A “fiction” implemented as environment variables, which the ffmpeg process would inherit, so there's nothing stopping ffmpeg from “indulging the fiction”. Depending on how frequently users expect this behavior to work, I might even call it a bug in ffmpeg (or whatever file handling library it relies on) that isn't even all that hard to fix.
TLDR: it's a concentrated solar plant (field of mirrors shine light on a tower to boil water) with a backup system that boils the water by burning stuff.
If I understand the article correctly, there is no boiling water, it uses hot air only. It says the concentrated solar generates air up to nearly 1000 degrees, and that's used to heat up compressed air to run through a turbine, with the eziting air at around 250 degrees. Burning fuel would replace the initial source of hot air. Burning fossil fuels to get hot air and then dumping 250 degree air to the environment doesn't seem very efficient, but the article doesn't mention anything about the efficiency of the process with either source.
Does say the hot air at the end can be used for industrial processes, so it might not be completely lost
The 1000 degree air is not used directly to drive turbines, but instead to deliver heat to a heat storage unit via a heat exchanger. The solar-heated air, after flowing through the heat exchanger, is still around 250 degrees and the article mentions some possible uses of that heated air (again, not generation).
Generation occurs using heat coming from the heat storage unit, not using the solar-heated hot air. Since the heat storage unit can also be fed by hot air heated via other means, this makes the heat storage unit "source neutral" - it can be heated by solar or fossil fuel combustion (or whatever).
The turbines are "downstream" of the heat storage unit.
There's actually no mention of the technology used by the turbines. This article is about how you heat up a heat storage facility that is then used (somehow) to drive turbines. Might be water, might not be.
