Classification society ClassNK has released the second edition of its 'Guidelines for Onboard CO2 Capture and Storage Systems,' which include what it says are world-first requirements for onboard CO2 capture systems using the membrane separation method.

The guidelines are intended to support the development, manufacturing, and installation of onboard CO2 capture systems (OCCS) using membrane separation, which are expected to be applicable to a wide variety of vessel types.

ClassNK first published guidelines for OCCS in 2023, which outlined requirements for systems using the amine absorption method. The newly issued Edition 2.0 expands the guidelines to include requirements for the membrane separation method, which has lower energy requirements compared to amine absorption and does not require a permanent supply of amine solution.

According to ClassNK, it has reorganized the fundamental functional requirements for OCCS, extracted common requirements across different capture methods, and compiled them into a set of generic requirements that apply regardless of the specific capture method.

Interest in capturing CO2 from ships' exhaust gas is growing as a way to reduce greenhouse gas emissions, with the development of onboard systems for capturing and storing CO2 being undertaken.

The guidelines are available to download via ClassNK's website for registered users.