Stirling Engines. See the individual pages for more details on each.
1) The hurricane as a Carnot heat engine:
Kerry Emanuel, Hurricanes: Tempests in a greenhouse. Physics Today 59(8): 74-75 (2006).
2) John E. Shaw, Comparing Carnot, Stirling, Otto, Brayton, and Diesel Cycles. Transactions of the Missouri Academy of Science, 42: 1-6 (2008).