It also creates some radioactive isotopes of gold, so it’d have to sit there for 12-14 years before being useful.

My guess is that once the radioactive cycle time is up, it’d create more gold than the economy knows what to do with, and the price would collapse. They’re quoting 5 metric tons of gold created per GWh of electricity created by the fusion reactor. There are 3,000 metric tons of gold mined every year. Worldwide energy production is 26,000,000 GWh. If we had 20% of that on one of these fusion reactors, there would be 26,000,000 metric tons produced.

It’s estimated that for all of human history, 244,000 metric tons has been mined.

Gold ain’t that useful, and it isn’t even that artistically desirable if it’s common. I think we’d struggle to use that much. Maybe if the price drops below copper we’ll start using it for electrical wiring (gold is a worse conductor than copper, but better than aluminum). Now, if the process could produce something like platinum or palladium, that’d be pretty great. Those are super useful as catalysts, and there isn’t much we can extract from the Earth’s crust.

If late stage capitalism hasn’t played itself out by then, what’s going to happen is similar to solar deployment now. Capitalists see that solar gives you the best return on investment. Capitalists rush to build a whole lot of solar farms. But focusing on just solar is a bad idea; it should be combined with wind, hydro, and storage to get the best result. Now that solar has to be turned off so it doesn’t overload the grid, and that cuts into the profits they were expecting.

Same would likely happen here. The first investors make tons of money with gold as a side effect of electricity generation. A second set of investors rushes in, collapses the price of gold, and now everyone is disappointed. Given the time it would have to sit before it’s at safe radiation levels, this process could take over 20 years to play out.