SoCalGas to test technology that separates hydrogen from natural gas when the two are blended in pipelines
With clean hydrogen gaining recognition worldwide as a carbon-free fuel capable of making a significant contribution to addressing climate change, Southern California Gas Co. (SoCalGas) will field test a new technology that can simultaneously separate and compress hydrogen from a blend of hydrogen and natural gas.
Created by Netherlands-based HyET Hydrogen, the technology is designed to provide pure highly-compressed hydrogen wherever a natural gas distribution system exists.
Operation principle of an electrochemical hydrogen compressor. Rhandi et al.
The new technology—Electrochemical Hydrogen Purification and Compression (EHPC)—works by applying an electrical current across a hydrogen-selective membrane to allow only hydrogen to permeate it while blocking the natural gas components. Continuously applying the electrical current builds up and pressurizes the hydrogen.
Hydrogen is supplied to the anode side of the membrane surface where a platinum-alloy catalyst splits the molecule into protons. The electrons are transferred via an external circuit to the catalyst layer on the opposite side of the proton exchange membrane (PEM).
An externally applied current forces the protons through the membrane inducing mass transport of hydrogen. After passing through the membrane, the protons recombine as hydrogen molecules on the output (cathode) side.
The current enables the transport of hydrogen against its concentration gradient, from low pressure on the anode side to high pressure on the cathode side in a single step. One electron equals one proton, equals half a hydrogen gas molecule.
As the (PEM) membrane is only permeable for hydrogen protons and acts as a barrier for other components in the gas. In this way, hydrogen can be extracted to fuel cell purity from mixes containing nitrogen, methane, argon, water (vapor), etc.
The core of the compressors is a series of compression cells that each act as an individual compressor and together form a compression stack.
To test the technology, SoCalGas will blend hydrogen in concentrations from 3-15%, with methane, the primary component of natural gas. That blend of gases will then be injected through a simulated natural gas pipeline testing system into the EHPC system to continuously extract and compress the hydrogen at a rate of 10 kg per day.
SoCalGas’ testing will provide performance data that will enable fine-tuning and optimization of the EHPC system to accelerate scaling up the technology. Within the next two years, the EHPC technology is expected to be scaled to produce 100 kg of hydrogen a day or more from a single EHPC system, enough to fill 20 fuel cell electric vehicles.
The project is scheduled to begin in March at SoCalGas’ Engineering Analysis Center in Pico Rivera, California and slated to be complete by the third quarter of 2021.
At scale, the technology would allow hydrogen to be easily and affordably transported via the natural gas pipeline system, then extracted and compressed at fueling stations that provide hydrogen for fuel cell electric vehicles (FCEVs).
SoCalGas also recently announced a program to study blending hydrogen into its natural gas pipelines. If approved by regulators, the program would be the first step toward establishing a statewide standard for injecting hydrogen into the natural gas grid.
This innovative technology could be a game-changer, allowing hydrogen to be distributed to wherever it is needed using the natural gas grid. As demand increases for zero-emissions vehicles such as fuel cell electric cars, California will need thousands more hydrogen fueling stations—and this technology may help make that possible.—Neil Navin, vice president of clean energy innovations at SoCalGas
Maha Rhandi, Marine Trégaro, Florence Druart, Jonathan Deseure, Marian Chatenet (2020) “Electrochemical hydrogen compression and purification versus competing technologies: Part I. Pros and cons,” Chinese Journal of Catalysis, Volume 41, Issue 5, Pages 756-769 doi: 10.1016/S1872-2067(19)63404-2