Coal's green potential: storing energy instead of burning it for coal
Coal is not generally considered a clean fuel source, but it may play a role in the push for green energy. The researchers say it could be an excellent material for storing hydrogen, one of the most promising sources of clean fuel currently being explored.
There is no doubt that hydrogen holds great promise as a clean energy source of the future. After all, when it's being used as fuel, its only output is water. However, with regard to its use, an open question is how to store it. Hydrogen is highly flammable, and finding ways to safely contain it has been a considerable challenge for researchers.
We've seen efforts that could lead to powders, pastes , gas content in cartridges , but at this point , hydrogen storage solutions are still more in the realm of theory than practice. Researchers at Penn State University have come up with a surprising idea, proposing the use of coal for batteries that may contain hydrogen.
Coal is known to be good at storing methane gas, which sticks to the material through a process called adsorption . Coal of this mass would also be converted to hydrogen, the researchers said.
To test the theory, the team built special pressure-generating devices to force hydrogen into the coal.
"We made a very novel and very challenging design," said Shimin Liu, an associate professor of energy and mineral engineering at Penn State. "It took years to figure out how to do this properly. We had to get an experimental system right and do trial and error based on our previous experience with coal and shale.
In an analysis of eight different types of coal from across the United States, the researchers found that the material is indeed very good at storing hydrogen. The best of these are the low-volatility bituminous coals found in Virginia and the anthracite coals of Pennsylvania . Coal's gas capture capabilities are based on its unique composting properties.
"Many people define coal as rock, but it's actually a polymer," Shimin Liu said. "It's high in carbon and has lots of small pores that can store more gas. So coal is like a sponge and can hold more hydrogen molecules than other non-carbon materials.
Further research will delve into the idea of coal as a hydrogen container, as the researchers examine the material's permeability and diffusivity. This will help them understand how quickly hydrogen can be pumped in and out of different kinds of coal, which in turn could lead to highly efficient coal-based hydrogen "batteries". Shimin Liu also noted that the research could offer hope to communities hit hard by the transition to coal.
"Coal communities are the most affected economically in the energy transition," he said. "There's definitely an opportunity to repurpose coal areas. They already have the expertise - energy engineers and skills. If we can build the infrastructure and change their economics - I think that's something we should be thinking about.
The research has been published in the journal Applied Energy .
Article source: newatlas
