The massive Golems are nearly impervious to harm. Thanks to the New Golem Army, the nascent Dutch Republic's castles and forts are now safe from harm. The century-long external threat has been finally and permanently put to rest, as the bones of our enemies are bleaching in the sun by our castle's walls.

A decision has been recently made in the Staten-Generaal council that defense is to give way to offense. We will no longer be content to defend ourselves in our high castles, leaving the enemy to roam free, but instead, we will march out and take the fight to them, and bring them down for good.

This brings up obvious problems. The strings of wind- and river-mills on our mighty rivers and polders are currently providing the power elektrik to galvanize our Golem troops.

The question now is how do we handle this out in the field, far away from the castles and the galvanic stations? A young apprentice has suggested that given the frequent storms that batter the lands of our neighbors, we could power our army from the lightning strikes themselves. Would that be plausible with our rough copper wiring? How much energy could we harness from these bolts?

Assume that golem insides are a black box, we don't care about that. Would capturing lightning be plausible with early renaissance technology? If so, how could it work and how much energy could we get?

For the sake of argument and specificity, let's assume that a fully charged golem can operate for 5-7 days on normal stress level, and for 1/2 day in intense combat. Before you ask, I didn't get the chance to run a voltampermeter by the golems, so I don't know their full capacity.

If lightning is deemed unfeasible, I'm willing to hear suggestions for alternative ways of charging up in field operations conditions.

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    $\begingroup$ Great premise, but electricity wasn't discovered until the end of the Renaissance and the battery not for another hundred years (see this). That your citizens know about electricity implies a higher technological level. $\endgroup$
    – Frostfyre
    Jul 30, 2015 at 18:54
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    $\begingroup$ Compound that with the fact that we still can't build a sufficiently high capacity, fast-charging-enough battery/storage system to handle the immense amount of current that a lightning bolt delivers. $\endgroup$
    – Green
    Jul 30, 2015 at 18:55
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    $\begingroup$ yeah, in this alternative world, Hero of Alexandria invented hydro and steam, and studied electricity, and was promptly forgotten (like in the real world), until a dutch-jewish glassmaker by the name of Baruch Spinoza rediscovers him. Combine it with his mad Kaballah knowledge, a Spanish invasion, and golemity ensues. $\endgroup$ Jul 30, 2015 at 18:59
  • $\begingroup$ But, since Golems at that tech-level are essentially magic, I'm wiling to go with some handwaving to make it happen. There's no hard-science. $\endgroup$
    – Green
    Jul 30, 2015 at 19:00
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    $\begingroup$ He specifically said how the golems work is not relevant. Just tell him how much power can be harnessed from a lightning bolt! $\endgroup$
    – James
    Jul 31, 2015 at 2:29

5 Answers 5


Lightning is quite conceivably a good source of power for the golems. An average bolt of negative lightning delivers 500MJ of energy, and a large negative bolt could deliver 35GJ of energy. Positive lightning bolts are very much rarer, but could deliver up to 3.5TJ. In terms of watt-hours, this equates to 138kWh for an average negative bolt, 9.72MWh for a large negative bolt, and 972MWh for a very rare positive bolt.

Assuming that a golem uses about a hundred times the energy per day of an average human male (11MJ or 3kWh), i.e 30kWh/d or 180kWh/charge (lasting an average of 6 days of non-combat operations), it might take two average lightning strikes to charge a golem, or one large one could charge up to 54 golems. You couldn't count on a positive bolt occurring all that often, but if it did occur - and polarity wasn't an issue - then it might charge up to 5400 golems in one strike.

Naturally, given that a lightning strike might more than charge a single golem, a golem force would be interconnected and charged as a unit, not as individuals.

We'd better hope that the golems can accept this fantastically high charging rate without exploding - Negative lightning can have currents of 30-120kA, and positive lightning 300kA, and if this energy was released over a very short period of time, might result in an explosion equivalent to nearly 12kg of TNT for an average lightning bolt.

The main problem with this is getting the lightning to strike where you want it to. Fortunately, the emerging field of rocketry can come to your rescue. A simple black-powder rocket (appropriately waterproofed for use in a thunderstorm) could drag a fine copper wire into the sky high enough to attract a lightning bolt, which will strike down the wire, incidentally turning it to plasma, but causing the bolt to strike right where it is needed.

Sure, you'd need a lot of copper wire and rockets to keep your golems charged, but war is expensive, and this is a minor cost. You just want to hope that thunderstorms in the area of operations are as frequent as people say they are.

  • $\begingroup$ Ah, this is great, having some numbers tho play with. Also, the positive lightning could be a plot device $\endgroup$ Jul 31, 2015 at 11:02

I would not base my strategies on that.

Seeing how they power their golems, we can safely assume that they have some knowledge of electricity. Technology isn't too complex, you need metallic rods and connect them to some batteries or directly to the golems.

However, I would recommend to think about another alternative. Indeed, storms are very local phenomena, and lightening strikes are hard to predict (you can improve by changing the voltage of your rod, but you probably want to save on energy. And what would be the autonomy of the golems after a storm? Plus your enemies might now that, and hide after a storm before attacking once the autonomy is over.

It is hard to devise a strategic campaign on seemingly random and unpredictable elements.


With the water mills, they have some alternator technology. A more flexible, based on the same technology are windmills. The Windwheels were known since antiquity. And it could be based on, e.g. the top of siege towers for large production. And individual wheels could be placed on more transportable poles. With the autonomy they have, you could be sure to prepare well for field battles.

  • $\begingroup$ I like it, windmill siegetowers! $\endgroup$ Jul 30, 2015 at 19:16
  • $\begingroup$ As an alternative to windmills, they could probably put some giant hamster wheels in their siege towers, and have the horses generate electricity whenever the army stops. That way, as long as you have the ability to move the generators, you also have the ability to power them. $\endgroup$ Jul 30, 2015 at 19:53
  • $\begingroup$ @DaaaahWhoosh that's a good upgrade. Maybe except for the horses. You need to carry around horses though. And they can't be used to move the towers as well as run the wheel. And you need food. But on the other hand, you have a more predictable source. One could try to combine... $\endgroup$ Jul 30, 2015 at 20:04
  • $\begingroup$ @bilbo_pingouin Are you suggesting that the windmills are running while they're being transported? I thought they'd be assembled when the army set up camp, at which time the horses aren't doing much. But otherwise, yes, a hybrid system would be preferable. $\endgroup$ Jul 30, 2015 at 20:09
  • $\begingroup$ @DaaaahWhoosh, No, of course not. But you still need to carry around the material. Do you want to write your own answer or should I edit mine? $\endgroup$ Jul 30, 2015 at 20:11

The problem with using lightning-power is that it's not a very reliable power source (unless you have weather mages on hand), plus it's probably way too powerful to be safely harnessed by Renaissance-era technology. Not only that, but once your golems power down, you'll have to wait for the next rainstorm to get them going again. It's very possible that the enemy could seek to recapture their lost land in that time, and without your golems you're going to be in a tight spot.

Other answerers have suggested wind power, but again, you have to rely on the wind, and in a wartime scenario I would not want to leave the effectiveness of my strongest units up to nature.

What I propose, then, is to make some adjustments to your watermills: in short, turn them into turnstiles or hamster wheels, and use good old-fashioned horsepower to generate electricity. This method will make use of things you should already have: the technology for horses turning cranks has been around for a very long time, horses are already a must-have for any military expedition, and the food to power them grows right out of the ground.

The downfall to this system is that it is not going to provide the energy you need nearly as fast as a lightning bolt. Your army is going to have to sit around for a while waiting for their golems to charge before attacking. But back during the Renaissance, this already happened; either you met the enemy at a field and discussed terms for a while, or you met the enemy at their castle and laid siege for a few months. This should give your army enough time to power their golems, at which point they can do their thing, then go straight back to recharging to fend off any counter-attacks.

  • $\begingroup$ Sure, ox-powered golems might not be sexy, but they will come in handy in a pinch... $\endgroup$ Jul 30, 2015 at 22:41

Ride the Lighning

As long as the Golems can shrug off the extra current from the lighting bolts they don't need, then using lightning to power them is completely feasible. In the context of the story, only being able to operate in the context of thunderstorms makes for some really interesting strengths and weaknesses. Golems only have the power to attack when there's a thunderstorm but when they do attack, they are unstoppable.

Attacks during a thunderstorm may prove exceedingly dramatic. "A wall of Golems advanced out of the gloom, lightning dancing along the charging towers looming behind them. An unearthly, crackling glow came from the Golems eyes striking fear into the hearts of the hapless defenders."

Large copper cables are sufficiently conductive to act as grounding wires for lightning rods. I expect that there would be a couple accidents where someone forgets to keep the lightning aggregators grounded and gets fried when a lightning bolt jumps to something/someone it wasn't supposed to.

Portable Windmills

This is the mundane approach. If military operations need to happen in the winter with it's despicable lack of lightning then this would be a good evolutionary push to develop windmills that are mobile. Certainly not self-powered but something that can be deployed behind friendly lines similar to cannon or siege weapons. With the right kind of demand, inventors could quickly discover ways of building portable galvanic generators. Even if the inventors don't know exactly how the portable generators work, they will know that they work and can experiment to find ever more powerful generators.

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    $\begingroup$ I like miniwindmills, but would that be enough to run a hairdrier, never mind a golem? $\endgroup$ Jul 30, 2015 at 19:26
  • $\begingroup$ Large modern windmills can generate up to 3 MW. That's a lot of juice. Building windmills that large wouldn't be feasible back then but you could build lots of smaller ones. gwec.net/faqs/… $\endgroup$
    – Green
    Jul 30, 2015 at 19:29
  • $\begingroup$ They're not windmills they're wind turbines. Windmills do not work that way. Also, you need to have 50 meter blades sweeping 7853 square meters at 100 meters off the ground to get the 3 MW range. $\endgroup$
    – Samuel
    Jul 30, 2015 at 21:26

You have golems. Consider building a giant dam if you have a suitable river. Hydro power will keep 'em going. Gonna need heavy duty extension cords though. Expensive but not undoable (wrap steel cable in rope and soak in wax, run at 10,000 volts).


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