The single biggest technological challenge to replacing fossil fuels in vehicles and other technological gadgets is finding a better battery. Electricity can do everything else that an internal combustion engine can do, often better, but is hard to store. Batteries are a way of storing electricity chemically, but an alternative to batteries, called supercapacitors, which store free electrons as ions in something akin to a static electricity state, are superior in terms of discharge speed, recharge speed and number of times the system can be charged and discharged before failing. But, they've been unattractive due to their cost and low energy denesity.
A new kind of supercapacitor made a graphene, a newly discovered form of carbon, which is an abundant and cheap material and is increasingly inexpensive to mass produce in this particular form, may change that. Graphene based supercapacitors with an energy density close to that of lead-acid batteries are close to reaching mass production.