A storage system includes a first storage node and a second storage node. The fastener comprises an elongate main part, which may be in the form of a bolt. The feed waveguide includes coupling elements on its face in contact with the radiating waveguides. A plurality of tool-lessly operable mechanical interfaces, locking mechanism, and fluid or electrical signal connectors allow the sponson to be selectively secured to the power pod such that the resultant watercraft is modular and transportable by a single person when necessary. At least part of the cooled second effluent stream is washed with a liquid alcohol-containing stream, at a third pressure greater than the first pressure but not greater than the second pressure, to produce a wash liquid stream, which comprises C3 and C4 olefins, and a wash vapor stream, which contains less C2 to C6 carbonyl compounds than the first vapor effluent stream.