Your going to have to give me a day cause I just got back from downing a few. Thrust is not "generated" by the winglets. The winglets give the airplane, in most cases, better L/D, such that it climbs better on takeoff and requires less thrust on approach. They also, if designed correctly, improve fuel burn in cruise.
ps. Any person that tells you that that thrust can be "derived" from winglets is not telling you correctly. B