All the power used by the flying Space Geneva Protocol violation that is the Research Vessel comes from here, the Vessel Engine Room. Not much engine-ing actually happens here; there's just a SMES Unit for the Vessel's solar arrays, plus a few furnaces and crates of char for backup/auxiliary power. In terms of more useful things, there's also a highly-versatile general fabricator that can be used to make certain tools and a whole bunch of table parts and chairs in a corner for some reason.
The Vessel's nuclear charge is also kept here. In event experiments on the Vessel go extremely awry/Research decides it's going to use its Space Geneva Convention violations on the Outpost, the Research Director and two other people with superuser access (or someone who can spoof the access) can use the a special TermOS program, nukeman (that's short for nuke manager) to activate the charge and blow the Vessel star-high, in one of the most powerful explosions in the game.
There is no vent. Only the furnaces need air, so they can burn their fuel, and they make plenty of their own...somehow.
The APC for this room is behind where the air scrubber would be, near the nuclear charge.