Two Types of Storage

Scientists are constantly researching new energy options, but one of the biggest challenges when it comes to creating usable hydrogen fuel cells is the storage of their main component, hydrogen. Current storage methods of hydrogen require huge, high-pressure tanks, much larger than the ones found in cars running on fossil fuels.

An alternative way of storing this kind of fuel is material-based storage. This type of storage uses chemical bonds to store hydrogen, which allows for the storage of higher amounts of the fuel for less volume. Scientists from Rice University have now developed a suitable material for storing hydrogen that takes advantage of chemical bonds. Their findings have been published in Langmuir.

Graphene sheets supported by boron nitride pillars. Credit: Lei Tao/Rice University

Using computer simulations, the researchers were able to develop a material made from layers of graphene that is held up by boron nitride nanotube pillars supplemented by oxygen. The space this creates is where the hydrogen atoms can be stored.

The team's best effort in the simulation held 11.6 percent of its weight in hydrogen with a volumetric capacity of roughly 60 grams per liter at room temperature (the U.S. Department of Energy's current goal for economic storage of hydrogen is at least 5.5 percent of its weight and 40 grams per liter under moderate conditions).

The next challenge for the researchers is to have the material fill with a sufficient amount of hydrogen and discharge it on command, a process that Rice lab of materials scientist Rouzbeh Shahsavari told would likely involve the application and release of pressure.

A Cleaner Alternative

According to the U.S. DOE, "Reducing our dependence on foreign oil for transportation is a key driver for using hydrogen as a form of energy," and this development would make hydrogen a more viable fuel for cars. By exploring both material-based and tank-based options for hydrogen storage, we increase our potential to find a method that works.

As the only byproduct of hydrogen fuel cells is water, making them a regular part of our energy consumption will bring us one step closer to complete independence from the fossil fuels currently destroying our environment.

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