands of vehicles have been operating safely for several years employing this technology, which is proving itself very effective. In addition, hydrogen buses have been operating safely in many cities around the world, including London (operating since 2011) and more recently Aberdeen.
The challenge moving forward is for the use of hydrogen vehicles to expand, which will bring its own challenges including:
Whilst stored at similar high pressures as for passenger vehicles, the additional safety challenge of hydrogen storage on trucks and vans arise from the larger inventories required to enable greater ranges, or a switch to liquid hydrogen (LH2). LH2 has been used in industry for many years (including most space programmes), but its use for more novel transport application is being addressed by the PRESLHY project5. In its cryogenic liquid state (LH2) hydrogen provides largest densities and some intrinsic safety advantages. Therefore, LH2 is attractive for scaling up supply infrastructures, eg for fuel cell driven trains, ships or car or truck fleets.
Industry knows how to handle LH2 safely. However, the new applications imply new conditions and untrained users. PRESLHY, an EU co-funded research and innovation activity, investigates respective knowledge gaps and will close these gaps with a large experimental programme providing new validated models and engineering correlations for efficiently safe design and operation of innovative hydrogen solutions.
So, hydrogen offers many opportunities for transport, by overcoming the remaining infrastructure and safety challenges to enable uptake at scale. A route to decarbonisation can be realised, coupled with the benefits of improved air quality and public health.
In many ways industry is the obvious place to start with hydrogen, as many of these environments are already used to it. Other applications foreseen are power generation using gas turbines (and fuel cells) powered by hydrogen6. To do this CCS will be essential, and include multiple industrial clusters, integrated with domestic and transport. Such opportunities with the hydrogen would bring together domestic, industrial and potentially transport use in hubs, with examples such as HyNet7 and Tees Valley8.
HyNet is based on the production of hydrogen from natural gas. It includes the development of a new hydrogen pipeline and the creation of the UK’s first CCUS infrastructure. Accelerating the development and deployment of hydrogen technologies and CCUS through HyNet positions the UK strongly for skills export in a global low carbon economy. On a practical level, the concentration of industry, existing technical skill base and geology means the region offers an opportunity for a project of this kind.
The Tees Valley Hydrogen Innovation Project (TVHIP) aims to support SMEs in the Tees Valley to stimulate the development of a hydrogen low-carbon economy, providing knowledge transfer services to SMEs. The project supports industry in a number of ways; collaboration through hydrogen network for knowledge and technical exchange, access to hydrogen productions which will all support the development of new products, and processes utilising hydrogen.
In terms of safety, these clusters offer great opportunity to bring together industrial expertise and practices interfacing with more novel applications utilising much of the safety knowledge developed from the projects, and as such are a very sensible way to scale hydrogen technologies.
Clearly this is an important time for hydrogen, which will have a key role in achieving Net Zero by 2050 in the UK, and international decarbonising targets more widely. It is clear that achieving this will need real pace in the development and implementation of technologies. It is essential that safety is fully considered as part of this rapidly developing pathway, building into all projects from the outset. It is essential that underpinning evidence base is robust and scientifically-based to ensure that all decisions are informed, and then effectively incorporated into standards and best practice.
This approach enables safety to be built into designs, using the best engineering, but also taking opportunities to use smart systems, data to optimise systems, and safety management.
Another important part of this picture is the growing critical national capability that will deliver scaleup and roll out this change. There is real concern in the community internationally that failure to enable developers to have the right knowledge and availability of expertise is a great risk, and could lead to inevitable loss of life and confidence in hydrogen as a solution.
1. The Chemical Engineer, issue 921, https://bit.ly/3g4YCbH
This is the 18th article in a series discussing the challenges and opportunities of the hydrogen economy, developed in partnership with IChemE’s Clean Energy Special Interest Group. To read more from the series online, visit the series hub at https://bit.ly/2z4wJ2W
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