A first system includes a feedstock load port and a feedstock discharge port. The first system also includes a tank configured to retain biomass feedstock for aerobic biodegradation. The first system further includes a mechanical ventilator in fluid communication with the tank. The mechanical ventilator is configured to supply air to facilitate the aerobic biodegradation of the biomass feedstock. The first system also includes an exhaust port configured to receive gas generated during the aerobic biodegradation. A second system includes a feedstock load port and a feedstock discharge port. The second system also includes a pressure vessel configured to retain biomass feedstock for anaerobic bio degradation. The second system further includes a gas release device to facilitate migration of gas within the pressure vessel. The second system also includes a water cycler configured to cycle water within the pressure vessel. The second system further includes an exhaust port
