Compressors are at the center of many industrial processes: Their job is to reliably compress gases and increase gas density without requiring much maintenance. Unlike axial compressors, radial compressors have a radial diffuser that can have a bladed or unbladed design. Unbladed radial diffusers allow a greater machine working area, since the cross-sectional area through which flow passes is greater. Bladed diffusers limit the working area because the blades reduce the cross-section. They do guide flow better in the partial-load range with the additional guide blades and can thus achieve higher efficiency. The University of Duisburg-Essen’s invention uses a parallel-walled radial compressor diffuser that works with moving blades: The operating area is expanded, and partial-load operation is more efficient. The blades can be sunk in a side wall recess, where there is a gap between the blade base and the bottom of the recess. If a pre-determined diffuser pressure level is reached, the blades are extended, stabilizing flow and increasing efficiency. For moving blades, intermediate positions are also conceivable, as is extension of individual blades as needed for different operating points.