Integrating Solar Energy, Desalination, and Electrolysis

Abstract

Solar electricity enables the advancement and deployment of technologies that are strongly influenced by clean energy availability and cost. The economics of both desalination and hydrogen production from water electrolysis are dominated by the cost of energy, and the availability of inexpensive solar energy creates markets and offers incentives to the desalination and electrolyzer industries. Herein, production of high‐purity water and hydrogen from seawater is focused on. Current electrolyzers require deionized water so they need to be coupled with desalination units. It is shown that such coupling is cost effective in hydrogen generation, and it also offers benefits to thermal desalination, which can utilize waste heat from electrolysis. Furthermore, such coupling can be optimized when electrolyzers operate at high current density, using low‐cost solar and/or wind electricity, as such operation increases both hydrogen production and heat generation. Results of technoeconomic modeling of polymer electrolyte membrane electrolyzers define thresholds of electricity pricing, current density, and operating temperature that make clean electrolytic hydrogen cost competitive with hydrogen from steam methane reforming (SMR). By using 2020 hourly electricity pricing in California and Texas, it is estimated that hydrogen can be produced from seawater in coupled desalination−electrolyzer systems at prices near $2 kg−1 H2, reaching cost parity with hydrogen produced from SMR.

Review of solar-enabled desalination and implications for zero-liquid-discharge applications

“…The large range of values of STEC and SEEC shown in table 1 reflects small and large, and old and modern plants. As shown, RO is less energy intensive than thermal processes in producing freshwater from brackish and seawater, but thermal processes have an advantage in treating high salinity feed water and producing completely demineralized water, as that is needed for hydrogen production via electrolysis (Ginsberg et al 2021).…”

Comment on Seibert, M.K.; Rees, W.E. Through the Eye of a Needle: An Eco-Heterodox Perspective on the Renewable Energy Transition. Energies 2021, 14, 4508

“…The authors did not list any of the hundreds of articles dealing with the production of "green H 2 " by using RE to power water electrolyzers; electrolytic H 2 currently costs 2-3 times more than SMR H 2 , but its learning curve shows that cost parity is being approached quickly. Recent studies on optimizing electrolyzer operation to follow electricity pricing patterns show that the levelized cost of Hydrogen can get as low as to $2/kg (H 2 ) with dynamic operation following simple enhancements in electrolyzer components [83]. This is supported by an IRENA 2019 analysis showing that Hydrogen produced from electricity can be competitive if the price of electricity falls to below USD 30/MWh, which is projected with increased solar energy penetration [84].…”

Microbial Water Electrolysis Cells for Efficient Wastewater Treatment and H2 Production

“…Water electrolysis (WE) is another effective method for H 2 production, which is expected to achieve cost competitive with hydrogen from steam methane reforming (SMR). − Water electrolyzers produce H 2 by splitting water with direct electrical current, requiring a voltage of 1.6 to 2.2 V, which is notably higher than the operating voltage of MECs . In recent years, anion exchange membrane water electrolysis (AEMWE) has been developed to address the cost and corrosion issues associated with conventional alkaline and proton exchange membrane water electrolysis. − Currently, AEMWE can achieve a high current density of 1 A/cm 2 for 25 h at 1.57 V and 80 °C .…”