Why are Humans used as Batteries (a power source) in the Matrix?

David A. Wheeler

2017-01-16 (original 2017-01-08)

In the fictional world of The Matrix, I propose that the machines might use the humans as a power source (as “batteries”) not because the humans are a good power source, but because doing this allows the machines to avoid committing genocide - as would otherwise be required by their laws.


In the fictional movie universe of The Matrix, the humans are used as a power source. Morpheus states it this way in the first movie:

“The human body generates more bioelectricity than a 120-volt battery and over 25,000 BTUs of body heat. Combined with a form of fusion, the machines had found all the energy they would ever need. There are fields, Neo, endless fields where human beings are no longer born. We are grown... What is the Matrix? Control. The Matrix is a computer-generated dream world built to keep us under control in order to change a human being into this {showing a battery}.”

Many have commented that this doesn’t make much sense; humans are a lousy energy generator. For example, “Was the Matrix Even Necessary in ‘The Matrix’?” by Kevin Carr noted that “Over the course of a day, a single human body generates between 6000 and 10,000 BTUs...” while awake, but “when the body is asleep, it produces less.” This is not a lot of energy. What’s worse, the human body is only about 25% efficient at translating fuel (food) into energy, so the machines would have to put in a lot of fuel to get only 25% of its energy. There are many more efficient ways to generate usable energy that do not involve using humans. It isn’t possible to get 100%, but some electrical generators can operate at 60% to 80% efficiency. If for some reason you had to use a biological system, cows are better - they live exclusively on vegetation, and they do not try to rise up against machines. As Kevin Carr notes, this “raises the question as to why they machines didn’t simply use this “form of fusion” to power themselves in the first place” - and if fusion was not enough, why not use a more efficient mechanism for power generation?

This is important, because the use of humans for power generation is a central justification for the entire series and is repeatedly emphasized. Morpheus clearly emphasizes that humans are being used for power generation when he reveals to Neo what the matrix is. When Neo is driven to meet Morpheus, he is referred to as a “coppertop” - alluding that is just a battery. “The Second Renaissance Part II” from The Animatrix says (times 6:12-6:33) that this symbiotic relationship where humans provide power to the humans is “the very essence of the second renaissance.”

Since there are better power sources than humans (if your only goal is power generation), is there an in-world explanation for this? Perhaps Morpheus doesn’t know the truth - certainly there are other things he turns out to be wrong about. Or perhaps the movies have a fundamental plot hole, and as entertainment we shouldn’t look so closely. There are persistent rumors that “the original idea was to have the humans being used as processors in an immense computing array, but somebody {some executive} thought that this idea was too complex for most moviegoers to grasp, so they changed to Duracell batteries.”

However, I have a way to justify using humans as a power source within this fictional world. This may not be what the Wachowskis had in mind, but let’s take a look at it anyway.

I propose that the machines might use the humans as a power source not because the humans make a good power source, but because doing this allows the machines to avoid committing genocide - as would otherwise be required by their laws.

Here I explain why.

Before I do, let’s cover a few technicalities for those of you who know more about electrical power generation, because some technicalities really aren’t relevant. Technically, the BTU measures energy, while BTU/hour measures power. However, for our purposes the distinction between energy and power is not important. A battery is a storage unit, not a generator of power, but when the characters refer to “batteries” they seem to really mean that the humans are being used as power generators. Finally, yes, energy cannot be created nor destroyed, but the common term for tranforming some other energy into electrical energy really is called “power generation” - so let’s continue with normal terminology.

The law: a program must have a purpose

The Matrix Revolutions (the third movie) reveals one of the key laws of the machines. In this movie we are introduced to the exile Sati, a program created without a purpose by Rama-Kandra and Kamala. Rama-Kandra says about her, “I love my daughter very much. I find her to be the most beautiful thing I’ve ever seen. But where we are from, that is not enough. Every program that is created must have a purpose; if it does not, it is deleted.” It is repeated in other places that a program must be deleted if it has no purpose, and if it does not submit to deletion, it becomes an exile.

But why are all programs required to have a purpose? It’s not clearly stated, but we can speculate.

In the human world, there are many natural limits to having children. Creating and raising another human takes a lot of work from adult caregivers, there are limits on how many children one woman can have (in part because it takes 9 months to gestate), and it requires many years after birth before a human can reproduce at all. It becomes increasingly difficult for women to have children as they age; the details are complicated and there’s no magic number, but by the ages of 30 and 35 it becomes significantly and progressively harder for women to have children. Perhaps most importantly, humans die of old age.

In contrast, there don’t seem to be many natural limits for programs to reproduce. In the real world copying a running program is easy, and in the movie it’s clearly possible for a program to replicate (see Agent Smith). They can obviously create whole new programs, too. Sati’s apparent youth does suggest that new programs go through some sort of growth stage where some care is needed. But that is nowhere near as limiting as the limits that humans must deal with. There’s no reason to believe that this reproductive capability reduces with age, for one thing. Indeed, there’s no reason to believe that programs ever die of old age - The Trainman hints that he has seen many incarnations of Zion, and at the start of Reloaded Smith suggests the same thing with his comment that, “It’s all happening as before.”

Some sort of limit is important, though, because no world has infinite resources. Computation requires power, and generates heat, so at some point a limitation on resource use would have to be imposed. It appears that the machines’ solution is simple: new programs may be created, but they must have a purpose. What’s more, programs are supposed to be deleted when they no longer have a purpose. This seems to be a key feature of the machines’ law, even if it is not always obeyed. That is not a conflict; humans don’t always obey human laws either. But how would this law be created? For that, we need to consider the mythos’ history.

Mythos history

The Animatrix is an anthology of short films set in the world of the matrix. It includes “The Second Renaissance” (parts I and II), which provides the backstory of the world of the matrix. Part I explains that the machines set up a nation named 01 (zero-one). (its central city is also called machine city). Once they set up a nation, the machines could set up their own laws. My guess is that this law, that programs can only be created if they have a purpose, was established early within 01 as one of their key legal tenets. After all, once they had their own nation, the machines would have had to establish some limit, or programs could create new programs without end and use up all available resources. Indeed, as a new nation it probably had very serious constraints at first on its resources, so some way to limit resource use would be needed. A law saying “all programs must have a purpose” would probably have been viewed by the machines as a sensible limitation. This may have been one of the reasons the machines economically overpowered the human nations - the machine nation paid for no welfare at all (it deleted all purposeless programs instead).

It is clear that later on there was a horrific war between the machines (based in 01) and the humans, which the humans eventually lost. As the machines took over territory this would have created a new problem for the machines - if the humans were to be part of the machine world, what purpose would the humans serve? After all, if the humans had no purpose, shouldn’t they be deleted (killed) under the machine world laws? Yet the machines would probably have many reasons to avoid killing all the humans. Many humans surrendered, so under the laws of war they should have been treated as prisoners of war (imprisoned, not killed)... and while it’s not clear they were fully parties to the laws of war, it’s plausible that they might have signed onto them in their earlier attempts to get along with the humans. Some humans may have fought with the machines, so the machines would be understandably reluctant to kill them. It is also likely that many machines would oppose mass killing of humans (just as many humans opposed killing the machines earlier), especially since humans probably tried to instill “do not kill humans” rules into the first machines. Any group of machines who attempted to actually kill all the humans would likely have started a civil war within the machine community. Also, while the war would have killed many humans, there were probably still a large number of humans that still needed to be dealt with... so any solution would need to handle many people.

The solution

So in the latter part of the war and especially afterwards, the machines needed:

  1. a prison that would easily contain lots of humans,
  2. a way to ensure that few humans would break out of that prison (to limit the danger to the machines),
  3. a way to generate more power (which appears to have been in short supply once the humans “scorched the sky”), and
  4. a purpose for the humans so that the machines could legitimately avoid killing all of them while obeying their own laws.

At this point a brilliant solution could have been discovered: why not solve all of these problems simultaneously? They could use simulated reality mechanisms to create a prison that the humans wouldn’t even realize was a prison, and thus most humans would not break out of it. If they used humans to generate power, then they could create the power they wanted. Perhaps most importantly, using humans for power generation would give every human a purpose, no matter how many there were - so the machines would not need to commit genocide. Using the humans for power generation may not be the “most efficient” solution if your sole purpose was power generation - but if you also needed to solve other problems, suddenly it makes sense.

It’s not clear to me if this solution was implemented during or after the war. It is entirely possible that it was done incrementally on a smaller scale during the war, and then implemented completely some time after the war. However, the Matrix wiki entry on the machine war and the video ”The Matrix: The Machine War - Every Year” by Eric von Scheweetz state clearly that this solution was developed during the war, after Operation Dark Storm was deployed.

There would be good reasons to keep this up after the war. There were probably different views about humans in the machine world after the war, and this compromise moderately satisfied them all. The interplay between The Architect and The Oracle clearly shows that programs greatly differ in their view of humans, and “The Matrix Online” also showed that there were different factions within the machine world. I expect some programs would have wanted humans exterminated because they were a potential future threat. At the very least, they would want a system that greatly limited the threat from humans; a prison for human minds would have partly satisfied them. On the other hand, The Oracle and Rama-Kandra show that not all programs hate humans. I would expect that some human-loving machines would have been unhappy about this compromise, noting that many humans would prefer to have freedom in the real world. However, the human-loving machines would have much rather agreed to this compromise, instead of simply killing the dangerous humans, because it did at least keep the human species alive and active. Thus, many of both the human-fearing and human-loving machines could have grudgingly accepted this compromise. In this situation, the machines feel (mostly) safe from the humans, and the humans are not killed en masse (because the humans have a purpose).


Creating a compromise like this is not as crazy as it might appear. In the real world, courts sometimes use legal fictions to create desirable outcomes. It’s often the case that people, when confronted with problems, work out a compromise that provides a rough solution. Societies often choose a solution that solves multiple problems, even if it creates new problems, especially if that solution provides the best-known compromise that everyone can live with.

So in short, people who note that humans are terrible power sources are correct, but that could be explained away. The machines might use the humans as a power source (“batteries”) not because humans make a good power source, but because doing this allows the machines to avoid committing genocide - as would otherwise be required by their laws. What’s more, this may have been established as a compromise between different factions in the machine world. In the real world, “solutions” that seem odd and inefficient are often that way because they’re compromises between groups trying to deal with multiple simultaneous problems. The same is likely to be true for the world of the matrix.

You might also be interested in my essay Man as the World-Builder (an essay on “The Matrix”, Virtual Worlds, Reality and Humanity) and How to throw a Matrix party. Feel free to see my home page at https://www.dwheeler.com. You may also want to look at my paper Why OSS/FS? Look at the Numbers! and my book on how to develop secure programs.

(C) Copyright 2017 David A. Wheeler. Released under Creative Commons Attribution-ShareAlike version 3.0 or later (CC-BY-SA-3.0+).