There is much promise in the decarbonization potential of “green” hydrogen produced via water electrolysis powered by renewable energy. A flurry of research activity across the globe is aiming to improve the efficiency and costs for electrolysis by investigating new catalysts, membranes and more. Less attention, however, is being paid to a primary input to electrolyzer cells — water. In this interview, Prakash Govindan, co-founder and chief operating officer of Gradiant Corp. (Boston, Mass.) describes the company’s integrated approach to water treatment, and how the expansion of green hydrogen production via water electrolysis is transforming the way water purification technologies are deployed.
Gradiant’s water-treatment platform for green hdyrogen (Source: Gradiant)
Gradiant’s water-treatment solution, called ProtiumSource, is said to be the industry’s first electrolyzer-ready water solution that works with any water source, including seawater, brackish water or even treated wastewater. “ProtiumSource combines advanced water treatment technologies into an integrated, three-phase system that is tailored for green hydrogen producers. No other solution in the market integrates all three facets of electrolyzer source water production: water purification; high-purity water for electrolysis; and brine management for zero-liquid discharge [ZLD],” says Govindan.
In the pretreatment and water purification phase (Step 1), reverse-osmosis (RO) technology and selective contaminant-extraction technologies efficiently remove a complete range of inorganic and organic contaminants from the feedwater, such as fluoride, potassium, iron, and more. During high-purity water-production phase (Step 2), large flow volumes are polished to produce water that exceed industry standards for electrolyzer use. This step is capable of achieving ultra-pure water with parts-per-trillion purity through a combination of ion-exchange, electrodeionization and ultraviolet technologies.
Finally, ProtiumSource incorporates integrated brine management for ZLD, ensuring that, unlike other systems, wastewater from high-purity water production (Step 3) is treated to the point where no liquid waste is released into the environment. This step employs Gradiant’s patented Counterflow Reverse Osmosis (CFRO) technology.
Brine management is a key element that enables the use of such a wide range of water sources. “The company’s ZLD solution recovers up to 100% of final brine concentrations, pushing the limits of salt saturation to minimize or eliminate liquid waste, leaving only solids for disposal or beneficial reuse. This is especially critical for green hydrogen production sites, where efficient water waste management is essential for business continuity. No liquid waste is discharged into the environment,” adds Govindan. This step concentrates the wastewater, leaving only salts, minerals and other contaminants removed from the feedwater as the final byproducts. The technology maximizes water recovery, leaving behind concentrated solids that can be more easily managed, eliminating the need for wastewater disposal and minimizing the environmental impact of green hydrogen production.
The system is said to operate with 40% less energy and deliver 60% cost savings compared to conventional technologies, while also accommodating a wide range of feedwater and operating conditions, due to lower equipment costs and minimized system downtime. Furthermore, says Govindan, CFRO technology significantly increases water-recovery rates to up to 99%, compared with 75% achieved by conventional RO systems, drastically reducing wastewater-disposal requirements. “This makes makes Gradiant’s CFRO a critical and differentiated solution for green hydrogen producers facing strict water management and environmental requirements,” he notes.