There are different processes for producing hydrogen using electrolysis. While in previous years only highly specialized companies were involved in this, recently many companies - including newcomers - are working hard to improve electrolyzers, make the technology more efficient and, above all, automate the production process in order to increase throughput and costs to lower.

The number of manufacturers of electrolysers is increasing. Our editorial team has examined the global offering and compiled the research results into a market overview. We found 92 systems from 17 manufacturers.

All systems were recorded using data sheets available on the Internet. If there is no publicly available data, we have not included the product in our list.

Products not directly comparable

As expected, we found different standards, for example when it comes to information on performance or generation capacities. This makes it impossible to directly compare the products with one another. We have also omitted any other detailed information. For example, information on the specific yield (in cubic meters) depends on the pressure level. In both cases, criteria for the quality of the systems cannot be derived from this.

As the lowest common denominator for comparability, we list the available systems according to nominal output, supplemented by manufacturer, type of electrolyser and type of generation. If no rated power was specified in the data sheets, we calculated it based on other available parameters. The market overview covers nominal outputs from 1 kilowatt to 100 megawatts.

Market overview of electrolyzers 2022: 100 kW – 1 MW
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Market overview of electrolyzers 2022: from 10 MW
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We have refrained from collecting prices. On the one hand, the still young market is constantly changing because many manufacturers are trying out mass production and can thus quickly achieve economies of scale. On the other hand, researchers are constantly working on replacing expensive components with mass-produced and therefore cheaper ones. Furthermore, electrolyzers are not yet products for home use. Tenders from interested industrial users, followed by individualized offers from manufacturers, are not uncommon, making list prices obsolete.

Four methods in application and research

Four processes in particular are currently used and tested for electrochemical water splitting:

• The most common method is alkaline electrolysis (AEL). The technology with industrial applications in series-production systems has been around since the first half of the last century: metal electrodes are immersed in an aqueous solution, separated by a membrane. By applying a voltage, the water is split into hydrogen (formed at the cathode, negative pole) and oxygen (formed at the anode, positive pole). If the electricity comes from renewable sources, the result is “green“Hydrogen.
• The proton exchange membrane electrolysis (PEM; Proton Exchange Membrane) or polymer electrolyte membrane (Polymer Electrolyte Membrane) is younger. Water is separated into hydrogen and oxygen using a proton-permeable membrane. The electrodes used are made of precious metal to reduce corrosion in the acidic environment. Research is primarily focused on extending the service life of the membrane material used.
• High-temperature solid electrolyte electrolysis (SOEC; Solid Oxide Electrolysis) is still in the research stage; industrial applications only serve to practically test new scientific findings. According to the manufacturer, the first systems will be available soon. High temperatures of 600 to 1.000 degrees Celsius are required. Adding thermal energy to split the water can reduce electricity requirements. The electrodes are separated by a ceramic material in a solid oxide fuel cell (SOFC).
• According to the company, the only company in the world currently using anion exchange membrane electrolysis (AEM) is Enapter AG, which developed the process. According to an explanation, the individual cell of the system is divided into two half-cells by the anion exchange membrane. Each half cell consists of an electrode, a gas diffusion layer and a bipolar plate. Several individual cells would be connected to each other through the bipolar plate and thus form the AEM stack. This arrangement enables the production of hydrogen at a pressure of 35 bar or oxygen at one bar. The pressure difference between the half cells prevents the oxygen produced from passing into the high pressure half cell, which ensures a very high hydrogen purity of 99,9 percent, says Enapter.

The two main processes currently used are AEL and PEM electrolysis. AEL is more cost-effective on a large scale; hydrogen production occurs at low pressure levels, but is not very dynamic. The PEM process is cost-effective in small units, but technologically complex. The membranes are subject to high levels of corrosion and are therefore only moderately durable. The pressure level is high, as is the dynamic. The advantages of PEM technology lie in its easily controllable behavior in the partial load range, which makes it suitable for mobile use in fuel cells.

Standard cubic meter as a measure

Due to technological developments, the specific energy requirement for the hydrogen volume flow produced using electrolysis falls below 4,5 kilowatt hours per standard cubic meter (kWh/Nm³). As a rule of thumb, the energy requirement is around 5 kWh/Nm³ of hydrogen.

A standard cubic meter is the amount of a gas contained in a volume of one cubic meter at a pressure of one bar. One kilogram of hydrogen corresponds to 11,1 standard cubic meters. The lower calorific value of hydrogen is around 3 kWh/Nm³ or 33,3 kilowatt hours per kilogram (kWh/kg).

scaling

The systems can be scaled up as required and the providers excel at multiplying and specifying overall performance. Mainly individual systems were included in the list and only larger scaled systems were shown if a special data sheet was available for them.

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Bosch is also starting to develop components for electrolyzers and wants to put PEM pilot systems with mass-market “Smart Modules” into operation as early as 2023. © Bosch