Hydrogen, as a green energy carrier, embodies the qualities of cleanliness, efficiency, and versatility. Green hydrogen—produced via renewable-powered electrolysis—emits only water when used, making it a truly clean energy source. Its high energy density allows it to store large amounts of energy, addressing the intermittency of solar and wind power by acting as a bridge between energy generation and demand. In green energy systems, hydrogen integrates seamlessly: excess renewable electricity is converted to hydrogen, which can then be transported, stored, and converted back to electricity or heat via fuel cells when needed. This flexibility enables its use across sectors: powering fuel cell vehicles, providing heat for homes and industries, and serving as a feedstock for green chemical production. As a key component of the green energy transition, hydrogen connects diverse energy systems, enabling a more resilient, low-carbon future.