[ water treatment ]
energy consumption for water treatment will still be significantly lower than for electrolysis , and it will consume no freshwater .
This means that although there is never one answer , SWRO is likely to be employed in most cases due to advantages in price , availability , and scalability .
The main challenge for a green hydrogen desalination system will be the huge reduction in salt concentration required to meet electrolyzer quality standards . The special operating conditions for green hydrogen systems with fluctuating demand for water will also mean that the desalination system must be designed differently compared to what is normally done in the desalination industry .
Using seawater for green hydrogen production does not have to be a future dream – the water treatment solutions already exist today . Even for desalination , the cost of water treatment will be much lower compared to the expenses associated with the electrolyzer . Therefore , it ’ s essential to highlight that using seawater for hydrogen production will not make the business case for an electrolyzer plant , but doing desalination wrong will break it .
Thermal systems have raised a lot of interest due to their ability to operate on waste heat , but in reality , this will not be enough . Thermal desalination systems that rely on heat still need access to electricity . Additionally , for these systems to function effectively , the temperature of the waste heat must typically be higher than 70 ° C . Therefore , while waste heat is beneficial , it alone cannot sustain the operation of thermal desalination systems .
The possibility of combining cooling and water treatment – because heat is removed from the electrolyzer to produce water – is a second advantage that is often brought forward for thermal systems . However , thermal systems require only 100 – 200 kWh of heat to produce 1 m ³ of ultrapure water , while electrolysis of the same 1 m ³ of ultrapure water will generate around 1,000 kWh of heat . Therefore , a thermal water treatment system can only utilize a fraction of the heat and cannot replace a cooling tower .
The main case for a thermal system would be in places where highly robust systems are required and where the produced water can be used directly in an alkaline electrolyzer or fed to an EDI or mixed bed to reach PEM quality . These systems might be more energy-intensive and expensive compared to SWRO systems , but they would offer a simpler system requiring minimal service .
About the authors
Henrik Tækker Madsen , PhD , is a water treatment specialist working within the interplay between water and energy . He works as Application Development Manager at the water treatment company Silhorko- Eurowater A / S – part of Grundfos , where he leads the work on establishing industry-leading knowledge within various water applications , including electrolysis . Dr . Madsen is a chemical engineer with more than 10 years of experience in business development , sales , R & D , and innovation .
Ozan Yucel holds a BEng in Environmental Engineering with a specialization in water treatment technologies . He works as Business Development Manager at the water treatment company Meco – part of Grundfos . With a decade of experience , he has developed a comprehensive understanding of both the technical and strategic aspects of the industry . Mr . Yucel ’ s work , spanning more than 20 countries , has afforded him a unique insight into diverse water treatment practices and market dynamics worldwide .
26 Hydrogen Tech World | Issue 16 | June 2024