> Are there super capacitors with expected lifetimes measured in centuries / millennia?
No, certainly not. Supercapacitors self-discharge significantly faster than batteries do. Capacitance is proportional to the surface area of the electrodes and inversely proportional to the distance between them. Resistance is the opposite, so roughly speaking higher capacitance means higher self-discharge.
The current go-to for long lasting batteries is lithium thionyl chloried, used in remote areas, embedded electronics and things like portable defibrillators. Those are some of the most energy-dense batteries available (though not rechargeable) and can hold most of their charge for over a half century.
The Oxford Electric Bell[1] was linked in the comments under the post, and it has been ringing since 1840. It's not known what kind of battery it has, but its some kind of dry pile. Dry piles generate voltage via corrosion of metal (eg zinc) and have extremely high resistances between plates since there is no liquid electrolyte. As long as they are kept relatively dry they have incredibly long lifespans, although their power output is miniscule- orders of magnitude smaller than even this motor.
It might make more sense to tap into an extremely long-lived source of power, such as geothermal. Over millennia tectonic shift is only a problem across a fault. As long as you can set up a thermal gradient (eg by pushing a stainless steel wire deep into a hole), you can run a Peltier (Seebeck) generator. Some semiconductors have meaningfully limited lifespans and eventually fail under normal use, but many are effectively inert and last as near to forever as we can figure. I'm pretty sure most thermoelectric junctions are the latter, with exceptions for radiation. They have a standard MTBF of just under 23 years with frequent thermal cycling, which is the most damaging thing you can do. It wouldn't be hard to imagine it lasting millennia in a sufficiently stable environment.
No, certainly not. Supercapacitors self-discharge significantly faster than batteries do. Capacitance is proportional to the surface area of the electrodes and inversely proportional to the distance between them. Resistance is the opposite, so roughly speaking higher capacitance means higher self-discharge.
The current go-to for long lasting batteries is lithium thionyl chloried, used in remote areas, embedded electronics and things like portable defibrillators. Those are some of the most energy-dense batteries available (though not rechargeable) and can hold most of their charge for over a half century.
The Oxford Electric Bell[1] was linked in the comments under the post, and it has been ringing since 1840. It's not known what kind of battery it has, but its some kind of dry pile. Dry piles generate voltage via corrosion of metal (eg zinc) and have extremely high resistances between plates since there is no liquid electrolyte. As long as they are kept relatively dry they have incredibly long lifespans, although their power output is miniscule- orders of magnitude smaller than even this motor.
It might make more sense to tap into an extremely long-lived source of power, such as geothermal. Over millennia tectonic shift is only a problem across a fault. As long as you can set up a thermal gradient (eg by pushing a stainless steel wire deep into a hole), you can run a Peltier (Seebeck) generator. Some semiconductors have meaningfully limited lifespans and eventually fail under normal use, but many are effectively inert and last as near to forever as we can figure. I'm pretty sure most thermoelectric junctions are the latter, with exceptions for radiation. They have a standard MTBF of just under 23 years with frequent thermal cycling, which is the most damaging thing you can do. It wouldn't be hard to imagine it lasting millennia in a sufficiently stable environment.
[1]: https://en.wikipedia.org/wiki/Oxford_Electric_Bell