Immense water resources needed for a fully-fledged transition to green hydrogen; water scarcity, need for extensive treatment poses threat.
Here’s an article posted in AECOM.
According to the post,
- Green hydrogen production requires significant water resources.
- Strategies such as desalination and treated wastewater can be implemented to meet the water demand.
- Additional investment and energy consumption are needed for water processing.
The production of green hydrogen through water electrolysis has very specific water quality requirements that must be met to ensure the efficient and reliable operation of the electrolysis equipment.
Alkaline Electrolysis
Alkaline electrolysis, one of the main commercial technologies for green hydrogen production, requires highly purified, demineralized water as the feedstock. The ideal water for alkaline electrolysis should have the following characteristics:
Our specialty focus areas include 
- Conductivity: Less than 1 microsiemens per centimeter (μS/cm)
- Total Dissolved Solids (TDS): Less than 0.1 parts per million (ppm)
- pH: Neutral, between 6.5 – 7.5
- Hardness: Less than 0.1 ppm
- Silica: Less than 0.1 ppm
- Chlorides: Less than 0.1 ppm
- Sulfates: Less than 0.1 ppm
Any impurities or minerals present in the water can degrade the performance and efficiency of the alkaline electrolyzer cells, reducing their output and lifespan.
Polymer Electrolyte Membrane (PEM) Electrolysis
PEM electrolysis has even stricter water quality requirements compared to alkaline electrolysis. The water used in PEM electrolysis must be of extremely high purity, with the following specifications:
- Conductivity: Less than 0.1 μS/cm
- Total Organic Carbon (TOC): Less than 50 parts per billion (ppb)
- Silica: Less than 10 ppb
- Cations (Na+, K+, Ca2+, Mg2+): Less than 1 ppb each
- Anions (Cl-, SO4 2-, NO3-): Less than 1 ppb each
- pH: Neutral, between 5.0 – 8.0
The PEM electrolysis process is more sensitive to impurities than alkaline electrolysis, and even trace amounts of contaminants can significantly degrade the performance and lifespan of the PEM membranes and catalysts.
In summary, the water quality requirements for green hydrogen production via electrolysis are extremely stringent, with PEM electrolysis having the most demanding specifications. Maintaining the necessary water purity is essential for ensuring the efficient, reliable, and sustainable operation of the electrolysis equipment.
Interestingly, we have some other posts related to this content:
Green Hydrogen Production: Water Needs and Availability Concerns: Mongabay article highlights concerns about water requirements for green hydrogen production, emphasizing efficient process management despite lower consumption than fossil fuel-based methods.
