Decarbonisation Technology August 2022 issue

and are at high pressure, yielding a high partial pressure of CO₂ that is ideal for cost-effective CO₂ capture (see Figure 4 ). An amine wash system is used at the Air Products SMR at the Repsol refinery at Tarragona in Spain. A vacuum pressure swing adsorption (VPSA) system has been used to capture CO₂ from the Air Products SMRs that operate at the Valero refinery in Port Arthur, USA. Figure 5 shows the basics of a VPSA process for CO₂ capture. It is evident there is a way to produce these synthetic fuels in a carbon-neutral or carbon- negative way if the CO₂ used in the process has been captured from BECCS. Also, the refining sector has a depth of experience capturing CO₂

from fossil fuel processing, and this expertise will be largely transferrable to biogenic CO₂ capture. Bioethanol as an alternative to synthetic e-fuels Bioethanol is an exceptional energy vector. A lot can be done with it, the CO₂ emissions from the process are very concentrated, and capture costs are low in comparison to carbon capture and storage (CCS) from a power plant, to name an example. The ideal locations for bioethanol production include those where there is suitable agricultural land to support it, where there is no deforestation to create that agricultural land, and where competing food uses are considered. Bioethanol is used today to blend with gasoline and reduce the climate impact of liquid fuels. In the US, blending is up to 15%, and in Europe, it is limited to 10%. In some countries, such as North

Steam methane reformer

CO lean ue gas

Regeneration gas

Charge absorbent

Discharge absorbent

Notes: – CO emissions are also associated with the energy and power requirements for this industry sector. –These can potentially be decarbonised with renewable power and electrical heating or microwaves. –CCS to capture CO from the process and/or the associated energy production is possible

CO rich ue gas

CO desorbed under vacuum

VSA- vacuum swing adsorption and desorption

Oil refining

Hydrogen production from methane reforming for fuels desulphurisation CH, + H 2 0  CO+ 3H 2 CO+ H 2 0  ➔CO 2 + H 2 Use turquoise hydrogen or green hydrogen to avoid the reforming reaction; or feed the reformer with biomethane instead of natural gas As above using renewable methane Ammonia, urea, methanol, gas-to-liquids

Application that releases CO 2

Separation principle Specific energy demand Typical temperature Typical pressure

Adsorption 1.7 GJ/t C02 (mostly power) <40°C Cycling between moderate pressure and vacuum

Chemical reaction producing CO 2

Decarbonisation approach for CO 2 generated by the process

Typical CO 2 removal Typical CO 2 purity

<90% <95% Cryogenic liquefaction 1,000-500,000 Demonstration / Commercial, eg Air Products Port Arthur SMRs, USA

Typically combined with Typical plant size (tonnes per year CO 2 removal) Technology maturity level

Reactions for the decarbonised process Other industries with similar applications

Figure 4 Process CO₂ emissions from steam methane reforming

Figure 5 VPSA adsorption technology for CO₂ capture


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