Coffee grounds suitable for storing methane

Scientists have found a way to turn waste coffee (coffee grounds) into an effective energy carrier. After relatively simple processing by soaking and heating, the coffee grounds can be used to store methane .

Currently, compressed methane is usually stored in cylinders under pressure. This is a rather dangerous way, given the explosiveness of the gas. Simple coffee grounds look like an eco-friendly alternative. True, it will be difficult to find coffee waste on an industrial scale. Maybe sometime in the future, the squeeze from drunk coffee will be bought from the population at the collection points for recycled materials, like metal waste, glass, waste paper and rags are now collected.

The process of processing the coffee grounds was developed by chemists from the National Institute of Science and Technology in Ulsan (Ulsan National Institute of Science and Technology, UNIST), South Korea.
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At the first stage, the material is soaked in potassium hydroxide (KOH, potassium liquor, caustic potash). Then heated in an oven to 700−900 ° C. The whole processing cycle takes less than a day, and the output is a stable material for capturing carbon-containing material.

The “coffee” energy carrier holds CH ₄ in the amount of ∼4.2 millimole g ⁻¹ at a pressure of 3.0 MPa and a temperature of +25 ± 10 ° C. The same material retains hydrogen 1.75 wt% at −196 ° C and
100 kPa.

“The important thing is that we were able to reduce production time and use cheap materials,” says research author Christian Kemp. He notes that it takes much longer to produce other materials with similar properties, and this is an expensive process. “The waste used here can be considered free of charge compared to all metals and the expensive organic chemicals needed for alternative processes.”

Interestingly, the idea came to the authors of the invention by chance. Kemp and his colleagues discussed a completely different project, drank coffee. At this time, the scientist looked at the thick at the bottom of the cup and suddenly thought: "Is it possible to use it to store methane?".

New energy carrier has a double benefit for the environment: it reduces the amount of biological waste, and reduces the amount of harmful gas in the atmosphere.

Coffee beans have an excellent absorption capacity, that is, it is an ideal absorbent. Due to their unique properties, it was possible to significantly simplify the process of manufacturing the energy carrier. Now scientists are testing its hydrogen storage qualities. As mentioned above, such qualities of the carrier have already been demonstrated in laboratory conditions at ultra-low temperatures of the order of −196 ° C. Now we need to increase the temperature.

The research results were published on September 3, 2015 in the journal Nanotechnologies (Nanotechnology. DOI: 10.1088 / 0957-4484 / 26/38/385602 , pdf ).