Feature Report: Hydrogen as an Energy Carrier

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Hydrogen Production

Hydrogen is the most abundant chemical element in the universe, found in the Sun, other stars and the gas planets in our solar system. It occurs naturally on Earth, but not in large enough quantities to be produced cost-competitively. It therefore needs to be separated from other elements.

A steam methane reformer used to produce hydrogen at the Jubail refinery in Saudi Arabia. © Labelle Michel / TOTAL

On Earth, hydrogenThe simplest and lightest atom, the most abundant element in the universe. is generally found in compounds with other elements. The most common are carbon, with which it forms methane (CH4)The main component of natural gas deposits and oil deposit gas caps. Methane is produced naturally by landfills..., and oxygen, with which it forms water (H2O). How is pure hydrogen made? To obtain pure hydrogen for industrial applications, it must be separated from the chemical elements to which it is bound.

Hydrogen can be produced by electrolysis using renewably-sourced electricity

Hydrogen Production Process Technologies

Today, 95% of hydrogen is produced either from wood or from fossil fuels, such as natural gas and oil. Three types of production process are currently in use:

Only 1% of the hydrogen produced in France is obtained using electrolysis technology. But as new uses for hydrogen energy emerge, requiring purer hydrogen, the horizons for this technology are broadening. R&D work aims to lower production costs, especially by using high-temperature (or steam) electrolysis at 700 to 800 °C.

Producing “Clean” Hydrogen

To ensure that this new energy carrierA synonym of secondary energy (see definition). is “green” — meaning that it emits little greenhouse gasGas with physical properties that cause the Earth's atmosphere to warm up. There are a number of naturally occurring greenhouse gases... — hydrogen production has to be as clean as possible.

Reforming produces few greenhouse gases when combined with carbon capture and storage processes; however, these significantly increase costs.

Today, 95% of hydrogen is produced from fossil fuels

Gasification is another option, because it covers the entire solid biomassIn the energy sector, biomass is defined as all organic matter of plant or animal origin... pathway: many types of organic matter can be burned to produce biogasA product of the methanation (anaerobic digestion) of organic waste.... Although wood (in the form of charcoal) is the main feedstock used, plant waste such as straw is also suitable. Because biomass sources can be replanted, the carbon footprintThe carbon footprint (also known as greenhouse gas inventory) of a good or service measures the impact human activities have on the environment ... is low.

Electrolysis also produces clean hydrogen when “green” electricity is used. But to overcome the issue of cost-competitiveness, large amounts of inexpensive electricity are needed year-round. Prototypes are under study, especially in Germany, to use intermittent production spikes from wind and solar energy. But for now, the cost of electrolysis is still prohibitive. 

Other hydrogen production processes are also being examined2

 

Sources:

(1) Ethesis

(2) French Alternative Energies and Atomic Energy Commission