How is hydrogen fuel obtained?

Hydrogen is the most abundant element in the Universe, and it is very common on Earth. Hydrogen is the simplest of atoms, made up of one proton and one electron. But pure diatomic hydrogen (H2) is the fuel used by batteries and does not exist naturally. Because hydrogen easily combines with other elements, it’s very likely that we’ll find it chemically bound in water, biomass, or fossil fuels.

To get hydrogen in a useful form, we must extract it from one of these substances (by electrolysis, natural gas, biomass sources, by photoelectrolysis). But they all require energy.

Electrolysis consists of passing an electrical current through H2O to separate it into hydrogen (H2) and oxygen (O2). Hydrogen gas rises from the negative cathode and oxygen gas accumulates at the positive anode. Electrolysis produces extremely pure hydrogen, which is necessary for some types of fuel cells. But a significant amount of electricity is required to produce a usable amount of hydrogen from electrolysis.

Hydrogen can also be extracted from natural gas. A two-step process at temperatures reaching 1100 °C in the presence of a catalyst produces four parts hydrogen from one part methane and two parts water (CH4 + 2 H2O >>> 4 H2 + CO2).

Hydrogen can be extracted from hydrogen-rich biomass sources such as wood chips and agricultural residues. When heated in a controlled atmosphere, biomass turns into syngas, which consists primarily of carbon monoxide (CO), carbon dioxide (CO2), and hydrogen (H2).

Photoelectrolysis uses sunlight to split water into its components through a sandwich of semiconductor material. It’s more or less like submerging a photovoltaic cell in water, where the incoming light stimulates the semiconductor to split the H2O directly into its constituent gases.

How is hydrogen produced?

Chemically bound hydrogen is found everywhere on Earth: in water, fossil fuels, and all living things. However, it rarely exists in nature free moving. Instead, it has to be extracted from water or hydrocarbons.

It is derived from natural gas through a steam reforming process. Natural gas reacts with steam in a catalytic converter. The process removes the hydrogen atoms, leaving carbon dioxide as the by-product, and unfortunately releases it into the atmosphere as a global warming gas.

Coal can also be reformed through gasification to produce hydrogen, but this is more expensive than using natural gas and also releases CO2, which scientists hope to keep in the ground through a process called “carbon sequestration.” Hydrogen can also be processed from gasoline or methanol.

Other Ways to Produce Hydrogen Fuel

However, there is another way to produce hydrogen without using fossil fuels in the process. Renewable energy sources (photovoltaic, wind, hydroelectric, geothermal and biomass) can be harnessed to produce electricity. Electricity, in turn, can be used, in a process called electrolysis, to split water into hydrogen and oxygen.

Hydrogen can be produced from a variety of sources, including fossil fuels; renewable sources such as wind, solar or biomass; thermochemical reactions that are powered by nuclear or solar heat; and solar photolysis or biological methods.

Although hydrogen is an abundant element in the universe, it does not naturally exist in large quantities or high concentrations on Earth; it must be produced from other compounds such as water, biomass or fossil fuels. Various production methods have unique needs in terms of energy sources (eg heat, light, electricity) and generate unique by-products or emissions.

Hydrogen fuel with methane

Steam making methane accounts for 95 percent of the hydrogen produced in countries like the United States. This is a catalytic process that involves reacting natural gas or other light hydrocarbons with steam to produce a mixture of hydrogen and carbon dioxide. The mixture is then separated to produce high purity hydrogen.

Oxidation as Hydrogen Fuel

Partial oxidation of fossil fuels in large gasifiers is another method of thermal hydrogen production. It involves the reaction of a fuel with a limited supply of oxygen to produce a mixture of hydrogen, which is then purified. Partial oxidation can be applied to a wide range of hydrocarbon feedstocks, including natural gas, heavy oils, solid biomass, and coal.

Hydrogen can also be produced by using electricity in electrolysers to extract hydrogen from water.