Custom-built ships are being planned to carry CO2 waste from power stations and other major industrial plants to underground storage facilities. Lloyd's Register is working on a number of projects with owners and shipbuilders.
"The ships will need to be newbuilds as very few existing ships can carry CO2 efficiently," said Jim MacDonald, Principal Surveyor at Lloyd's Register's London Design Support Office.
The cargo tanks on LPG ships are built for carrying lesser specific (SG) liquids than CO2, which can only exist as a liquid under pressure (which must be higher than 5.3bar to avoid snowing up at a carrying temperature of around -500ºC).
"Its liquid SG of 1.155 is significantly higher than most other liquefied gases carried at sea, so existing LPG ships would not be able to carry CO2 efficiently as it would have to be a part cargo to avoid the vessel's tank supports being overloaded," said MacDonald.
LR said the ship designs it has been working on would be able to carry CO2 and other types of liquefied gases. The vessels may be designed to carry the other cargoes on the return legs of voyages or as part of triangular voyages.
