Star Wars: Imperial Power Generation

Written: 1998.08.14
Last Revised: 1999.10.06

DS2 hypermatter reactorPower Output

As demonstrated by the hypermatter reactor of DS2 (seen at right), Imperial power systems are far more advanced than Federation power systems. The original Death Star's hypermatter reactor was roughly 16km in diameter as seen in the detailed cutaway details in Star Wars Cross Sections, yet it produced 3 million times more power than the Federation homeworld's sun, as described in the Imperial beam weapon analysis.

The hyperdrive of a Star Destroyer consumes as much energy in a single hyperjump as many planetary civilizations will consume in their entire lifetimes (ref. Star Wars Technical Journal). Primitive 20th century Earth nations were never able to merge into a planetary civilization, but this is a chart of yearly energy consumption of just one of their prominent nations (the United States) over a 20-year period (ref. A Physicist's Desk Reference, 2nd Edition):

Year

Energy

1970

7.00E19 J

1975

7.44E19 J

1980

8.01E19 J

1985

7.80E19 J

The average energy consumption over this period averaged to 7.56E19 J/year for a population of roughly 250 million. A smallish Imperial planetary civilization will have at least 10 billion citizens (and in many cases, several orders of magnitude larger than this; there are billions of beings in the orbital shipyards of Kuat alone). Therefore, even if its citizens only consume as much energy as a primitive 20th century Earth civilization like the United States, such a planetary civilization would consume 40 x 7.56E19 J/year, or roughly 3E21 J/year (3E23 J/century). Most of the planetary civilizations of the Old Republic have existed for at least 25,000 years, so if we again take a relatively "young" planetary civilization that has only persisted for 10,000 years or so, its lifetime energy consumption would be well over 3E25 J. Since the power systems of a Star Destroyer can initiate a hyperjump with no charging period necessary, their reactors' peak output must therefore be at least 1E25 watts, if not much larger.

This is similar to a small star's power output; Earth's sun generates 3.827E26 watts at the current stage in its life-cycle. Since the solar ionization reactor of a Star Destroyer is invariably described as a "miniature sun" in the official literature, this result is not unexpected. It is also fairly consistent with the size of the reactor in comparison to the Death Star's reactor. The 16km diameter DS1 main reactor must put out at least 1.2E33 watts to be able to unleash 1E38 J superlaser blasts once per day, so the 140m diameter main reactor of an ISD should generate 8E26 watts if it produces the same number of watts per cubic metre of reactor volume.

This is completely consistent with other aspects of Imperial powerplant performance. The Death Star 2 is more than 3.2 billion times as large as a single Star Destroyer. If hyperjump energy requirements are proportional to the size of the vessel (the most likely situation) then a DS2 hyperjump probably requires ~5E30 joules. Some Federation cultists might undoubtedly claim that these numbers are far too large (which only indicates the massive discrepancy between their sense of scale and our own), but these scales of energy are completely consistent with other incidents as well, such as the first Death Star's circumnavigation of Yavin. During the last 5 minutes of the battle, the Death Star was averaging 670 km/sec. Its diameter was roughly 160km (ref. Star Wars Visual Dictionary), and if we assume similar density to a Federation GCS, then the first Death Star's mass was roughly 1E18 kg. The kinetic energy associated with a velocity of 670 km/sec is 2.2E29 joules. Therefore, we can plainly see that stellar-level energy outputs are required to perform the simple act of moving the Death Star, never mind the acts of performing hyperspace jumps and obliterating planets.

Starfighter propulsion systems also produce a prodigious amount of power: TIE fighters easily overcome the 6E7 J/kg minimum energy requirement for escaping the gravity of a planet, and by comparing the size of a TIE fighter with the size of a Star Destroyer we can compute that hyperdrive-equipped TIE fighters most likely consume at least 1E15 J every time they jump into hyperspace, assuming that hyperjump energy requirements are proportional to volume.

Although there are no SI unit quantifications of the energy required to create artificial gravity, it is nevertheless still interesting that interdictor cruisers can simulate the gravity well of an entire stellar mass, and that Centrepoint Station could throw a similarly powerful field over an entire star system. Centrepoint Station could also cause supernovae from many light years away, and it could move entire planets through hyperspace and through realspace while the Federation flagship Enterprise was unable to even nudge a small moon. And finally, the Death Star releases 1E38 J of energy from its primary weapon, which could be recharged in a "matter of minutes" (ref. Star Wars Essential Guide to Vehicles and Vessels) for DS2, as opposed to a "matter of hours" for DS1. More than 60 minutes would obviously be regarded as a matter of hours rather than minutes, and more than 24 hours would obviously be regarded as a matter of days rather than hours. Therefore, a maximum for the recharge time of DS1 is 24 hours, and a maximum for the recharge time of DS2 is 60 minutes. This necessitates power output on the order of 2E34 watts for DS2 and 1E33 watts for DS1. This is 72 million and 3 million times the power output of Earth's sun respectively.

Even Imperial transport ships have demonstrated superior power generation capabilities. A single Imperial transport fleet carried the entire "planet-encircling oceans" of Gholondreine-b away in Slave Ship. If Gholondreine-b was similar to Earth, then the mass of its oceans would have been roughly 1.4E21 kilograms and more than 8E28 joules would have been required to carry those oceans into orbit. We don't know how large this transport fleet was, but even if it was composed of a million ships, each ship would have to expend at least 8E22 joules, simply to raise the water from the planet's surface to orbit. This amount of energy is equal to the entire three-year fuel capacity of a top-of-the-line Federation warship such as the Enterprise-D.

Hypermatter

The nature of hypermatter is difficult to discern precisely, which is unfortunate since it is so critical to the operation of the Death Star (although this obviously hasn't stopped certain Federation cultist technobabble afictionados from their usual antics of trying to figure out what it is exclusively from its name). A cursory examination of the Death Star diagram from SWICS reveals a fascinating aspect of its design: it has no fuel tanks! This is not an insignificant revelation- a vessel the size of a small moon will consume staggering amounts of fuel simply to move around and power its onboard systems, even if we disregard the stupendous act of delivering 1E38 joules of kinetic energy into the mass of a planet. Furthermore, there are no huge fuel transport lines running from the docking area deep inside the station,

There are several theories which attempt to explain this remarkable omission:

  1. "The DS has fuel tanks- they're just small and out of the way." This theory is poor because SWICS cuts away one full quadrant of the Death Star for inspection, revealing every other important major system. Furthermore, the Death Star must consume more than 1E21 kg of fuel with each full-power shot, even with perfect mass/energy conversion. If the Death Star has any fuel tanks at all, they must be huge. If it carries matter/antimatter fuel at the density of uranium, it would drain a spherical fuel tank with a diameter of nearly five hundred kilometres, just to fire one shot! This is several times the size of the entire battle station!

  2. "The DS is refueled on the fly." This would require a constant flow of huge transport vessels to and from the Death Star, which was never observed in the films or described in the novelizations. Another serious problem with this theory concerns logistics: if the Death Star was dependent upon huge fuel supply convoys, storage facilities, and refineries, then the Rebels would have logically attacked them instead making suicidal attacks upon the Death Star itself.

  3. "The fuel is ultra-dense." This would explain the apparent absence of fuel tanks, but it would require an exotic type of matter such as neutronium or perhaps even a black hole. It should be noted that this is a distinct possibility, and in fact, one might surmise that since matter, antimatter, and energy become indistinguishable inside a black hole, a black hole could potentially be referred to as "hypermatter".

  4. "The Death Star requires no onboard fuel." This theory would require that it can somehow draw mass/energy from a source outside of itself, such as the theoretical vacuum zero-point energy of the universe, a source of mass/energy in hyperspace, or a distant source such as a quasar or black hole (presumably connected to the Death Star's hypermatter reactor through some kind of wormhole).

The first and second theories are unacceptable. The first theory replaces nonexistent fuel tanks with miniscule hidden fuel tanks, which is improbable and would hardly solve the problem even if it were true. The second theory opens up so many logistical vulnerabilities for the Death Star that it would been easily disabled through attacks on its support structure. A direct assault on the Death Star would never have been necessary.

The third theory holds more promise. A singularity or other form of ultra-dense mass would explain the following:

However, the obvious question remains: what happens to this ultra-dense energy source? If it explodes when the Death Star explodes, then one would imagine that the blast should have devastated or destroyed Endor immediately (irrespective of any long-term "nuclear winter" holocaust scenarios). If it continues to move through space after the Death Star explodes, one would tend to imagine that it would have been observed. However, it is important to note that this cannot entirely be ruled out. In fact, the ANH novelization contains the following description of the immediate aftermath of DS1's destruction:

"The collapsed residue of the battle station would continue to consume itself for several days, forming for that brief span of time the most impressive tombstone in this corner of the cosmos."

This suggests that in spite of the violence of the explosion, a significant quantity of the Death Star's mass was gravitationally attracted back to its original location. This is what one might expect if there was an ultra-dense object inside the Death Star, thus lending credence to the theory that a singularity or other ultra-dense object was contained in the Death Star's hypermatter reactor. However, the fate of the Endor sanctuary moon demands explanation, since such a large mass in such a low orbit would have created tremendous tidal forces in the planet's crust. Han Solo's strike team should have felt as if they were a small fraction of their normal weight (if not actually flying up into the air).

This brings us to the fourth theory: the theory that the Death Star is drawing energy from a source external to itself. This theory is certainly not without its flaws: the ZPE theory requires a high cosmological constant, which would be incompatible with the observed expansion rate of the universe. The "hyperspace tap" theory requires that hyperspace is filled with mass/energy, which may or may not be true. The wormhole theory requires that an artificial wormhole can be created which is anchored at one end and moved freely about at the other end, and this may not be strictly impossible but it definitely stretches credibility. However, the theory seems to suffer from fewer flaws than competing theories, and if true, it would explain the following:

The theory requires that the reactor be capable of drawing as much as 1E38 joules out of its mass/energy source to fire its weapon without having to store the energy beforehand (hence the lack of gravitational effects upon the Endor sanctuary moon), which begs the question of why it requires a long delay between firings. The theory has been advanced, as described in numerous official texts, that it was "recharging". However, this seems bizarre: in what sort of batteries or capacitors is this "charge" being contained? An alternate, and perhaps more realistic possibility is that the refire delay was due to the need to vent enormous amounts of waste heat from reactor subsystems, coolant systems, superlaser subsystems, etc. before firing again. Upper limits on the rate of heat dissipation may have dictated the refire delays rather than any energy generation restriction.

Flexibility

Unlike Federation engineers who seem to restrict themselves exclusively to matter/antimatter reactors for warp drive and fusion reactors for impulse drive, Imperial engineers use any and all means of power generation depending on applicability. The extreme high-density energy requirements of the Death Star called for hypermatter (ref. Star Wars Incredible Cross-Sections), since the Death Star's massive interior cavity could effectively isolate crewmembers from the hazardous effects of hypermatter. The World Devastators used artificially sustained miniature black holes in conjunction with the consumption of planets. Small, poorly maintained vehicles like landspeeders, airskiffs, and similar repulsorlift vehicles use fusion reactors because of their convenience and high safety factor (ref. Star Wars Essential Guide to Vehicles and Vessels).

Our fusion reactors operate on a completely different principle than the primitive fusion reactors of 20th century Earth science, and are related to those reactors only through the use of the word "fusion", which is actually an extremely oversimplified way of describing what happens in our reactors. The "fusion reactors" used in all standard Imperial starfighters are obviously not based on conventional nuclear fusion, because they can induce fusion in "heavy metals, liquid reactants, or virtually any substance" (ref. Star Wars Essential Guide to Vehicles and Vessels). Nuclear fusion is impossible in those situations, so our "fusion reactors" are clearly based on a completely different principle than nuclear fusion. This should dispel the unfounded rumours that Imperial power generation is based on nuclear fusion.

Acknowledgements