We are back with the third part of the Frequently Asked Questions about Hydrogen. In this series, we try to answer questions circulating on the web and increasingly appearing in the public debate to bring closer the potential of hydrogen as a fuel and make knowledge about it more familiar.
In today’s part, we focus on methods of hydrogen production, and how hydrogen production is currently shaped in Europe and the world.
6. How is hydrogen produced?
Currently, there is a lot of talk about hydrogen in the context of future areas of its use in transport or energy. However, hydrogen is already widely used in many sectors of the economy, including in the chemical, petrochemical, fuel, and manufacturing industries. Therefore, it is obtained in several processes characterized by different emissivity levels. Let’s look at some of them:
Steam Methane Reforming (SMR)
This is currently the most common hydrogen production process based on a series of reactions of superheated steam with syngas or light hydrocarbons, such as methane or biogases resulting from the methane fermentation of organic matter. The final products of individual stages, as well as of the entire process, are carbon oxides and hydrogen.
The efficiency of the process is about 75-80%, and the purity of the hydrogen obtained can reach 95-99.999%. The emissivity of methane steam reforming is estimated at 9 kg of CO2 for each kilogram of H2 obtained, with the consumption of approx. 3.5 kg of gas for each kilogram of hydrogen obtained. The process can use carbon dioxide capture technology, which, depending on the type, is characterized by different efficiency. Then we are talking about blue hydrogen.
Autothermal Reforming (ATR)
It involves the simultaneous reforming of methane and steam and the oxidation of carbon monoxide. The main difference between autothermal reforming (ATR) and steam reforming (SMR) is the theoretical possibility of capturing the entire volume of carbon oxides during the process.
Autothermal reforming depends on the feed preparation technology (i.e. methane and steam), as well as on the energy consumption of the oxygen separator and subsequent processes. With CCS technology, it is possible to theoretically reduce emissions to the atmosphere of almost all CO and CO2 generated during methane reforming. However, there remains the emission of carbon oxides associated with the generation of the temperature needed to initiate the process.
Coal gasification
It consists of the complete conversion of a solid substrate into a gaseous form. The process can be fed with raw materials with a wide range of parameters, e.g. coal, as well as waste and coal concentrates with a low calorific value. The result of gasification of coal and fossil fuels, biofuels or waste is syngas, composed of carbon and hydrogen oxides and smaller amounts of water and methane.
Coal gasification with CO2 capture allows for obtaining low-emission hydrogen, at the level of several kg of CO2 for each kg of hydrogen.
Natural gas pyrolysis
It is an endothermic reaction that requires a temperature of approx. 1000°C to initiate. Such a high temperature raises material issues. The reaction temperature can be lowered to about 800°C by using catalysts. Flow reactors are often used to separate the by-products (graphite, carbon nitrides) from the mixture of hydrogen and unprocessed natural gas during the reaction. After leaving the flow reactor, the mixture is cooled to ambient temperature and subjected to pressure swing adsorption, from which approx. 90% of the separated hydrogen with a purity of approx. 99.9% is recovered. The residue is recycled in the flow reactor. The heat that initiates the reaction is provided by an external source, which may be a source of additional emissions.
Pyrolysis of solid fuels
Including hard coal and solid biomass. It leads to the formation of a solid residue in the form of tar, decomposition water, and gases. The material supplied for the reaction is subjected to high temperature, causing the separation of particles with a lower molecular weight from the particles of the original raw material.
Water electrolysis
It is a well-recognized process of obtaining hydrogen, and the technology itself has been developed since the 18th century. In this method, the flow of electric current between the electrodes through the electrolyte causes the course of chemical processes at the boundary of the medium, i.e. between the solid conductor (electrode) and the liquid conductor (aqueous solution).
Globally, electrolysis accounts for approximately 2% of total hydrogen production. Due to the significant advantage of production using energy from the grid, it is difficult to determine how large a carbon footprint it can generate (strong dependence on the energy mix of individual countries).
For the transformation, it is important that the electricity involved in the process ultimately comes from sources with low and zero emissions (nuclear energy, RES). Only hydrogen produced in this way will be characterized by a completely neutral impact on the natural environment, and at the same time, as a storage, it will enable the stabilization of the energy system based on renewable sources.
Read the other articles in this series:
Frequently Asked Questions about Hydrogen #1
Frequently Asked Questions about Hydrogen #2
7. Where is the most hydrogen produced?
Currently, over 120 Mt of hydrogen is produced in the world, of which approximately two-thirds is hydrogen produced in dedicated installations (approx. 74 Mt), and the remaining part is a raw material that is a by-product of technological processes or produced in a mixture with other gases.
Among the largest producers in the world are China, the United States, and the European Union (11.4 Mt per year), with approx. 86% of the hydrogen produced in the EU comes from dedicated production. According to the data, Poland ranks among the top countries with the highest production efficiency in the world, producing on average about 1 Mt of raw material per year and thus ranks third among producers in Europe. Only Germany (approx. 2 Mt) and the Kingdom of the Netherlands (approx. 1.5 Mt) rank higher.
