Scientists have discovered a compound called Metal-Organic Framework No. 177(called MOF-177 for short). This crystal could become the "fuel tank of the future." It is light and 95% of the volume is just empty space. Dr. Yaghi, a professor of chemistry at the University of Michigan, thinks that the crystals will act as hydrogen sponges. They will store gas at room temperature under less pressure. Hydrogen is bulky at room temperatures so fitting a large amount of it into a regular-size fuel tank would require hydrogen to be squeezed to very high pressures. This might create a hazard in a collision. This is why scientists have come up with the idea of using crystals to hold the hydrogen in it's empty spaces. If a one-inch cube of MOF-177 could be laid out, it would cover 38,000 square feet. Hydrogen binds to the surfaces. Making a crystal with more surface area makes it possible for more molecules to fit inside. Molecules could then pack onto a surface without having to apply quantities of pressure. http://college3.nytimes.com/guests/articles/2004/02/17/1142556.xml