Eliminating the traditional electrolyte from electrolysis, a new electrolyzer design is aiming for higher efficiencies and lower costs in green hydrogen production. Tobe Energy (Oklahoma City, Okla.; www.tobe.energy) has developed a high-voltage all-stainless-steel electrolysis system that operates at much lower temperatures — and with significantly less energy loss — than traditional electrolyzers.
“We wanted to update the electrolysis infrastructure to reflect current topologies that are super, super efficient. So instead of adding something like potassium hydroxide, as traditional electrolyzers do, to increase the electrolyte concentration and increase the conductivity of the water, we ended up using the water as a dielectric fluid, so as more of an insulator compared to a conductive medium,” explains Colby DeWeese, founder and CEO of Tobe Energy.
Source: Tobe Energy
This means that instead of a resistive load, where electrolyte is added to make the system more resistive and more conductive, Tobe’s system has a capacitive load with water acting as the dielectric medium, supporting operations at lower temperatures (around 30˚C) than traditional electrolysis. DeWeese likens this configuration to the efficiency difference between the energy use of an incandescent lightbulb and a light-emitting diode (LED) bulb. “Usually, in electrolysis systems, anywhere between a quarter and half of their footprint can be their cooling systems, but we completely negate that need for cooling, and that’s really where all the cost reductions are. Because we’re not trying to eke out slightly more efficiency to offset cooling costs and lost heat, that also allows us to use standard, rather than exotic, metals for the anode and cathode,” says DeWeese. The company operates an in-house manufacturing facility in Oklahoma City where the stainless-steel electrolysis stacks are constructed.
The company is currently working to patent a novel anode-cathode geometry that helps to optimize bubble size, bubble formation and residence time on the electrode surface. “We were at first using a flood-cell design, but we are moving to a dry cell with the first commercial prototype, which we think will be even better, with lower humidity and less water droplets,” says DeWeese.
Tobe Energy has operated a 25-kg/d demonstration unit for over 1,000 h, showing energy efficiencies as high as 95%. Now, the company is working with Zeeco, Inc. (Broken Arrow, Okla.; www.zeeco.com) to significantly scale up via a 20-stack pilot plant at Zeeco’s Advanced Research Complex, and early talks are underway to partner with an e-fuels company. “We’re also concurrently developing a 250-kw unit, which would produce around 125 kg/d of hydrogen. This would support mid-scale commercial industrial needs, like food hydrogenation companies,” adds DeWeese.