[Scientists are getting closer to finding ways to store larger amounts of hydrogen within an ice-like solid]

Recently, Professors Kun-Hong Lee and Bo Ram Lee at POSTECH have introduced a new concept for improving hydrogen storage capacity inside the structure formed by water molecules called gas hydrates.

Simply, gas hydrates are ice-like solid compounds including gas. In case of naturally occurring methane hydrates, it is estimated as a future energy resource since trillions of tonnes of methane are trapped as methane clathrates in nature all over the world.

One volume of hydrates contains about 160 times the volume of gas at standard temperature and pressure, and this leads scientists to look for ways to use gas hydrates as a medium for hydrogen storage. The main problem facing scientists so far has been storing hydrogen in the hydrate structure at milder condition consuming less energy (it typically needs at least 200 megapascals for pure hydrogen hydrates or 10 megapascals even with the injection of thermodynamic promoter), and simultaneously, increasing hydrogen capacity even at these mild conditions.

To overcome this intrinsic issue of gas hydrates, a team of scientists in Korea and the US (Colorado School of Mines) investigated the abnormal behaviour of metastability of gas hydrates. Here, the metastability is determined as a stable state of a dynamical system: a state that can be changed by the addition of a small amount of energy. By using the metastability of gas hydrates, they successfully made hydrogen hydrates stable at very mild pressure (0.5 to 1 megapascals) and demonstrated highly increased hydrogen storage (up to 52% larger amount) in the hydrates.

“If an appropriate process is designed to trap the system in this metastable state with a high concentration of gas, coupled with the benefits of hydrate self-preservation, a new paradigm will be born for gas storage in clathrate hydrates,” the researchers conclude.

The research has been chosen to be on the front cover (February issue) of the Journal of Physical Chemistry C published by American Chemistry Society.