The use of water electrolysis facilitates the economical production of hydrogen gas using low-cost electricity.
Many different industrial uses of hydrogen, including using hydrogen as a fuel, require the gas to be compressed to minimize its storage volume and to meet the required process pressures. Due to the extremely light nature of hydrogen in its natural state (at atmospheric pressure) it has a very low density, meaning when it is not compressed, a small container filled with hydrogen would contain very little. For this reason, compression of hydrogen fuel in storage tanks often uses pressures of up to 10,000 psi.
Compression of Hydrogen Gas
Compression has historically been achieved via the motion of mechanical pistons, which must work extremely hard to compress the diffused gas into a small volume. For this reason, and the need for precisely built high-specification systems, piston-compression can be extremely energy intense and prohibitively expensive.
In addition, the pistons often require lubrication to function at an appropriate efficiency which can result in contamination of the gas which must then be filtered out – adding another layer of expenses.
A more modern method of compressing hydrogen, which doesn’t require mechanical force, is electrochemical compression. Electrochemical compression involves using a proton exchange membrane (PEM), surrounded by electrodes, to pull low-pressure hydrogen through the membrane into a highly pressurized container.
Research has demonstrated that using electrochemical compression is cheaper and more effective than mechanical compression and it is expected to become a key hydrogen compression technology in the future.
Presently, electrochemical hydrogen compressors are capable of compressing hydrogen to pressures as high as 5,000 psi. It is believed that once the technique has been fully developed pressures beyond 10,000 psi will be attainable.
Electrochemical compression is expected to allow hydrogen generators to both generate and compress hydrogen without the need to use an external, mechanical compressor. This will improve the energy to hydrogen production ratio, and therefore lower the cost of supplying compressed hydrogen fuel.
Commercial PEM Hydrogen Generators
Nel Hydrogen can provide commercial PEM hydrogen generators, which use electrochemical compression to produce hydrogen at up to 435 psi pressure. Applications that require lightly-compressed hydrogen (i.e. 435 psi and under) will benefit from using these systems as external compressors will not be needed – saving money and efficiency.
This information has been sourced, reviewed and adapted from materials provided by Nel Hydrogen.
For more information on this source, please visit Nel Hydrogen.