Hydrogen

With an annual global production of around 110 million tonnes, hydrogen is an essential molecule in our modern societies. Although it is currently used mainly in the chemical industry (ammonia, methanol, etc.) and in refining (desulphurization, hydrocracking, etc.), hydrogen could play a major role in the energy sector in the future.

For around a century, hydrogen production has been dominated by steam methane reforming (SMR), a process characterised by extremely high carbon intensity, emitting globally more than 10 tonnes of CO₂ equivalent per tonne of H₂ produced!

Water electrolysis, when powered by low-carbon electricity, offers a promising route to producing “green” hydrogen. However, this process remains highly energy-intensive due to the high enthalpy of water dissociation (285 kJ/mol), which corresponds to 40 kWh per kg of H₂ at the thermodynamic limit and approximately 50–60 kWh per kg of H₂ using the most efficient current technologies. This energy constraint is holding back its large-scale deployment, with production costs currently estimated at between €4 and €8 per kg of H₂, which explains why, at present, hydrogen production via water electrolysis accounts for only 2–5% of global production.

H₂O → H₂ + ½ O₂  ΔHr = 285 kJ·mol⁻¹

Carbon black

Carbon black is one of the most widely used forms of solid carbon in industry. Around 15 million tonnes are produced worldwide each year, using an extremely polluting process devised over a century ago.

Ranked among the world’s fifty most important chemicals by tonnage, it is mainly used as a reinforcing filler in tyres, as a pigment, or as an electronic conductor (in batteries, etc.). Its production is based primarily on the incomplete combustion of heavy hydrocarbons. These traditional production processes are characterised by high CO₂ emissions and low material yields, which limits both their material efficiency and their environmental performance.