China, People’s Republic

Waste heat recovery was considered as a promising candidate for energy conservation and emission reduction. Methanol steam reforming was considered to be an effective means for hydrogen production because of its advantages. In this work a micro reactor was constructed and thermoelectric generation coupled with hydrogen production from methanol steam reforming was innovatively used to recycle waste heat which was simulated by hot air from a hot air gun. The waste heat was converted into electricity and hydrogen at the same time. The characteristic of thermoelectric generation coupled with methanol steam reforming was investigated. It was experimentally verified that both the hydrogen production rate and methanol conversion increased with the increasing inlet temperature but thermal efficiency increased firstly and then decreased with the increasing temperature. The methanol steam reforming could effectively maintain cold side temperature distribution of thermoelectric generation. In the case of the thermoelectric module (1) the highest temperature difference of 37 ◦C was determined and the maximum open circuit voltage of 2 V was observed. The highest methanol conversion of 64.26% was achieved at a space velocity of 0.98 h−1 when the temperature was 543 K comprehensively considering the CO content and thermal efficiency.

Biomass-based gasification is an attractive and promising pathway for hydrogen production. In this work a biomass-based hydrogen production system integrated with organic Rankine cycle was designed and investigated to predict the performance of hydrogen production yield and electricity generation under various operating conditions. The modified equilibrium model presented desirable results for the produced syngas compositions compared with the experimental data. Hydrogen yields from four types of biomass (wood chips daily manure sorghum and grapevine pruning wastes) were compared under the same operating condition with wood chips exhibiting the maximum hydrogen yield of 11.59 mol/kg. The effects of gasification temperature equivalence ratio and steam-to-biomass ratio on the hydrogen yield and electricity generation were investigated by using the response surface method. Furthermore the system was optimized using a genetic algorithm based on the response surface model. A preferred optimal solution with a hydrogen yield of 39.31 mol/kg and an output power of 3558.08 kW (0.99 kW h/kg) was selected by the linear programming technique for multidimensional analysis of the preference method.

With the gradual popularization of hydrogen fuel cell vehicles (HFCVs) the construction and planning of hydrogen refueling stations (HRSs) are increasingly important. Taking operational HRSs in China’s coastal and major cities as examples we consider the main factors affecting the site selection of HRSs in China from the three aspects of economy technology and society to establish a site selection evaluation system for hydrogen refueling stations and determine the weight of each index through the analytic hierarchy process (AHP). Then combined with fuzzy comprehensive evaluation (FCE) method and artificial neural network model (ANN) FCE method is used to evaluate HRS in operation in China's coastal areas and major cities and we used the resulting data obtained from the comprehensive evaluation as the training data to train the neural network. So an intelligent site selection model for HRSs based on fuzzy comprehensive evaluation and artificial neural network model (FCE-ANN) is proposed. The planned HRSs in Shanghai are evaluated and an optimal site selection of the HRS is obtained. The results show that the optimal HRSs site selected by the FCE-ANN model is consistent with the site selection obtained by the FCE method and the accuracy of the FCE-ANN model is verified. The findings of this study may provide some guidelines for policy makers in planning the hydrogen refueling stations

Exposing and stabilizing undercoordinated platinum (Pt) sites and therefore optimizing their adsorption to reactive intermediates offers a desirable strategy to develop highly efficient Pt-based electrocatalysts. However preparation of atomically controllable Pt-based model catalysts to understand the correlation between electronic structure adsorption energy and catalytic properties of atomic Pt sites is still challenging. Herein we report the atomically thin two-dimensional PtTe₂ nanosheets with well-dispersed single atomic Te vacancies (Te-SAVs) and atomically well-defined undercoordinated Pt sites as a model electrocatalyst. A controlled thermal treatment drives the migration of the Te-SAVs to form thermodynamically stabilized ordered Te-SAV clusters which decreases both the density of states of undercoordinated Pt sites around the Fermi level and the interacting orbital volume of Pt sites. As a result the binding strength of atomically defined Pt active sites to H intermediates is effectively reduced which renders PtTe₂ nanosheets highly active and stable in hydrogen evolution reaction.

Melt spinning was successfully utilized to prepare Mg₂₅−_xY_xNi₉Cu (x = 0 1 3 5 7) alloys producing nanocrystalline and amorphous structures with improved hydrogenation and dehydrogenation performances. The influence of spinning rate on hydrogenation and dehydrogenation thermodynamics and kinetics was studied in detail. XRD and TEM were utilized to characterize the alloy structures. Hydrogenation and dehydrogenation performances were investigated by Sievert apparatus DSC and TGA connected to a H₂ detector. Dehydrogenation activation energies were estimated using both Arrhenius and Kissinger methods. Results show that melt spinning significantly decreases thermodynamic parameters (ΔH and ΔS) and ameliorates desorption kinetics. Dehydrogenation activation energy markedly lowers with increase in spinning rate and is the real driver of amelioration of dehydrogenation kinetics caused by increasing Y content.

Biofuels from biomass gasification are reviewed here and demonstrated to be an attractive option. Recent progress in gasification techniques and key generation pathways for biofuels production process design and integration and socio-environmental impacts of biofuel generation are discussed with the goal of investigating gasification-to-biofuels’ credentials as a sustainable and eco-friendly technology. The synthesis of important biofuels such as bio-methanol bio-ethanol and higher alcohols bio-dimethyl ether Fischer Tropsch fuels bio-methane bio-hydrogen and algae-based fuels is reviewed together with recent technologies catalysts and reactors. Significant thermodynamic studies for each biofuel are also examined. Syngas cleaning is demonstrated to be a critical issue for biofuel production and innovative pathways such as those employed by Choren Industrietechnik Germany and BioMCN the Netherlands are shown to allow efficient methanol generation. The conversion of syngas to FT transportation fuels such as gasoline and diesel over Co or Fe catalysts is reviewed and demonstrated to be a promising option for the future of biofuels. Bio-methane has emerged as a lucrative alternative for conventional transportation fuel with all the advantages of natural gas including a dense distribution trade and supply network. Routes to produce H2 are discussed though critical issues such as storage expensive production routes with low efficiencies remain. Algae-based fuels are in the research and development stage but are shown to have immense potential to become commercially important because of their capability to fix large amounts of CO₂ to rapidly grow in many environments and versatile end uses. However suitable process configurations resulting in optimal plant designs are crucial so detailed process integration is a powerful tool to optimize current and develop new processes. LCA and ethical issues are also discussed in brief. It is clear that the use of food crops as opposed to food wastes represents an area fraught with challenges which must be resolved on a case by case basis.

Hydrogen can serve as a carrier to store renewable energy in large scale. However hydrogen storage still remains a challenge in the current stage. It is difficult to meet the technical requirements applying the conventional storage of compressed gaseous hydrogen in high-pressure tanks or the solid-state storage of hydrogen in suitable materials. In the present work a gaseous and solid-state (G-S) hybrid hydrogen storage system with a low working pressure below 5 MPa for a 10 kW hydrogen energy storage experiment platform is developed and validated. A Ti−Mn type hydrogen storage alloy with an effective hydrogen capacity of 1.7 wt% was prepared for the G-S hybrid hydrogen storage system. The G-S hybrid hydrogen storage tank has a high volumetric hydrogen storage density of 40.07 kg H2 m−3 and stores hydrogen under pressure below 5 MPa. It can readily release enough hydrogen at a temperature as low as −15 °C when the FC system is not fully activated and hot water is not available. The energy storage efficiency of this G-S hybrid hydrogen storage system is calculated to be 86.4%−95.9% when it is combined with a FC system. This work provides a method on how to design a G-S hydrogen storage system based on practical demands and demonstrates that the G-S hybrid hydrogen storage is a promising method for stationary hydrogen storage application.

A compact air-breathing jet hybrid-electric engine coupled with solid oxide fuel cells (SOFC) is proposed to develop the propulsion system with high power-weight ratios and specific thrust. The heat exchanger for preheating air is integrated with nozzles. Therefore the exhaust in the nozzle expands during the heat exchange with compressed air. The nozzle inlet temperature is obviously improved. SOFCs can directly utilize the fuel of liquid natural gas after being heated. The performance parameters of the engine are acquired according to the built thermodynamic and mass models. The main conclusions are as follows. 1) The specific thrust of the engine is improved by 20.25% compared with that of the traditional jet engine. As pressure ratios rise the specific thrust increases up to 1.7 kN/(kg·s⁻¹). Meanwhile the nozzle inlet temperature decreases. However the temperature increases for the traditional combustion engine. 2) The power-weight ratio of the engine is superior to that of internal combustion engines and inferior to that of turbine engines when the power density of SOFC would be assumed to be that predicted for 2030. 3) The total pressure recovery coefficients of SOFCs combustors and preheaters have an obvious influence on the specific thrust of the engine and the power-weight ratio of the engine is strongly affected by the power density of SOFCs.

China has promised to reach the peak carbon dioxide emission (ca. 10 billion tons) by 2030 and carbon neutrality by 2060. To realize these goals it is necessary to develop hydrogen energy and fuel cell techniques. However the high cost and low intrinsic safety of high-pressure hydrogen storage limit their commercialization. NH3 is high in hydrogen content easily liquefied at low pressure and free of carbon and the technology of NH3 synthesis has been commercialized nationwide. It is worth noting that the production of NH3 in China is about 56 million tons per year accounting for 35% of worldwide production. Hence with the well established infrastructure for NH3 synthesis and transportation and the demand for clean energy in China it is feasible to develop a green and economical energy roadmap viz. “Clean low-pressure NH3 synthesis → Safe and economical NH3 storage and transportation → Carbon-free efficient NH3-H2 utilization” for low-carbon or even carbon-free energy production.<br/>Currently the academic and industrial communities in China are striving to make technological breakthroughs in areas such as photocatalytic water splitting electrocatalytic water splitting mild-condition NH3 synthesis low-temperature NH3 catalytic decomposition and indirect or direct NH3 fuel cells with significant progress.<br/>Taking full advantage of the NH3 synthesis industry and readjusting the industrial structure it is viable to achieve energy saving and emission reduction in NH3 synthesis industry (440 million tons CO2 per year) as well as promote a new energy industry and ensure national energy security. Therefore relevant academic and industrial communities should put effort on mastering the key technologies of “Ammonia-Hydrogen” energy conversion and utilization with complete self-dependent intellectual property. It is envisioned that through the establishment of “Renewable Energy-Ammonia-Hydrogen” circular economy a green technology chain for hydrogen energy industry would pose as a promising pathway to achieve the 2030 and 2060 goals.

Fully decarbonizing global industry is essential to achieving climate stabilization and reaching net zero greenhouse gas emissions by 2050–2070 is necessary to limit global warming to 2 °C. This paper assembles and evaluates technical and policy interventions both on the supply side and on the demand side. It identifies measures that employed together can achieve net zero industrial emissions in the required timeframe. Key supply-side technologies include energy efficiency (especially at the system level) carbon capture electrification and zero-carbon hydrogen as a heat source and chemical feedstock. There are also promising technologies specific to each of the three top-emitting industries: cement iron & steel and chemicals & plastics. These include cement admixtures and alternative chemistries several technological routes for zero-carbon steelmaking and novel chemical catalysts and separation technologies. Crucial demand-side approaches include material-efficient design reductions in material waste substituting low-carbon for high-carbon materials and circular economy interventions (such as improving product longevity reusability ease of refurbishment and recyclability). Strategic well-designed policy can accelerate innovation and provide incentives for technology deployment. High-value policies include carbon pricing with border adjustments or other price signals; robust government support for research development and deployment; and energy efficiency or emissions standards. These core policies should be supported by labeling and government procurement of low-carbon products data collection and disclosure requirements and recycling incentives. In implementing these policies care must be taken to ensure a just transition for displaced workers and affected communities. Similarly decarbonization must complement the human and economic development of low- and middle-income countries.