From what I remember, the Enterprise was said to have three reactors in the engineering hull at least (The original post and at least one other post in this thread mentioned three reactors -- and in the first post, the alien entity left the ship through the engineering room suggesting all three reactors were in that room) -- probably all matter/anti-matter reactors it would appear as the energy from those reactors go to the warp-engines and probably power the whole ship (Warp engines are powered by matter/anti-matter reactions and matter/anti-matter is more efficient than fusion or fission). It was stated at least once about matter and anti-matter being used up in the nacelles. However I'm not sure how this should be interpreted. First of all they were called matter/anti-matter nacelles, not warp-nacelles, second of all it would seem that most of the data points to reactors in the engineering-hull providing their power. It would be interesting however if the ship had three matter/anti-matter reactors in the main hull for powering the warp-nacelles, nav-deflector, and possibly the whole ship, *and* had a back-up matter/anti-matter reaction chamber in each nacelle to provide some warp capability (say Warp 3.5 or Warp 4.5* instead of the typical Warp 6) in the event of battle-damage or 2 or more reactors failing (the warp-engines and nav-deflectors both require enormous energy... and the reactors have to power the ship too! If you lost two reactors you might be able to do everything, at least you could run the nav-deflectors, some ship systems and use the fusion reactors in the impulse deck to do anything left over). Granted you'd need to still pump matter and anti-matter up into the nacelles, but that can be managed on limited power conditions (and I suppose there's no rule that says you can't have a liquid hydrogen tank, and a bunch of anti-matter tanks up in each nacelles as a on demand reserve) CuttingEdge100 * - Warp 4.5 is around 91 times the speed of light. That would cover you a light year every four days. However considering in Star Trek, warp factors mean whatever the writers wanted it to be Warp 3.5 sounds like a number that is reasonably low enough, yet "fast" enough by writer standards to "limp around".
Energizer(s) This thread may be dead(?), but I was just re-watching "The Doomsday Machine" and a line stood out (in regard to TWOK's "The main energizer's out!" from Scotty and to the whole reactor issue): Communications officer Palmer to Spock right after the Planet Killer has knocked down the Enterprise's shields: "Sir, deck seven reports power failure in main energizers. Implementing emergency procedures." And looking through the transcripts turns up this from Masters in "The Alternative Factor": "The energizer has shorted. Get out of here. Sound the alarm." However, the relationship between reactor(s) and energizer(s) seems to remain unclear.
Re: Energizer(s) Probably some sort of power converter or transformer. That, or the little pink bunny with the bass drum suddenly stopped.
"The Doomsday Machine" is a mixed bag as far as tech references go. Some of them are useful, like the indications that the engine room is in a lower part of the ship and that the impulse engines are powered by fusion reactors, but the anything referring to the warp drive is pretty much technobabble (the difference being that the impulse engines had something to do with the ultimate resolution to the plot, whereas what exactly happened to the warp drive was largely irrelevant). Like I said, in this context, "energizer" sounds like some sort of power transfomer in the system, converting the raw power from the main power plants to something more usable to, say, that computer terminal on the table, or the transporter. Kinda makes sense the suckers'd blow under those circumstances.
i dunno, what exactly is an energizer? edit: ignore this, the chap above me hit the Post button a little faster than I did
Also makes sense, then, that dilithium crystals would be involved. Ever since "Mudd's Women", we have known that the ship's power flows through them (but apparently doesn't emanate from them). The dialogue of ST2:TWoK also suggests that the energizer is a tight bottleneck of some sort that can be quickly repaired by a brave hand, rather than a major component - and "manually realigning dilithium crystals" is a perfectly valid explanation to what Spock is doing in those scenes, as he operates on a device not too unlike the dilithium cradle of TOS. OTOH, "energizer" could also be a device that nurtures the dilithium so that it can do its job. Nonenergized dilithium is no good, as we learn in "The Alternative Factor". The non-main energizer that is used for restoring the dilithium to working order in that episode could be an "intensive care unit", while the main energizer is the device that does the constant nurturing when the crystals are at work in the actual reactor. So perhaps the closest analogy would be a preheater in a sodium nuclear reactor? If the sodium is cold, nothing works, as the circulating fluid isn't fluid any more. An auxiliary preheater would be needed to get the sodium circulating initially, after which the main heat exchanger would make sure the stuff didn't freeze solid during regular operations. Or it could be llike the hydraulic compressors of an aircraft. A separate APU is needed for "priming" the hydraulic fluid, giving it initial pressure, so that the main engines can be started. A component in the main engines then takes over the task of pressurizing the hydraulics, of "nurturing" them. Timo Saloniemi
I dunno. To me, it just makes more sense that it's some sort of high powered voltage regulator, that occasionally has to be worked around in emergencies in order to get power to where it's needed (Scotty's comment in TWOK about the main energizer being wired up like a Christmas tree, f'r instance).