Couldn’t we have a lead box lined with these radiation to electricity converters with a small amount of radioactive material in the center, and have an energy generating device that would last for thousands or even millions of years? Imagine putting the sun in a box lined with solar cells, but on a much smaller scale.
Is there a reason this wouldn’t work?
Betavoltaic devices are exactly what you’re describing. They convert beta radiation (energetic electrons) into electricity in the same way that photovoltaic cells (solar panels) convert photons into electricity. You can create a nuclear battery by putting some radioactive material that decays via beta emission in one of these.
The downside of these devices is that they generate very little power. It takes a dangerous amount of radioactive material to generate the power needed for say a phone or laptop. Commercial betavoltaic devices generate ~tens of microwatts. They’re useful if you need a low power battery somewhere that you don’t want to replace, like in a remote sensor.
I wonder sometimes about the efficiencies/outputs of some technologies lagging because other technologies are plentiful and easier, even if the potential is there for a better system.
Obviously internal combustion engines come to mind, and the reliance on fossil fuel. I guess it only took us 10 focused years to get to the moon once upon a time, so humanity will pull it off at the last minute.
With betavoltaics it’s more a matter of physics than lack of engineering refinement. Even assuming 100% efficiency, you would need something like 250 gallons (1000 liters) of tritium gas at atmospheric pressure to power a 100 Watt lightbulb.
Nuclear reactors, however, absolutely should be supplying a larger fraction of our electrical grid. Traditional, large reactor facilities have such a high cost and long timescale for permitting/construction that it’s difficult to get newer, more modern reactors built in the US. There are some exciting developments in small, modular reactors that would sidestep these issues. I believe a few designs are in the process of being built for full scale testing.
So you need to consider the relationship between the amount of decay radiation and how long a substance lasts. The more radiation, the faster the fuel will decay. If you want something to last a long time this way it will probably be too stable to generate a lot of energy.
What the hell is this thumbnail?
Looks like some imitative ML hallucinated it.
The doodad is working at peak efficiency
This article has a good breakdown. The biggest issue is efficiency. RTGs are around 5-9% efficient. Standard steam cycle generators are around 30% (see this article ) . You get much more usable energy from fuel used in a commercial reactor vice a RTG.
From the article it looks like RTGs are just converting the heat energy into electricity. Seems like there’s a lot unused potential being missed.
Can you ELI5 why the efficiency is so low on the RTGs?
They take the waste heat from nuclear decay and convert it to electricity through the use of a peltier device. Those work off of differential temperature and are pretty inefficient to begin with. Unmderated Nuclear decay doesn’t produce a lot of heat at one time, which is why reactors use a moderator to increase the power output.
It works, but if I remember well my material science course, the yield is pretty bad compared to a simple steam-turbine. Therefore engineer chose the simplest and most efficient design. And this is how the most advanced energy source humanity have end-up being controlled by a good old steam machine
Looking into it, it should be theoretically possible to get a material that decay into beta particles trapped in sphere that would gather these particles and thus electrically charge the sphere.
I don’t see how you turn it on or off though, which might be a problem.
On of the fusion reactor designs works this way. Sorta.
The reactor creates a magnetic field, then fusion happens, creating a magnetic (or electric… iono. Not a nuclear engineer) field flux in the same coils that created the initial field. Fusion stops, then the flux is ‘harvested’ somehow to generate electricity directly. Then the field is primed again, and fusion happens again. It’s pulsed and happens 60-100 times a second.
I think the company working on this is called Helion.
