What Power Source Can Last and Function for Over 10,000 Years?

[BernieM]

I am going to be building a small 'monument' that will be intended to last thousands or more years. I would like to include some electronic/electrical appartus that will have a small power consumption when demanded (no power use until a button is pushed or something). My question is this (and I know there may be many reasonable answers)... What kind of power generating or power storage equipment could I build that would be the most simple and most reliable over a very long period of time. The power I would need would be less than 40 Watts instant demand, and probably 10 watts continuous for a few hours at a time. Of course more is better.

Picture this example:

Someone 10,000 years from now happens into a cave and finds a simple apparatus that intrigues them. Upon examination they realize there is a button to push and push it. This apparatus then displays some information to them in some manner. If they see it is broken, provided they are not the intellectual equivalent of a monkey, they may see what it is that needs to be set right and repair it.

I don't want some device that is the size of a house or that requires materials that will definitely put me on some terrorism list (think uranium or plutonium). Simpler is better. Something that is easily repaired or replaced by someone that is intelligent yet unskilled would be nice.

A voltaic pile would be really cool provided I could rely on it to function 10,000 years from now and that it would last an extremely long time. I know there are some still working today, but I really don't know what to expect of them over millenia ...

However a very simple bike like or crank device that would power a small generator may be very workable, however, it would have to be of a design that was very robust and virtually indestructible.

Solar is mostly out of the question unless someone knows of a glass that never needs cleaning and will remain unbroken over millenia.

Anyone want to shoot me some good solid ideas?

 

[mfb]

I think I would go for the mechanical power input and a simple generator. It should be more robust than anything you do with your electric power afterwards.
The real challenge is not the lifetime of the mechanism inside, it is the storage of the object. If it survives for several thousand years, our descendants are probably smart enough to study it.

Radioisotope thermoelectric generators would be better, but they need significant amounts of long-living radioactive material.

 

[Travis_King]

What's going to be displaying the information? If it's electronic, I think that's where you're device would falter in 1000+ years.

 

[AlephZero]

Historically, "mechanisms" that have already survived thousands of years mostly use the rest of the solar system, or even naked eye stars, as "moving parts". They don't have to be as elaborate as Stonehenge. Even a single standing stone can mark the two solstices, if you can align it with a couple of mountain peaks on the horizon.

The only problem is that, without the user manual, it's hard to figure out what those "mechanisms" were really meant to do.

 

[BernieM]

The display mechanism may be something like an 1800's Zoetrope, a purely mechanical device.

Is thorium a good candidate for a radioisotope generator? I know that it is used in gas lantern mantles and that tungsten welding electrodes can contain several % thorium. I figure it would be much less efficient than plutonium and might have to have a larger mass of it or a much larger device to compensate for the inefficiency of using it ... but that might be workable.

Anyone know how well an Earth battery might work?

 

[justsomeguy]

Personally I like the hand crank. You could store a 'box' of spare parts (sprockets/gears, graphite lube, chains if it's a chain drive) right there with it. Throw a flywheel (rechargeable mechanical battery!) into the mix so your future investigators can crank for a bit and then stop to watch.

 

[BernieM]

I think spare parts and a good, simple diagram of the system's use, maintenance and repair (users manual) is definitely called for.