So the ideal of solarpunk is obviously that you would not need one, but if not every nation went in a solarpunk direction at the same time, you would likely need a defense against those that did not go in this direction and wanted the natural resources of solarpunk societies that obviously aren't as interested in exploiting their own resources.

Politically, the society is somewhat more decentralized than modern capitalist ones, but they still have a degree of quasi-national government for certain things(like a military to defend against a foreign aggressor, keeping electrified railroads between cities active, and monitoring those who might cheat on extremely strict environmental regulations). How might a military be structured for such a society?

Starfleet from Star Trek might be a source of inspiration given the shared optimistic focus, but it really doesn't work all that well. The problem is that Star Trek posits an extremely advanced society in terms of technology and especially energy output. Their reliance on starships and orbital/air power is fairly hard to adapt to a society that is deliberately relying on less energy than is required. The closest modern equivalent would be a powerful air force whose fighter squadrons pretend they are primarily for aerospace testing and airshows in support of extremely light ground forces that pretend they do something other than soldiering and thus generally lack the proper equipment to do it.

The likely enemy is a more or less cyberpunk nation that heavily uses mercenary companies to back up the government military that is one of the few things more or less funded, but for the sake of simplicity, assume a more or less modern tech level. The tech will probably advance a fair bit, but it is easier to ignore this for now and convert things later.

EDIT: The real question I think should be about how to make a military less wasteful overall. What changes would have to be made here?

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    $\begingroup$ To comment to my own post for something off topic, it occurs to me that there is something insidious about the way Starfleet recruits. They take recruits who joined up to become scientists and explorers and wind up turning them into front line soldiers. Even worse is that unlike most soldiers from highly prosperous societies, they lack the proper equipment that increases their odds of survival because they don't want to admit that they actually are a military. Though the real problem with Starfleet is that their issues are largely a case of production limitations becoming worldbuilding. $\endgroup$ – Adam Reynolds Sep 13 at 8:08
  • $\begingroup$ You might look at the US military's research into green fuels & solar power, e.g. reuters.com/article/us-usa-military-green-energy-insight/… $\endgroup$ – jamesqf Sep 14 at 3:00

Frame Challenge: Militaries by nature require waste and reducing it reduces your military potential.


In order to have proper soldiers, they need quite a bit of training. This means you can't reasonably put a 1 month trained recruit squad against a SEAL squad and expect them to perform well. The SEALs are trained much more stringently.

Reducing the number of available personnel also reduces the chance of military success. Due to the training time, if you don't keep a populated enough military then when the conflict happens you likely won't have enough personnel to send to the battlefield and won't have proper useful personnel added for quite some time.

Training troops requires resources. Keeping those troops for extended periods is more resources. Using more resources to keep your military in tip-top shape without conflict could be considered "Wasteful".


Just as with your troops, keeping equipment available and ready to go is also wasteful. Additionally, you have to expend some of that equipment in order to keep your troops properly trained. (If I had the link for how long equipment can be operated before replacing vital components I would put it here probably).


Potentially you can find a balance where the amount of troops and equipment you have is enough to buy you time to alter manufacturing and recruiting to gather more equipment and troops. Although, exactly what timeframe that would require is a whole question worth asking.

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Solar panels on military vehicles wont happen

Perfect utilisation of solar power gives about 1kW/m^2 during peak daylight. This is actually a lot of power. However it's not enough for direct use in a military as we know it.

An F-35 fighter with 100% efficient solar panels over its skin could absorb a peak of about 70kW of power. That's a lot of power, until you realise that one of its engines is rated at 22MW.

You have the same problem with APC's, tanks, etc. They need more power than the sun provides. You need to have batteries on board anyway for nighttime use, but this just results in a poor duty cycle, eg the solar powered F-35 could only fly for 1 hour for every 300 sunlit hours on the ground.

Submarines don't get much sun underwater. Ships aren't much better. If the USS Gerald R Ford had solar panels embedded in it's flight deck it would get 26MW of power at peak, its reactors currently give up to 1.4GW.

But you can have a green, solar powered military

  • You have a massive field of solar panels, cranking out GWs of power.
    • Current tech levels you can get 38MW per Square KM, theoretically up to 1GW is possible.
  • Adjacent to that, you have a Power-To-Methane factory, which takes power, CO2, and water, and puts out methane and oxygen.
  • And adjacent to that, you have a Methane-To-Methanol factory.

That methanol contains the captured solar energy (5.4kwh/L), and is used as a low risk, easy transport fuel, similar to gasoline now. Batteries will probably still be needed, by methanol should be preferred, as they're 25-50 more efficient per kg.

Really high power / low weight applications (like the F-35) might be better off just using methane (or liquefied hydrogen / oxygen if we're really getting extreme), but storage of a high pressure gas is much more fickle than storage of a liquid.

As an extension; Liquid hydrogen and liquid oxygen can be made from the power to methanol plant. (Basically hydrolysis and then refrigeration). This would allow for a Green Space Program

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  • $\begingroup$ You could also fuel some vehicles using biofuel made from food waste as a supplement if you want to crank up the green credentials even more. Chip-fat fueled tank, anyone? $\endgroup$ – Joe Bloggs Sep 13 at 10:53
  • $\begingroup$ But that F-35 would probably work perfectly well on biofuel, since other jet fighters (and other planes) have been tested with it: en.wikipedia.org/wiki/Aviation_biofuel $\endgroup$ – jamesqf Sep 14 at 3:02
  • $\begingroup$ Cut out the middleman, there are solar bioreactors that should be able to produce butanol sciencedaily.com/releases/2019/07/190726094651.htm $\endgroup$ – DWKraus Sep 14 at 16:56
  • $\begingroup$ Methane is not as fickle as you might think. Compressed to 5000PSI in a fiberglass tank, it is lighter, safer to handle, and better for the environment than gasoline (petrol) while having about the same energy density to volume ratio. By pre-compressing it, you can also fill a methane tank just as fast as a gasoline tank. $\endgroup$ – Nosajimiki Sep 14 at 19:39

Flying drone avatars.



Solar power is collected by high altitude dirigibles, floating well above the weather and transmitting power wirelessly. Flying humanoid robots patrol everywhere, and see everything. Perhaps they return to the dirigibles to recharge.

These flying robots are autonomous most of the time. They are capable of striking from altitude, like the drones we have now. They can come close for a better look. They can land and interact with persons on the ground - not for hand to hand fighting but for police and rescue actions, and to ask questions.

Like an automated answer system which can put a live operator on, one of these robots can be taken over by a remote operator. This might be a paramedic, a person with expertise in car repair or nuclear technology, or whatever the situation warranted. This person inhabits the robot and can carry out operations on the ground.

High flying humanoid drones would be flexible and able to help this society in many ways. There is also a hint of Big Brother(s) which could be good for a futuristic fiction.

As regards military operations, the drones would be very effective. They could demonstrate their abilities from altitude, then a negotiator would come down with one of the drones and interact with insurgents or enemy military.

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Decentralize operations, especially in theater. Smaller, modular, deployable field bases that provide greater opportunities for in-situ resource utilization can help break your dependency on the great weakness of modern militaries, the supply chain. You don't need to rely on shipping tankers of fuel or piles of ammunition from supply depots to the front lines, which means your supplies can't be intercepted or stolen, they're harder to sabotage, and you aren't painting a big bright truck-shaped arrow saying "they're over here!".

Actually achieving full resupply in the field is a tall order. You'd need power generation - solar, hydropower in some areas, maybe biofuel generators - and you'd need the ability to convert some of that power into liquid fuel of some kind for vehicles. You would need the ability to recover or create ammunition. (Coilguns would be ideal here because the propellant is electricity and the projectile can be anything ferromagnetic; you could make your own bullets from scrap if need be.) You would need to be able to provide food and medical supplies, either from some kind of field production or from very efficient storage. (Read: military rations will still be unpalatable.) However, even if you still need to metaphorically come up for air once in awhile, anything you can do to reduce the size and frequency of supply shipments will pay dividends in your units' maneuverability and security.

Decentralized operations also provide a useful (but potentially very dangerous) political independence for your troops. If you're reliant on Acme Co. or the City of Wherever for your supply lines, you're not going to do anything that could upset them: even if they didn't simply let you starve (for fuel, for ammo, or just literally) the tension between you would invariably result in less efficient supply shipments and thus weakness on the field. But if your supplies are independent, you can go over and put pressure on the city whenever the central government needs you to, without worrying where your next meal is coming from. As I said, dangerous as well as useful - this also means your government can't reign in a rogue operator as easily.

Finally, from an out-of-universe perspective, this gives you an excuse (or opportunity, if you prefer) to justify why your group of protagonists are operating without a million forms and constant logistics shipments and oversight and everything. They can go where you need them to go, fight who you need them to fight, without worrying about it. And for a videogame specifically, it's pretty much tailor-made for the conventions of most of your major genres: relatively small numbers of troops, a mobile base that can meet most of your needs, on-site production, etc.

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I don't know if this helps but what I immediately thought of was the setting for 00 Gundam. In this world, all the major countries have access to "Solar Elevators", which are towers that extend past the atmosphere and have solar panels miles in length, to collect energy. The solution for these countries was to focus on single units rather than mass production of jets/tanks/ships. This requires the individual units to have the strength of multiple, smaller units. The amount of materials used to manufacture a single, higher output machine, far outweighs the cost of mass producing hundreds of weaker machines. This is far less wasteful. The GN drive that powers the titular mecha, Gundam Exia, has six times the output of a mass produced mecha, the Union Flag. Incidentally, these GN drives are also known as solar reactors or furnaces. Individual units also have the capacity for one on one combat rather than large scale battles which leads to quicker conflict resolution. For another thing, who prefers a Stormtrooper to Darth Vader? At least in this show, mass-production always gives way to fine-tuned individual units.

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Go small, go swarmy, go green

Going solarpunk also meant for your society to go greenpunk. Higher integration of technology with the biosphere.
They may be able to control swarms of insects (mosquitoes, hornets, fleas, etc) after converting them to accept hive like instructions. These species may be able to produce special toxins on demand or, as a safer option, to go collect toxins from special reservoirs setup by the army.
Integrated hardware in the insects would allow the army to direct and support them (providing food and shelter, integration in tactics together with army squads on the field and so on).

They would not be able to destroy an APC but neither would the APC be able to destroy (or detect) them. But they would be able to spy the enemy unseen and report back either with the movements like the dance of the bees or strightforward hardware integration.

The enemy would need to resort to chemical warfare against them and there would be an arms race in this field.

Of course they should not be the only weapon available to the solarpunk society but more an important asset to be used in combined arms tactics.

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Humans have been shaping the creatures around us for tens of thousands of years; just because lifeless mechanical equipment has outpaced bioengineering lately (with regard to war machines anyway) there's not much reason to expect biotech to sit around content with plagues & cyborgs:

Almost any conceivable piece of equipment could be made from living organisms, largely self-repairing, & reproducible at higher efficiencies than metal & plastic units.

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