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Background to the Study
Large-scale CO2 storage will entail substantial transportation of CO2 from either point-sources or hub
collection points to geological formations capable of storing thousands of tonnes of CO2 in supercritical
form. In many parts of the world the most suitable storage options for large-scale capacity will be in
offshore formations such as the North Sea. Consequently, it is important to build an understanding of
the most suitable techno-economic solutions for the trans-shipment of CO2 from shore facilities to
offshore storage locations. This study has explored a series of options to gain a more detailed
comparison of shipping CO2 either directly by sea tanker to a storage site, or via an intermediate stage,
to a shore facility in closer proximity to a storage site prior to transfer via pipeline. These options have
also been compared to direct transfer via pipeline.
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Key Messages
- The results from this study demonstrate that for long distance transport of low volumes of CO2 (~1-2 Mtpa), such as in cross-border shipping from several industrial CCS clusters across Europe, shipping can provide a cost-effective option.
- Based on the four different scenarios modelled in this study, more CO2 could be stored annually by shipping to an intermediate port, and then transporting CO2 to a storage site via a pipeline, compared with direct delivery to the site by tanker.
- Of the four scenarios modelled here, based on a shipping distance of 1,000 km, there is little cost advantage from increasing the ship size above 10,000 tCO2. Conversely, there is also little penalty in cost by using larger ships. However, the optimum ship size will be highly dependent on the flow rate (Mtpa). Ideally, size and capacity could be customised for each specific logistics chain.
- A comparison of the levelised cost of four different scenarios conducted in this study suggests that direct injection at a storage site from a ship is the most cost-effective solution (32 €/t CO2). The cost advantage may vary under different scenarios.
- Transfer of CO2 from a tanker into a floating storage injection (FSI) unit is the least cost effective solution even though it can allow continuous injection (41 €/t CO2). Moreover, this system is unproven and less well understood compared with onshore facilities therefore direct comparison needs to be treated with caution.
- The modification of LPG tankers for CO2, or dual purpose, will be influenced by the contrast in fluid density of the different gases. Consequently, only 50-60% of a tank capacity designed for LPG can be used for CO2. Partially filled cargo tanks will also have a structural impact on a ship and its motion.
- Tankers specifically designed for CO2 transportation can be optimised for maximum capacity and investment cost.
- A comparison between CO2 delivered by sea tanker and a pipeline to an offshore storage site, based on minimum unit costs, shows that the pipeline option is cheaper over shorter distances. The break-even distance depends on the volume of CO2 and whether tankers are pre-pressurised or non-pressurised (see Figure 9).
- A review of the legal instruments (international treaties, EU law & Norwegian Law), that relate to the movement of CO2, shows that there are no evident showstoppers to the international shipment of CO2.
- A decision taken at the 14th meeting of the Contracting Parties to the London Protocol on 7th – 11th October 2019 means that Contracting Parties who choose to are able to legally transship CO2 for storage.
- An unfortunate result of having two monitoring reporting and verification (MRV) regimes for CO2, is that ship operators will have to manage two separate reporting schemes for the fuel that they use. The European Commission has reviewed the MRV regulation and is considering potential alignment with the International Maritime Organisation Data Collection System (IMO DCS).
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