Hydrocarbon refrigerants use fossil fuels such as butane and propane to keep products cold, claims the Environmental Protection Agency. Refrigerants work by taking advantage of the phenomenon of "heat transition". 

When water turns from a solid to a liquid, it gains heat to facilitate "melting", according to A refrigerant comes in the form of pressurized liquid and turns to a gas when pressure is released. The gas soaks up heat from the surround environment, hence refrigeration.