Electrolysers have become a key part of green hydrogen production. In this article we explain what they are, how they work and why they are key to the energy transition.
An electrolyser is a device that uses electricity to split water into its two basic elements: hydrogen and oxygen.
This process, known as electrolysis, makes it possible to produce high-purity hydrogen with no carbon emissions, provided the electricity used comes from renewable sources.
The concept of electrolysis was developed in the 19th century, but its large-scale application has become relevant in the current context of energy transition. Electrolysers have become a key technology for storing renewable energy and producing sustainable fuels. Their design varies depending on the type of electrolyser and the electrolyte used, but they all operate on the same basic principle of splitting water into its elementary components by applying an electric current.
An electrolyser works by passing an electric current through water (H₂O), causing the molecules to split into hydrogen (H₂) and oxygen (O₂).
The process takes place in an electrolytic cell, which consists of three main components:
When an electric current is applied, hydrogen ions move to the cathode where they capture electrons to form hydrogen gas molecules. At the same time, oxygen ions at the anode release electrons and combine to form molecular oxygen.
An electrolyser works by applying electricity to water to separate the molecules into hydrogen and oxygen
Electrolysers can be divided into four main types based on the type of electrolyte they use and the way they conduct electricity: alkaline electrolysers, PEM electrolysers, solid oxide electrolysers and AEM electrolysers.
Electrolyser capacity is growing worldwide, with China leading the way with 60% of global electrolyser manufacturing capacity, according to the International Energy Agency’s (IEA) latest Global Hydrogen Review. Other regions are also stepping up their efforts, with Europe being one of the main players in scaling up its electrolysis projects.
Europe with 25%, Latin America with 15% and the US with 15% together account for more than half of the potential low-emission hydrogen production by 2030. Specifically, Spain, Denmark and Germany, in that order, are the leaders in water electrolysis projects and could account for more than 40% of European low-emission hydrogen production by 2030.
Spain aims to lead the European hydrogen market thanks to its optimal conditions and has the most ambitious EU target for installed capacity, up to 11GW by 2030.
To achieve this, public support is and will be essential. The recent inauguration of the Accelera by Cummins electrolyser factory in Guadalajara, the largest of its kind in Spain, is an example of the commitment to this key technology for the development of renewable hydrogen. With an annual production capacity of 500 MW, this plant will supply large-scale electrolysers for projects in Europe, strengthening the hydrogen value chain and consolidating our country’s role.
On the other hand, the Ministry for Ecological Transition and the Demographic Challenge (MITECO) recently allocated a total of 1.214 billion euros of NextGenEU funds to seven renewable hydrogen projects located in different autonomous communities. It will create 9,000 direct jobs and around 11,000 indirect jobs, with 90% of the electrolysers being manufactured in Europe.
In this context, research into new materials and manufacturing processes to reduce costs and improve the efficiency of electrolysers will be of paramount importance. Furthermore, the integration of this technology with other hydrogen storage and distribution solutions will be crucial for its mass adoption.
