A flywheel (6) is provided that comprises a rotatable shaft (7). At least one end of the rotatable shaft (7) is provided with a recess (51) and two magnets (15, 20, 31, 36). The flywheel (6) is provided with support means (18, 23, 34, 39) with the support means comprising: a first arrangement (18, 34) of magnets (17, 33) for vertical stabilization of the shaft (7); and a second arrangement (23, 39) of magnets (22, 38) for horizontal stabilization of the shaft (7). The first of the two magnets (15, 31) of the shaft (7) interacts with the first arrangement (18, 34) and the second of the two magnets (20, 36) interacts with the second arrangement (23, 39).