Steam vs Compressed air

http://www.gizmowatch.com/human-powered-velomobile-ensures-enhanced-comfort.htmlhttp://www.youtube.com/watch?v=2hlVTwrka0k

 Realize that compressed air is limited, Steam works much better? But not for this size.
http://www.motoredbikes.com/showthread.php?p=343755#post343755


http://motoredbikes.com/showthread.php?t=36782


http://www.velomobiel.nl/allert/Recumbent%20motorbike.htm

http://pesn.com/2006/05/11/9500269_Engineair_Compressed-Air_Motor/