There are 3 main types of a Fuel Cell.

1. Hydrogen Fuel Cell. This is the main one people use nowadays.

2. Solid Oxide Fuel Cell.

3. Alkaline Fuel cell. Made from Alkaline metals.

cell emf for electrolysis of molten lead (II) iodide

Calcium carbonate (limestone) is used in blast furnaces to capture impurities and form a slag that floats above the molten iron to keep the impurities from mixing back into the iron.

Not strictly renewable since it is produced from minerals that are finite, but there are very large amounts available, no risk of running out.

A fuel cell oxidizes a fuel source, a standard cell is an electrochemical reaction.