Power reception/billing between multiple portable power supply devices

A server apparatus operable to communicate with a portable first power supply device being a portable engine-driven type generator, including a first terminal connectable to a first load, and configured to supply power to the first load, and a second power supply device including a second terminal connectable to a second load, configured to receive power from the portable engine-driven type generator and configured to supply the power to the second load, the server apparatus comprising:

• a first processor;
• and
• a first communication circuit connected to the first processor,
• wherein the first processor is configured to:
• acquire, via the first communication circuit, a reception amount which is an amount of power that the second power supply device received from the first power supply device, which is an engine-driven type generator;
• convert the reception amount into a virtual currency;
• and
• transmit, to the second power supply device, via the first communication circuit, a money transfer instruction in order to instruct a money transfer, to a virtual currency wallet associated with the engine-driven type generator or a virtual currency wallet associated with the server, of the virtual currency,
• wherein
• the money transfer instruction is an instruction for causing the second power supply device to generate a money transfer request in order to perform a money transfer of a virtual currency to a virtual currency wallet associated with the engine-driven type generator or a virtual currency wallet associated with the server, and for causing the second power supply device to transmit the money transfer request to a virtual currency network.

A portable engine-driven type generator, comprising:

• a power generation unit;
• a power storage unit configured to store power generated by the power generation unit;
• a first connection unit configured to connect to a load;
• a second connection unit configured to connect to a power line connected to another power supply device;
• a supply unit configured to, in order to supply at least a portion of excess power stored in the power storage unit to the other power supply device, supply at least a portion of the excess power to a power line via the second connection unit;
• a reception unit configured to receive deposit information indicating that a virtual currency has been deposited in a virtual currency wallet as compensation for supply of at least part of the excess power;
• and
• an output unit configured to output the deposit information,
• wherein the output unit comprising a display for displaying the deposit information indicating that the virtual currency has been deposited in the virtual currency wallet as compensation for supply of at least part of the excess power.