Boiler system and method for operating boiler system

A boiler system comprising:

• a water electrolysis device that electrolyzes electrolysis target water with electric power supplied from a natural energy power generation device to generate hydrogen and oxygen;
• a boiler that heats makeup water by combusting fuel to generate steam;
• a heat exchange device that exchanges heat between the electrolysis target water and a heat medium;
• and
• a control device having a heating controller that heats the electrolysis target water by supplying hot fluid generated in the boiler as the heat medium to the heat exchange device when a preset heating start condition is satisfied.

A method for operating a boiler system including

• a water electrolysis device that electrolyzes electrolysis target water with electric power supplied from a natural energy power generation device to generate hydrogen and oxygen,
• a boiler that heats makeup water by combusting fuel to generate steam, and
• a heat exchange device that exchanges heat between the electrolysis target water and a heat medium, the method comprising:
• performing at least one of an operation of circulating the makeup water as the heat medium to the heat exchange device when a preset cooling start condition is satisfied or an operation of circulating hot fluid generated in the boiler as the heat medium to the heat exchange device when a preset heating start condition is satisfied.