[L20] Hydrogen

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Last updated 11:36 PM on 4/17/26
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10 Terms

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Current situation

  • used to be on the rise

  • lot of investment in the past

  • present: less talk

  • appeared in 1800s

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Properties

  • lightest element (atomic mass = 1)

  • gas at atmospheric conditions

  • colourless, odourless, tasteless, non-toxic, highly combustible

  • stable in form H2

  • not naturally available alone, abundant in compounds with other elements

melting point: -259°C

boiling point: -252°C

  • high pressures needed to keep H2 liquid at room temperature or cryogenic temperatures

  • energy carrier ➔ high energy density but low mass density (0.08 kg/m3, 120 MJ/kg, 9.6 MJ/m3)

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Sources of hydrogen

Green hydrogen → 1%

  • water electrolysis & renewable electricity

Blue hydrogen

  • fossil fuel but CO2 captured & stored underground

  • carbon capture, storage and utilisation (CCSU) → expected to be carbon neutral

Gray hydrogen → 99% (95% natural gas by SMR, 4% partial oxidation)

  • from fossil fuel & commonly uses steam methane reforming method (extracts H2 from methane using steam)

  • CO2 produced & released

Pink hydrogen

  • from nuclear energy

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Future

  • many more uses to come

  • planned H2 in the world is much larger than current H2

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From electrolysis

separation of H20 into H2 & O2

efficiency ~ 70-85%

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From methane

several options w/ CO2, high T &/or high P

Steam-methane reforming reaction

CH4+H2O (+heat) → CO +3H2

Partial oxidation of methane reaction

CH4 + 1/2O2 → CO + 2H2 (+heat)

95% natural gas by SMR, 4% partial oxidation

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Storage

  • can be stored either as a gas or as a liquid.

  • gas storage done in high pressure tanks (350-700 bar or 5000-10,000 psi)

  • liquid hydrogen storage done in cryogenic temperatures to prevent it boiling back into a gas

  • hydrogen can also be stored on the surface of (adsorption) or within solid materials (absorption)

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Energy extraction

Fuel cells

  • hydrogen batteries

  • efficiency 40-60%

  • output H2O

Combustion

  • efficiency 40-50%

  • output H2O

<p>Fuel cells</p><ul><li><p>hydrogen batteries</p></li><li><p>efficiency 40-60%</p></li><li><p>output H2O</p></li></ul><p></p><p></p><p>Combustion</p><ul><li><p>efficiency 40-50%</p></li><li><p>output H2O</p></li></ul><p></p>
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Opportunities

  • Isolated systems (no access to grid) where changing infrastructure may result cost-effective: steel production, shipping and planes; but not consumer cars (electric grid is more available already).

  • Highly volatile future, subject to regulations against fossil fuels or technology breakthroughs.

  • There can be a strong industry lobby (from CH4 owners) to push further.

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Challenges

  • Production of H2: energy demanding (only 1% is currently green hydrogen) = mainly non green

  • Difficult storage (and transport): high pressure or cryogenic conditions

  • Highly leak able and flammable – difficulties for infrastructure adaptation

  • Production technology not deployed at market level and infrastructure clearly lagging behind