We present a model for launching relativistic jets in active galactic nuclei ( AGN ) from an accreting Kerr black hole ( BH ) as an effect of the rotation of the space-time , where the gravitational energy of the accretion disc inside the ergosphere , which can be increased by the BH rotational energy transferred to the disc via closed magnetic field lines that connect the BH to the disc ( BH-disc magnetic connection ) , is converted into jet energy . The main role of the BH-disc magnetic connection is to provide the source of energy for the jets when the mass accretion rate is very low . We assume that the jets are launched from the disc inside the BH ergosphere , where the rotational effects of the space-time become much stronger , being further accelerated by magnetic processes . Inside the ergosphere , we consider a split topology of the magnetic field , where parts of the disc connect to the BH and other parts to the jets via magnetic field lines . The rotation of the space-time channels a fraction of the disc energy ( i.e. , the gravitational energy of the disc plus the rotational energy of the BH which is deposited into the disc by magnetic connection ) into a population of particles that escape from the disc surfaces , carrying away mass , energy and angular momentum in the form of jets , allowing the remaining disc gas to accrete . In this picture , the BH can undergo recurring episodes of its activity with : ( i ) a first phase when the accretion power dominates and ( ii ) a second phase when the BH spin-down power dominates . In the limit of the spin-down power regime , the model proposed here can be regarded as a variant of the Blandford-Znajek mechanism , where the BH rotational energy is transferred to the disc inside the ergosphere and then used to drive the jets . As a result , the jets driven from a disc inside the BH ergosphere can have a relatively strong power for low mass accretion rates . We use general-relativistic conservation laws to calculate the mass flow rate into the jets , the launching power of the jets and the angular momentum transported by the jets for BHs with a spin parameter a _ { * } \geqslant 0.95 . As far as the BH is concerned , it can ( i ) spin up by accreting matter and ( ii ) spin down due to the magnetic counter-acting torque on the BH . We found that a stationary state of the BH ( a _ { * } = const ) can be reached if the mass accretion rate is larger than \dot { m } \sim 0.001 . The maximum value of the BH spin parameter depends on \dot { m } being less but close to 0.9982 ( Thorne ’ s model ) . In addition , the maximum AGN lifetime can be much longer than \sim 10 ^ { 7 } yr when using the BH spin-down power .