One of the most significant challenges critics of renewable energy cite is the lack of consistency in its energy supply —for example, a lower supply of solar energy when the sun isn't shining, or less wind power when it's calm outdoors.
Hydrogen, however, is an energy carrier that is unaffected by the time of day, the weather, or any other environmental factor. It is energy-dense relative to its volume, does not contain carbon, and exists naturally as an element in water. Despite these benefits, its production cost continues to be a challenge for the wide-scale distribution of hydrogen power, and splitting water molecules is energy-intensive.
The cost of oil is lower than the cost of hydrogen. Today, hydrogen costs between €2.05 - €5.58/kg ($2.50 - $6.80/kg) to produce, while a kilogram of hydrogen has the energy equivalence of a gallon of oil (3,8 kg of oil), which as of June costed around $1.67 per gallon.
As long as that differential exists, the hydrogen industry may struggle to gain wider adoption.
Two of the most common hydrogen production methods —steam-methane reforming (SMR) and electricity-consuming electrolysis— each have at least one, if not more fundamental flaws. SMR is sustainable, although not renewable because the chemical energy used to make hydrogen comes from fossil fuels. Electrolysis is renewable if the electricity required to split water molecules comes from a natural, carbon-free source, like wind or solar.
Because these approaches are flawed when implemented alone, combining them may well be the best path to create renewable, consistent, cost-efficient power.
From the efficiency perspective, direct electrification is preferable but not easily exploitable in all areas. In some energy-intensive sectors, such as the steel industry, long-haul aviation, and maritime shipping, the role of green hydrogen will therefore be significant.