Say I have an infinite cylinder filled with monoatomic gas and on one end has a piston attached to it. I now supply heat to the cylinder. The gas expands thereby converting all of heat energy into physical work(displacement of the piston). Since the cylinder is very long it eliminates the requirement of a cyclic process and could in theory provide work for a very long time until the piston reaches the cylinder's length. Have I not just violated kelvins statement? Provided friction is zero? W=P.dV?