PTQ Q3 2024 Issue

reducing the need for gas pretreatment and a smaller H₂ compressor compared to ATR. A key advantage is that the POX reaction does not require steam as a reactant. Instead, high-pressure steam is generated using waste heat from the reaction, which can satisfy the steam consumption within the blue H₂ process and some internal power con- sumers. Also, with no need for feed gas pretreatment, gas POX technology has a far simpler process line-up than ATR. ATR is the combination of SMR and POX, resulting in a net reaction enthalpy of zero. ATR uses O₂ and steam with direct firing in a refractory-lined reac - tor with a catalyst bed, having several advantages compared to SMR: • Increased energy efficiency (more cost-effective) • Faster start-up times • Faster response time to transient operation. And compared to POX: • Increased energy efficiency • Higher hydrogen production efficiencies. As a disadvantage, ATR requires a substantial feed gas pretreatment investment and a large investment for an oxygen production plant. It would also be more suited for a pre-combus-

Blue hydrogen production processes comparison using CO₂ intensity²

Option

CO₂ intensity excl. power

CO₂ intensity incl. grey power

CO₂ intensity

incl. green power

kg/kg

SMR base case w/o capture

9.0 1.5 0.5 0.6

9.0 1.7 0.7 1.3

9.0 1.5 0.5 0.6 0.6

SMR syngas capture SMR flue gas capture

ATR + GHR

POX

0.6 0.0

1.4

Electrolyser

0.5

Grey power:

Green power: 10g CO₂/kWh

300g CO₂/kWh

Table 2

Blue hydrogen production processes comparison using CO₂ avoidance cost and levelised cost of hydrogen²

Levelised cost of hydrogen at varying unit rates Power 100 $/MWh 40 $/MWh 20 $/MWh NG 4 $/GJ NG 4 $/GJ NG 5 $/GJ Power Power

CO₂ avoidance cost, $/t n.a.

Option

SMR w/o capture

1.00 1.50 1.45 1.55 1.70

1.00 1.30 1.25 1.25 1.35

1.00 1.25 1.15 1.15 1.25

70 60 70 75 >100 Power: 100 $/MWh NG: 4 $/GJ

SMR syngas capture SMR flue gas capture

ATR + GHR

POX

Electrolyser

Table 3

Comparison by SGP Shell Gas Partial Oxidation (SGP) technology provides sub- stantial savings compared with ATR. It can result in a 22% lower levelised cost of hydrogen, as shown in Figure 3 . These savings come from a 17% reduction in capital expenditure owing to the potential for higher operating pressure, leading to a smaller hydrogen compressor (single-stage compres- sion), CO₂ capture, and CO₂ compressor units. Additionally, there is a 34% reduction in operating expenditure (excluding the natural gas feedstock price) from reduced compression duties and increased steam generation for internal power. SGP technology consumes 6% more natural gas but is offset by power generation from the excess steam. The process is designed for 99%+ CO₂ capture. Comparison by Darcy Partners Mora Fernández Jurado at Darcy Partners compared the three mature technologies for blue hydrogen manufacture. The findings report that the key advantage of SMR is that it is the most common hydrogen production technology, for which there is currently much research and development. However, partial oxidation (POX) and ATR technologies are more cost-effective than SMR. Compared to SMR, POX technology saves money by maximising carbon capture efficiency and simplifying the process line-up, both of which offset O₂ production costs. Additionally, it does not require steam as a reactant,

tion carbon capture system.

Linde’s comparison Linde² has compared the major blue hydrogen production processes using three unique parameters. The first param - eter is a comparison based on carbon intensity (see Table 2 ). The results using SMR as the base case without any capture of CO₂ and no impact of imported power will have a carbon intensity of 9.0 kg CO 2/kg H₂. Secondly, SMR with 85% CO₂ capture case will have a carbon intensity of 1.5 kg CO₂/kg H₂. The third SMR process with flue gas capture and ATR and POX processes shows an intensity of 0.5 and 0.6 kg CO₂/kg H2 . Note that hydrogen from the electrolyser, with zero CO₂ emissions, is due only to the consumption of power. In practice, this case is far from the truth. In the second case (Table 2) involving grey power con- taining 300 g CO₂/KWh, the results reveal that all processes other than the SMR base case show increases in carbon intensity, with electrolyser hydrogen being the most affected. Oxygen-based processes are also affected. In the third case, where green power with 10 g CO 2/KWh is used, the results are nearly back to the first case, except for green hydrogen from the electrolyser, with a carbon intensity of 0.5 kg/kg. Moving to the second parameter, ‘CO₂ avoidance cost’ (see Table 3 ) is the cost required in $/ton to remove CO₂ from the process. The results show all the processes have an avoid- ance cost in the range of 60-70 $/ton CO₂. When we consider

PTQ Q3 2024