Thanks for the article!

No idea if it's ancient or anything but none the less it was informative.

I have to admit, as a person interested in cannabis specifically for its agricultural feed / bio-fuel potential, the idea of classifying pyrolysis as a way of extracting hemp oil seems.... curious.

The temperatures involved are almost certainly going to damage the oil products to the point where it isn't significantly hemp oil anymore. It's a mixture of other half-decayed hydrocarbons or outright component ingredients (carbon monoxide / hydrogen).

Still! Good news to be said on the supercritical fluid front!

Quick safety warning: Supercritical CO2 requires over 1000 PSI and that's potentially super dangerous. If you're a hobbyist (like myself at this time! ~.^) take appropriate care to make sure that any potential bursting containers are safely contained. When I fuck around with turbines and high pressure pumps I use a lot of home made sand/dirt bags.

Also don't be afraid to start simpler like I intend for this project: Liquid CO2 can exist at only 75 PSI.

So my point! The disc-style pump, usually referred to as a 'Tesla pump' (a la the 'Tesla turbine'), is very well suited to acting as a compressor for highly viscous fluids like liquid CO2. It's easy enough for a hobbyist to manufacture a functional one, it doesn't involve any rare components (you'll want stainless steel for the discs while aluminum can be the housing - I'm starting with standard 304 for discs) and can even be built to extract energy/heat from the CO2 on its way by making the device in to a turbo-pump:

Volute casing -> Pump -> Tesla valve -> Turbine -> Tesla Valve -> Pump -> Tesla valve -> Volute casing to exit nozzle. All on a single shaft.

You'll have to figure out the dimensions of your discs yourself though. Just remember one key insight Nikola Tesla shared in his Scientific American interview: The most efficient way to get a fluid to change direction is to do so gradually over a long distance. So let things spiral around!

You'll have to do the dimensions and the rest of the design on your own but it's really not super high level stuff to do a functional turbopump.