PSI - Issue 60

Ram Niwas Singh et al. / Procedia Structural Integrity 60 (2024) 411–417 RNSingh/ Structural Integrity Procedia 00 (2023) 000 – 000

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and volumetric hydrogen densities (greater than or equal to 9 wt% and greater than or equal to 70 g of H 2 per liter of storage system), Safety under operating conditions and public acceptance and reasonable cost of hydrogen storage system (Edwards 2007).

Table 1: Different colors of hydrogen. Produced form Fossil fuels with CO 2 emissions

Fossil fuels with CO 2 Capture

Pyrolysis fossil fuels

Electrolysis

Electrolysis

Electrolysis

Input

Natural Gas + water, Coal+ air

Natural Gas + water + air

Natural Gas + air

Electricity from Renewable + Water

Electricity from Nuclear + Water

Electricity from Solar / grid + Water

Process

SMR and Coal gasification

SMR + CCS

Pyrolysis

Electrolysis

Electrolysis

Electrolysis

Output

Grey H 2 +CO 2

Blue H 2 + CO 2 (partly captured)

Cyan H 2 +C (solid carbon)

Green H 2 + O 2

Pink H 2 + O 2 + Nuclear waste

Yellow H 2 + O 2 / CO 2

Table 2: Comparison of various hydrogen storage methods (Züttel 2003). Storage Methods Gravimetric density, % Volumetric density, kg/m 3 T, °C

P, bar

Remarks

High Pressure gas Cylinders Liq. H in cryogenics tanks

13

<40

25

800

Compressed H 2 in cylinder of high specific strength (~2GPa) material

Size dependent

70.8

-252

1

Liquid H 2 , permeability loss of ~1%/day at RT

Adsorbed H

2

20

-80

100

Physisorption, large surface area, porous materials, Carbon, fully reversible Metallic hydrides working at RT, fully reversible and safe. AB 5 , AB 2

Absorbed H in Metals

2

150

25

1

Complex Compounds

18

150

>100

1

[AlH 4 ]

- or [BH

4 ] - desorption at elevated T and

absorption at high P

3. Hydrogen /hydride embrittlement Hydrogen induced Embrittlement (HIE) reduces the impact and fracture toughness and ductility of materials containing hydrogen (Lee 2016, Marchi and Somerday 2012). Three major forms of hydrogen have been recognized. These are hydride embrittlement (HE), dissolved hydrogen embrittlement (DHE) and hydrogen attack. HE results in the degradation of selected mechanical properties under certain conditions that occur when hydrogen reacts with the metal matrix itself to form metal hydride at relatively low temperatures. This form of embrittlement can occur in materials such as Zr, Ti, Ta, Nb, U, Th etc. (Marchi and Somerday 2012, Bind and Singh 2021, Murty 2022, Alvarej 2004, Peterson 1992). Dissolved Hydrogen Embrittlement (DHE) causes the degradation of certain mechanical properties due to the dissolved hydrogen into susceptible metals during forming or finishing operations or service. Hydrogen attack (HA) leads to the degradation of mechanical properties when hydrogen reacts with the metal matrix itself to form gas (CH 4 , NH 3 , H 2 S). This form of hydrogen damage can occur in materials in some types of iron or steels used in power and process industries especially at elevated temperatures.