The Hydrogen Ladder is my attempt to synthesise all the information known to me about all the factors driving technology uptake across all sectors of the economy in all countries of the world. Not ambitious at all!

What the Hydrogen Ladder is designed to do is to show how likely it is that any proposed use case ends up being a significant user of hydrogen (perhaps via one of its derivatives) in a decade or so, say 2035. That doesn't mean it's game over, the transition has happened, it just means it is absolutely clear by then that hydrogen is either the answer, or a major answer, to decarbonizing that use case.

In other words, it looks forward to a time after the current firehose of subsidies has subsided to affordable proportions, after there has been enough time for a bit more tweaking of technologies, after the emergence of supply chains, after a bit of familiarity has grown in the project finance sector, and so on.
As for what the rows mean, here's how I think about them:

• A - no alternative (though this does not mean the use case is growing)
• B - decent market share highly likely
• C - some market share likely
• D - small market share plausible
• E - niche market share possible
• F - niche market share in some geographies possible
• G - the Row of Doom

The Hydrogen Ladder is not all about efficiency, as its detractors claim. It does not include information about market size. It does not include information about speed of adoption. It does not include information about relative emissions reduction per kg of hydrogen or kWh of electricity. I leave it to others to add that information to the discussion.

Conversely, it does take into account cost, safety, convenience, critical mineral availability, co-benefits, externalities like air pollution, geopolitics, human behaviour and - underlying it all - thermodynamics, physics, chemistry, other sciences and economics.