Liquid Carrier Storage
This is the technical term for the hydrogen being stored in the fossil fuels that are common in today's society. Whenever gasoline, natural gas methanol, etc.. is utilized as the source for hydrogen, the fossil fuel requires reforming. The reforming process removes the hydrogen from the original fossil fuel. The reformed hydrogen is then cleaned of excess carbon monoxide, which can poison certain types of fuel cells, and utilized by the fuel cell. Reformers are currently in the beta stage of their testing with many companies having operating prototypes in the field. See hydrogen production>Steam methane reforming (SMR) @Hydrogen production section
Chemical bonding
It's similar to Liquid Carrier Storage. Many of these compounds are utilized as a hydrogen storage method. The hydrogen is combined in a chemical reaction that creates a stable compound containing the hydrogen. A second reaction occurs that releases the hydrogen, which is collected and utilized by a fuel cell. The exact reaction employed varies from storage compound to storage compound. Some examples of various techniques include ammonia cracking, partial oxidation, methanol cracking, etc. These methods eliminate the need for a storage unit for the hydrogen produced, where the hydrogen is produced on demand. The best weight percent efficiency for secondary storage is approximately 20 % for BH3NH3, for which hydrogen release is achieved by thermal decomposition at 100-300 degC.
DERA's info:
Hydrolysis (reaction with water)- Primary hydrides- e.g. LiH, LiBH 4 , NaBH 4
Thermolysis (decomposition by heat)- NH4X + MH - NH3BH3
Metal hydrides
Metal hydrides are specific combinations of metallic alloys that act similar to a sponge soaking up water. Metal hydrides posses the unique ability to absorb hydrogen and release it later, either at room temperature or through heating of the tank. The total amount of hydrogen absorbed is generally 1% - 2% of the total weight of the tank. Some metal hydrides are capable of storing 5% - 7% of their own weight, but only when heated to temperatures of 2500 C or higher. The percentage of gas absorbed to volume of the metal is still relatively low, but hydrides offer a valuable solution to hydrogen storage.
Metal hydride sorption and desorption formulae:
M + xH2 <-> MH2x Features:
Good volumetric performance: theoretical 100 g/L,1860 Wh/L.
Poorer gravimetric performance: theoretical 1-2 wt %, 186-370 Wh/kg.
Desorption endothermic - requires heat.
H2 stored at constant P - safe storage.
Metal hydrides offer the advantages of safely delivering hydrogen at a constant pressure. The life of a metal hydride storage tank is directly related to the purity of the hydrogen it is storing. The alloys act as a sponge, which absorbs hydrogen, but it also absorbs any impurities introduced into the tank by the hydrogen. The result is the hydrogen released from the tank is extremely pure, but the tank's lifetime and ability to store hydrogen is reduced as the impurities are left behind and fill the spaces in the metal that the hydrogen once occupied. H2 could be purified via ceramic membranes: http://www.et.anl.gov/sections/ceramics/research/ceram_mem.html
One volumetric unit of lithium during the reaction with hydrogen is able to absorb about 1600 units of this gas. A significant improvement in storage efficiency is required for transport applications, which in the case of a typical car has a fuel requirement of ~ 1 kg of H2 per 100 km travelled.
This is the technical term for the hydrogen being stored in the fossil fuels that are common in today's society. Whenever gasoline, natural gas methanol, etc.. is utilized as the source for hydrogen, the fossil fuel requires reforming. The reforming process removes the hydrogen from the original fossil fuel. The reformed hydrogen is then cleaned of excess carbon monoxide, which can poison certain types of fuel cells, and utilized by the fuel cell. Reformers are currently in the beta stage of their testing with many companies having operating prototypes in the field. See hydrogen production>Steam methane reforming (SMR) @Hydrogen production section
Chemical bonding
It's similar to Liquid Carrier Storage. Many of these compounds are utilized as a hydrogen storage method. The hydrogen is combined in a chemical reaction that creates a stable compound containing the hydrogen. A second reaction occurs that releases the hydrogen, which is collected and utilized by a fuel cell. The exact reaction employed varies from storage compound to storage compound. Some examples of various techniques include ammonia cracking, partial oxidation, methanol cracking, etc. These methods eliminate the need for a storage unit for the hydrogen produced, where the hydrogen is produced on demand. The best weight percent efficiency for secondary storage is approximately 20 % for BH3NH3, for which hydrogen release is achieved by thermal decomposition at 100-300 degC.
DERA's info:
Hydrolysis (reaction with water)- Primary hydrides- e.g. LiH, LiBH 4 , NaBH 4
Thermolysis (decomposition by heat)- NH4X + MH - NH3BH3
Metal hydrides
Metal hydrides are specific combinations of metallic alloys that act similar to a sponge soaking up water. Metal hydrides posses the unique ability to absorb hydrogen and release it later, either at room temperature or through heating of the tank. The total amount of hydrogen absorbed is generally 1% - 2% of the total weight of the tank. Some metal hydrides are capable of storing 5% - 7% of their own weight, but only when heated to temperatures of 2500 C or higher. The percentage of gas absorbed to volume of the metal is still relatively low, but hydrides offer a valuable solution to hydrogen storage.
Metal hydride sorption and desorption formulae:
M + xH2 <-> MH2x Features:
Good volumetric performance: theoretical 100 g/L,1860 Wh/L.
Poorer gravimetric performance: theoretical 1-2 wt %, 186-370 Wh/kg.
Desorption endothermic - requires heat.
H2 stored at constant P - safe storage.
Metal hydrides offer the advantages of safely delivering hydrogen at a constant pressure. The life of a metal hydride storage tank is directly related to the purity of the hydrogen it is storing. The alloys act as a sponge, which absorbs hydrogen, but it also absorbs any impurities introduced into the tank by the hydrogen. The result is the hydrogen released from the tank is extremely pure, but the tank's lifetime and ability to store hydrogen is reduced as the impurities are left behind and fill the spaces in the metal that the hydrogen once occupied. H2 could be purified via ceramic membranes: http://www.et.anl.gov/sections/ceramics/research/ceram_mem.html
One volumetric unit of lithium during the reaction with hydrogen is able to absorb about 1600 units of this gas. A significant improvement in storage efficiency is required for transport applications, which in the case of a typical car has a fuel requirement of ~ 1 kg of H2 per 100 km travelled.
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