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Comment by gus_massa | Hacker News Reader

Stupid title, but interesting article. They try to use radioactive Carbon-14 to make diamonds to produce heat in a RTG power source.

Obviously it doesn't have near infinite power. The amount of power will be very small, but it may be useful for some applications. Also, the half-life of C14 is 5750 years, so after a few milenia it will need a replacement.

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Ok, we've stripped the title of near-infinite power above.

It's not an RTG, it's a betavoltaic device. They directly convert the beta radiation to electricity, using a semiconductor also made of carbon.

Half-life means that after 5750 years half of it will have decayed, then half of that in another 5750 years, half of what's left in another 5750 years, and so on. That's about 20000 years for still 10% of the original power output, and it won't go totally dead for some million years more.

Yes, but it's the operational energy that he's talking to and it's even shorter than that.

If the power output is expected to be 1000W, usually you design the system to utilize all of it. So as the power starts to degrade, even when you're really far from the half life, it may not be enough to power the systems.

Specifically, the Voyager's RTGs have degraded a lot since Pu-238's half life is much shorter[0], but most of the machine's systems can't run at ~67% power. We're basically down to the very last few experiments running intermittently.

So for useful energy, parent comment is largely right. You've got <5750 yrs of usable work, which is absolutely fantastic.

[0] https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...

usually you design the system to utilize all of it

So, don't do that then. Adding capacitance is a problem, dumping heat is not. Seems a small issue (at low power) for a doubling of operational lifespan.

No chance of using some sort of capacitor or staged voltage operation so different components deactivate as the power degrades?

You'd have to design a capacitor, or the equivalent, that could last thousands of years for stuff that you can't service (like a space probe). That is a pretty big ask for many materials in general.

Right out of the gate aluminum electrolytic capacitors are out as getting 10-20 years out of consumer grade ones is pretty good. I have a single monitor I've replaced caps in 3 times now (and they weren't even a known bad batch) in the past 10 years. Electrolytic caps will go bad even faster if they aren't regularly receiving electricity, many have a 2 year shelf life. If you've ever plugged in a vintage electronic (say an Atari/Commodore computer) and you've had smoke-like stuff come out, that's usually the electrolytic capacitors going. If you open up an old device that has had one or more fail, you'll find this brownish-black stuff all over the insides after they go.

Most super-capacitors would die from use long before useful power output, they're usually good for a million cycles or less so even at one cycle a day you're only looking at 2700 years and change.

Polymer electrolytic capacitors are good in use for 10-15 years.

Pretty much every capacitor out there right now has a 5-15 year lifespan.

A data point from the Apollo Guidance Computer restoration: we found all the capacitors worked perfectly after 50 years. This included a bunch of electrolytic and tantalum capacitors.

They weren't in use that entire time though and I'm guessing they were kept somewhat climate controlled too which helps a ton unlike other vintage electronics that get shoved in attics/garages and exposed to wide temperature ranges year after year. First thing I do when I buy a new vintage computer or computer accessory (I'm an 8-bit Atari guy) is change the caps (period) and then remove anything socketed and clean the leads.

You actually worked on restoring them? Do public images of the innards exist anywhere from that? I'd love to see that, the innards of old electronics and machines are just so beautiful in their simplicity. You can look at them and actually understand what is going on.

Edit: found your blog, getting lost in the images.

Climate controlled? No, the AGC was in a junkyard in Houston and then years in a barn. The capacitors worked because they were aerospace quality and thoroughly tested.

For more information on the restoration, see my blog http://righto.com and videos at http://youtube.com/curiousmarc

Already subscribed and a few posts deep now, really cool stuff! If you see a spike in visitors I shared it on the AtariAge Facebook group as a lot of them will probably also dig your content.

Voltage is part of the problem for sure, which a variable transformer can definitely help keep voltage at a steady operation (you may not even need that since it's a Thermoelectric generator... I'm not familiar enough).

But it's primarily wattage - at some point the overall power dips too low to maintain voltage at that amperage to keep the system alive.

Indeed the title is not great. I assume that by 'near infinite power' they mean in duration, not magnitude.

Power is a measure of energy per time, so to get nitpicky about it that's the equivalent of saying "near infinite speed" about something that goes a mile per hour for a few thousand years.

It'll cover some distance, yeah, but it's not what I'd call speedy.

> "Primarily though, they are best for devices requiring long lifetime, low power and where it is difficult to replace energy sources."

Infinite power or low power? I think they mean infinite energy. As in "The power went out".

It's a lot anyway. Although peak power is not great.

Over 5000 years the output would be a few tera Joules of energy. The first prototype used nickel-63 (see https://en.wikipedia.org/wiki/Diamond_battery)

It could be interesting coupled with an ultra-capacitor, if you have something that has sporadic high energy demands, but not always. Think a remote sensor, or pace maker, or such devices that need a short spike of power, but on average the energy requirements are not huge.

Literally the inverse of power!

I guess you would not get much power given the long half life (as the stuff decaing is what gives you power and this thing doesn not decay a whole lot), but it will give you that power level for quite a while.

I can't hear 'carbon-14' without thinking of archaeology.

Archaeologists of 3020: We carbon dated this object, and it comes from the future.

It will likely end up in a landfill after a year or 2.

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