Hydrogen is often hailed as a silver bullet solution to emissions-free fuel since it burns clean, leaving nothing but water vapor, but the reality of using and producing green hydrogen is much more complicated. Hydrogen is already used as a power source in a lot of modern industries, including ammonia production, in refineries and as a feedstock for chemicals. The vast majority of the hydrogen in use, however, is not green hydrogen, but instead is what is known as “gray hydrogen.” While the hydrogen itself burns clean, the means of producing that hydrogen is actually fossil-fuels intensive (most often using coal or natural gas) and therefore does nothing in the way of decarbonizing the industries in which it is used.