watermill .

Question description: 

This mill is designed to work on the reverse osmosis method in which water from salt water (sea) penetrate through the semi-permeable plug into the tube. The tube is inserted deep into the sea so that there will be sufficient pressure on the plug for reverse osmosis. Now water from the tube will come out of the sea surface as shown in figure which can be used to rotate a mill (generate energy). So, this design contineously gives you energy with nothing to loss!!! 

You have to prove that this design will not work and submit the answer to the PGSA officers!