Session: 09-10-01: Hydrogen Production, Storage, and Integrated Hydrogen Energy Systems I

Paper Number: 173112

Over 12% Efficiency Solar-Powered Green Hydrogen Production From Seawater 

Hydrogen produced by renewable energy through water electrolysis is known as green hydrogen, which plays a vital role in the deep decarbonization of hard-to-abate sectors, such as high-capacity energy storage, transportation, and chemical industry. Sustainable development of green hydrogen technologies is limited by significant water consumption, because producing per kilogram of hydrogen at least needs nine kilograms of water. Clean water supply has become one of the major sources of operational costs for green hydrogen production. More importantly, considering that two thirds of global population is facing severe water scarcity, producing green hydrogen by consuming clean water poses a critical challenge at the water-energy nexus toward sustainability. Natural sunlight and seawater are the most abundant and accessible resources on Earth, and they can provide infinite energy and water supplies for green hydrogen production. Although seawater electrolysis has been recognized as a promising means, existing approaches either rely on complex electrocatalysts or require additional desalination and purification facilities, increasing the cost, energy consumption, and carbon emission of hydrogen production. In this work, we provide a sustainable pathway “Seawater + Sunlight = Green Hydrogen + Clean Water” to address the water-energy nexus associated with green hydrogen.

In this work, we demonstrate a solar-powered approach to produce green hydrogen directly from seawater with high STH efficiency and low cost. This method takes advantage of the full-spectrum utilization of solar energy by combining photovoltaic (PV) and photothermal (PT) effects. High-energy photons are converted to electricity through a PV panel to drive electrolysis whereas the rest of the absorbed solar energy is converted to heat to produce clean water through interfacial thermal distillation. By exploiting the full potential of waste heat produced by the PV panel, we achieve in situ water purification to address the critical fouling and corrosion of electrodes without consuming electricity. All electricity produced by the PV panel is used for electrolysis, promising a high STH efficiency toward the fundamental limit dictated by the solar-to-electricity conversion. More notably, owing to the passive operation nature, we can minimize the cost associated with water purification and electricity supply, which dominates the operational expenditure (OPEX) of existing water electrolysis. To prove our concept, we developed a hybrid solar distillation-water electrolysis (HSD-WE) prototype, which integrates a proton exchange membrane (PEM) electrolyzer with a PV panel and an interfacial thermal distillation device. With natural sunlight and seawater as the sole inputs, we demonstrate green hydrogen production with 12.6% STH efficiency using a 17.3% efficiency silicon (Si) PV panel. Under one-sun illumination (1000 W/m²), we achieved 35.9 L/m²/h production rate of dry hydrogen with 1.2 L/m²/h distilled water continuously fed into the PEM through interfacial thermal distillation. Due to the simple architecture and solar-powered passive operation, the technoeconomic analysis shows that the cost of green hydrogen production with our approach is expected to be $5/kg with three-year operation and $1/kg with 15-year operation.

Presenting Author: Xuanjie Wang Lehigh University

Presenting Author Biography: As an Assistant Professor at Lehigh University, I’m working on renewable energy and energy storage. I have my
postdoctoral training at MIT, with the focus on radiation heat transfer and green hydrogen production.

Authors:

Xuanjie Wang Lehigh University
Jintong Gao Cornell University
Yipu Wang Cornell University
Yayuan Liu Johns Hopkins University
Xinyue Liu Michigan State University
Lenan Zhang Cornell University