Energy

New method quickly converts natural gas into solid form for storage

New method quickly converts na...
A new method creates solid hydrates of "combustible ice" that can store natural gas safely and at practical temperatures
A new method creates solid hydrates of "combustible ice" that can store natural gas safely and at practical temperatures
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A new method creates solid hydrates of "combustible ice" that can store natural gas safely and at practical temperatures
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A new method creates solid hydrates of "combustible ice" that can store natural gas safely and at practical temperatures
Researchers Praveen Linga (left) and Dr Gaurav Bhattacharjee (right) hold up samples of the natural gas hydrates
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Researchers Praveen Linga (left) and Dr Gaurav Bhattacharjee (right) hold up samples of the natural gas hydrates

Engineers at the National University of Singapore (NUS) have developed a new way to convert natural gas into a solid form, allowing it to be stored and transported more safely and easily. The process can be done in just 15 minutes using a low-toxicity mixture.

It may be a fossil fuel, but natural gas remains a key energy source for now, and some argue it might help us bridge the gap towards more renewable energy. It still has its problems though – the stuff can be hazardous to store or transport, and it is often converted into liquid form to make it easier to work with. However, that requires extremely cold temperatures of around -162 °C (-260 °F).

An emerging method is to instead convert the gas into a solid for easier transport and storage. In fact, nature already does this under certain conditions, as molecules of natural gas can become trapped in “cages” of water molecules, forming what are known as gas hydrates or combustible ice. It’s far from a quick process though, taking upwards of millions of years.

Researchers have been trying to speed that up, and now the NUS team claims the fastest conversion time on record. The key ingredient in the new mixture is L-tryptophan, an amino acid that speeds up the reaction rate and traps more of the gas into solid hydrates faster. Taking just 15 minutes, the team says the new method is more than twice as fast as the current standard.

Researchers Praveen Linga (left) and Dr Gaurav Bhattacharjee (right) hold up samples of the natural gas hydrates
Researchers Praveen Linga (left) and Dr Gaurav Bhattacharjee (right) hold up samples of the natural gas hydrates

“Our breakthrough can really be put into perspective when you consider that it takes millions and millions of years for gas hydrates to form in nature, yet with our correct addition of secret ingredients to the system in small quantities, the same process can be effected in the laboratory in a matter of minutes,” says Gaurav Bhattacharjee, an author of the study.

The end product is much more convenient and safer to store and transport. As a block of ice it’s shrunk in volume by 90 times, and is non-explosive and stable enough to be stored in a regular freezer at -5 °C (23 °F). The new method also apparently requires less toxic additives than usual.

While it’s so far only been tested in the lab, the researchers next plan to try a pilot scale experiment, with the aim of converting around 100 kg (220 lb) of gas per day. Eventually, they hope to scale it up for industrial use.

The research was published in the journal Energy & Environmental Science. The team outlines the process in the video below.

Converting natural gas into a non-explosive solid

Source: National University of Singapore

10 comments
10 comments
windykites
This is a fantastic achievement, and there will be many applications. There will be an energy saving, by not having to compress and liquefy natural gas. The only problem I can see is how it is stored. I guess small pellets is the answer, but they must not stick together, so maybe they could be coated with thin plastic.
Would this work with Hydrogen from electrolysis, using spare solar electricity? No CO2 problem.
anthony88
Energy to create the solid gas + Energy to store the solid gas = ?
paul314
Similar energy density to liquefied natural gas, only without the devastating-explosion propensities? Sounds like a good idea.
Scott Mckinsey
The energy density is far less that LNG, how could it be otherwise when the lattice itself is composed of water ice? It is uneconomical due to transportation and storage requirement, when compared to LNG. Here is one scholarly study on the matter; https://ou.edu/class/che-design/a-design/projects-2008/Gas%20Hydrate%20Transportation.pdf
Username
How is it converted back? does it just melt? How is it inserted into the existing pipes?
TechGazer
How much energy and possibly expensive raw materials are required to produce the tryptophan? Are they planning to remove the tryptophan from the food supply, the way they diverted starches to produce fuel alcohol?
Andrew Klepatsky
The project has a substantial drawback.
Solid natural gas hydrates contain 85% water molecules.
It would be quite expensive to transport that staff instead of LNG.
Catweazle
Concerning methane hydrate, there are vast quantities to be had from the seabed in huge areas.

Japan and China have already successfully conducted pilot extraction schemes with a view to commercialising the process.

An intriguing aspect of this process is that it may be possible to extract the methane by replacing it with CO2.
Simon Redford
Although this is interesting, the energy density (MJ/Litre) is not spectacular. LNG has an energy density over 600 times NG at atmospheric pressure, and compressed NG at 250 Bar (gas bottle pressure) has an energy density around 250 times. Although containment is safer and cheaper as a hydrate, the density is reported to be only around 90 times that of NG at atmospheric. Maybe good for long-term storage?
Kpar
Pretty cool tech. Make it cheap enough, and portable machines might be able to economically recover "flare gas" at oil and gas production wells, where excess natural gas must be burned to prevent large amounts of the explosive gas accumulating. Once in a solid form (especially in North Dakota in the winter) it can then be safely transported and stored.