Patent ID: 8857635

Claim:
A method for operating a crane, said crane comprising a power consumer system for providing energy; a primary energy source for feeding primary energy into a power consumer system; at least one secondary energy source, controllable independent from the primary energy source, for feeding secondary energy into the power consumer system, wherein the secondary energy source is connected to the power consumer system, and configured such that energy returned from operation of the at least one secondary energy source is at least partially fed as secondary energy into the power consumer system, said secondary energy source comprising at least one crane component; at least one energy storage unit arranged locally on the crane associated with the at least one crane component and connected to the power consumer system for storing primary energy and/or secondary energy; and at least one drive motor connected to the power consumer system for operating the at least one crane component in response to energy fed into the power consumer system, the method comprising: activating, in a working operation of the crane, said at least one crane component; deactivating, in a no-load operation of the crane, the at least one crane component; wherein in the working operation said at least one crane component is working and wherein in the no-load operation, said at least one crane component is non-working; providing a total energy amount comprising at least one of primary energy generated by means of said primary energy source and secondary energy generated by means of said at least one secondary energy source; determining an energy usage fraction demanded by the at least one crane component; controlling a ratio of the energy usage fraction to an energy storage fraction by a control unit, wherein the control unit is in signal connection with the power consumer system, the primary energy source and the at least one secondary source to control an energy supply to the at least one crane component, wherein the control unit is configured to cause secondary energy to be supplied to the at least one crane component to meet the energy usage fraction, and wherein the control unit is configured to cause secondary energy from the secondary source to be used preferentially over the primary energy supplied by the primary energy source to provide for the energy usage fraction; and storing the energy storage fraction in the at least one energy storage unit, wherein the total energy amount comprises the energy usage fraction and the energy storage fraction, and wherein the secondary energy is energy returned from operations performed by the at least one crane component.