Understanding advanced alkaline water electrolysis: hydrogen production
Water electrolysis is a critical process for hydrogen production.
This technology has been getting loads of attention recently, as hydrogen produced employing this method can be harnessed to decarbonize energy and hard-to-abate sectors, such as ammonia and steel production.
In simple terms, electrolysis relies on an electric current to drive a chemical reaction. Water (H₂O) consists of two hydrogen atoms bonded to one oxygen atom. When an electric current passes through water, the chemical bonds are broken, releasing hydrogen (H₂) and oxygen (O₂) gases.
The chemical reaction can be represented as:
The process occurs inside an electrochemical cell, the core of any electrolysis setup.
An electrochemical cell for water electrolysis has a straightforward design. It consists of two electrodes — a positively charged anode and a negatively charged cathode — immersed in water.
To improve electrical conductivity, an electrolyte substance (such as salts, acids, or alkaline solutions) is added to the water.
When an electric current flows through the cell:
• At the cathode (negative electrode), water molecules gain electrons and are split into hydrogen gas and hydroxide ions (OH⁻).
• At the anode (positive electrode), hydroxide ions lose electrons and form oxygen gas.
The anode and the cathode are separated by a diaphragm, which allows the two gases to be collected separately, with hydrogen being the main product for energy and other industry applications. The efficiency of the process depends heavily on the design of the cell and the materials used for the electrodes and electrolytes.
Traditional water electrolysis methods can be energy-intensive, but technological progress has made them more efficient. In this sense, traditional alkaline water electrolysis, a type of electrolysis that occurs at basic pH and was developed more than a century ago, has been substituted by advanced alkaline water electrolysis.
In these innovative systems, the electrodes are coated with De Nora’s propriety electrocatalysts, which speed up the reaction, while thinner diaphragms enhance the separation of hydrogen and oxygen. The advanced design features a zero-gap configuration, where the anode and cathode are in direct contact with the diaphragm. These improvements reduce electrical resistance, minimizing energy loss and increasing cell efficiency.
Another advantage of alkaline systems is their cost-effectiveness. Unlike some newer methods, such as proton exchange membrane (PEM) electrolysis, alkaline electrolysis does not rely on expensive materials like iridium for the electrodes and other components. This makes it a practical choice for large-scale hydrogen production.
Hydrogen produced through water electrolysis is called “green hydrogen” when the electricity used comes from renewable sources like solar or wind. This clean hydrogen can be used in fuel cells to power vehicles, produce electricity, or even as a raw material for industrial processes.
When used as a chemical reagent, its only byproduct is water, making it a sustainable energy carrier in the fight against climate change.
Water electrolysis is a simple yet powerful process that unlocks hydrogen’s potential as a clean energy source.
With progress like the development of the advanced alkaline water electrolysis, the solution is becoming more efficient and affordable, paving the way for a greener future.
Whether it’s fueling cars or storing renewable energy, the hydrogen produced through electrolysis plays a key role in the energy transition.