Early gas grills used a piezoelectric starting mechanism... these have a tendency to wear out, and are hard to change. Modern gas grills use a battery powered starting mechanism... these last longer, but you still have to change the battery.
Introducing... the gas powered gas starter!
Well, actually it's just a battery powered gas grill starter, except that it's powered by a rechargeable battery, and that battery is recharged by a thermopile, which in turn is heated by the burning gas.-- goldbb, Mar 08 2010random, halfbakery