So­lar push for Rail­ways

In­dian Rail­ways can re­duce its car­bon diox­ide emis­sions by 239 tonnes per year per train by fix­ing so­lar pan­els atop coaches

Down to Earth - - TECHNOLOGY - MEGHA PRAKASH

THE RAIL­WAYS' DE­CI­SION to ex­per­i­ment with so­lar en­ergy to elec­trify train coaches can sub­stan­tially re­duce its car­bon foot­print, say re­searchers. Union rail­way min­is­ter D V Sadananda Gowda in June an­nounced a 7-crore pilot project to elec­trify 30 train

` coaches with so­lar power.The so­lar-pow­ered coaches will start ply­ing within six months on the Delhi-Ut­tar Pradesh and Del­hiHaryana routes.

A team of re­searchers from In­dian In­sti­tute of Sci­ence in Ben­galuru cal­cu­late that in­stalling pho­to­voltaic pan­els atop coaches can re­duce 239 tonnes of car­bon diox­ide emis­sions per year per train, which is roughly equal to the an­nual emis­sions of 50 cars in the city. On an av­er­age, 11,000 trains ply in In­dia ev­ery day.The re­searchers say the Rail­ways can save close to 60 lakh an­nu­ally

` on each train by shift­ing to so­lar pan­els. Their pa­per on the use of so­lar en­ergy to fuel rail­way coaches is sched­uled to be pub­lished in Cur­rent Sci­ence jour­nal.

Lead re­searcher Sheela K Ra­mase­sha and her team cal­cu­lated the en­ergy con­sump­tion pat­tern of a train with 19 Linke Hof­mann Busch (lhb) coaches, which are used in su­per­fast trains such as Ra­jd­hani, Shatabdi and Du­runto.The Rail­ways plan to in­tro­duce lhb coaches in all the trains in the com­ing years.

They found that to make a 1,800 km trip, a rake (com­pris­ing of 19 lhb coaches) con­sumes 3,000 litres of diesel for aux­il­iary en­ergy needs such as light­ing and cool­ing. “As­sum­ing that the rake makes 188 trips in a year, our cal­cu­la­tions in­di­cate that 90,804 litres of diesel can be con­served ev­ery year, with a sav­ing of 59,93,064,by putting so­lar

` pan­els on the train, ”says Ra­mase­sha.

The re­searchers sug­gest that the es­ti­mated price of an lhb rail coach with a so­lar power gen­er­a­tion sys­tem is 4 per cent higher than the price of the present lhb coaches.The in­vest­ment would be re­cov­ered within two-three years, they say.

Talk­ing about the fea­si­bil­ity of the pro--

ject, the pa­per says, “It is clear that the en­ergy that can be har­nessed dur­ing sun­shine hours is much more than the re­quire­ments of the train even dur­ing the shorter days of win­ters.” The re­searchers, as a re­sult, sug­gest the in­stal­la­tion of bat­ter­ies to store ex­cess en­ergy to be used at night.

Tech­nol­ogy trou­bles

While the Rail­ways’ move to go green is pos­i­tive, re­searchers say in­tro­duc­ing so­lar pan­els in trains will not be easy.For one, it will be a con­struc­tional chal­lenge to in­stall the pan­els on curved train rooftops. “The so­lar pan­els need to be man­u­fac­tured spe­cially based on the di­men­sions suit­able for mount­ing. We have sub­mit­ted a de­sign pro­posal to of­fi­cials at the Rail­way Coach Fac­tory in Ka­purthala,” says Shra­vanth Va­sisht, one of the re­searchers. “We are wait­ing to get a nod from the Rail­ways au­thor­i­ties to test our de­sign,” he adds.

Su­nil Dayal, a Delhi-based ex­pert on so­lar power tech­nol­ogy, points out an­other prob­lem. He says the rooftop so­lar mod­ules will have to sur­vive ex­treme weather con­di­tions such as rain, dust storms and snow. Be­sides the ob­vi­ous wind pres­sure that will be cre­ated dur­ing the mo­tion of the train, the pan­els will be ex­posed to sand and dust par­ti­cles, es­pe­cially in dif­fi­cult ge­o­graph­i­cal lo­ca­tions. “For ex­am­ple, dust par­ti­cles in Ra­jasthan are coarse and they may set­tle in huge quan­ti­ties.In that case, the mod­ule’s ef­fi­ciency is lost by three per cent and the pan­els will re­quire fre­quent clean­ing,” Dayal says.

He warns that clean­ing the so­lar mod­ules will be an ar­du­ous task. “While clean­ing th­ese mod­ules, ex­tra cau­tion has to be taken to avoid erod­ing the thin film of semi­con­duc­tors used in them. Though re­cent ad­vances such as wa­ter pump suc­tion sys­tem have been made to­wards main­tain­ing so­lar pan­els, they are ex­tremely ex­pen­sive,” he says.

The other ma­jor chal­lenge will be stor­ing the sur­plus en­ergy. Though ef­forts are be­ing made by nu­mer­ous groups across the globe, an ef­fi­cient bat­tery model is still a dream. There are two ways to use the so­lar en­ergy; one is through a grid sys­tem and the other is by us­ing stand-alone pho­to­voltaic power sys­tems.The grid sys­tem, with­out a bat­tery, can sup­ply elec­tric­ity between sun­rise and sun­set. “The other op­tion of a stand alone sys­tem that uses a bat­tery sup­port to store en­ergy will in­crease the cost, which might make the project un­eco­nom­i­cal,” says Dayal.

The prob­lems, though dif­fi­cult, can be tack­led, the re­searchers be­lieve. They say the Rail­ways can learn a lot from the Shim­laKalka toy train named Hi­malayan Queen, which is the first train to suc­cess­fully use so­lar power. Each of its coaches is fit­ted with 100Watt so­lar pan­els, each of which cost 1.25

` lakh.The pan­els gen­er­ate enough elec­tric­ity to meet the coaches’ light­ing needs for two days. The use of so­lar pan­els has also made the coaches lighter by 500 kg and re­duced the fre­quency of main­te­nance.

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