In a groundbreaking move, Ulsan, South Korea has introduced the world's first 'hydrogen apartment' block at the Yuldong-With-U complex. This innovative approach sees 437 households powered entirely by hydrogen fuel cells for heat and electricity, marking a significant step towards sustainable urban development. The complex's method of harnessing hydrogen has proven to be highly cost-effective, with the generation of 840MWh of power in June at a fraction of the cost of traditional utility bills. The Yuldong Combined Heat and Power Plant, utilizing hydrogen received via a nearby pipeline, demonstrates the environmental benefits and efficiency of this approach. The fuel cells on the rooftop contribute 1.31 megawatts of electricity per hour, enough to sustain four-person households continuously. By capturing and storing heat in a thermal accumulator, the complex ensures efficient heating using the excess energy produced. Fuel cells, operating similar to batteries but without depletion, offer higher efficiencies and continuous energy production. Plans to amend regulations for direct access to affordable hydrogen-generated electricity indicate a commitment to eco-friendly living in Ulsan's urban landscape, aiming for a 100% carbon-neutral residential complex.