I remember these being advertised in the back pages of car mags in the 60's. They were used as an add-on to VW transaxles (there were several different variations of this theme over some period of time), but a pair of them on a go kart would be a VERY fast cart!!!
These turbines made a ton of heat, and were more or less "on" or "off". Finding the fuel "Thermolene" (propyl nitrate) might be a bit problematic, should he want to actually try to run this deal, but there are other options, I'm sure, than the original fuel; this type of engine is known for being not picky as to what fuel it runs on- but the specific engines here might be a different story.
I still own and occasionally run a Mac 101 w/3 carbs, on alcohol- and it is fast. But this deal will be in another league all together!
As for the cart, the laid down tanks along side the seat are for oxygen (used to get the fire started) and nitrogen (used to push the Thermolene into the combustion chamber) and the other tank behind the seat is for the Thermolene itself. As kids, we'd dream of rigging one of these things up to whatever was at hand at the time!
They were actually seen fairly often, usually not running, but installed into various and sundry vehicles, around Florida.
There was a VW that I remember from my youth that actually had some success w/this power plant. I remember it running in Florida fairly often, always as an exhibition-type deal. It ran (not at the same time) with Tommy Ivo's 4-engined Buick dragster and the "Lil' Red Wagon" wheelstander at the Valkaria drag strip in FL one time.