Its not in the power plant. First you have togo back to the gym (mistys gym) a team rocket grunt will run out. Follow him to the large bridge north of Vermillian city onto the bridge. Battle him. Then once yo beat him, find misty on the cape. Meet her back at the gym once you talk to her. Then battle her at the gym. Finally Find the power plant peice in the tube on the upper left hand corner!
