Decarbonisation Technology - May 2023 Issue

May 2023 Decarbonisati n Technolo gy Powering the Transition to Sustainable Fuels & Energy






ERTC 2022


The world’s energy system is changing. To solve the challenges those changes present, Shell Catalysts & Technologies is developing its Decarbonisation Solutions portfolio — to provide services and integrated value chains of technologies, designed to help industries navigate their path through the energy transition. Our experienced teams of consultants and engineers apply our diverse, unique owner-operator expertise to co-create pathways and technology solutions to address your specific Decarbonisation ambitions — creating a cleaner way forward together. Learn more at

Decarbonisation Solutions



May 2023


Decarbonisation and sustainability value chains Deciding which decarbonisation pathway to adopt can be difficult, as there are multiple technologies to consider, each with its own risks and rewards Chris Egby Shell Catalysts & Technologies Safety, risks, and hazards of hydrogen The safe use and distribution of natural gas are fully understood, but a similar level of technical understanding is now required for the key properties of hydrogen Sarah Kimpton DNV Feedstocks and utilities for green hydrogen and e-fuels High purity water, carbon dioxide and nitrogen are essential utilities for green hydrogen generation using electrolysis Stephen B Harrison sbh4 Consulting




Biofuels syncrude pathway for producing SAF from waste A waste-to-fuels process converts refuse derived fuel to syncrude that can be readily refined

and co-processed to form SAF using conventional refining Candice Carrington and Mohammed Navedkhan Petrofac


Journey toward decarbonisation of the shipping industry Alternative fuels for the shipping industry are explored along with methods to increase fuel efficiencies and reduce emissions Nathan D Wood, Robert Moorcroft and Torill Bigg Tunley Engineering Conversion of CO 2 to methanol CO 2-to-methanol conversion has the potential to play a significant role in reducing greenhouse gas emissions and advancing a more sustainable energy system Nieves Alvarez MERYT Catalysts & Innovation Cleaner alternatives to heavy fuel oil Industries are waking up to the reality of climate change, and oil-in-water emulsion fuels stand out as an immediate transition solution Jack Williams Quadrise Carbon utilisation to accelerate the transition to net zero Captured carbon can be converted into valuable products, enabling circularity and decarbonisation of hard-to-abate industries Cecilia Mondelli Sulzer Chemtech, Brent Konstantz Blue Planet Systems





CREATING JET FUEL FROM THIN AIR. Introducing Honeywell UOP eFining™. We are ready to make eSAF a reality today. Reliable, scalable and cost-effective, our latest technology enables the conversion of CO 2 into high yield, high quality eSAF. It also reduces greenhouse gas emissions by 88% compared to conventional jet fuel.* Learn more at

*Reduced GHG emissions is based on UOP carbon intensity analysis, derived from a 3rd-party study of bio-methanol production from organic waste and green hydrogen, in comparison to fossil fuels.

In April 2023, the Decarbonisation Technology European Summit opened with a discussion on the need to balance the transition to renewable energy and sustainable fuels while ensuring the security and reliability of affordable energy supplies for the consumer. Progress with the energy transition is noteworthy as companies move on from agreeing targets and developing plans to project implementation. Innovation is at the forefront of this transition, touching every aspect and incorporating existing as well as emerging technologies. Investments in renewable sources of electricity, particularly solar and wind power, are reducing the reliance on imported gas and thereby improving energy security. Similarly, the progressive substitution of oil with renewable biogenic feedstocks is underway. Industrial clusters are encouraging investment in new infrastructure for the supply of hydrogen and the transport, storage, and utilisation of carbon dioxide (CO 2) . First-of-a-kind demonstration plants are being commissioned, for example, to gasify the organic fraction of household waste to produce a range of low-carbon transport fuels, including sustainable aviation fuel (SAF). Successful full-scale trials using hydrogen in commercial steel and glassmaking furnaces were highlighted. Other notable points included the utilisation of CO 2 for the production of chemicals and fuels. Perhaps the biggest highlight is the spirit of co-operation and the emergence of partnerships across different industries with government, academia, and other stakeholders. It is good to report such success and encouraging progress with the energy transition. Yet the road to net zero is clearly long and difficult. Over the next two decades, investment must increase exponentially. Even though we are likely to overshoot the 1.5ºC target, we must endeavour to minimise the amount and duration of the overshoot. With this in mind, reducing methane emissions between now and 2030 can make a vital contribution. This magazine will follow reports from the monitoring entities (IEA and IMEO) and highlight actions taken by companies to deliver on their commitments. None of this should surprise those employed in the transition, especially the contributors and readers of Decarbonisation Technology magazine. In this edition, we are pleased to share a special feature on hydrogen safety. Other topics include the integration of a range of low-carbon technologies, electrolytic hydrogen production, and waste-to-fuels. These are followed by the production and economics of SAF and marine fuels, as well as carbon capture storage and utilisation in hard-to-abate industries, such as cement. Together these articles emphasise that decarbonisation covers the whole value chain, from the energy source to the end user.

Managing Editor Rachel Storry tel +44 (0)7786 136440

Consulting Editor Robin Nelson robin.nelson@

Editorial Assistant Lisa Harrison

Graphics Peter Harper

US Operations Mark Peters tel +1 832 656 5341

Business Development Director Paul Mason tel +44 844 5888 771

Managing Director Richard Watts

EMAP, 10th Floor Southern House Wellesley Grove, Croydon CR0 1XG

Cover Story Distillation columns


A long history of looking

For nearly a century, Grace catalysts have kept fuel and petrochemical feedstocks flowing from the industry’s largest refineries to the trucks, trains, planes, and ships that keep our world running. We are leveraging our long history of innovation in fluid catalytic cracking to develop products that enable lower carbon fuels and help meet the challenges of the energy transition.

Decarbonisation and sustainability value chains Deciding which decarbonisation pathway to adopt can be difficult, as there are multiple technologies to consider, each with its own risks and rewards

Chris Egby Shell Catalysts & Technologies

R educing carbon dioxide (CO 2 ) emissions is an important goal for the operators of refineries, petrochemical plants, and those in hard-to-abate industries such as steel and cement manufacturing. There are numerous decarbonisation pathways and technologies to consider, including renewable fuels, hydrogen, and carbon capture and storage (CCS). As each carries its own risks and rewards, deciding which to adopt can be challenging. Shell has been actively decarbonising its own refineries by transforming them into energy and chemicals parks, with Shell Catalysts & Technologies playing a central role in this process. We have been supporting companies in other sectors, too. So in this article, we will share our experience to provide insights into some of the options available. First, let us look at why decarbonisation is necessary. The Paris Agreement poses an ambitious goal of maintaining the average global temperature increase below 2°C compared with the pre-industrial level and, ideally, limiting it to 1.5°C. Achieving these targets is a daunting task that requires almost halving the net CO 2 emissions in the next 30 years, from 32 Gt in 2017 to 18.4 Gt per annum by 2050. This is exacerbated, however, by the increasing global population, which is expected to increase from about 8 billion in 2023 to almost 10 billion by 2050. In the same period, energy demand is expected to rise by a third. While social and investor pressures are growing, many countries have set net-zero targets and begun implementing energy transition policies.

Shell’s net-zero targets Shell’s net-zero target is to reduce scope 1, 2, and 3 CO 2 emissions from 1.7 Gt per annum to zero by 2050. Interestingly, as most of the company’s CO 2 emissions come from energy products that customers have bought and used themselves (Scope 3), it believes that working with customers, sector by sector, is the way to do this. So it intends to work with customers across many sectors, including aviation, shipping, road freight and industry, to decarbonise value chains. It will do this by listening to them and learning with them. Shell is working to meet its decarbonisation targets. For example, by the end of 2022, it had reduced emissions from its operations by 30% and reduced the net carbon intensity of the energy products it sells by 3.8% (both compared with 2016). It also more than doubled its solar and wind generation capacity, and increased the number of electric vehicle charge points it owns or operates by around 62% (both compared to 2021). It is also developing renewable (green) hydrogen and growing its biofuels portfolio. To achieve this, Shell is transforming some of its refineries into energy and chemicals parks (see Figure 1 ) – integrated lower-carbon clusters that can better adapt to future changes in customer demand. Among the sites undergoing this transformation are Europe’s largest refinery, Pernis, which has become Shell Energy and Chemicals Park Rotterdam, and Germany’s largest, Rheinland, which is becoming Shell Energy and Chemicals Park Rheinland. These energy and chemicals parks are diversifying their energy inputs by replacing


Bio fuel

Other fuels

Performance chemicals



Lub es

Bitume n

Trading & optimisation

Fuels for road transport & aviation

Resilient products





Biomass & waste oil/gas

Plastic waste and municipal solid waste

Solar energy

Crude oil

Wind energy

Figure 1 The energy and chemicals parks concept plays a central role in Shell’s decarbonisation strategy

crude oil with renewable and circular sources such as solar, wind, plastic waste, and biomass. Shell is also changing its mobility products portfolio to include more hydrogen, biofuels, and renewable energy. The company is adding greater flexibility to produce more performance chemicals, lubricants, and bitumen while capturing and storing its operational emissions to reduce the carbon intensity of the products it sells. Shell has several decarbonisation projects in operation or development at its energy and chemicals parks, demonstrating that decarbonisation is happening now, not just being discussed. For example, the Refhyne I project produces renewable hydrogen right now, and the Refhyne II and Holland Hydrogen I projects will bring step-change capacity increases. It is also producing biofuels through co-processing, and dedicated units in development at Rotterdam, Rheinland, and other sites will increase capacity substantially. CCS is another important decarbonisation lever. Shell Catalysts & Technologies is providing key technologies for both long-running projects like Shell’s Quest CCS venture and others in development, including Porthos in the Netherlands, which will receive CO 2 from Shell Energy and Chemicals Park Rotterdam. We are performing an important enabling role for those energy and chemical parks by providing key technologies for a number of those projects. For example, we are providing the Shell Renewable Refining Process that

Rotterdam will be using to produce biofuels and sustainable aviation fuels. ADIP Ultra carbon capture technology is already in use at Quest and will also be used at Rotterdam and Rheinland. Gas POx technology will enable Rotterdam to produce decarbonised (blue) hydrogen when Porthos comes online. However, Shell Catalysts & Technologies is not only working with refineries and petrochemical plants. For example, it plays an important enabling role in the cross-sector Humber Zero and Northern Lights projects, which comprise power, steel, cement, pulp, and paper companies, as well as oil and gas producers. In addition, the Cansolv CO2 Capture System has recently been selected for numerous projects in other sectors. After operating at Boundary Dam power station in Canada for many years, the technology was recently selected by VPI Immingham and Calpine for their power plants, as well as Hafslund Oslo Celsio (formerly known as Fortum Oslo Varme) for its waste-to-energy plant in Norway, among others. In this new world, collaboration is more important than ever. We believe technology development and partnering are key to achieving our decarbonisation goals. Our solutions are available to third parties for mutual benefit. Through partnerships, we will evolve and continuously improve our technologies. For example, the Shell Renewable Refining Process is evolving to process an increasingly wide range of advanced feeds.


Integrated decarbonisation value chains Figure 2 shows that, to decarbonise, there are numerous renewable and circular feedstocks (left-hand side) from which numerous desirable products (right-hand side) can be made. Furthermore, as shown in the centre, there are multiple potential pathways from left to right. Because it is a complex pathway from left to right, breaking it down into five separate value chains can be very useful, especially because they all have different levels of maturity and drivers and, in some cases, are applicable to different industries. These value chains are renewable fuels, plastic circularity, hydrogen, CCS, and syngas production and utilisation, each of which is discussed below. Renewable fuels value chain In the renewable fuels space, we are seeing strong drivers and legislation that offer clear direction on how companies can generate value. The EU, for example, has the Renewable Energy Directive (RED II), and the US has the Renewable

Fuel Standard and the Blender’s Tax Credit, plus the Low Carbon Fuel Standard in California and some other states. In the Asia Pacific region and China, this legislation is regarded as an opportunity to generate carbon credits through the export of renewable fuel feedstocks. As shown in Figure 2, there are several ways in which renewable feedstocks, such as vegetable oils and animal fats, can be processed into renewable fuels. One option is co-processing and another is to use a dedicated hydrotreated vegetable oil (HVO) unit, such as the Shell Renewable Refining Process. However, the feeds are already in short supply, and this is expected to get more severe with time as, for example, lignocellulosic biomass and municipal solid waste will potentially be mandated in the future. Consequently, it can be important to consider future-proofing assets. One way to do this is through a phased investment that begins with co-processing, a low-capital option, and then investing in a full HVO unit before adapting it for the more challenging feedstocks of the future.

Renewable fuels

Plastic circularity



Syngas products

Renewable naphtha/SAF/ renewable diesel

Shell R enewable R efining P rocess

Vegetable oil /animal fat



HTL/ pyrolysis oil

Shell R ecovered P lastic U pgrader

HTL/pyrolysis oil

Low carbon intensity diesel

Steam cracker

Plastic primary conversion


Upgraded plastic

HTL/pyrolysis oil

HTL/ pyrolysis oil


Shell G asification P rocess

Ethanol to SAF

Municipal solid waste

Renewable base oils


Upgraded biomass

Ligno- cellulosic biomass

HTL/pyrolysis oil

Biomass primary conversion

‘Shell biomass upgrader’

Cellulosic- ethanol

Upgraded biomass

Shell Fi b er C onversion T echnology

Distillers corn oil



Shell reverse water-gas shift

C ansolv CO or ADIP U ltra


Fischer – Tropsch

Chemical intermediates


Industrial syngas Residues

Multiple residues from a variety of processes

Decarbonised ammonia

Shell Blue H ydrogen P rocess

Natural gas

Decarbonised hydrogen

Established pathway

Likely future pathway

Figure 2 Shell’s integrated value chains



Process Technology • Reliability • Mechanical Engineering • Corrosion & Materials • Instruments & Electrical • Machinery • Strategic Business Planning


Turnaround • Advisor Resources • Fired Heaters • Inspection Planning • Heavy Lift • Capital Projects


Becht Equipment Reliability Plans • Risk-Based Work Selection • Becht Fitness for Service • Electronic Corrosion Control Documents • Fired Heater Risk • BechtCONNECT


Public & In-House Training • Performance-Based Training • Customized Courses • Mentoring • Production Support

Becht sources the best minds in the energy, process, and power industries around the world. By matching our clients’ project needs with our global pool of experts, our focus is on partnership and collaboration. We believe the best people tailored to a specific task provide the best results in any project, in any industry. This is why Becht’s services have extended beyond engineering to a full lineup of offerings in a multitude of rising industries. Our 55-year success proves our model outshines the rest.

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Pyrolysis oil storage Primary conversion collaborators

Feed storage/cracker Shell otake option

BP shift 3



1 Pretreatment

2 Upgrading

Figure 3 The Shell Recovered Plastic Upgrader enables the use of diverse feeds and provides a wider range of final compounds

Plastic circularity value chain At the end of their life cycle, many waste plastics are taken to landfills and incinerators or leak into the environment. Existing reuse and recycle technologies apply to only a small portion of waste plastic. Plastic circularity helps meet sustainability targets by providing pathways to chemically recycle and reuse plastic waste currently perceived by many as non-recyclable. To encourage plastic recycling, non-governmental organisations, media outlets, politicians, celebrities, company investors and citizens have voiced their support for recycled and recyclable plastics, even if it means paying a slight premium. Brand owners also prioritise the use of 100%-recycled and recyclable materials. Shell is therefore developing a technology portfolio that can facilitate multiple plastic upgrading routes. One such route includes collaboration with technological partners that perform primary conversion and pyrolysis of plastic waste. The pyrolysis oil is then processed with the Shell Recovered Plastic Upgrader (SRPU), which is capable of processing a wide range of feeds with varying properties and purity levels. The method involves pretreatment to remove most impurities and a feed upgrading stage to remove the remaining contaminants, followed by a boiling point shift and fractionation for enhanced selective conversion. Proprietary catalyst technologies are used to maintain a high yield and achieve the desired properties of the final compounds. Depending on a customer’s needs, Shell Catalysts & Technologies can provide a complete value chain or individual processing

blocks. For example, a pyrolysis oil refining company may benefit from the pretreatment unit in the SRPU process (see Figure 3 , Step 1) to remove corrosive contaminants and enable a variety of feeds to be processed. Alternatively, a chemical company lacking integrated refining technology may want to maximise naphtha production as a drop-in feed for its steam cracker and opt for an offtake of the heavier compounds. In this case, the client would benefit from the entire SRPU value chain (Figure 3, steps 1-4) and an offtake agreement with Shell. Hydrogen value chain While the markets for hydrogen need to be further developed, the ability to produce low carbon intensity hydrogen is well established. Shell Catalysts & Technologies is currently licensing the Shell Blue Hydrogen Process (SBHP), a non-catalytic, oxygen-based process involving methane partial oxidation combined with cost-effective, pre-combustion carbon capture technology. Shell Catalysts & Technologies is involved in a wide range of decarbonised hydrogen industrial multisectoral projects, as represented in Figure 4 , that enable the production of low-carbon chemicals, decarbonised (blue) ammonia (as an efficient hydrogen carrier), electricity, and consumer goods. We believe that, initially, decarbonised hydrogen can complement renewable hydrogen production. The high cost and low availability of renewable electricity currently makes renewable hydrogen considerably more expensive than decarbonised hydrogen. Forecasts suggest that cost parity


will be achieved in the next 15-20 years. In the meantime, decarbonised hydrogen provides an interim solution to help build the necessary infrastructure while reducing emissions. As the economic drivers boost the hydrogen demand across the globe, new value chains for both commercial and domestic use are being developed. The concept of industrial clusters (shown at the bottom of Figure 4) is becoming increasingly important as it enables heavy-industry emitters to develop collective, cost-effective hydrogen production pathways. Rather than establishing dedicated decarbonised hydrogen production for each emitter, clusters can benefit from a single centralised hydrogen production unit that supplies all the users. CCS value chain According to the IEA, CCUS is one of the most cost-effective solutions available to reduce emissions from some industrial and fuel transformation processes. Government mandates in some countries are driving projects forward, whereas other regions are closely monitoring the situation. At Shell Catalysts & Technologies, we have found that the pipeline of opportunities has so far been doubling roughly every 18 months. While CO 2 collection and transport via pipeline

into established storage locations is mature, more complex value chains, including ship transport for storage and utilisation, are in development. We are very active in this sector, licensing our pre-combustion technology, ADIP Ultra, and our post-combustion technology, the Cansolv CO 2 Capture System. Shell’s ambition is to store more than 25 Mt of CO 2 annually by 2035, which will involve multiple CCS projects across the globe and enable the decarbonisation of multiple value chains. As an example, the Quest facility in Canada uses ADIP-X, an earlier iteration of ADIP Ultra, to capture 1 million tonnes per annum of CO 2 from three hydrogen manufacturing units. This project has been highly successful, with more than 6 Mt of CO 2 captured, transported, and permanently stored two kilometres underground. The project has achieved better than projected reliability, cost and storage performance, with more than 99% uptime and an operating cost of approximately $25 per tonne of CO 2 . Furthermore, Shell could now reduce the cost of such a project by 30%. To further improve the affordability of CCS, Shell Catalysts & Technologies has an alliance with Technip Energies that is focused on driving down the cost of carbon capture. This combines both companies’ extensive technology and

Pipeline gas

Decarbonised hydrogen

Low-carbon products

Oil, chemicals and gas industries

Rening, Petchem, LNG


Excess decarbonised hydrogen to other industries

Fuel gas

Decarbonised ammonia (for export)

Pipeline gas


Low-carbon ammonia

Natural gas industr y

Natural gas


Pipeline gas

Low-carbon electricity Low-carbon products

Power industry



Consortiums of industries (clusters)

Pipeline gas







Decarbonised hydrogen


Figure 4 Integration of SBHP into the production of low-carbon chemicals, ammonia, electricity, and consumer goods


ENERGY & SUSTAINABILITY FORUM Decarbonizing the Downstream Industry 31 May–2 June 2023 | San Francisco, California 2023 ESF North America


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Bryan Glover President & CEO HONEYWELL UOP

Emma Lewis SVP Chemicals & Products SHELL Jennifer Haley CEO KERN ENERGY

Andy Walz President, Americas Products CHEVRON Chris Cooper President NESTE US


Michael Cohen Chief US Economist and Head of Oil & Refining BP Jolie Rhinehart General Manager, San Francisco Refinery PHILLIPS 66

Leon de Bruyn President & CEO LUMMUS TECHNOLOGY


KEY TOPICS INCLUDE: • Decarbonization from pathways to delivery

A Yokogawa Company

• Hydrogen & CCUS • Sustainable fuels,

feedstocks and catalysts

• Plastic circularity • Energy and operational efficiency • Exclusive WOOD and HONEYWELL UOP seminars

Syngas uses Chemicals such as methanol and ammonia Integrated gasication combined-cycle power

Gasi f ication Plastics

Organic materials, including wood chips and municipal waste



Synthetic natural gas


Power-to-liquids Renewable hydrogen from renewable power

Fischer – Tropsch

Synthetic hydrocarbon liquids Transport fuels L u bricants

CO including pre-combustion (ADIP U ltra ), post-combustion (Cansolv CO), pyrolysis of biomass and future direct air capture




Figure 5 Shell Catalysts & Technologies offers technologies that can create syngas from multiple renewable feedstocks and creates a range of desirable low-carbon products from syngas

engineering backgrounds to create simple, standard units using modular offsite building techniques that can be conveniently transported by truck to their destinations. One example of this collaboration is the CCS project with Hafslund Oslo Celsio, which recently received a final investment decision, with the intent to be fully operational by 2026. This project is set to reduce the city of Oslo’s emissions by 17%. Syngas value chain Syngas deserves a special focus because it is a path that holds a lot of promise for creating

sustainable aviation fuel (SAF) and other synthetic hydrocarbon liquids. The syngas value chain, shown in Figure 5 , begins with the gasification of renewable feedstocks such as organic biomass and waste plastic into syngas and hydrogen, which is then converted to SAF or other products using the Fischer–Tropsch process. Additionally, the power-to-liquids route, which uses captured CO 2 , can be used for syngas production. The use of reverse water-gas shift to turn CO 2 directly captured from the air into carbon monoxide could be a potential solution for achieving total carbon circularity in the


Nature-based solutions


Shell buys low-carbon electricity for its own use and sale



Power station

Power station benets from guaranteed stable otake and Shell’s distr i bution network

Shell’s onshore Canadian gas elds

C ansolv CO capture system


Residential and commercial


Shell CCS, Alberta

Shell underground CO storage (Onshore, Alberta)

Figure 6 Shell’s integrated approach could enable the company to reach its net-zero transition milestones while delivering benefits for multiple parties:  supply of natural gas;  post-combustion CO 2 capture;  CO 2 transport and storage;  carbon credits;  electricity purchase agreements


future. However, obtaining renewable hydrogen via electrolysis for use in the Fischer–Tropsch process currently requires very large quantities of renewable power and a large water source. The catalytic gas-to-liquid conversion of syngas into synthetic hydrocarbon liquids through the Fischer–Tropsch process, followed by long-chain hydrocarbon hydrocracking, is gaining interest from the industry and could become a significant technology for the production of renewable fuels, chemicals, and lubricants in the long term. Opportunities of an integrated approach Shell Catalysts & Technologies, together with other parts of Shell, recently suggested a wide scope of offerings to a strategic partner that operated a power station. As shown in Figure 6 , this potential opportunity demonstrates an integrated way of working that combines technology, energy, supply, and offtake. Shell could supply gas to fuel the plant. Shell Catalysts & Technologies could provide its Cansolv CO 2 capture system. Other parts of Shell could handle the transport and storage of the captured CO 2 . The company could also

supply carbon credits using nature-based solutions and electricity purchase agreements. Conclusions Decarbonisation is needed at greater speed and scale if companies are to comply with legislation and remain viable and profitable. Shell is transforming its business, supporting the energy transition journeys of its customers across multiple industry sectors and has numerous interesting and significant decarbonisation projects underway at its sites. In supporting Shell and other companies, Shell Catalysts & Technologies is developing a portfolio of integrated technologies in five main value chains. It is keen to leverage the experience it has gained to help its customers navigate the energy transition while remaining compliant and profitable.

ADIP ULTRA and CANSOLV are trademarks of Shell Catalysts & Technologies .

Chris Egby

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Safety, risks, and hazards of hydrogen

The safe use and distribution of natural gas are fully understood, but a similar level of technical understanding is now required for the key properties of hydrogen

Sarah Kimpton DNV

T here is an emerging consensus that low-carbon and renewable hydrogen will play an important role in a future decarbonised energy system. How prominent a role remains uncertain, but various estimates point to hydrogen being anything from 10-20% of global energy use in a future low-carbon energy system. DNV’s Pathway to Net Zero has hydrogen at 13% of a net-zero energy mix by 2050 (DNV, 2021). Scaling global hydrogen use is beset by a range of challenges: availability, costs, acceptability, safety, efficiency, and purity. While it is widely understood that urgent upscaling of global hydrogen use is needed to reach the Paris Agreement, the present pace of development is far too slow and nowhere near the acceleration we see in renewables, power grid, and battery storage installations. Nevertheless, there is a great deal of interest among a range of stakeholders and the media in the promise of hydrogen. Yet some commentators are taking a careful, dispassionate look at the details behind hydrogen’s likely global growth pathway, including safety. Hydrogen properties Hydrogen is the most abundant element in the universe. However, on Earth it is found only as part of a compound, most commonly together with oxygen in the form of water but also in hydrocarbons. Hydrogen is the simplest of all the elements, but processes to produce it in pure form are not so simple; they are energy intensive and involve large energy losses, have significant costs, and can produce their own carbon emissions.

Safety, risks, and hazards Hydrogen is not new to society; it has been produced and used in large quantities for more than a century. However, this has mostly been in industrial environments where there is a good degree of control, and where facilities are managed by people who have a clear understanding of the potential hazards. The forecasted significant market growth of hydrogen as an energy carrier will introduce many new hydrogen facilities that are very different from those we have had in the past. Moreover, some of the facilities will be in much closer proximity to the public. They will be built and operated by new entrants who may not have relevant experience in hydrogen safety. Scaling global hydrogen use is beset by a range of challenges: availability, costs, acceptability, safety, efficiency, and purity Risk perception will be an important factor in acceptance of hydrogen use. Accidents involving hydrogen are likely to receive more media attention than comparable events with conventional fuels (at least initially). This could induce public resistance and prompt a more restrictive regulatory environment. The sensitivities to risk and risk perception will likely vary among sectors. However, they will be highest where the public is near the actual use of hydrogen, such as in aviation and domestic heating, and less so in more industrial-type applications, such as hydrogen storage.


Hydrogen property

Gaseous (compressed) hydrogen


Release rate

Being one-eighth of the density of methane, in equivalent conditions the volumetric flow rate of hydrogen is 2.8 times that of methane; conversely, the mass flow of methane is 2.8 times that of hydrogen. Isolated hydrogen pressure systems will depressurise faster than for methane, but larger flammable clouds may result. The higher energy density per unit mass of hydrogen means the energy flow (like for like) is similar. Hydrogen is more buoyant than methane and will have a strong tendency to move upwards, an aspect that can be used to minimise the potential for hazardous concentrations to develop. The minimum spark energy required to ignite a hydrogen-air mixture is less than a tenth of that required for methane or natural gas. However, this does not significantly increase the chance of ignition. Testing by DNV has shown that many potential ignition sources either ignite both hydrogen and natural gas mixtures or neither. Only a small proportion will ignite hydrogen but not natural gas. Additionally, equipment approved for use in hydrogen systems is readily available. Concentrations of hydrogen in air between 4% and 75% are flammable, which is a much wider range than for natural gas (5-15%). This will increase the likelihood of ignition. Released compressed hydrogen gas will burn as a jet fire. Flame lengths correlate well with the energy flow rate, and as this is similar for hydrogen and methane, in like-for-like conditions, the jet fire hazards are similar. The explosion potential for hydrogen is much greater compared to methane as at higher concentrations in air (>20%), the speed of the flame is much more than for methane. In addition, hydrogen-air mixtures can undergo transition to detonation in realistic conditions, which would not occur with methane.

Dispersion and gas



Ignition energy





Liquid hydrogen (additional to compressed gas hazards) Temperature Liquefaction Liquid hydrogen (additional to compressed gas hazards)

In many ways, liquid hydrogen is a cryogenic liquid like liquefied natural gas (LNG). But due to the lower temperature, spillages can liquefy and solidify air from the atmosphere. The resulting mix of liquid hydrogen and liquid/solid air has exploded in small-scale field experiments. This does not occur with LNG.


Buoyancy and dispersion As liquid hydrogen vapourises and mixes with air, it cools the air, increasing its density. Consequently, a hydrogen-air cloud produced from a liquid hydrogen release will not be as strongly buoyant as in a gaseous hydrogen case. This also occurs with LNG, but in this case the LNG-air mixture will be denser than air.

Table 1 Comparison of hydrogen and natural gas/methane properties and hazardous outcome

Safety represents a significant business risk to investors and developers. There have already been examples where incidents at hydrogen refuelling stations have halted hydrogen use in vehicles for significant periods.

The industry has tried-and-tested methods for managing the safety of flammable gases that have been used for decades and these come with some very important, hard-won lessons:  Safety must be based on an understanding of


Figure 1 Detonation of hydrogen is entirely credible at scales representative of many scenarios where it is not for traditional hydrocarbons. This image shows a 15 m 3 hydrogen detonation conducted as a demonstration at DNV’s Research & Testing facility in Cumbria, UK Credit: DNV

how the properties of hydrogen and hydrogen derivatives affect the potential hazards  It is by far most effective (in terms of both safety and cost) if appropriate risk-reduction measures are added early in the design stage. In many instances, if addressed early, these measures can be incorporated at little (and at times no) extra cost and can result in inherently safer designs  The design intent needs to be maintained through the full lifecycle: safety measures should not degrade. Achieving all this requires an understanding of the key properties of hydrogen (and its derivatives) that affect the hazards. As hydrogen is very different to its derivatives, we need to consider those separately. Hydrogen hazards Hydrogen is a flammable, non-toxic gas in ambient conditions. The effect of its properties on hazards and hazard management is probably best understood by reference to another flammable, non-toxic gas that is widely accepted by society: natural gas (or its primary component, methane). So how do the properties of hydrogen change

the potential hazards? For hydrogen, as with natural gas, ignition of accidental releases can result in fires and explosions. Research is very active in these areas, and DNV is engaged in large-scale experimental studies at our Research & Testing facility in Cumbria, UK. Although our understanding is still developing, we know enough to recognise where to concentrate efforts with hydrogen. Table 1 summarises the differences between hydrogen and natural gas/methane in both gaseous and liquid forms. Ignition of a flammable gas cloud does not always result in an explosion. Pressure is generated when either the gas cloud is confined within an enclosure or the flame accelerates to high speed (or both). This could occur in a wide range of possible scenarios, from low-pressure leaks in domestic properties, medium-pressure leaks in hydrogen production facilities or marine applications, to high-pressure leaks from storage facilities. The severity of an explosion will depend on many factors, but in general, the more ‘reactive’ the fuel, the worse the explosion. Reactivity, in this sense, relates to how fast a flame moves through a flammable cloud. At its worst,


If concentrations are kept below about 15% hydrogen in air, it is no worse than methane at similar concentrations. The implication is that a key element of managing hydrogen safety is the control of gas dispersion and build-up to prevent the concentration of hydrogen in air from exceeding 15% as far as is practicable. This is a particular challenge where dispersal space is constrained – for example, on board ships. Gas detection and rapid isolation of hydrogen inventories will be key measures. Consideration of ventilation rates and ventilation patterns is also critical. Importantly, current simulation methods can model gas dispersion and build-up with reasonable confidence. In summary, although hydrogen’s high explosion reactivity is justifiably concerning, by being aware of this issue and designing to avoid high hydrogen concentrations in the atmosphere, it is reasonable to expect we can engineer facilities that are as safe or better than widely accepted natural gas facilities. If based on a sound technical understanding and addressed in early design, the cost implications of such engineering solutions may not be significant. Hydrogen derivatives Arguably, the most important hydrogen derivative in relation to hazard management is ammonia. Ammonia is flammable, but it is relatively difficult to ignite, and as its burning velocity is well below that of methane, the explosion risk is small. The key hazard with ammonia is its toxicity; it is harmful to personnel at concentrations well below its lower flammability limit of 15% in air. For example, UK HSE indicates a concentration of 0.36% could cause 1% fatalities given 30 minutes of exposure. Concentrations of 5.5% could cause 50% fatalities following five minutes of exposure. While ammonia has been widely manufactured for more than 100 years and is used in considerable amounts in the manufacture of fertilisers, its potential hazards need now to be understood in the context of new energy transition applications, as is the case with hydrogen. A very relevant example is the likely use of ammonia as a fuel in the maritime sector. An ammonia release within the hull of a ship has the possibility to develop

hydrogen flames can burn about an order of magnitude faster than natural gas and much faster than most commonly used hydrocarbons. To add to this, when a flame travels very fast, going supersonic, the explosion can transition to a detonation. A detonation is a self-sustaining explosion process with a leading shock of 20 bar that compresses the gas to the point of autoignition. The subsequent combustion provides the energy to maintain the shockwave. Detonability varies from fuel to fuel, and detonations would not occur in any realistic situation with natural gas but are entirely credible for hydrogen. It is also notable that current explosion simulation methods used by industry are not able to model the transition to detonation but only indicate when it might occur, though there is still considerable uncertainty in this area. This sounds like bad news for hydrogen facilities, yet we know that these properties depend on the concentration of the fuel in air. Figure 2 DNV’s HyStreet Facility sits at the end of the most complete onshore ‘beach to burner’ demonstration of hydrogen use anywhere in the world. DNV’s HyStreet supplies the domestic end-use with 100% hydrogen boilers providing heating, Northern Gas Network’s H21 project demonstrates distribution in the below 7 barg regime, and National Gas’s currently under- construction FutureGrid facility will demonstrate transmission in large-diameter, high-pressure systems (up to 70 barg) Credit: DNV


noted that hydrogen will be required during production and will be produced at the point of utilisation (as may also be the case for ammonia). Hydrogen applications need to be researched further to fully understand the fuel, before it is rolled out to decarbonise the hard-to- abate sectors. Work to qualify hydrogen and understand the risks, has been underway for years at DNV’s Research & Testing facility in Cumbria, UK. This work will continue to ensure that this clean fuel is safe for different applications within society. Further information about hydrogen can be found in DNV’s Hydrogen Forecast to 2050 . This includes sections about hydrogen policies and strategies, hydrogen production, storage and transport, hydrogen forecast demand and supply, hydrogen infrastructure, and a deep dive into hydrogen value chains (DNV, 2023).

potentially fatal concentrations in confined spaces. Unlike hydrogen, this hazard cannot be reduced by measures that lower the chance of ignition; ammonia has a direct effect if released and comes into contact with personnel. There is, therefore, no guarantee that the risks are lower than for hydrogen, even though it has no real explosion potential. Risk assessment would involve application of standard hazard management methods. It would need to consider aspects such as the types of release that could occur, the potential concentrations that could be generated, and the likelihood of personnel being exposed to harmful levels. Mitigation methods would include ammonia release detection and emergency shutdown of ammonia systems and ventilation. However, they could also require the availability of emergency breather units and very well-defined escape routes. Liquid organic hydrogen carriers (LOHCs) have the lowest safety risks as their properties are close to those of liquid hydrocarbons already handled in large quantities. Safety management should be straightforward, though it should be


Sarah Kimpton

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Feedstocks and utilities for green hydrogen and e-fuels High purity water, carbon dioxide and nitrogen are essential utilities for green hydrogen generation using electrolysis

Stephen B Harrison sbh4 Consulting

F or several years, attention has focused on green hydrogen as a clean energy vector. When produced on electrolysers using renewable electrical power generated by wind, solar, or hydro schemes, green hydrogen has a very low carbon footprint. Ammonia is derived from hydrogen through reaction with nitrogen, sourced from air, in the Haber-Bosch process. Many of the largest green hydrogen schemes proposed worldwide will convert green hydrogen to green ammonia for cost-effective shipping to international markets. Conversion of hydrogen to ammonia adds cost at the production location but means that ammonia, rather than hydrogen, can be shipped to the end-user destination. Liquid hydrocarbon fuels are incredibly useful energy vectors due to their high energy density and ease of handling. As such, gasoline, diesel, aviation kerosene, and heavy fuel oil have become the fuels of choice for cars, trucks, planes, and shipping. The challenge of the energy transition and decarbonisation is to substitute these refined products with sustainable, convenient, and cost- effective alternatives. Synthetic aviation fuel (SAF) is one such solution. SAF is a broad term meaning the fuel has been derived from non-fossil origins. The largest source of SAF today is biofuel, and more than 300,000 commercial flights operated by more than 40 airlines have used pure SAF or blends with fossil kerosene over the past five years. Thirteen major airports can refuel aircraft with SAF or SAF/kerosene blends. Alternatively, SAF can be produced using renewable electrical power to make green

hydrogen or syngas for conversion to e-fuels through power to liquid (PtL) technology. In this pathway, carbon dioxide (CO 2 ) is required as the source of carbon to build the hydrocarbon molecules. E-methanol burns with almost no emissions of particulates or sulphur dioxide. Methanol, like diesel and heavy fuel oil, does produce CO 2 emissions during combustion. However, since e-methanol is made from CO 2 captured from stack emissions or the air, its use is carbon neutral. Whether the fuel is green hydrogen, green ammonia, e-methanol, or SAF, certification to identify the CO 2 intensity of the production process will be required as a guarantee of origin. In many markets, there are clear requirements emerging that the definitions of renewable fuels must move beyond simple ‘grey’ or ‘green’ labels to a more scientifically valid and environmentally robust classification system. Certification from an independent party to validate the product claims will inevitably be required. Water, air, nitrogen, and CO 2 are the fundamental feedstocks to the above reaction pathways. Water and nitrogen also play key roles as utilities to enable safe and efficient operations (see Figure 1 ). Crystal clear water: natural hydrogen carrier Pure water supply to an electrolyser is essential. Electrolysis splits water molecules into oxygen and hydrogen. Supply of pure water to the electrolyser must be guaranteed. Failure to supply water means the electrolyser scheme must shut down. For a proton exchange


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