What is an Hydrogen Electrolyzer?

An electrolyzer is a device that uses electrical energy to drive a non-spontaneous chemical reaction, typically the decomposition of water into hydrogen and oxygen gases. This process, known as electrolysis, involves passing an electric current through water, causing it to split into its constituent elements.

Electrolysis Process:

Electrolysis is the fundamental process that electrolyzers perform. When an electric current is applied to water (H₂O), it splits into hydrogen (H₂) and oxygen (O₂) gases. The overall chemical reaction is: 

2H2O(l)→2H2(g)+O2(g)

Components of an Electrolyzer:

  • Anode: The positive electrode where oxidation occurs. In water electrolysis, oxygen is produced at the anode.
  • Cathode: The negative electrode where reduction occurs. In water electrolysis, hydrogen is produced at the cathode.
  • Electrolyte: A medium that allows the flow of ions between the anode and cathode. It can be an acidic, alkaline, or solid polymer substance.
  • External Power Source: Supplies the electrical energy required for the electrolysis process.

Types of Electrolyzers:

  1. Proton Exchange Membrane (PEM) Electrolyzers: Use a solid polymer electrolyte membrane that conducts protons from the anode to the cathode. These electrolyzers offer high efficiency and are capable of operating at higher current densities.
  2. Alkaline Water Electrolyzers (ALK): Use a solution of potassium hydroxide (KOH) or sodium hydroxide (NaOH) as the electrolyte. These are well-established and widely used due to their lower cost and mature technology.
  3. Solid Oxide Electrolyzers (SOE): Operate at high temperatures (typically 700-1000°C) and use a solid ceramic material as the electrolyte. They are highly efficient and can directly convert water and CO₂ into syngas.
  4. Anion Exchange Membrane (AEM) Electrolyzers: Utilize an anion-conducting polymer membrane as the electrolyte. They are a newer technology with the potential for lower costs and improved performance.

How to Choose a Suitable Hydrogen gas generator for You.

Main Types of Electrolyzers and Their Characteristics


Alkaline Electrolysis Technology (ALK)

Alkaline electrolysis technology uses an alkaline environment, such as a potassium hydroxide aqueous solution, as the electrolyte, and asbestos as the diaphragm to separate hydrogen and oxygen. Compared to other technologies, one significant advantage is that the anode and cathode plates do not contain precious metals, resulting in relatively low electrolyzer costs. This technology has been developed for a long time and has a well-established technical and commercial ecosystem, currently accounting for about 80% of the market.

Disadvantages:
It is difficult to start quickly and adapt to changes, requiring stable power, and is not suitable for fluctuating power sources like photovoltaics and wind power. This means it cannot participate in the “boom” of wind and solar energy development.

Solid Oxide Electrolyzer (SOE)

Solid oxide electrolyzers use solid oxides such as zirconia as the electrolyte and operate at high temperatures. The core barrier lies in the development of cathode and anode materials, which have long been in the laboratory stage. However, there have been some breakthroughs recently.

Anion Exchange Membrane Electrolyzer (AEM)

Anion exchange membrane electrolysis is also in the laboratory stage, and future advancements will depend on breakthroughs in related materials. Currently, the proton exchange membrane electrolyzer (PEM) is the most promising to replace ALK.

PEM Electrolyzer

PEM electrolyzers include components such as proton exchange membranes, catalysts, gas diffusion layers, and bipolar plates. The advantages are fast startup and adaptability to flexible power sources like wind and solar power. However, the electrodes and catalysts heavily rely on precious metals like iridium, platinum, and titanium. Overall, compared to ALK, the disadvantage of PEM is its higher cost. From a life-cycle cost perspective, PEM costs $2.77/kg, higher than ALK’s $2.45/kg.

Of course, PEM is also striving to reduce costs through technological development, domestic substitution, and economies of scale. Compared to ALK, PEM electrolyzers are more compact, reducing the footprint for the same hydrogen production scale by half, which is also a consi

Considering the need for stability in power supply compatibility, ALK alkaline electrolyzers will be used in large-scale hydrogen production fields, such as chemical and metallurgical industries. In regions with abundant wind and solar power, PEM proton exchange membrane electrolyzers will be favored.