A comprehensive review of the hydrogen storage systems and investigations performed in search for development of fast refueling technology for fuel cell vehicles are presented. Nowadays, hydrogen is considered as a good and promising energy carrier and can be stored in gaseous, liquid or solid state. Among the three ways, high pressure (such as 35 MPa or 70 MPa) appears to be the most suitable method for transportation due to its technical simplicity, high reliability, high energy efficiency and affordability. However, the refueling of high pressure hydrogen can cause a rapid increase of inner temperature of the storage cylinder, which may result not only in a decrease of the state of charge (SOC) but also in damages to the tank walls and finally to safety problems. In this paper, the theoretical analysis, experiments and simulations on the factors related to the fast refueling, such as initial pressure, initial temperature, filling rate and ambient temperature, are reviewed and analyzed. Understanding the potential relationships between these parameters and the temperature rise may shed a light in developing novel controlling strategies and innovative routes for hydrogen tank fast filling.

A B S T R A C T Hydroxyapatite (HAP, Ca 10 (PO 4 ) 6 (OH) 2 ) has all the criteria of a catalyst support, in particular its high thermal stability. However it is still less studied in the heterogeneous catalysis. For the first time, hydroxyapatite supported bimetallic Co-Ni catalysts were prepared and evaluated in the dry reforming of methane (DRM) process. Nanoparticles containing both nickel and cobalt were well formed on the surface of HAP by conventional impregnation methods. No modification of HAP structure was observed after metals deposition. DRM reaction was carried out at 700-750°C and around 1.6 bar, using a fixed-bed reactor which was fed with a mixture of 20%vol CH 4 , 20%vol CO 2 and 60%vol N 2 . CH 4 and CO 2 conversion reached up to 60 and 68% at 700°C, respectively, and 73 and 79% at 750°C, respectively during long reaction times of 50-160 h. Water as a by-product could be quantified along the catalytic reaction indicating the implication of reverse water-gas-shift reaction. TEM-EDX analysis of the used catalysts recovered after catalytic tests showed that coke deposition was limited and there was slight modification of metals particle size. The results obtained were very promising for the design of an efficient catalytic system for DRM process.

Nowadays, around 96% of hydrogen is produced from fossil resources, and particularly from natural gas, oil and derivatives, and coal. Chemicals synthesized from these fossil resources are usually obtained via synthetic gas, which is produced by steam reforming of natural gas. Details about steam reforming will be discussed later. Scheme 4.1 below illustrates the most common products that can be obtained from syngas, including hydrogen, methanol, liquid fuels, synthetic natural gas (SNG), ammonia, and heat and power.Hydrogen from water electrolysis accounts only for about 4% of total hydrogen production. Naturally, water electrolysis using electricity from renewable resources, such as solar, wind, or hydro is a promising way for green hydrogen production. However, the process still needs to be improved in order to reach the competitive cost required by the hydrogen market.Another way to produce green hydrogen is the valorization of bioresources, such as biogas. This last one is obtained from biomass, residues, or wastes by anaerobic digestion. In general, two types of biogas are distinguished:(1) digested gas from anaerobic digester, which is commonly called biogas, and (2) landfill gas from landfill sites (IEA, 2009). The production of hydrogen from biogas and landfill gas can be achieved via a syngas route as shown in Scheme 4.2 below. Syngas is obtained from biogas or landfill gas by different reforming processes, which will be detailed later. Then a mixture of H 2 and CO 2 can be obtained from syngas by the watergas-shift (WGS) reaction. Finally, hydrogen can be separated from the mixture with CO 2 by using a pressure swing adsorption (PSA) or an equivalent process.Both biogas/landfill gas reforming and WGS are catalytic processes. The reforming step can be achieved with catalytic steam reforming process, which is already commercialized for natural gas. However, the energy balance of the steam reforming is not optimized because of a large excess of water vapor, which is required with current catalysts. Because the composition of Natural gas Oil and derivatives Charcoal Stem reforming Syngas •Hydrogen •Methanol •Liquid fuels by Fisher-Tropsch •Synthetic natural gas •Ammonia •Heat and power •Energy in chemical looping SCHEME 4.1 Chemicals and energy from fossil resources via steam reforming. Biomass Residus Wastes Bio-degradation Biogas Landfill gas Reforming Syngas WGSR H 2 , CO 2 H 2 PSASCHEME 4.2 Main steps for the production of hydrogen from biogas or landfill gas via syngas route. Adapted from IEA, 2009. IEA bioenergy, Task 37-Energy from biogas and landfill gas.(4.1) Dry reforming of methane (DRM); (4.2) Boudouard reaction; (4.3) water-gas-shift (WGS) reaction; (4.4) methane cracking; (4.5) steam reforming of methane; (4.6) steam reforming of carbon; (4.7) partial oxidation of methane; (4.8) methane combustion; (4.9) partial oxidation of carbon; (4.10) carbon combustion; and (4.11) Methane reforming with large excess of steam. All molecules are in the gas state except carbon (C), which is in the solid state.