There's a use of "per" that nobody in the VS debate seems to have noticed, that makes perfect sense in this context:
"Per normal operating parameters."
"Per standard idle rate."
"Per regulations."
Under no circumstances does a barely-heard "per" at the end of the line - I seem to recall this is one of the cases where the script and the line onscreen are reported differently - really impact the line. There's not really any meaningful thing that we'd use for "per" in terms of units except for "number of warp cores," or "percent of warp core safe maximum," or something similarly silly. Unless you're engaging in absurdity, take it or leave it at 12.75 exawatts.
As I've pointed out before, the things the
Enterprise does do at times require that amount of effective power. The rate of change of gravitational potential energy involved in moving quickly from point A to point B are significant when point A is right next to a star or singularity (TNG: "Half a Life," TNG: "Relics," TNG: "Descent," ENT: "Singularity," to name a few), and when aliens modify the
Enterprise's own warp system to travel outside the galaxy in moments, the requirements are similarly quite high (TOS: "Day of the Dove," TNG: "Where None Have Gone Before," to name a couple) - presumably, the aliens haven't installed a free energy conduit somewhere, they've just made the warp core more efficient in some fashion and able to run at maximum levels for much longer.
It's also a power level that makes sense for an antimatter-based power system; it's too high for you to conveniently manage with fusion, but low enough that you're not chugging through significant quantities of your fuel reserve per second.
Two Homer Simpsons per second - or twenty - is actually a pretty reasonable flux of matter when you're at an absurdly high temperature and pressure, as warp cores are.
You get a little more trouble with fuel storage; if you're burning 2 m^3 of frozen fuel per second on the E-D, you get about a day per percent of the total volume of the ship dedicated to fuel storage. So unless you're refueling along the way, with those Bussards that the ship is supposed to have, or storing the fuel in a compressed form, you could be in trouble.
I did this all before, so I'll stop typing and quote myself:
In "Allegiance," Geordi states that operating engine efficiency is 93%. This is improved during the episode to 96%. In a notably similar example in "New Ground," Data notes that the low energy loss of the soliton wave (<2%) makes it 450% more efficient than the warp drive of the Enterprise. This could refer to the efficiency of the warp engines at either a bit over 91%, which would lie closely in line with the above figures, although it could also be interpreted as placing warp drive efficiency at ~21.8%. In "Chains of Command," Jellico demands a 15% increase in warp coil efficiency, suggesting engine efficiency below 85%. The highest efficiency figure mentioned in the series is 99%.
These efficiencies are too high to allow a single order of magnitude's gap between base system output and use... and too low to be the entire story.
Assuming efficiency between 80-99% and a normal generation level of 12.75 exawatts, this means the Enterprise must annihilate 143-177 kg of matter per second normally, and produce 0.13-3.2 exawatts of waste heat normally. This also means the Enterprise must somehow sink or radiate waste heat/energy at a rate comparable to a world-wide nuclear war while the warp core is in operation - dozens to hundreds of megatons every second.
We may suggest that this waste energy is somehow recycled into another form, e.g., trilithium, which is known to be highly volatile and a waste product of the Enterprise's warp drive, as noted in "Starship Mine;" it is also possible that some portion of this represents energy loss through the generation of neutrinos while converting matter into energy or back into matter. The ability of cloaked ships to remain undetected at warp while ships have sensitive neutrino detectors suggests this is not a significant source of energy loss.
The problem of fuel capacity is easier to solve. The Enterprise has, after all, Bussard ramscoops that can be used to suck interstellar hydrogen; if these may be operated at warp speed, the 10-21 kg/m3 of interstellar hydrogen typically present can be taken partial advantage of. By reconverting energy gained from matter/antimatter reactions back into antimatter, the Enterprise can breed its own antimatter stores from collected matter.
A ramscoop with a cross section roughly equal to the Enterprise's front end would need to travel roughly 10 billion times the speed of light. In order to avoid consuming fuel too quickly, the ramscoop would need to be extended tens or hundreds of kilometers outward. As this does not exceed the limits to which the deflectors can be extended, it is quite possible that the Enterprise is largely self-sustaining so long as it can keep cruising peacefully.
It fits pretty neatly, which is surprising when you consider that the people writing the show generally didn't know very much about science. We do run into a bit of trouble in terms of starships running out of fuel in a matter of weeks or months at "normal" operating rates, but if you can use warp cores / replicators / transporters / et cetera to "breed" antimatter back out of matter, it's fairly easy to pick up enough hydrogen somewhere. If you're not scooping up interstellar hydrogen, there's always the option of taking a quick pass through the outer atmosphere of a gas giant.
On the other hand, if we use a low level of power generation, now we have to explain where all the free energy comes from; and in the extreme cases, e.g., the Saxtonites' preferred "terawatt" figures on SDN, you have to ask why they don't just use fusion power rather than antimatter; it's a great deal safer and more convenient.
