Traditionally, natural gas has been transported over long distances via pipelines or LNG. For some time, technologists have been grappling with a third method: to make hydrates of gas, or blocks of ice containing the gas.
Gas hydrates form naturally and have been long known to be a great source of energy — if only we could mine it safely. India has large gas hydrate deposits off the Krishna-Godavari coast and in the Andaman seas. A National Gas Hydrate Programme has been working on how to make use of these deposits for over a quarter century.
Mining naturally-occurring gas hydrates may be fraught with challenges, but in today’s world, a leading industrial manufacturing philosophy is to mimic nature. We can make hydrates of natural gas in factories, which can then be pelletised and transported in refrigerated trucks or ships.
The question remains of commercial viability. You have to pack more gas per block of hydrate and/or, you have to produce the hydrate blocks faster.
Packing more gas
And now, BusinessLine has learnt that Indian scientists have made a significant contribution. A team of scientists from IIT Madras and SN Bose National Center for Basic Sciences, Kolkata, has come up with surfactants that improve gas intake in hydrates. Surfactants are chemicals that have a water-loving (hydrophilic) head and a water-hating (hydrophobic) tail, and are therefore like a hook to pull out substance like dirt in clothes or crude oil in wells.
A team comprising Rajnish Kumar of IIT Madras, Suman Chakrabarty of SNBNCBS and Vrushali Hande and Nilesh Chaudhary of National Chemical Laboratories, Pune, found out that surfactant molecules like Sodium dodecyl sulfate (SDS), when mixed with another surfactant, Cocamidopropyl betaine (CAPB) can increase the efficiency of methane uptake significantly in the formation of methane hydrates. (Natural gas is mostly methane).
A one-cubic meter block of gas hydrate can easily contain 160 cubic meters of natural gas, though this can be improved to 200 cubic meters. The surfactants investigated by the scientists help pack gas twice as fast as the best methods available today.
Storage and shipment
Hydrates score more in transportation as compared with LNG. LNG has to be liquefied (using a lot of energy) and the liquid gas needs to be maintained at -160°C as it is shipped in special containers. Hydrates can be made into pellets need to be kept at around negative 10-20°C, which means they can be transported in regular refrigerated trucks.
“For long-distance transportation, economics are in favour of gas hydrate-based shipping,” Rajnish Kumar told Business Line . He said that the technology for making gas hydrates has been quite mature over a long time, and research in the last 4-5 years has thrown up “many significant breakthroughs”, making economics even better.
“India is not a gas producing country, we have to look at a very different business proposition,” he said, adding that when you transport gas hydrate, you deliver both gas and water to that place.
However, billions of dollars have been invested in creating liquefaction, shipping and transportation of LNG. The industry will be loathe to a new method of transportation.