A semi-closed cycle power system for net carbon negative operation, the power system comprising: an engine subsystem including an engine producing exhaust; a semi-closed-cycle (SCC) oxygen plant subsystem connected to the engine subsystem ; an intake subsystem connected to the SCC oxygen plant subsystem ; a carbon capture gas cleanup system (GCS) connected to the SCC oxygen plant subsystem ; a pyrolysis subsystem producing exhaust and connected to the engine subsystem ; a waste-heat-to-power subsystem connected to the pyrolysis subsystem to receive the exhaust from the pyrolysis subsystem ; an exhaust water separator subsystem connected to the waste-heat-to-power subsystem ; an inlet hopper receiving a renewable feedstock; characterised in that the semi-closed cycle power system further comprises a pyrolysis reaction chamber, the pyrolysis reaction chamber comprising: a pipe ; a heating jacket surrounding the pipe; a separator vessel , wherein the separator vessel provides a liquid/tar product , a gaseous product , and a char product ; a screw concentric with the pipe for moving material through the pipe to the separator vessel ; and a burner connected to the heating jacket , and wherein the separator vessel is connected to the burner and wherein the burner is designed to use the liquid/tar product provided from the separator vessel and the exhaust from the engine . an engine subsystem including an engine producing exhaust; a semi-closed-cycle (SCC) oxygen plant subsystem connected to the engine subsystem ; an intake subsystem connected to the SCC oxygen plant subsystem ; a carbon capture gas cleanup system (GCS) connected to the SCC oxygen plant subsystem ; a pyrolysis subsystem producing exhaust and connected to the engine subsystem ; a waste-heat-to-power subsystem connected to the pyrolysis subsystem to receive the exhaust from the pyrolysis subsystem ; an exhaust water separator subsystem connected to the waste-heat-to-power subsystem ; an inlet hopper receiving a renewable feedstock; a pyrolysis subsystem producing exhaust and connected to the engine subsystem ; a waste-heat-to-power subsystem connected to the pyrolysis subsystem to receive the exhaust from the pyrolysis subsystem ; an exhaust water separator subsystem connected to the waste-heat-to-power subsystem ; an inlet hopper receiving a renewable feedstock; characterised in that the semi-closed cycle power system further comprises a pyrolysis reaction chamber, the pyrolysis reaction chamber comprising: a pipe ; a heating jacket surrounding the pipe; a separator vessel , wherein the separator vessel provides a liquid/tar product , a gaseous product , and a char product ; a screw concentric with the pipe for moving material through the pipe to the separator vessel ; and a burner connected to the heating jacket , and wherein the separator vessel is connected to the burner and wherein the burner is designed to use the liquid/tar product provided from the separator vessel and the exhaust from the engine . a pipe ; a heating jacket surrounding the pipe; a separator vessel , wherein the separator vessel provides a liquid/tar product , a gaseous product , and a char product ; a screw concentric with the pipe for moving material through the pipe to the separator vessel ; and a burner connected to the heating jacket , and wherein the separator vessel is connected to the burner and wherein the burner is designed to use the liquid/tar product provided from the separator vessel and the exhaust from the engine . <EOS>