Crane and method for operating a crane using recovery of energy from crane operations as a secondary energy source

1. 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.

2. The method according to claim 1 , further comprising providing the energy usage fraction to the at least one crane component by feeding energy into the power consumer system.

3. The method of claim 1 , further comprising providing the energy usage fraction to the at least one crane component using at least one energy converter connected to the at least one crane component to convert energy from operation of the at least one crane component into power.

4. A method of operating a crane, said crane comprising a power consumer system for providing energy; a primary energy source for feeding primary energy into the 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 the following steps:

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, wherein the amount of the demanded energy usage fraction of the at least one crane component is previously known;

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 control the power consumer system for supplying the energy usage fraction preferentially to at least one crane component over another crane component, and

storing an energy storage fraction in said 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 components.

5. The method according to claim 4 , further comprising the step of providing the energy usage fraction to the at least one crane component by causing energy to be fed into the power consumer system.

6. The method according to claim 4 , further comprising the steps of:

converting energy from operation of the at least one crane component into power using at least one energy converter connected to the at least one crane component, and

providing the energy usage fraction to the at least one crane component using the power from the at least one energy converter.

7. The method according to claim 6 , further comprising the step of determining an excess energy fraction such that a sum of the energy usage fraction and a maximum energy storage fraction is equal to a sum of the excess energy fraction and the total energy amount.

8. The method according to claim 4 , further comprising the step of controlling the supply of energy to the at least one crane component by controlling a ratio of the energy usage fraction to the energy storage fraction.