Hempel attended Kunstakademie Dusseldorf from 1987-1992.
He has shown work in many exhibitions including at Andrea Rosen Gallery in New York, at P.S. 1 in New York and Lab of Gravity in Hamburg. Hempel has also exhibited at a number of important museums and galleries such as Tate Liverpool, England, Ars Futura in Zürich and the Stedelijk Museum in Amsterdam. He is represented by Anton Kern in New York, Stuart Shave/Modern Art in London and Atle Gerhardsen in Berlin.