Electrolysis

Water + Electricity = Hydrogen

Hydrogen’s ability to combine with oxygen was first noted by Henry Cavendish in 1766. The first electrolyzer subsequently appeared in 1800 when Nicolson and Carlisle induced a static charge into water. More than 200 years later Hydrogenics continues to evolve and improve on these fundamental discoveries.

Electrolysis cells are characterized by their electrolyte type. There are two types of low temperature electrolysis where Hydrogenics is active: Alkaline and Proton Exchange Membrane (PEM).

Thanks to decades of research and development in both technologies, Hydrogenics has the unique capability to offer PEM and Alkaline systems and to select the most appropriate one based on the cost, capacity and use of it.

Both Alkaline and PEM technologies have the ability to deliver:

  • On site and on demand hydrogen (load following)
  • Pressurized hydrogen without a compressor
  • 99.999% pure, dry and carbon-free hydrogen 

AN: 2H2O = 4H+ + O2 + 4e-
CA: 2H+ + 2e- = H2
Overall: 2H2O = 2H2 + O2

Alkaline electrolysis is a mature technology in which the reaction occurs in a solution composed of water and liquid electrolyte (KOH).  

When a voltage is applied across two electrodes in an aqueous solution, a water splitting reaction occurs. Hydrogen will evolve at the cathode, while oxygen will evolve at the anode.

Recombination of hydrogen and oxygen at this stage is avoided by means of the highly efficient and patented IMET® ion-exchange.  Our IMET® membrane is made of highly resistant inorganic materials and does not contain any asbestos. The electrolyte remains in the system, thanks to a clever and pump-free closed-loop recirculation system.

The HySTAT
® electrolyzers are installed at hundreds of industrial plants, power stations, energy storage facilities and fueling stations around the world.  They are safe and reliable systems used by all major industrial gas suppliers in heavy-duty applications. 

pem-electrolysis-diagram
AN: 4H- = 2H2O + O2 + 4e-
CA: 2H2O + 2e- = 2OH-
Overall: 2H2O = 2H2 + O2

PEM electrolysis is based on the use of a solid conducting polymer that conducts ions when hydrated with water.

A potential difference (voltage) is applied between the two electrodes. The water molecules, which have a polarity, are forced to dissociate into H+ and OH-. The H+ ion (proton) is attracted to the cathode where it receives an electron and becomes a neutral H atom.

The H atom then encounters another like it, and forms a molecule of H2 gas.

Attracted to the anode, the negatively charged OH- ion gives up its extra electron and combines with three like molecules to form two water molecules and one O2 molecule.

Cell Stack

The core component of an electrolyser is the cell stack, where both hydrogen and oxygen are produced. Our expertise then also involves the setup of a complete system around the cell stacks. 

Some cooling will be required to cool down the process and produced gas, a water treatment system will be installed in order to produce demineralized water from the supplied tap water, a purification system will clean the hydrogen to deliver high purity gas according to the customer’s specifications, a power rack will be installed to manage the power needed for the reaction (converting the AC current delivered by the grid into a direct current used for the process) and a control panel will allow the operator to have an overview of the complete package. All these wisely selected and specifically manufactured equipment will then either be installed in a building or packaged in an outdoor housing