TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Process: The electric current is generated by application of an electric potential across electrodes in contact with the organic material. It has 3-6 volts electric potential.A portion of hydrogen produced from the organic material is used in an energy conversion process to provide energy for generating intermittently the electric current.The electric current is generated at intervals determined with reference to levels of hydrogen and/or methane detected in gas produced from the organic material.The carbon dioxide is separated from hydrogen produced from the organic material by preferential absorption of the carbon dioxide in a pressurized fluid to escape the hydrogen to collection tube. The resulting carbon dioxide-containing pressurized fluid is heated and permitted to expand to release carbon dioxide and to transfer energy to a motor.The expanded fluid is cooled, pressurized, and recycled for further absorption of carbon dioxide.Preferred Components: The anaerobically decomposed organic material comprises composted cellulosic materials and/or digested sewage sludge.The pressurized fluid has a column of water having 300 m height which is maintained at 4-16 degreesC.    TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Apparatus: The apparatus has helical fin(s) positioned about the axis of the column. The top of the helical fins (406) is connected with the collection tube.A controller is provided for controlling the temperature of the container.Expansion engines (430, 432, 434, 436, 438, 440) are adapted to receive carbon dioxide-containing pressurized fluid from the fluid withdrawal tube.The apparatus further comprises heat exchangers (414, 416, 418, 420, 422, 424) for heating carbon dioxide-containing pressurized fluid passing from the fluid withdrawal tube to the expansion engine, and counter current heat exchanger (456) and pump (454) for cooling and pressurizing fluid collected from the expansion engine, respectively.