How coal of all things could support the energy transition

Hydrogen is considered an important source of clean energy in the mix of the future. This is understandable, because hydrogen is easy to produce and only leaves water when it burns.

The only problem is its storage, because the material is highly flammable. It can be compressed and stored in high-pressure tanks at extremely low temperatures.

However, a less complex option would be better. For example, efforts are being made to enclose the gas in powders, pastes and cartridges. There are currently no practical solutions.

Now is a researcher at Penn State University in Pennsylvania, USA a surprising idea came. They want to use coal as a kind of battery to store hydrogen in it.

It is already known that coal can store methane gas well. The gas adheres to the material through a process known as adsorption.

The researchers wanted to know whether this also works with hydrogen gas. The research team therefore built a special system that can press the hydrogen into the coal.

“We came up with a very new and very sophisticated design,” says Shimin Liu, associate professor of energy and mineral engineering at Penn State. “It took us years to figure out how to do it right. We had to design an experimental system based on our previous experiences with coal and shale.”

In fact, the attempts were extremely successful, although there were differences in the charcoal used. The ability of coal to trap gas is based on its unique composition.

“Many people define coal as a rock, but it’s actually a polymer,” Liu said. “It has a high carbon content with many small pores that can hold much more gas. So coal is like a sponge that can hold many more hydrogen molecules compared to other non-carbon materials.”

The researchers now want to investigate how quickly hydrogen can be pumped into and out of different types of coal. What they find particularly interesting is that their research could bring hope to communities that have been hard hit by the shift away from coal.

“In the energy transition, it’s the coal communities that are hit hardest economically,” says Liu. “This is certainly an opportunity to repurpose the coal regions.”

The research results were published in the journal AppliedEnergy published.