Breakthroughs Bring Low-Pressure Hydrogen Storage Closer to Reality

By Editors on October 13, 2008 7:33 AM
Two recent advances involving the innovative use of engineered carbon nanostructure materials could help solve one of the biggest challenges on the road to making hydrogen a viable fuel of the future by eliminating the need to store it under extremely high-pressure conditions.

In Greece, a team of scientists at University of Crete have developed a new kind of substrate made of pillared graphene that can theoretically hold up to 41 grams of hydrogen per liter under "normal" temperature and pressure conditions. That quantity is far closer to the 45 gram-per-liter target mandated by the U.S. Department of Energy than any other to date -- and nearly triple the capacity of metal-hydride, which is currently the best-performing alternative. The elegantly geometric structure of this high-tech "sponge" consists of parallel layers of graphene sheets supported by nano-porous carbon pillars. A layer of lithium ions applied to the surface further enhances its absorptive properties. While the basic research on opillared graphene is focused on using it to safely and economically store hydrogen, the developers say the inherent "tunability"of its nanotube elements also makes it suitable for that duty with other kinds of gaseous mediums.

Here in America, another research team from the University of Missouri and Midwest Research Institute is working on a high-density/low-pressure nanoporous biocarbon storage medium based on specially processed corncobs. The group just received a $1.9 million grant from the Department of Energy to continue its study on this low-cost but potentially very efficient solution. According to Dr. Peter Pfeifer, head of the MU Department of Physics, the cobs are transformed into carbon briquettes with a relatively huge surface area. These are "doped" with boron to make them even more capable at holding hydrogen in a low-pressure environment. The long-term goal is to devise a vehicle storage system that while smaller, lighter and less complex will significantly boost the range of fuel-cell vehicles beyond the present limit of about 200 miles.