Coal or charcoal
Derived from the Middle High German word 'kol', referring to coal. It likely originated as an occupational surname for a coal miner or a charcoal burner before being adopted as a rare given name.
Less common today
Kohle isn't in the latest US Top 1000. It last peaked at #5,094 in 1991.
US births per 5-year period, 1990βpresent (SSA data).