China, People’s Republic

All diesel-only trains in the UK will be phased out by 2040. Hydrogen and ammonia emerge as alternative zerocarbon fuel for greener railway. Solid Oxide Fuel Cells (SOFCs) provide an alternative prime mover option which efficiently convert zero-carbon fuels into electricity without emitting nitrogen oxides (NOx) unlike traditional engines. Superior to Proton Exchange Membrane Fuel Cells (PEMFCs) in efficiency SOFCs fulfil MW-scale power needs and can use ammonia directly. This study investigates innovative strategies for integrating SOFCs into hybrid rail powertrains using hydrogen or ammonia. Utilizing an optimization framework incorporating Particle Swarm Optimization (PSO) the study aims to minimize operational costs while considering capital and replacement expenditures powertrain performance and component sizing. The findings suggest that hybrid powertrains based on ammonia-fueled SOFCs may potentially reduce costs by 30% compared to their hydrogen counterparts albeit requiring additional space for engine compartments. Ammonia-fueled SOFCs trains also exhibit a 5% higher efficiency at End-of-Life (EoL) showing less performance degradation than those powered by hydrogen. The State of Charge (SoC) of the batteries in range of 30–70% for both cases is identified as most costeffective.

As the country that emits the most carbon in the world China needs significant and urgent changes in carbon emission control in the transportation sector in order to achieve the goals of reaching peak carbon emissions before 2030 and achieving carbon neutrality by 2060. Therefore the promotion of new energy vehicles has become the key factor to achieve these two objectives. For the reason that the comprehensive transportation cost directly affects the end customer’s choice of heavy truck models this work compares the advantages disadvantages and economic feasibility of diesel liquefied natural gas (LNG) electric hydrogen and methanol heavy trucks from a total life cycle cost and end-user perspective under various scenarios. The study results show that when the prices of diesel LNG electricity and methanol fuels are at their highest and the price of hydrogen is 35 CNY/kg the total life cycle cost of the five types of heavy trucks from highest to lowest are hydrogen heavy trucks (HHT) methanol heavy trucks (MHT) diesel heavy trucks (DHT) electric heavy trucks (EHT) and LNG heavy trucks (LNGHT) ignoring the adverse effects of cold environments on car batteries. When the prices of diesel LNG electricity and methanol fuels are at average or lowest levels and the price of hydrogen is 30 CNY/kg or 25 CNY/kg the life cycle cost of the five heavy trucks from highest to lowest are HHT DHT MHT EHT and LNGHT. When considering the impact of cold environments even with lower electricity prices EHT struggle to be economical when LNG prices are low. If the electricity price is above 1 CNY/kWh regardless of the impact of cold environments the economic viability of EHT is lower than that of HHT with a purchase cost of 500000 CNY and a hydrogen price of 25 CNY/kg. Simultaneously an exhaustive competitiveness analysis of heavy trucks powered by diverse energy sources highlights the specific categories of heavy trucks that ought to be prioritized for development during various periods and the challenges they confront. Finally based on the analysis results and future development trends the corresponding policy recommendations are proposed to facilitate high decarbonization in the transportation sector.

Hydrogen-blended natural gas (NG) pipeline network transport is the most effective approach for solving the problem of large-scale hydrogen use. Hydrogen-blended NG that contains water vapour is prone to water vapour condensation when it passes through complex NG pipeline networks leading to pipeline network failures. To analyse the condensation behaviour of hydrogenblended NG containing water vapour in a Laval nozzle a condensation model of water vapour was established. A computational fluid dynamics approach was used to calculate the condensation process of hydrogen-blended NG containing water vapour in Laval nozzles for four countries: Iran USA Russia and Australia. Hydrogen-blended NG components affect the flow characteristics of the gas mixture in the nozzle. The gas components have the greatest effect on the Mach number. The difference between the maximum and minimum Mach numbers at the outlet was 0.02 Mach. Hydrogen-blended NG containing water vapour condenses downstream of the throat of the Laval nozzle. Hydrogen-blended NG from Russia had the largest condensation ratio (79.63%). The largest droplet radius and liquid mass fraction were observed in the hydrogen-blended NG from Australia. The condensation process can accelerate the future research and engineering application of water vapour into hydrogen-blended NG.

To address the inherent intermittency and instability of renewable energy the construction of large-scale energy storage facilities is imperative. Salt caverns are internationally recognized as excellent sites for large-scale energy storage. They have been widely used to store substances such as natural gas oil air and hydrogen. With the global transition in energy structures and the increasing demand for renewable energy load balancing there is broad market potential for the development of salt cavern energy storage technologies. There are three types of energy storage in salt caverns that can be coupled with renewable energy sources namely salt cavern compressed air energy storage (SCCAES) salt cavern hydrogen storage (SCHS) and salt cavern flow battery (SCFB). The innovation of this paper is to comprehensively review the current status and future development trends of these three energy storage methods. Firstly the development status of these three energy storage methods both domestically and internationally is reviewed. Secondly according to the characteristics of these three types of energy storage methods some key technical challenges are proposed to be focused on. The key technical challenge for SCCAES is the need to further reduce the cost of the ground equipment; the key technical challenge for SCHS is to prevent the risk of hydrogen leakage; and the key technical challenge for SCFB is the need to further increase the concentration of the active substance in the huge salt cavern. Finally some potential solutions are proposed based on these key technical challenges. This work is of great significance in accelerating the development of salt cavern energy storage technologies in coupled renewable energy.

Hydrogen is crucial in achieving global energy transition and carbon neutrality goals. Existing market estimates typically presume linear or exponential growth but fail to consider how market demand responds to the declining cost of underlying technologies. To address this this study utilizes a learning curve model to project the cost of electrolyzers and its subsequent impact on hydrogen market aligning with a premise that the market demand is proportional to the cost of hydrogen. In a case study of China’s hydrogen market projecting from 2020 to 2060 we observed substantial differences in market evolution compared to exponential growth scenarios. Contrary to exponential growth scenarios China’s hydrogen market experiences faster growth during the 2020–2040 period rather than later. Such differences underscore the necessity for proactive strategic planning in emerging technology markets particularly for those experiencing rapid cost decline such as hydrogen. The framework can also be extended to other markets by using local data providing valuable insights to investors policymakers and developers engaged in the hydrogen market.

This study presents a Two-Layer Deep Deterministic Policy Gradient (TL-DDPG) energy management strategy for Hydrogen fuel cell hybrid train that aims to solve the problem that traditional reinforcement learning strategies require high initial values and are difficult to optimize global variables. Augmenting the optimization capabilities of the inner layer a frequency decoupling algorithm integrates into the outer layer furnishing a fitting initial value for strategy optimization. This addition aims to bolster the stability of fuel cell output thereby enhancing the overall efficiency of the hybrid power system. In comparison with the traditional reinforcement learning algorithm the proposed approach demonstrates notable improvements: a reduction in hydrogen consumption per 100 km by 16.3 kg a 9.7% increase in the output power stability of the fuel cell and a 1.8% enhancement in its efficiency.

The hydrogen cycle system one of the main systems used for hydrogen fuel cells has many advantages. It can improve the efficiency the water capacity and the management of thermal fuel cells. It can also enhance the safety of the system. Therefore it is widely used in hydrogen fuel cell vehicles. We introduce the structure and principles of hydrogen cycle pumps ejectors and steam separators and analyze and summarize the advantages of the components as well as reviewing the latest research progress and industrialization status of hydrogen cycle pumps and ejectors. The technical challenges in hydrogen circulation systems and the development direction of key technologies in the future are discussed. This paper aims to provide a reference for research concerning hydrogen energy storage application technology in hydrogen fuel cell systems.

A new technical route to incorporate excess electricity (via green hydrogen generation by electrolysis) into a biorefinery to produce modern bioenergy (advanced biofuels) is proposed as a promising alternative. This new route involves storing hydrogen for mobile and stationary applications and can be a three-bird-one-stone solution for the storage of excess electrical energy storage of green hydrogen and high-value utilization of biomass.

The energy transition from hydrocarbon-based energy sources to renewable and carbon-free energy sources such as wind solar and hydrogen is facing increasing demands. The decarbonization of global transportation could come true via applying carbon-free fuel such as ammonia especially for internal combustion engines (ICEs). Although ammonia has advantages of high hydrogen content high octane number and safety in storage it is uninflammable with low laminar burning velocity thus limiting its direct usage in ICEs. The purpose of this review paper is to provide previous studies and current research on the current technical advances emerging in assisted combustion of ammonia. The limitation of ammonia utilization in ICEs such as large minimum ignition energy lower flame speed and more NOx emission with unburned NH3 could be solved by oxygen-enriched combustion ammonia–hydrogen mixed combustion and plasma-assisted combustion (PAC). In dual-fuel or oxygen-enriched NH3 combustion accelerated flame propagation speeds are driven by abundant radicals such as H and OH; however NOx emission should be paid special attention. Furthermore dissociating NH3 in situ hydrogen by non-noble metal catalysts or plasma has the potential to replace dual-fuel systems. PAC is able to change classical ignition and extinction S-curves to monotonic stretching which makes low-temperature ignition possible while leading moderate NOx emissions. In this review the underlying fundamental mechanism under these technologies are introduced in detail providing new insight into overcoming the bottleneck of applying ammonia in ICEs. Finally the feasibility of ammonia processing as an ICE power source for transport and usage highlights it as an appealing choice for the link between carbon-free energy and power demand.

Vigorously developing an integrated energy system (IES) centered on the utilization of hydrogen energy is a crucial strategy to achieve the goal of carbon peaking and carbon neutrality. During the energy conversion process a hydrogen storage system releases a large amount of heat. By integrating a heat recovery mechanism we have developed a sophisticated hydrogen energy utilization model that accommodates multiple operational conditions and maximizes heat recovery thereby enhancing the efficiency of energy use on the supply side. To harness the potential of load-side response an integrated demand response (IDR) model accounting for price and incentives is established and a ladder-type subsidy incentive mechanism is proposed to deeply unlock load-side response capacity. Considering system economics and low carbon an IES source-load coordinated optimal scheduling model is proposed optimizing source-load coordinated operation for optimally integrated economy factoring in reward and punishment ladder-type carbon trading. Demonstrations reveal that the proposed methodology not only improves the efficiency of energy utilization but also minimizes wind energy wastage activates consumer engagement and reduces both system costs and carbon emissions thus proving the effectiveness of our optimization approach.