Basics

Carbon Dioxide held above the Critical Point
Here (and other Supercritical Fluids ) it behaves essentially as both a Liquid and a Gas
It can be abbreviated as sCO2

Uses

Involves dissolving sCO2 into the material, then rapidly depressurizing it to form a foam
Need to look into this further for more specific details

Need to look into this for specifics, but essentially using CO2 as the solvent for the reaction
Of interest to the Pharmaceutical Industry, as the Product may be "precipitated" by expanding the mixture out of a nozzle, leaving a fine dry product akin to Spray Drying

Can be used for Analytic Chemistry, or in Simulated Moving Bed Chromatography at an industrial scale for purification/separation of desirable (or in the case of Decaffeination etc, undesirable) Compounds

Unlike other solvents, sCO2 has virtually no toxicity (short of it being an Asphyxiant Hazard ) so Disposal/Handling concerns are far less

Supercritical fluid extraction is very common in the Essential Oil Industry (for Fragrances / Food Additives ) ( ~~And also in the Cannabis Industry for High Value High Purity Oils/Resins/Waxes~~ )
It is effective, and also has little risk of contamination since simply depressurizing the mixture separates out the CO2 (which can then be collected and recycled)
Main issue is initial cost of equipment
It is also used for Decaffeination

It can be used as a Refrigerant , or as a Working Fluid in a Rankine Cycle (Although using Hydrocarbons in the Organic Rankine Cycle may be of more interest, pending a proper Decision Making Matrix or similar investigation as per the relevant OSE Specifications )
It has the advantage over Butane and other similar proposed hydrocarbons in that it is not flammable
The Allam-Fetvedt Cycle is a novel Power Generation system utilizing Oxy-Fuel Combustion in an all Supercritical Carbon Dioxide Atmosphere