Other forms of energy-releasing fusion exist beyond hydrogen fusion, primarily involving helium and other light elements, ultimately producing iron as a final product. While these fusion processes are theoretically possible, they are considered impractical for power generation. The discussion highlights that stars transition to these fusion reactions when hydrogen is depleted. The mention of iron relates to its low binding energy per nucleon, which explains its prevalence in stellar processes. Overall, while alternative fusion reactions are recognized, they are not viable for energy production.