Hydrogen production

Hydrogen production is the family of industrial methods for generating hydrogen. Currently the dominant technology for direct production is steam reforming from hydrocarbons. Many other methods are known including electrolysis and thermolysis.

In 2006, the United States was estimated to have a production capacity of 11 million tons of hydrogen. 5 million tons of hydrogen were consumed on-site in oil refining, and in the production of ammonia (Haber process) and methanol (reduction of carbon monoxide). 0.4 million tons were an incidental by-product of the chlor-alkali process. Hydrogen production is an estimated $100 billion industry. According to the U.S. Department of Energy, only in 2004, 53 million metric tons were consumed worldwide. There are no natural hydrogen deposits, and for this reason the production of hydrogen plays a key role in modern society.

As of 1999, the majority of hydrogen (∼95%) is produced from fossil fuels by steam reforming or partial oxidation of methane and coal gasification with only a small quantity by other routes such as biomass gasification or electrolysis of water. Around 8GW of electrolysis capacity is installed worldwide, accounting for around 4% of global hydrogen production (Decourt et al., 2014).

There are four main sources for the commercial production of hydrogen: natural gas, oil, coal, and electrolysis; which account for 48%, 30% 18% and 4% of the world’s hydrogen production respectively. Fossil fuels are the dominant source of industrial hydrogen. Hydrogen can be generated from natural gas with approximately 80% efficiency, or from other hydrocarbons to a varying degree of efficiency. Specifically, bulk hydrogen is usually produced by the steam reforming of methane or natural gas. The production of hydrogen from natural gas is the cheapest source of hydrogen currently. This process consists of heating the gas in the presence of steam and a nickel catalyst. The resulting exothermic reaction breaks up the methane molecules and forms carbon monoxide CO and hydrogen H₂. The carbon monoxide gas can then be passed with steam over iron oxide or other oxides and undergo a water gas shift reaction. This last reaction produces even more H₂. The downside to this process is that its major byproducts are CO, CO₂ and other greenhouse gases. Depending on the quality of the feedstock (natural gas, rich gases, naphtha, etc.), one ton of hydrogen produced will also produce 9 to 12 tons of CO₂.

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