PPC
FT
H /CO price: 4000/50 $/t
PPC
Carbonation
Carbonation
CH
Urea
CH
FT
Urea
0
Oxo (butanal)
Polyols
0
Polyols
Oxo (butanal)
MeOH
MeOH
Xylenes
Xylenes
H /CO price: 1500/200 $/t
Feed/product value addition Electricity/fuel/steam
H cost
CO revenue
Figure 5 Operating cost/revenue balance – 2030 scenario
Fixed Opex
Figure 4 Operating cost/revenue breakdown – 2050 scenario elements in more detail, as well as the capital cost and technology readiness. Hydrogen consumed The hydrogen utilisation intensity (HUI) heavily depends on the CU technology considered and largely correlates with the destination of the oxygen atoms in the utilised CO₂ molecule. The process of producing oxygen-free products involves separating the oxygen atoms in the CO₂ molecule from the carbon atom, which is done by binding the oxygen with hydrogen and generating water. Hence, hydrogen is not only required to generate hydrocarbon but also to capture the oxygen atoms of the CO₂ into water molecules. The HUI and carbon utilisation intensities (CUI) of the process can be defined as the tonnes of hydrogen and carbon consumed to produce one tonne of product, respectively. Figure 7 is a theoretical hydrogen intensity chart. The x
and y axes are the ratio of the number of oxygen and hydrogen-to-carbon atoms in the product. Acetic acid (CH₃COOH), for example, has an #H/C and #O/C ratio of 2 and 1, respectively. The lines on the graph show lines of equal hydrogen intensity, i.e. lines of equal hydrogen intake for products produced from CO 2 , as a function of the oxygen and hydrogen content of the products. Acetic acid is located close to the line of 0.13 t H2 / t product . Therefore, a green acetic acid facility with a production capacity of 100 t/h of acid out of CO₂ will require just over 13 t/h (~150 kNm 3 /h) of hydrogen. The graph shows that even the production of hydrogen-free carbon from CO₂ requires more than 0.3/t of hydrogen per tonne of product, only to remove the oxygen atoms from CO₂.
5
0.50 t /t product H
Methanol
0.40 t /t H product
4
0.20 t /t H product
Methane
0.30 t /t H product
3
0.15 t /t H product
Mid distillate/FT
PPC
H /CO price: 1500/200 $/t
2
Acetic acid
Butanal
FT
Xylenes
Carbonation
Acrylic acid
1
0.13 t /t H product
CH
Urea
Carbon
0
0
Oxo (butanal)
Xylenes
MeOH
Polyols
0.0
0.2
0.4
0.6
0.8
1.0
# O /C ratio in product
Figure 6 Operating cost/revenue balance – 2050 scenario
Figure 7 Theoretical H₂ utilisation intensity for product synthesis for CO₂ and H₂
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