The Type dimension of Air-cooled Fuel Cell Stack segmentation distinguishes four principal chemistries: Polymer Electrolyte Membrane (PEM), Solid Oxide (SOFC), Molten Carbonate (MCFC), and Alkaline. PEM stacks dominate the market due to their low operating temperature (60‑80 °C), rapid start‑up, and suitability for automotive and portable uses, accounting for roughly 55 % of total revenue. SOFC units, operating above 600 °C, contribute 25 % by capturing high‑efficiency stationary power applications where thermal integration offsets the thermal management burden. MCFC stacks, with temperatures near 650 °C, serve niche industrial cogeneration projects and represent about 12 % of sales, reflecting higher material costs and longer start‑up times. Alkaline stacks, though limited by catalyst degradation, retain a 8 % share, primarily in legacy backup‑power systems. Collectively, these types shape the overall market size, with each chemistry’s cost structure, performance envelope, and supply‑chain maturity dictating its revenue share within the Air-cooled Fuel Cell Stack market.