Producing hydrogen now costs less and emits less carbon than ever before. In part, that is the result of the United States’ newfound abundance of natural gas, the source of most of the hydrogen produced. But it is also the result of technological improvements in the process of "reforming" natural gas into hydrogen. It now costs around as much to produce a gallon of gasoline as it does to produce the energy-equivalent amount of hydrogen with natural gas. Meanwhile, another method of producing hydrogen-electrolysis, which uses electricity to split water into hydrogen and oxygen-has seen major cost reductions as well. What makes electrolysis particularly attractive is that when powered by renewable sources such as wind and solar power, it directly emits zero carbon. ... Hydrogen storage has also improved. Prototypes used to feature bulky containers that were retrofitted into vehicles designed for conventional engines. But the latest tanks save space by being better integrated into the design of a car and by safely storing hydrogen at a higher pressure, leaving more room for passengers and their belongings. This new generation of containers allows a car powered by hydrogen fuel cells to travel as many miles on a single tank as a gasoline vehicle can and take about the same amount of time to refuel. ... The obstacles to distribution are beginning to fall away, too. True, with relatively few dedicated pipelines in existence, hydrogen has yet to show up at the vast majority of gas stations. But there are promising work-arounds. Most of the developed world does have good natural gas distribution infrastructure, which could feed smaller reactors that produce hydrogen. Hydrogen could also be produced on-site through electrolysis. ... estimates of what it would cost to mass-produce fuel-cell systems have decreased tremendously, from $124 per kilowatt of capacity in 2006 to $55 per kilowatt in 2014. The durability of these systems has improved dramatically as well, and they now meet the expectations of customers used to conventional automobiles.