Whatever the stuff is, I hope it works.
FYI ... refrigerators in the 3rd world can run on kerosene. In the first world, the Amish have some that run on propane.
They might be few and far between but they are available.
It’s the transport between refrigerators that’s the biggest issue.
It’s a tricky thing to keep vaccines and other cold chain items cold enough there with no excursions above a certain temp.