[Sonicmouse]

"14-year-old creates eco-battery with aluminum foil, old guitar strings, and club soda."

Because aluminum foil, old guitar strings and club soda are so prominent in 3rd world countries.

And also... How come I didn't win 25K for my 6th grade science fair projects?

[elinchrome]

This is only a stepping stone. He's working on a plastic-wrap, sitar string, and mango lassi battery.

[mikeash]

"Doshi was inspired by conversations with his father, a doctor, and trips to poor and polluted towns in India."

I'm going to make a guess here than he may have a better idea of what materials are available in third world countries than you do.