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Material World
Element · H

Hydrogen

The lightest and most abundant element in the universe, and the one most often proposed as a replacement for the fuels we currently burn.

Fuel

Hydrogen is the simplest possible atom: one proton, one electron. It makes up about three quarters of the ordinary matter in the universe and almost none of the Earth's atmosphere, because it is light enough to escape the planet's gravity.

As a material it is awkward in ways that get understated. It embrittles steel by diffusing into the metal's grain boundaries, it leaks through seals that hold every other gas, and liquefying it requires cooling to twenty kelvin. Most discussion of hydrogen as a fuel is really a discussion about containing it.

Uses

Overwhelmingly industrial rather than energetic: roughly half of world production goes into making ammonia for fertiliser, and much of the rest into refining petroleum. Its role as a fuel is small today and is the subject of most of the investment.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is used as

  • Fertiliser — application · via ammonia synthesis, which consumes about half of world production

is found in

  • Sulfuric acid — compound
  • Polyvinyl chloride — material
  • Natural rubber — material
  • Polypropylene — material · the rest of it; polypropylene is carbon and hydrogen and nothing else
  • Polyethylene terephthalate — material · on the ring and the chain
  • Nylon — material · including the amide hydrogens that bond to the next chain along, which is where the strength comes from
  • Polystyrene — material · the balance
  • Polycarbonate — material · the balance
  • Coal — rock · in the volatile matter, and what distinguishes a coal that makes gas from one that makes coke
  • Cotton — material · with the oxygen, in the hydroxyl groups that make the fibre absorb water
  • Seawater — material · as water, which is the other 96.5 per cent of it
  • Ethylene — compound · four, and nothing else — ethylene is as simple as a useful monomer gets
  • Propylene — compound · six
  • Styrene — compound · eight
  • ABS — material · the balance
  • PMMA — material · the balance
  • POM — material · two per carbon, and no side groups at all
  • PEEK — material · on the rings
  • PLA — material · the balance
  • Aramid fibre — material · including the amide hydrogens whose bonding between chains carries the load across the fibre
  • Silicone rubber — material · on those methyl groups
  • Neoprene — material · the balance
  • Epoxy resin — material · the balance
  • Polyurethane — material · the balance
  • Phenolic resin — material · the balance
  • Crude oil — material · roughly one to two per carbon depending on the fraction
  • Naphtha — material · the balance
  • Gypsum plaster — material · in that water, which is driven off in a fire and takes a great deal of heat with it
  • Resin — material · the other half of the hydrocarbon
  • Amber — material · around 10 per cent
  • Water — compound · two atoms of it, and eleven per cent of the mass
  • Beeswax — material · the rest of the chains
  • Sodium hydroxide — compound PubChem
  • Apatite — mineral · substitutes within a solid solution — an individual specimen may hold little of it
  • Azurite — mineral Wikidata
  • Borax — mineral Wikidata
  • Gypsum — mineral Wikidata
  • Lepidolite — mineral · substitutes within a solid solution — an individual specimen may hold little of it
  • Malachite — mineral Wikidata
  • Muscovite — mineral Wikidata
  • Pollucite — mineral Wikidata
  • Talc — mineral PubChem
  • Topaz — mineral · substitutes within a solid solution — an individual specimen may hold little of it

is produced by

is an alternative to

  • Helium — element · as a lifting gas: hydrogen lifts slightly better and is far cheaper and flammable, which is why airships stopped using it and why weather balloons still do

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • PubChem
    US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors
  • NIST — National Institute of Standards and Technology
    United States Department of Commerce · US Government work — public information, credit requested

Questions this page answers

Where it comes from, and what it becomes

Follow Hydrogen back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

  • Hydrogen → is produced by (the third product, often burned for process heat rather than sold) → Chlor-alkali electrolysis → takes as input (the largest single use of salt, and the process the whole chlorine and caustic soda industry rests on) → Salt → is produced by (in the solar route — the same process, read from the other end) → Brine evaporation → takes as input (the feedstock for solar salt and, in the salars, for the far stronger brines that lithium comes from) → Seawater → is composed of (about 96.5 per cent by mass — seawater is 3.5 per cent dissolved solids and the rest of it is this) → Water
  • Hydrogen → is produced by (the third product, often burned for process heat rather than sold) → Chlor-alkali electrolysis → takes as input (as the brine the cell electrolyses, and as the source of the hydrogen that comes off the cathode) → Water → is sourced from (by desalination, where energy is cheap and coastline available — the only route that adds fresh water rather than moving it) → Seawater
  • Hydrogen → is produced by (the third product, often burned for process heat rather than sold) → Chlor-alkali electrolysis → takes as input (as brine; the salt is the feedstock for both products at once) → Halite
  • Hydrogen → is produced by (the third product, often burned for process heat rather than sold) → Chlor-alkali electrolysis → takes as input (the largest single use of salt, and the process the whole chlorine and caustic soda industry rests on) → Salt → is sourced from (by solar evaporation, which needs a dry sunny coast and is the cheapest route there is) → Seawater → is composed of (about 96.5 per cent by mass — seawater is 3.5 per cent dissolved solids and the rest of it is this) → Water
  • Hydrogen → is produced by (the third product, often burned for process heat rather than sold) → Chlor-alkali electrolysis → takes as input (the largest single use of salt, and the process the whole chlorine and caustic soda industry rests on) → Salt → is sourced from (mined as rock salt from bedded deposits, or dissolved in place and pumped up as brine — which is what the chemical industry wants anyway) → Evaporite → is composed of (precipitated early, when the water has reduced to roughly a fifth of its volume) → Gypsum
  • Hydrogen → is produced by (the third product, often burned for process heat rather than sold) → Chlor-alkali electrolysis → takes as input (the largest single use of salt, and the process the whole chlorine and caustic soda industry rests on) → Salt → is sourced from (mined as rock salt from bedded deposits, or dissolved in place and pumped up as brine — which is what the chemical industry wants anyway) → Evaporite → is composed of (the bulk of most evaporite sequences, and the reason the rock is called salt) → Halite

These are the most distinct paths back. Hydrogen can be traced through others besides.

Downstream — what it becomes

  • Hydrogen → is used as (via ammonia synthesis, which consumes about half of world production) → Fertiliser