To solve the problems of the cale and the cost of a plant for generating hydrogen as a new type of energy for global warming prevention measures using biogas generated from livestock excreta as raw materials.

Biogas is generated by collecting and fermenting livestock excreta caused in the dairy industry area. A plasma reactor is worked by comparatively slight power supply by means of photovoltaic power generation, wind power generation and the like to carry out desulfurization and deodorization. The generated hydrogen is stored as storage battery energy in liquid, and a reusable byproduct obtained in the process of the series of systems is returned to the area.