To solve the following problems: while an advantage of power generation using natural energy such as photovoltaic or wind power is to be clean, its disadvantage is to depend on a natural environment and to require a huge area and high installation cost, and biofuel has only some effect of reduction in exhaust emissions but still causes noise from an internal combustion engine and, under present circumstances, inexpensive and effective in-house power generation is close to non-existent and such private power generators as to cover fields from ordinary homes to all industries are nowhere to be found.

Using a small amount of industrial electric power, a great amount of low-voltage power is generated for power storage. Otherwise, in a remote area without industrial electric power, power generation is implemented for power storage, using electric power for residence, and generating electric power more than consumed, thus creating a great amount of clean electric power.