Understanding the Cost of Retrofitting CO₂ Capture in an Integrated Oil Refinery

Background: Energy intensive industries such as iron and steel, cement, oil refining, petrochemicals, and chemicals contribute to about 70 to 75% of the global CO₂ emissions from industrial sources, not including the power sector. CO₂ capture and storage (CCS) is the only technology that can significantly reduce carbon emissions from this industrial sector. Globally, the refining sector contributes to around 4% of the total anthropogenic CO₂ emissions. It is expected that no new refineries will be built in the coming decades in most OECD countries, especially in Europe. To understand the impact of CCS in the oil refining sector, it is essential to have a good understanding of the cost of retrofitting CO₂ capture technology in existing refineries. Therefore, this project has aimed to evaluate and understand the cost of retrofitting CO₂ capture technologies in an integrated oil refinery.

Results: Modern oil refineries are characterized by the large number of exhaust streams, emitting varying amounts of CO₂ in varying concentrations. (Figure 1)

The CO₂ emission points are distributed over the refinery, and in order to capture CO₂ from several points, several capture plants are required. The installation is not straightforward, due to limited space.

Four different generic oil refineries with varying complexity were defined in the project, and a total of 16 different capture cases with 90% capture rate from 1-5 exhaust streams were investigated. The cost for avoiding CO₂ emissions from refineries was determined to 161-210 USD/tonne CO₂ avoided (Figure 2).

The results from ReCap show that:
• The cost of CO₂ capture and compression constitute less than half of the total cost. This is related to that it was assumed that all steam and power required for CO₂ capture and compression is supplied by a newly-built natural gas fired combined heat and power (CHP) plant. The reason for this is a desire to investigate generic base cases. It must be emphasized here that it is known also from many other studies that the cost of amine capture is highly depending on how steam is produced.
• A natural gas fired CHP plant, without CO₂ capture, for steam and power generation will significantly reduce the capture rate. Even if a 90% capture rate was assumed for the investigated exhaust gas stream, the net CO₂ capture rate for these streams is approximately 60%.
• CO₂ concentration has an impact on cost – for instance the CO₂ concentration is low in case 04-01 and high in case 04-04.
• For some streams, also sulphur removal is required prior to CO₂ capture. This contributes to increased cost.
• There is an economy of scale effect for the capture plant with respect to costs, but the impact from factors such as CO₂ concentration and sulphur removal is more significant.
• The cost for interconnecting the CO₂ capture with the refinery is non-negligible (for instance piping and moving of existing components).
• There are no variations in cost that are directly related to refinery complexity.

Conclusions and recommendations: ReCap has not found any fundamental obstacles to integrating CO₂ capture in modern oil refineries. But in order to be able to evaluate if a specific refinery is suitable for full scale CO₂ capture and for instance can deliver CO₂ for storage on the NCS, this must be investigated using data from this specific refinery. The challenge with space requirement for CO₂ capture and compression must be included in the evaluation.

As far as possible, a separate CHP plant for steam and power generation should be avoided, since this will increase the cost considerably and also reduce the CO₂ capture rate (unless the CHP plant is equipped with CO₂ capture, but this will further increase cost and complexity).