hydrogen is the third most abundant chemical element on Earth’s surface, after oxygen and silicon, it is not available in its pure form, and thus it cannot be considered an energy source. Conversely, hydrogen is an energy carrier that should be produced from other sources. Although hydrogen production from water through electrolysis dates back to the 19th century, today’s hydrogen demand is mostly fulfilled by other processes based on fossil fuels (natural gas, coal, and oil), including steam methane reforming (SMR), auto thermal reforming (ATR), partial oxidation and coal gasification. Those processes are usually referred to as grey hydrogen pathways. When coupled to CCS, they can be transformed into low-carbon solutions, and they are called blue hydrogen pathways.
Conversely, hydrogen production from water electrolysis, which was abandoned due to higher costs, can be coupled to power generation from RES to produce green hydrogen. While current costs remain higher than fossil-based solutions, the expected learning curves for both RES electricity generation and electrolyzers could make it a viable solution in the next decades.
An estimation of future cost trends for green and blue hydrogen is reported in Figure below, based on estimations from BNEF data. The figure reports the costs both in terms of hydrogen mass, on the left axis, as well as in terms of energy content, considering hydrogen’s lower heating value (120 MJ per kg, or 33.3 kWh per kg). Renewable hydrogen costs are based on large projects with optimistic projections for capital expenditure. Blue hydrogen is based on natural gas prices of USD 1.1–10.3/MMBtu, and coal prices of USD 40–116/t. The uncertainty of future cost ranges is related to multiple aspects.
Other studies report comparable values and future estimations. The International Renewable Energy Agency (IRENA) estimates a Levelized cost of hydrogen by 2050 as low as 0.95 USD per kg when produced from wind electricity, and as low as 1.2 USD per kg when based on solar electricity.
In addition to green and blue hydrogen pathways, it is important to remark that other options may be considered, in particular in specific countries or regions. Hydrogen production from nuclear electricity is rarely mentioned in European strategies, but it may become a viable alternative in different world regions, such as China and Russia. Other solutions for renewable hydrogen may be based on biomass gasification or SMR based on biogas feedstock, although these solutions may be harder to scale-up than electrolysis.
