PTQ Q1 2023 Issue

natural gas. CO₂ can be captured from the high- pressure process gas after the CO-shift reaction (i.e., pre-combustion CO₂ capture). This enables an approximate 60% reduction of total CO₂ emis- sions produced in an SMR, and a consequent reduction of refinery Scope 1 CO₂ emissions by 20% in our case. Post-combustion CO₂ capture This can be applied to all refinery flue gases but is less economical than pre-combustion capture due to lower CO₂ partial pressures, as shown in Table 5 . CO₂ use CO₂ to storage/greenhouses The study considers two options: CO₂ liquefaction and transportation (by ship) to remotely located underground reser- voirs for permanent storage, and CO₂ routing to nearby (approximately 40 km distance) existing greenhouses. Pertinent cost numbers are reported in Table 6 . CO₂ to e-fuels/chemicals There are established process pathways to conveniently use CO₂ as a feedstock to produce other fuels/chemicals. With green hydrogen, CO₂ can be transformed into e-methanol or e-fuels. With e-ammonia (from green hydrogen), CO₂ can be converted into urea. At present, the high electricity price, electrolyser capital cost, and pertinent inefficiencies result in a high cost of green hydrogen and, consequently, high prices of e-methanol/e-fuels. The expecta- tions are that the cost elements and system inef- ficiencies will improve in the years to come. As an example of the use of CO₂ to produce other chemicals, the production of ethylene carbonate (EC) from ethylene oxide (EO) and CO₂ is consid- ered. The EC market is rapidly developing as it is used in lubricants and as an electrolyte in lithium- ion batteries. 7,8 Some of these CO₂ utilisation options imply the refinery is to be expanded with petrochemical facil- ities, with all its challenges with respect to market positioning, logistics, and so on. For example, the production of EC requires importing, transferring, and handling of EO. The costs in Table 7 are highly dependent on feedstock prices (such as hydrogen, ethyl- ene oxide) and CO₂ derived products. The CO₂ abatement costs also consider the difference in

CO₂ reduction and associated cost, Pre- and post-combustion CO₂ capture, 2019 Western European pricing

It em

CO₂

Invest- €/t CO₂

€/t CO₂

reduction,

ment, avoided2 avoided

KTA

M€

(30% higher utility prices)

CO₂ capture Pre-combustion capture Post-combustion capture 1. Indicative only 2. Excluding the cost of CO2 disposal

378

128 294

33 93

11721

112

Table 5

CO₂ reduction and associated cost, CO₂ disposition, 2019 Western European pricing

Item

CO₂ KTA

Invest-

€/t

€/t CO₂

ment,

CO₂ (30% higher

M€

utility prices)

CO₂ disposal Liquefaction, transportation & storage 1

1172

152

To greenhouses (new pipeline)

436 8 1. Reference cost of CO2 transportation and storage 5,6 respectively; 10 km onshore pipeline, 1000 km by ship to remote storage 33 8

Table 6

CO₂ use and associated cost (excluding the cost of CO2 capture), 2019 Western European pricing

Item

CO₂ use, KTA

Invest-

€/t CO₂ avoided1

€/t CO₂ avoided

ment,

M€

(30% higher utility prices)

CO₂ use E-methanol

100 100 100 100

207 285 456

6132 4732 3742 -663

792 612 459 -784

E-fuels

Urea

Ethylene carbonate

1. Also taking into account savings in operational cost and CO2 emissions from reduced conventional production methods from fossil fuels 2. Based on a 100 €/t premium of products relative to their fossil fuel equivalents 3. Price of ethylene carbonate is 0.55 x price of ethylene oxide 4. As captured CO2 is already available instead of being generated by on-demand combustion of natural gas followed by subsequent carbon capture, the ‘green’ ethylene carbonate route i.e., CO2 + EO --> EC consumes less energy than the conventional route. A higher utility cost further widens the difference resulting in even lower CO₂ abatement cost for the ‘green’ route.

Table 7

instead of the CO₂ being generated from the conventional urea production process using natural gas as feedstock. In the case of crop growth, only a portion of the CO₂ routed to the greenhouses will be captured as biomass. However, this is captured and reused CO₂ rather than CO₂ produced by burning fossil fuels specifically for feeding greenhouses. Pre-combustion CO₂ capture It is assumed that the refinery has an existing hydrogen plant based on SMR of

operating cost and CO₂ emissions associated with the conventional method of producing the various products versus those employing CO₂ as a feedstock. This is not applicable for EC production as the economics consider the direct purchase of EO as a feedstock but not the CO₂ emissions that come with it for both the green and con- ventional routes. The numbers exclude the cost of CO₂ capture as previously developed. Capturing CO₂ for additional EC production would seem

PTQ Q1 2023