In deep-ocean sequestration of CO2, it is difficult technically and co
stly to transport the CO2 with the use of pipelines on the sea floor,
especially when the disposal site is deep and far from land. A promisi
ng alternative is using a ship as CO2 carrier and a pipe suspended ver
tically from a floating base at the site. The mechanical strength of t
he pipe has been investigated with consideration of the static tension
due to the weight of the pipe itself and buoyancy of additional float
ers, as well as the dynamic tension due to wave-induced motion of the
floating base. We found that a pipe length of 4,000m is a feasible ext
ension of conventional techniques. A pipe longer than 6,000m requires
development of innovative technologies that are not yet developed.