# Zombie perpetual motion machines

Lo and behold! A zombie apocalypse broke out inside Roman territory. In the Iberia peninsula. Being smart as vitruvius is, he devised a plan on how to deal with the zombies. Use them as power sources!

Provided everything worked ok, what's the maximum power that can be extracted from this setup? Is there an alternative means to extract power from zombies? Would this provide enough power to move a war machine?

• Consider them to be human-like, with characteristic zombie gait, only differing in that they don't need to eat, they eat out of taste for human flesh, not out of nutrition. Do not consider normal metabolism. They can very well run continously, accumulating lactic acid without pain. There are no thermodynamic limits for them, besides that they can do whatever a normal human can do physically. They feel no pain and have an IQ between a cockroach and an anemone. In other words they are purely reactive. They seem to not have immune systems, so they rot under anything that consumes flesh. They only stop moving when they are out of muscle tissue. The difference in speed is due to activity in cerebellum, it's a matter of remembering how to run. The smart variety still remebers how to do trivial tasks, like opening doors. The dumb ones can only run towards a target. If they lack a leg they will be unable to stand up, walk or run.
• I'm trying...but I don't think these could power a war machine of the 'ancient tank' type that you proposed in another thread. It's simply too heavy. Still at drawing board Mar 24, 2015 at 19:13
• @DustinJackson - it doesn't have to generate electric power to be useful. The Romans certainly knew how to use water wheels.
– BenM
Mar 24, 2015 at 21:54
• I think a zombie hamster wheel might be more efficient than a treadmill. Mar 25, 2015 at 0:02
• Not quite perpetual. You will need to replace the human flesh as insects, bacteria and other non-zombie flesh eaters slowly disintegrate it. Mar 25, 2015 at 3:56
• but if you burn the flesh it will generate less energy than those generated by the zombies. ie.: above unit efficience Mar 25, 2015 at 3:59

140 Watts

We have the data for humans on treadmills, so the assumption is that the maximum power for a zombie is the same. They were once humans, right?

You might shave off a few tens of watts due to the shuffling nature of their gait. But at least the power generation is more constant for a zombie, humans get tired too quickly.

You'd be much better off teaching one of them to ride a bike. Or maybe that's one of those things zombies never forget either? In any case, the maximum for a bike is closer to 400 Watts. Just don't let them escape after that, we don't need any zombies riding bikes around after people.

• Now I want to see a zombie marathon ride, and I don't even like zombies! Mar 24, 2015 at 18:45
• What a great, specific, and short answer to this question, love it. Mar 24, 2015 at 20:29
• That correlates to roughly 0.2 horse power for walking and 0.5 horse power for riding a bike. You'd be better off with horses and we already have a question about the feasibility of horse driven tanks (hint: any size tank you build will need more horses than can fit inside it) Mar 25, 2015 at 4:07
• @slebetman Can a horse make more horses by biting the enemy? Because if you lose half your team that's a pretty convenient zombie trick to replace them. Mar 25, 2015 at 16:44
• we don't need any zombies riding bikes around after people. Cue the dramatic "What have I done??!!!" moment. Aug 25, 2015 at 22:23

A typical human can produce and sustain between 50 and 150 Watts walking, or as high as 400 Watts on a bicycle. However, that is for long-term, sustained output; since these zombies essentially never get tired, they actually can produce a lot more power. By setting the treadmill at an incline, stepping up the gears, and adding hand/footholds for the zombie to use as leverage, the zombies should be able to attain peak energy production of a human, around 2000 Watts, or 2.68 HP. As a plus, higher gear ratios means that zombies won't run; this leverages strength, not speed.

Wear-and-tear will play a role over time, but as long as you have reserve zombies to replace those that fall apart, you should be able to power whatever you want. Romans already had several slave-powered devices, and zombies are much cheaper than slaves, not to mention easy to store: dump them in a sealed bucket of oil, and they'll last forever!

Would this provide enough power to move a war machine ?

Do catapults and chariots count? They can pull from a catapult until it's set up in place. And if they can pull chariots at 30 km/h, even if that's not much, they can pull longer and farther than horses.