Currently, most hydrogen is made this way from natural gas. An electrical current can also be used to separate water into its components of oxygen and hydrogen. This process is known as electrolysis. Some algae and bacteria, using sunlight as their energy source, even give off hydrogen under certain conditions.
Originally, metal roofs were made of corrugated galvanized steel: a wrought ironâsteel sheet was coated with zinc and then roll-formed into corrugated sheets. Another approach is to blend zinc, aluminum, and silicon-coated steel.
1 8% of Earth's outer crust (by weight) is made of aluminum. 2  A block of aluminum weighs one third as much as a block of steel the same size. 3  Aluminum foil is typically less than 0.15 mm (0.0060 in.) thick. 4  Pure aluminum reacts rapidly with air to form a rustproof protective layer of aluminum oxide.