As hydrogen gains momentum as a clean and versatile energy carrier for decarbonizing hard-to-abate sectors, ensuring the safety of hydrogen infrastructure becomes critical for its widespread adoption. This review draws on peer-reviewed literature, industrial reports, and international standards for hydrogen technologies. It systematically examines safety risks across the hydrogen value chain, from production to end-of-life and assesses the effectiveness of existing mitigation strategies as well as identifying key research gaps. Common risks such as hydrogen leaks, over-pressurization, and material degradation are present at nearly every stage. Less frequent but potentially severe hazards include the risk of ice formation or equipment damage from cryogenic hydrogen leaks, and toxic exposures from chemical carriers like ammonia or hydrides used for hydrogen storage and transport. The mitigation technologies evaluated include leak detection systems, quick-release valves, emergency ventilation, and both material-based and physical barrier systems. While these safety solutions provide considerable protective potential, their long-term effectiveness depends on real-time responsiveness, and regulatory enforcement. The review also highlights critical gaps in predictive modeling, material durability under extreme conditions exacerbated by climate change, and human error analysis. Emerging technologies, such as AI-enabled safety systems and digital twins, remain underexplored, and current hydrogen safety frameworks have a limited understanding of hydrogen combustion behavior and effective fire suppression strategies. To support the safe and scalable deployment of hydrogen infrastructure, the study calls for targeted research, stakeholder education, and harmonized safety standards. This review provides a timely synthesis of risks and controls to guide future development, policy, and innovation in hydrogen safety. This review will support industry stakeholders, and researchers in developing safer, more reliable, and standardized hydrogen infrastructure.

The safe operation of hydrogen pipelines and storage tanks is essential for the development of a sustainable hydrogen economy. However, these systems are exposed to significant risks that must be effectively managed to prevent hazardous outcomes. The present study therefore assessed the hazards and risks associated with hydrogen transport through pipelines and storage in tanks using the preliminary hazard analysis (PreHA) on the Hydrogen Incident and Accident Database (HIAD2.1), developed as part of the European Network of Excellence, HySafe. This database reports 34 accidents involving pipelines and 28 accidents involving storage tanks over the past 5 decades. The outcomes of these incidents vary, as majority of pipeline incidents led to fires, whereas storage tank failures were more likely to escalate into explosions. Other reported consequences in both pipeline and storage tanks included leaks with no ignition and near misses which are incidents that did not cause harm but had the potential to escalate into serious accidents. The PreHA analysis further identified corrosion and welding related issues as the main hazards for pipelines, while storage tanks were more often affected by operational failures as well as corrosion. Less frequent but high-impact event of natural disasters also posed catastrophic risks to both systems. Specific to pipeline integrity, it was observed that civil/construction work had a rare but notable impact. The findings of this study provide insights into the critical vulnerabilities of hydrogen pipelines and storage tanks and highlight the need for continuous improvement in safety management practices.

Den globala strävan att minska beroendet av fossila bränslen i energisystem har resulterat i att vätgas har börjat användas som en ren, mångsidig och hållbar energibärare som kan minska koldioxidutsläppen i sektorer som tung industri, transport etc. För att åstadkomma denna övergång måste en robust infrastruktur etableras för att underlätta produktion, lagring, distribution och användning av vätgas. I takt med att vätgasinfrastrukturen skalas upp blir det dock avgörande att hantera de tillhörande säkerhetsriskerna för att säkerställa en hållbar och säker integrering i energisystemet. Denna rapport identifierar risker i vätgasinfrastruktur, bedömer tillförlitligheten hos begränsningsstrategier och identifierar forskningsluckor, i syfte att stödja en säker utbyggnad av vätgasinfrastruktur i Sverige. Rapporten undersöker systematiskt säkerhetsutmaningar i hela vätgasens värdekedja. 

Vätgasproduktionsmetoder, inklusive elektrolys och ångmetanreformering (SMR), medför risker såsom läckage, högtrycksfel och kemisk exponering, vilket leder till bränder, explosioner och miljöföroreningar. Lagringsmetoder, oavsett om det är som komprimerad gas, kryogen vätska eller i kemiska bärare, medför risker som tankbrott, försprödning, kryogena brännskador och exponering för giftiga kemikalier. Distribution av vätgas via rörledningar, vägar, järnvägar eller fartyg medför faror i samband med höga tryck, kryogena fel, läckage och materialnedbrytning, vilket ökar sannolikheten för bränder eller explosioner. Vid användning står bränsleceller, industriella applikationer och tankstationer inför utmaningar som fel på bränsleceller, övertryck, ofullständig förbränning och elektriska faror. Riskidentifieringen visade att vätgasläckage, övertryck och materialförsprödning är vanliga risker som kvarstår i alla faser, medan explosiva syre-vätgasblandningar, luftkondensation på grund av vätgasens extremt låga temperaturer och toxicitet i materialbaserade bärare är ovanliga.

För att minska dessa risker har olika säkerhetsåtgärder utvärderats, t.ex. läckagedetekteringssystem, automatiska avstängningsventiler, nödventilation och barriärteknik. Detektering av vätgasläckage bygger på olika sensortekniker, inklusive katalytiska partiklar, elektrokemiska, ultraljuds-, halvledar- och nanoplasmoniska sensorer, var och en med styrkor och begränsningar i fråga om noggrannhet, känslighet och miljöanpassning. Automatiska snabbventiler, t.ex. magnetventiler, kulventiler, backventiler, tryckavlastningsventiler och snabbkopplingar, ger snabb inneslutning och flödeskontroll för att förhindra farliga vätgasutsläpp. Deras effektivitet beror på svarstid, hållbarhet och integrering med detekteringssystem. Nödventilationssystem, inklusive naturliga, mekaniska, explosionsklassade, smarta och hybridlösningar, hjälper till att sprida vätgasansamlingar och förhindra explosiva koncentrationer. Smarta system och hybridsystem har dynamiska, energieffektiva kontroller. Barriärsystem, både materialbaserade och fysiska, ger strukturell säkerhet genom att begränsa diffusionen och minska brand- och explosionsriskerna. Avancerade material som keramiska, metalliska, polymerbaserade och kolbaserade beläggningar förbättrar vätgasinneslutningen, medan fysiska barriärer som sprängväggar, brandväggar, explosionsbeständiga kapslingar och lagstadgade separationsavstånd fungerar som kritiska skyddsåtgärder i vätgasinfrastruktur. Även om dessa åtgärder är mycket effektiva krävs ytterligare forskning, teknisk utveckling och tillsyn för att säkerställa långsiktig säkerhet och tillförlitlighet för vätgas. 

Rapporten har också sammanställt forskningsluckor som hindrar en säker och effektiv utbyggnad av vätgasinfrastruktur i hela värdekedjan. Viktiga tekniska luckor inkluderar begränsad användning av säkerhetssystem som bygger på sakernas internet (IoT) och artificiell intelligens (AI), digitala tvillingar och cybersäkerhetslösningar. Det finns fortfarande utmaningar med materialens hållbarhet under högt tryck och kryogena förhållanden, särskilt när det gäller väteförsprödning och miljövänliga materials långsiktiga prestanda. Riskbedömningsmodellerna behöver förfinas för att ta hänsyn till vätgasens unika egenskaper, medan verktyg för prediktiv modellering och maskininlärning fortfarande är underutnyttjade inom vätgassäkerhet. Mänskliga faktorer och miljösäkerhet är också otillräckligt utforskade, med begränsade studier av operatörsbeteende, mental prestanda och miljöeffekter av vätgasteknik. Slutligen är nuvarande strategier för brandbekämpning och kontroll av antändning inte tillräckligt anpassade till vätgasspecifika risker. Att överbrygga dessa forskningsluckor är avgörande för att förbättra vätgassäkerheten och främja allmänhetens och industrins förtroende för dess utbredda användning.

Slutligen innehåller rapporten viktiga rekommendationer för att förbättra vätgassäkerheten genom att prioritera kritiska risker, åtgärda forskningsluckor och stärka riskkommunikation och standardisering. Rapporten identifierar vätgasläckage, övertryck och materialförsprödning som akuta riskområden som kräver åtgärder från den akademiska världen, industrin och tillsynsmyndigheter. Rekommendationerna omfattar utveckling av avancerade material, övervakningssystem i realtid och automatiserade säkerhetsmekanismer. Dessutom betonas behovet av forskning inom prediktiv modellering, explosionsbegränsning och mänskliga faktorer inom vätgassäkerhet. Slutligen efterlyses harmoniserade globala säkerhetsstandarder och utbildningsinitiativ för intressenter för att stödja en säker och skalbar utbyggnad av vätgasteknik.

The study aimed to test the hypothesis that biochar's unique properties, such as its microporous structure, can enhance concrete's resilience to high temperatures. Despite expectations of reduced crack formation and enhanced fire resistance, the experimental results revealed a limited impact on concrete's fire behaviour. The investigation involved the use of two biochar types, fine and coarse biochar as replacements for cement and aggregates, respectively. Fine biochar exhibited higher water absorption and Young's modulus than coarse biochar, but both resisted ignition at 35 kW/m2 radiative heat flux and had peak heat release rates below 40 kW/m2. Incorporating these biochars at varying weight percentages (10, 15, and 20 wt.%) into concrete led to a gradual decline in compressive and tensile strength due to reduced binding ability with increased biochar content. Exposure to 1000 °C compromised mechanical properties across all the samples. However, the biochar concrete maintained compressive strength (compared to the control) with up to 20 wt.% biochar as a fine aggregate substitute after exposure to 600 °C, and as a cement replacement after exposure to 200 °C. This substitution also yielded a significant reduction in CO2 emissions (50 % reduction as the biochar loading amount doubled) from concrete manufacturing, showcasing biochar's potential for sustainable construction practices. Despite not fully supporting the initial hypothesis, the study demonstrated biochar's viability in reducing carbon footprint while maintaining concrete strength under certain fire conditions.

This paper examines the reaction-to-fire behaviour of building materials containing phase change materials by predicting their fire classification according to the European reaction-to-fire classification system (Euroclasses). While various building materials containing PCMs exist today, their application in buildings has been somewhat limited due to the fire behaviour of these building materials. Existing research has focused on small scale testing which does not allow determination of the Euroclass of the material. In this application, large scale performance is predicted based on previously published small scale data to provide some valuable insights into the expected fire performance of these materials. As a starting point, a systematic literature review on phase change materials (PCM) and fire behaviour was conducted, with the purpose of identifying all existing literature concerning experimental investigation of the fire behaviour of building materials containing PCMs. In total, 816 articles were selected from the literature search. After screening of these papers, 51 articles were fully reviewed and included in the next step of the study. In the next step, the reaction-to-fire behaviour of the building materials with PCMs that were identified from the literature was predicted using the ConeTools simulation program. The input data required for ConeTools was obtained from the identified literature. Initially, 27 of the 51 studies used cone calorimetry as a fire testing method and could therefore be considered for the Euroclass assessment. However, of the 27 studies, only 17 studies provided information on both the heat release rates (HRR) and time to ignition (TTI) and were selected for use in the ConeTools program. The ConeTools program predicted Euroclasses for all the building materials containing PCMs from the selected 17 studies. The predicted Euroclasses for most materials was low (i.e. fire classes ‘D' or ‘E or worse') which confirms that materials containing PCMs generally have a low react-to-fire behaviour even with addition of flame retardants (FR). Our findings indicate that the fire behaviour, typically Euroclass ‘D' or ‘E or worse', of the building materials containing PCMs is indeed a barrier to their implementation in the building applications where Euroclass C or higher is required, e.g. in evacuation pathways or certain public spaces. The predictions of the Euroclasses based on ConeTools need to be confirmed using Single Burning Item tests (EN 13823) and/or Room Corner tests (ISO 9705) in the future, to enable a better understanding of fire behaviour of these building materials.

Low pressure, medium pressure and high pressure water-based fire suppression systems were tested in a medium scale tunnel (scale 1:3). The primary objective was to investigate which of these systems are most effective in the suppression or control of different types of tunnel fires. The default low, medium and high pressure systems refer to full scale water flow rates of 10 mm/min, 6.8 mm/min and 3.7 mm/min, respectively. Some other water densities were also tested to investigate the effects, as well as different ventilation velocities and activation criteria. Several series of fire tests were conducted for different fire scenarios. The fire scenarios considered included idle wood pallet fires, loosely packed wood crib fires, loosely packed wood and plastic crib fires, and pool fires, with or without a top cover on the fuel load. Comparisons of the three default systems based on the three parameters: heat release rate, energy released and possibility of fire spread, show that the performance of the default low pressure system is usually the most effective based on the parameters studied. The default high pressure system usually yields results less effective in comparison to the default low pressure system. The performance of the default medium pressure system usually lies in between them. The high pressure system behaves very differently in comparison to the others, in terms of tunnel ventilation velocity, water density, operating pressure, and the presence of the top cover.

In this study, Kraft lignin was modified by ammonium dihydrogen phosphate (ADP) and urea for achieving phosphorylation and carbamylation, aiming to protect wood against biological and fire attack. Scots pine (Pinus sylvestris L.) sapwood was impregnated with a water solution containing Kraft lignin, ADP, and urea, followed by heat treatment at 150 °C, resulting in changes in the properties of the Kraft lignin as well as the wood matrix. Infrared spectroscopy, 13C cross-polarisation magic-angle-spinning (MAS) nuclear magnetic resonance (NMR), and direct excitation single-pulse 31P MAS NMR analyses suggested the grafting reaction of phosphate and carbamylate groups onto the hydroxyl groups of Kraft lignin. Scanning electron microscopy with energy dispersive X-ray spectroscopy indicated that the condensed Kraft lignin filled the lumen as well as partially penetrating the wood cell wall. The modified Kraft lignin imparted fire-retardancy and increased char residue to the wood at elevated temperature, as confirmed by limiting oxygen index, microscale combustion calorimetry, and thermogravimetric analysis. The modified wood exhibited superior resistance against mold and decay fungi attack under laboratory conditions. The modified wood had a similar modulus of elasticity to the unmodified wood, while experiencing a reduction in the modulus of rupture.

Scheimpflug lidar is a compact alternative to traditional lidar setups. With Scheimpflug lidar it is possible to make continuous range-resolved measurements. In this study we investigate the feasibility of a Scheimpflug lidar instrument for remote sensing in pool flames, which are characterized by strong particle scattering, large temperature gradients, and substantial fluctuations in particle distribution due to turbulence. An extinction coefficient can be extracted using the information about the transmitted laser power and the spatial extent of the flame. The transmitted laser power is manifested by the intensity of the 'echo' from a hard-target termination of the beam located behind the flame, while the information of the spatial extent of the flame along the laser beam is provided by the range-resolved scattering signal. Measurements were performed in heptane and diesel flames, respectively.