AS a teacher at Pesantren (Islamic boarding school) Isti Daduddarain in Lombok, West Nusa Tenggara (NTB), Haryadi occasionally supervises the school's kitchen. The kitchen looks like any other with two gas stoves placed in a small space, he said, but with one difference: although the stoves use gas, no LPG (liquid petroleum gas) cylinders are used.

"The back of the stoves are not connected to cylinders, but instead, to pipes that run underground,"