In this contribution we point out the challenges in Model-Based development of industrial plants regarding the integration of requirements. With the case study of a conveyor sorting system for parcels we show (i) that the specification of requirements is usually still only text based and (ii) what difficulties are entailed with that approach. The conceivable benefits of a Model-Based requirements engineering approach in the machinery and plant building industry are explained and compared to the state of the art requirements modeling techniques of other technical fields. Although, our proposed Model-Based requirements engineering approach points into the right direction, some shortcomings still remain. They have to be solved in the future work to enable a seamless Model-Based development from the requirements to detail design of industrial plants and other complex mechatronic systems.