Low temperature electrolysis

Low Temperature Electrolysis

An electrolysis cell uses electricity to split water molecules (H2O) into hydrogen (H2) and oxygen (O2). In this way electrical energy is transformed into chemically bound energy in the hydrogen molecules. This is the reverse of the process that occurs in a fuel cell.

Electrolysis cells can be used for the production of hydrogen using surplus power from, e.g., wind turbines. The hydrogen can be stored and – using a fuel cell – reconverted into electricity again when the demand arises. This allows the storage of electricity when production exceeds demand.

The cell type determines the operation temperature. Our research is both on low temperature electrolyses (below approx. 300 °C) and high temperature electrolysis. At low temperatures two types of cells are currently used: alkaline electrolysis cells and polymer electrolyte membrane (PEM) cells, each with their strengths. The alkaline cells can use non-noble metal catalysts in their electrodes, while the PEM cells have higher efficiencies.

The technologically mature electrolysis technology is alkaline electrolysis of water at temperatures below 100 °C. Here, our focus is to increase the conversion efficiency, without increasing cost, by developing a ‘zero-gap’ cell with a novel electrolyte. This will combine the advantages of alkaline and PEM cells.

Two less technologically mature but very promising electrolysis concepts are also pursued: A high pressure, high temperature (> 100 °C) alkaline or mildly acidic electrolysis
cell where the electrolyte is aqueous KOH, KHCO3 or phosphates immobilized in an inorganic mesoporous foam, and polymer electrolyte membrane (PEM) electrolysis with a cell which is closely related to the corresponding fuel cell. In both cases, the promise of very high current density and increased conversion efficiency is the main motivation.

The Department of Energy Conversion and Storage is building on its extensive experience within fuel cells as the basis for electrolysis research. In a number of projects with partners from industry and academia we develop the technology for a number of different applications. Our research span from fundamental investigations of the electrochemical properties of materials to manufacture and test of entire cells and modules.

The main research topics are:

  • Development of polymer-based electrolytes for alkaline electrolysis, e.g. anion exchange membranes or KOH-imbibed polymers
  • Computational design, synthesis, and characterization of catalysts without noble metals for alkaline electrolysis
  • Detailed characterization of electrolysis cells using impedance spectroscopy
  • Solid or liquid inorganic proton conductors for electrolysis above 200 °C.


Jens Oluf Jensen
DTU Energy
+45 45 25 23 14