The Order of Secrets
Compressed Gas Tank
Used for storage of most types of gas.
Coal-Gas Fuel Cell
This system converts coal into a combustible gas and feeds it into a fuel cell, where it combines with oxygen to yield electric current.
Fluidized coal is actually finely ground coal, which flows like a liquid. This allows it to be stored and used like a gas, eliminating the need for stokers in steam engines by using a fuel pump instead.
These are squat cylinders of dull metal, with massive terminals emerging from the top surface.