Technology
CO 2 reduction achievable
Surplus fuel gas
Estimated
Remarks
date of commercialisation
Firing hydrogen from reforming
65-85%
No
Now
Requires a route to use CO 2 , CO 2 reduction depends on CO 2 footprint of electricity
Firing hydrogen from electrolysis
0-70%
Yes
Depends on progress in cost reduction and increases in size
CO 2 reduction depends on
CO 2 footprint of electricity
of electrolysers
Electrification
10-25%
Yes (depending
Now
Requires a low CO 2 source
on cracker feed slate/
of electricity
Low CO 2 furnace
30-40%
2023
configuration)
Electric furnaces
0-90%
Yes
2025
CO 2 reduction depends on CO 2 footprint of electricity
Carbon capture
90-95%
No
Now
Requires a route to use CO 2
and storage/utilisation
Table 3 Summary of CO 2 reduction techniques
Summary The above CO 2 reduction techniques are summarised in Table 3 .
Surplus fuel gas The ethylene cracking process typically generates most of the fuel required for the furnaces. For gas cracking plants, some imported fuel gas may be required, whereas liquid cracking plants typically export fuel gas. As noted above, for several CO 2 reduction solutions, the reduced fuel gas firing within the cracker results in surplus fuel gas. The fuel gas will typically contain 10-80 mol% hydrogen, depending on the feeds cracked. The surplus fuel gas can be used for power generation in a combined cycle gas turbine (CCGT), which may generate power with a lower CO 2 footprint than the local power grid and the power could be used to power an electrified cracker. However, CO 2 is still emitted, unless CC is added to the CCGT. Fuel gas can be converted to products; however, the available technologies are not fully commercialised and/or have a low product yield. Technip Energies believes the best solution is to convert the fuel gas to a high hydrogen product in a reformer, as described above.
Conclusions A range of possible solutions to reduce the CO 2 emissions from steam crackers has been discussed. Technip Energies believes that a variety of solutions is appropriate, because of different conditions worldwide, in particular the availability of large quantities of reliable, low CO 2 electricity, different time scales for implementation of projects, the different considerations of new build plants and revamps, and the early stage of development of some technologies. Both CC and hydrogen firing can be retrofitted to existing crackers with relatively few modifications, as the new plant construction is alongside the cracker. Both technologies can be applied to not only the cracker, but other plants in a complex, such as an adjacent refinery.
Jim Middleton jim.middleton@technipenergies.com VIEW REFERENCES
www.decarbonisationtechnology.com
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