How to get en­ergy from set­ting ice on fire

Ja­pan has been pro­duc­ing meth­ane gas from flammable ice deep be­neath the sea floor, which is open­ing up the ex­cit­ing pos­si­bil­i­ties in power gen­er­a­tion. The com­bustible com­bi­na­tion is pre­dicted to be com­mer­cially vi­able in less than a decade, For­eign Corre

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Ja­pan re­cently re­ported that it had suc­cess­fully pro­duced meth­ane gas from de­posits of flammable ice, or meth­ane hy­drate, off its cen­tral coast, open­ing up a po­ten­tially vast new source of en­ergy.

By low­er­ing the pres­sure or rais­ing the tem­per­a­ture, the hy­drates break down into water and meth­ane – a lot of meth­ane. One cu­bic me­tre of the com­pound re­leases about 160 cu­bic me­tres of gas, making it a highly en­ergy-in­ten­sive fuel.

“Ja­pan is one of the most ac­tively en­gaged coun­tries for meth­ane hy­drate ex­ploita­tion since [its] par­tic­i­pa­tion in the first hy­drate field trial in Mal­lik, Canada done in 2002,” Praveen Linga, as­so­ciate pro­fes­sor at the Univer­sity of Sin­ga­pore’s depart­ment of chem­i­cal and biomolec­u­lar en­gi­neer­ing, tells The Na­tional.

A state-run cor­po­ra­tion un­der Ja­pan’s min­istry of econ­omy, trade and in­dus­try, the Ja­pan Oil, Gas and Me­tals Na­tional Cor­po­ra­tion (Jog­mec), is the or­gan­i­sa­tion con­duct­ing the drilling. Jog­mec says the gov­ern­ment has in­vested about ¥106 bil­lion (Dh3.54bn) from 2001 to 2016 to de­velop flammable ice as a do­mes­tic nat­u­ral gas re­source.

Meth­ane hy­drate has the ap­pear­ance of com­mon ice crys­tals, but at a molec­u­lar level the meth­ane mol­e­cules are trapped within water mol­e­cules. It looks like com­pacted snow, but put a match to it and it will burst into flame and burn vig­or­ously.

Orig­i­nally thought to oc­cur only in the outer re­gions of our so­lar sys­tem, where tem­per­a­tures are low and water ice is fairly com­mon, sig­nif­i­cant de­posits of meth­ane hy­drate have been found un­der sed­i­ments on the ocean floors of the Earth. Eco­nomic de­posits of meth­ane hy­drate are termed Nat­u­ral Gas Hy­drate (NGH). Some 95 per cent of NGH is found be­neath the sea floor, where it ex­ists in ther­mo­dy­namic equilib­rium – a state in which it is in me­chan­i­cal, chem­i­cal and ther­mal equilib­rium and in which there is there­fore no ten­dency for spon­ta­neous change.

Ac­cord­ing to ex­perts, the global sed­i­men­tary meth­ane hy­drate reser­voir prob­a­bly con­tains be­tween two and 10 times the known re­serves of con­ven­tional nat­u­ral gas. In­deed, ac­cord­ing to Ge­ol­, meth­ane hy­drate de­posits are be­lieved to be a larger hy­dro­car­bon re­source than all of the world’s oil, nat­u­ral gas and coal re­sources com­bined. “Enor­mous amounts of meth­ane hy­drate have been found be­neath Arc­tic per­mafrost, be­neath Antarc­tic ice, and in sed­i­men­tary de­posits along con­ti­nen­tal mar­gins world­wide. In some parts of the world they are much closer to high-pop­u­la­tion ar­eas than any nat­u­ral gas­field. These nearby de­posits might al­low coun­tries that cur­rently im­port nat­u­ral gas to be­come self-suf­fi­cient. The cur­rent chal­lenge is to in­ven­tory this re­source and find safe, eco­nom­i­cal ways to de­velop it,” says Hobart King, a pro­fes­sional ge­ol­o­gist regis­tered in Penn­syl­va­nia.

This rep­re­sents a po­ten­tially im­por­tant fu­ture source of hy­dro­car­bon fuel but, in the ma­jor­ity of sites, de­posits are thought to be too dis­persed for eco­nomic ex­trac­tion. Other prob­lems fac­ing com­mer­cial ex­ploita­tion are the de­tec­tion of vi­able re­serves and de­vel­op­ment of the tech­nol­ogy for ex­tract­ing meth­ane gas from the hy­drate de­posits.

For Jog­mec re­searchers to ex­tract the gas, spe­cialised equip­ment was used to drill into and de­pres­surise the hy­drate de­posits, caus­ing the meth­ane to sep­a­rate from the ice. The gas was then col­lected and piped to sur­face where it was flared.

Pre­vi­ously, gas had been ex­tracted from on­shore de­posits, but never from much more com­mon off­shore de­posits. The Ja­panese hy­drate field from which the gas was ex­tracted is lo­cated 50 kilo­me­tres from cen­tral Ja­pan in the Nankai Trough, 300 me­tres un­der the sea. The ini­tial oper­a­tion was stopped be­cause of sand pro­duc­tion dur­ing the test, dam­ag­ing process equip­ment such as pip­ing, chokes, valves and fit­tings. “Ja­pan has re­cently over­come this chal­lenge,” Mr Linga says.

Ja­pan’s re­cently started field pro­duc­tion tests in two lo­ca­tions in the Nankai Trough re­gion have re­port­edly re­cov­ered about 35,000 cu­bic me­tres of gas over 12 days. “These steps are in the right di­rec­tion to­wards the path to com­mer­cial­is­ing tech­nol­ogy for en­ergy re­cov­ery from NGH,” Mr Linga says.

How­ever, a lot still needs to be done be­fore real­is­ing this po­ten­tial. Pro­duc­tion tests need to be car­ried out over months to en­sure a sus­tain­able out­put of gas. “The gas pro­duc­tion prom­ise is not the only cri­te­ria for ex­ploit­ing this re­source, but also the re­cov­ery should be done in an en­vi­ron­men­tally safe and se­cure man­ner,” Mr Linga adds. Vol­umes of Ja­panese NGH are es­ti­mated to be of the range of 2 tril­lion to 14 tril­lion cu­bic me­tres (TCM). “Ac­cord­ing to Jog­mec, the amount of meth­ane in place in the east­ern Nankai Trough alone is 1.1 TCM, which is equiv­a­lent to about 11 years of the amount of LNG im­ported to Ja­pan,” Mr Linga says.

How­ever, Ingo Pecher, a se­nior lec­turer of geo­physics at the Univer­sity of Auck­land’s school of en­vi­ron­ment, em­pha­sises the im­por­tance of dis­tin­guish­ing be­tween low-con­cen­tra­tion gas hy­drates, which are present along many of the world’s con­ti­nen­tal mar­gins, and con­cen­trated gas hy­drate de­posits in high-qual­ity reser­voirs that may be of com­mer­cial in­ter­est.

In sev­eral gas hy­drate prov­inces world­wide, the amount of gas stored in such con­cen­trated gas hy­drates is thought to be many tens of TCM, Mr Pecher says. “These are large num­bers but do not ex­ceed the vol­umes of gas in many con­ven­tional nat­u­ral-gas prov­inces,” he points out.

Cur­rently, ex­trac­tion meth­ods are focusing on de­pres­suri­sa­tion. Gas hy­drate re­quires mod­er­ate pres­sure and low tem­per­a­tures to re­main sta­ble. If pres­sure is low­ered, meth­ane hy­drate de­com­poses to freely mov­ing gas and water. “From an en­gi­neer­ing per­spec­tive, reser­voir de­pres­suri­sa­tion is a fairly stan­dard tech­nique for con­ven­tional hy­dro­car­bon pro­duc­tion, which may well be one of the main rea­sons why gas hy­drate ex­trac­tion tests have over­all been so suc­cess­ful,” Mr Pecher says.

Once the gas is out of the reser­voir, stor­age and trans­port is the same as for con­ven­tional nat­u­ral gas, he says. In prac­tice, Ja­panese meth­ane gas is likely to be trans­ported as liq­ue­fied nat­u­ral gas as these lo­ca­tions are off­shore, Mr Linga says.

The value of gas from hy­drates is highly de­pen­dent on the tech­nol­ogy and costs in­curred to pro­duce it, Mr Linga says. “How­ever, it is too early to put a re­al­is­tic cost as­so­ci­ated with the pro­duc­tion of gas, as the tech­nolo­gies are still un­der field trial to ob­tain a steady pro­duc­tion of gas from hy­drates,” he says.

In Mr Pecher’s view, is­sues such as gas value, who would get it and in what mar­ket, as well as a timetable to reach com­mer­cial vi­a­bil­ity, are all com­mer­cial con­sid­er­a­tions be­cause once at the sur­face it is ef­fec­tively the same as stan­dard nat­u­ral gas. For his part, Mr Linga be­lieves ex­port­ing the NGH is prob­a­bly un­likely as Ja­pan is a ma­jor im­porter of gas.

“Given the chal­lenges in­volved and the pro­duc­tion tar­gets to be met, the pro­jected time for com­mer­cial vi­a­bil­ity may be around 2025 or later,” Mr Linga says.

The suc­cesses in short-term field tests are just a be­gin­ning to­wards as­sess­ing com­mer­cial vi­a­bil­ity. Also, “as high­lighted, the po­ten­tial en­vi­ron­men­tal risk has to be eval­u­ated, and the min­ing tech­nol­ogy has to be cost of pro­duc­tion to cost ef­fec­tive for com­mer­cial vi­a­bil­ity,” Mr Linga says.

Mr Pecher adds that per­haps there is a way to lower pro­duc­tion costs by tak­ing bet­ter ad­van­tage of the fact that hy­drates are rel­a­tively close to the sea floor at hun­dreds of me­tres be­low the sur­face, com­pared to most con­ven­tional gas reser­voirs which are of­ten thou­sands of me­tres un­der the seabed.

Mean­while, other coun­tries are jump­ing on the flammable ice band­wagon. China re­ported last month it had suc­ceeded in col­lect­ing sam­ples of com­bustible ice in the South China Sea. “In ad­di­tion to China and Ja­pan, South Korea, In­dia and the US are lead­ing R&D into gas hy­drate as a po­ten­tial en­ergy source,” Mr Pecher says.

China de­scribes its lat­est re­sults as a break­through and, speak­ing to the BBC, Mr Linga agrees. “Com­pared with the re­sults we have seen from Ja­panese re­search, the Chi­nese sci­en­tists have man­aged to ex­tract much more gas in their ef­forts.

“So in that sense it is in­deed a ma­jor step to­wards making gas ex­trac­tion from meth­ane hy­drates vi­able.”

An av­er­age of 16,000 cu­bic me­tres of gas with high pu­rity have been ex­tracted per day in the Shenhu area of the South China Sea, ac­cord­ing to Chi­nese me­dia.

Re­gard­ing the en­vi­ron­ment, since the 1990s, many rep­utable me­dia out­lets have car­ried warn­ings that the pro­duc­tion of gas from hy­drates may pose a sig­nif­i­cant risk to cli­mate. In re­al­ity, ex­perts say, this is a mix-up of two sto­ries, that of gas hy­drate pro­duc­tion and the role of nat­u­ral gas hy­drates in cli­mate change, Mr Pecher says.

Such a process is to­tally un­re­lated to gas hy­drate pro­duc­tion, he says. “Even if there were an un­ex­pected leak­age of gas into the ocean dur­ing pro­duc­tion, the amounts would be tiny com­pared to the amounts that may be re­leased from a melt­ing Arc­tic.”

Louise Mur­ray / Rex / Shutterstock

Meth­ane hy­drate gas re­leased from seabed sed­i­ment.

Qian­long (2); Ky­odo

Above: Ma­rine nat­u­ral gas hy­drate in ice­like crys­tals. Left: the drilling rig Frigstad Shekou, now called Blue­whale I, ex­tract­ing gas hy­drate in ice­like crys­tals in the South China Sea. Right: The deep-sea drilling ves­sel Chikyu in the Pa­cific; it...

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