The CU-Boulder research team created a new system that uses sunlight, mirrors, and a tower that measures a few hundred feet tall. The mirrors, which sit at the top of the tower, collect the sunlight, which is converted into heat inside the tower. The heat (approximately 2,500 degrees Fahrenheit) gets transferred to a reactor that contains metal oxides (iron, cobalt, aluminum, and oxygen). As those metal oxides get warmer, oxygen atoms are released. When steam is added to the system, the metal oxides suck up all the oxygen, leaving hydrogen behind. That hydrogen can then be collected as a gas and stored.