Scientists have developed a simple "soak and heat" process to treat waste coffee grounds to allow them to store methane.

The process has a double environmental return - it removes a harmful greenhouse gas from the atmosphere that can then be used as a fuel that is cleaner than other fossil fuels.

The process developed by the researchers at Ulsan National Institute of Science and Technology (UNIST), South Korea, involves soaking the waste coffee grounds in sodium hydroxide and heating to 700-900 degree Celsius in a furnace.

This produced a stable carbon capture material in less than a day -- a fraction of the time it takes to produce carbon capture materials.

"The big thing is we are decreasing the fabrication time and we are using cheap materials," said one of study authors Christian Kemp.

"The waste material is free compared to all the metals and expensive organic chemicals needed in other processes - in my opinion this is a far easier way to go," Kemp explained.

The absorbency of coffee grounds may be the key to successful activation of the material for carbon capture.

"It seems when we add the sodium hydroxide to form the activated carbon it absorbs everything," Kemp said.

"We were able to take away one step in the normal activation process - the filtering and washing - because the coffee is such a brilliant absorbant," he added.

The work also demonstrates hydrogen storage at cryogenic temperatures, and the researchers are now keen to develop hydrogen storage in the activated coffee grounds at less extreme temperatures.

The results are published in the journal, Nanotechnology.