Publications

Gas leak detection on a production site is a major challenge for the safety and health of workers for environmental considerations and from an economic point of view. In addition flammable gas leaks are a safety risk because if ignited they can cause serious fires or explosions. For these reasons Acoem Metravib in collaboration with TotalEnergies One Tech R&D Safety has developed for the past four years a system called AGLED for the early detection localization and classification of such leaks exploiting acoustics and artificial intelligence driven by physics. Numerous tests have been conducted on a theater representative of gas production facilities created by TotalEnergies in Lacq (France) to build a robust learning database of leaks varying in flowrates exhaust diameters and also types (hole nozzle flange...). Moreover to limit the number of false alarms a relearning strategy has been implemented to handle unexpected disturbances (wildlife human activities meteorological events...). The presented paper describes the global architecture of the system from noise acquisition to the gas leak probability and coordinates. It gives a more in-depth look at the relearning algorithm and its performance in various environments. Finally thanks to a complementary collaboration with Air Liquide an example of test campaign in a real industrial environment is presented with an emphasis on the improvement obtained through relearning.

Hydrogen is one of the most promising alternative sources to relieve the energy crisis and environmental pollution. Hydrogen can be stored as cryogenic compressed hydrogen (CcH2) to achieve high volumetric energy densities. Reliable safety codes and standards are needed for hydrogen production delivery and storage to promote hydrogen commercialization. Unintended hydrogen releases from cryogenic storage systems are potential accident scenarios that are of great interest for updating safety codes and standards. This study investigated the behavior of CcH2 releases and dispersion. The extremely low-temperature CcH2 jets can cause condensation of the air components including water vapor nitrogen and oxygen. An integral model considering the condensation effects was developed to predict the CcH2 jet trajectories and concentration distributions. The thermophysical properties were obtained from the COOLPROP database. The model divides the CcH2 jet into the underexpanded initial entrainment and heating flow establishment and established flow zones. The condensation effects on the heat transfer and flow were included in the initial entrainment and heating zones. The empirical coefficients in the integral model were then modified based on measured concentration results. Finally the analytical model predictions are shown to compare well with measured data to verify the model accuracy. The present study can be used to develop quantitative risk assessment models and update safety codes and standards for cryogenic hydrogen facilities.

The NREL Hydrogen Sensor Laboratory was commissioned in 2010 as a resource for sensor developers end-users and regulatory agencies within the national and international hydrogen community. The Laboratory continues to provide as its core capability the unbiased verification of hydrogen sensor performance to assure sensor availability and their proper use. However the mission and strategy of the NREL Sensor Laboratory has evolved to meet the needs of the growing hydrogen market. The Sensor Laboratory program has expanded to support research in conventional and alternative detection methods as hydrogen use expands to large-scale markets as envisioned by the DOE National Clean Hydrogen Strategy and Roadmap. Current research encompasses advanced methods of hydrogen leak detection including stand-off and wide area monitoring approaches for large scale and distributed applications. In addition to safety applications low-level detection strategies to support the potential environmental impacts of hydrogen and hydrogen product losses along the value chain are being explored. Many of these applications utilize detection strategies that supplement and may supplant the use of traditional point sensors. The latest results of the hydrogen detection strategy research at NREL will be presented.

The introduction of hydrogen in natural gas pipeline systems introduces integrity challenges due to the nature of interactions between hydrogen and line pipe steel materials. However not every natural gas pipeline is equal in regards to the challenges potentially posed by the repurposing to hydrogen. Existing codes and practices penalise high-grade materials on the basis of a perceived higher susceptibility to hydrogen embrittlement in regards to their increased strength. This philosophy challenges the realisation of a hydrogen economy because it puts at economical and technical risk the conversion of almost half of the natural gas transmission systems in western countries.

The paper addresses the question whether pipe grade is actually a good proxy to strength and predictor to assess the performance of steel line pipes in hydrogen. Drivers that could affect the suitability of pipeline conversion in hydrogen from an integrity management perspective and industry experience of other hydrogen-charging applications are reviewed. In doing so the paper challenges the basis of the assumption that low-grade steels (up to X52 / L360) are automatically safer for hydrogen repurposing while at the other end of the spectrum higher-grade materials (>X52 / L360) are inevitably less suitable for hydrogen service.

Ultimately the paper discusses that materials sampling and testing of representative line pipes populations should be placed at the core of hydrogen repurposing strategies in order to safely address conversion and to maximize the hydrogen chain value. The paper addresses alternatives to make the sampling smart and cost-effective.

This review article provides a comprehensive analysis of the hydrogen landscape outlining the imperative for enhanced hydrogen production implementation and utilisation. It places the question of how to accelerate hydrogen adoption within the broader context of sustainable energy transitions and international commitments to reduce carbon emissions. It discusses influencing factors and policies for best practices in hydrogen energy application. Through an in-depth exploration of key factors affecting hydrogen implementation this study provides insights into the complex interplay of both technical and logistical factors. It also discusses the challenges of planning constructing infrastructure and overcoming geographical constraints in the transition to hydrogen-based energy systems. The drive to achieve net-zero carbon emissions is contingent on accelerating clean hydrogen development with blue and green hydrogen poised to complement traditional fuels. Public–private partnerships are emerging as catalysts for the commercialisation of hydrogen and fuel-cell technologies fostering hydrogen demonstration projects worldwide. The anticipated integration of clean hydrogen into various sectors in the coming years signifies its importance as a complementary energy source although specific applications across industries remain undefined. The paper provides a good reference on the gradual integration of hydrogen into the energy landscape marking a significant step forward toward a cleaner greener future.

Hydrogen energy is now a crucial technological option for decarbonizing energy systems. Comprehensive utilization is a typical mode of hydrogen energy deployment leveraging its excellent conversion capabilities. Hydrogen is often used in combination with electrical and thermal energy. However current hydrogen utilization modes are relatively singular resulting in low energy utilization efficiency and high wind curtailment rates. To improve energy utilization efficiency and promote the development of hydrogen energy we discuss three utilization modes of hydrogen energy including hydrogen storage integration into a fuel cell and gas turbine hybrid power generation system and hydrogen methanation. We propose a hydrogen energy system with multimodal utilization and integrate it into an electrolytic hydrogen–thermal integrated energy system (EHTIES). A mixed-integer linear programming (MILP) optimization scheduling model for the EHT-IES is developed and solved using the Cplex solver to improve the operational feasibility of the EHTIES focusing on minimizing economic costs and reducing wind curtailment rates. Case studies in northwest China verify the effectiveness of the proposed model. By comparing various utilization modes energy storage methods and scenarios this study demonstrated that integrating a hydrogen energy system with multimodal utilization into the EHT-IES offers significant technical benefits. It enhances energy utilization efficiency and promotes the absorption of wind energy thereby increasing the flexibility of the EHT-IES.

This paper provides an in-depth review of the current state and future potential of hydrogen fuel cell vehicles (HFCVs). The urgency for more eco-friendly and efficient alternatives to fossilfuel-powered vehicles underlines the necessity of HFCVs which utilize hydrogen gas to power an onboard electric motor producing only water vapor and heat. Despite their impressive energy efficiency ratio (EER) higher power-to-weight ratio and substantial emissions reduction potential the widespread implementation of HFCVs is presently hindered by several technical and infrastructural challenges. These include high manufacturing costs the relatively low energy density of hydrogen safety concerns fuel cell durability issues insufficient hydrogen refueling infrastructure and the complexities of hydrogen storage and transportation. Nevertheless technological advancements and potential policy interventions offer promising prospects for HFCVs suggesting they could become a vital component of sustainable transportation in the future.

This study presents a technoeconomic analysis of renewables-based hydrogen production in Queensland Australia under Optimistic Reference and Pessimistic scenarios to address uncertainty in cost predictions. The goal of the work was to ascertain if the target fam-gate cost of AUD 3/kg (approx. USD 2/kg) could be reached. Economies of scale and the learning rate concept were factored into the economic model to account for the effect of scale-up and cost reductions as electrolyser manufacturing capacity grows. The model assumes that small-scale to large-scale wind turbine (WT)-based and photovoltaic (PV)-based power generation plants are directly coupled with an electrolyser array and utilises hourly generation data for the Gladstone hydrogen-hub region. Employing first a commonly used simplified approach the electrolyser array was sized based on the maximum hourly power available for hydrogen production. The initial results indicated that scale-up is very beneficial: the levelised cost of green hydrogen (LCOH) could decrease by 49% from $6.1/kg to $3.1/kg when scaling PV-based plant from 10 MW to 1 GW and for WT-based plant by 36% from $5.8/kg to $3.7/kg. Then impacts on the LCOH of incorporating curtailment of ineffective peak power and electrolyser overload capacity were investigated and shown to be significant. Also significant was the beneficial effect of recognising that electrolyser efficiency depends on input power. The latter two factors have mostly been overlooked in the literature. Incorporating in the model the influence on the LCOH of real-world electrolyser operational characteristics overcomes a shortcoming of the simplified sizing method namely that a large portion of electrolyser capacity is under-utilised leading to unnecessarily high values of the LCOH. It was found that AUD 3/kg is achievable if the electrolyser array is properly sized which should help to incentivise large-scale renewable hydrogen projects in Australia and elsewhere.

In this study real voyage data and ship specifications of a general cargo ship are employed and it is assumed that diesel generators are replaced with hydrogen proton exchange membrane fuel cells. The effect of the replacement on CO2 NOX SOX and PM emissions and the CII value is calculated. Emission calculations show that there is a significant reduction in emissions when hydrogen fuel cells are used instead of diesel generators on the case ship. By using hydrogen fuel cells there is a 37.4% reduction in CO2 emissions 32.5% in NOX emissions 37.3% in SOX emissions and 37.4% in PM emissions. If hydrogen fuel cells are not used instead of diesel generators the ship will receive an A rating between 2023 and 2026 a B rating in 2027 a C rating in 2028–2029 and an E rating in 2030. On the other hand if hydrogen fuel cells are used the ship will always remain at an A rating between 2023 and 2030. The capital expenditure (CAPEX) and operational expenditure (OPEX) of the fuel cell system are USD 1305720 and USD 2470320 respectively for a 15-year lifetime and the hydrogen fuel expenses are competitive at USD 260981 while marine diesel oil (MDO) fuel expenses are USD 206435.

The abundant plastic wastes become an imperative global issue and how to handle these organic wastes gains growing scientific and industrial interest. Recently converting plastic wastes into hydrogen fuel has been investigated and the “waste-to-value” practice accelerates the circular economy. To accelerate the development of plastic-to-hydrogen conversion in this review recent advances in plastic-to-hydrogen conversion via thermochemical photocatalytic and electrocatalytic routes are analyzed. All of the thermo- photo- and electrochemical processes can transform different plastic wastes into hydrogen and the hydrogen production efficiency depends heavily on the selected techniques operating parameters and applied catalysts. The application of rational-designed catalysts can promote the selective production of hydrogen from plastic feedstocks. Further studies on process optimization cost-effective catalyst design and mechanism investigation are needed.