The end-use of hydrogen was originally in mainly chemical industries and oil & gas. Hydrogen is used for purpose of reduction in a redox reactions; and they are also used to produce ammonia by reacting it with nitrogen through the Haber Bosch process. Hydrogen is so tiny and its density so low that it is hard to properly store them; so they are typically produced onsite before they are fed into the reactions that require them as a feedstock.
The world of sustainability suddenly turned towards hydrogen as the magic low carbon energy vector. Besides the fact that it contains no carbon, the combustion of hydrogen will only produce water as a by-product. It is about the cleanest possible fuel if you treat it as one. And on a per unit weight basis, its energy density is incredible. Just 760g of hydrogen can power a Toyota Mirai (a fuel-cell electric vehicle) for 100km. That is lighter than the fossil fuel required to power an internal combustion engine car over the same distance.
But for everyone to use it, all the cars on the roads will have to be able to take in hydrogen as fuel; and there will have to be hydrogen refueling stations. In Japan where the government laid out plans more than half a decade ago to push for hydrogen adoption in the country. Even after supporting the production of fuel cell electric vehicles and some combined heat power systems for households utilizing hydrogen, even subsidizing the capital investment in hydrogen refueling stations, the adoption is still poor.
Perhaps to add insult to injury, the hydrogen used in most of these use cases were not even green hydrogen. They were produced by steam methane reforming – ie. extracting hydrogen from methane (giving off yet more carbon dioxide emissions). But I’d argue we have to start somewhere and it is really difficult to transform the end-use part of the whole value chain. Getting adoption even before mass availability of green hydrogen is the only way we can shift the world today to prepare for a cleaner future.
Again, it seemed when it comes to carbon emissions, that it has to go up to come down.