This document reviews research on two-stroke single cylinder compressed air engines. It discusses the history of compressed air technology dating back to the 17th century. It summarizes several research papers that studied prototype compressed air engines and analyzed their performance, efficiency, and environmental impact. The document concludes that while compressed air engines eliminate emissions compared to fossil fuel engines, more research is needed to improve their load capacity, material selection, and duration of operation. Compressed air engines show potential as a more sustainable alternative propulsion technology.