Alkaline Water Electrolysis: Efficient Bridge to CO₂‐Emission‐Free Economy

Abstract

Water electrolysis is a key technology to realize sector coupling and renewables integration. To establish CO 2 -free or -reduced value chains as well as carbon capture and utilization, ''green hydrogen'' is the essential element, serving as fuel, energy carrier, and feedstock for ''green chemicals''. As a well-developed technology, alkaline water electrolysis (AWE) enables industrial scale hydrogen production in high purity. The electrolyzers are highly dynamic in operation and can also serve as primary control reserve, thus further stabilizing the power grid.

Optimized Demand-Side Day-Ahead Generation Scheduling Model for a Wind–Photovoltaic–Energy Storage Hydrogen Production System

“…where f is the fitness value, and if the jump probability serves as the fitness value of p ibest , then the jump probability of p ibest is used to substitute that of G best . The calculation is as follows: (17) Adaptive simulated annealing PSO made an adaptive change to parameters and employed annealing simulation in ways that made the optimizing process faster and more accurate. Given that, the algorithm was adopted to develop the optimized generation scheduling model for the wind−PV−ES hydrogen production system, whose flow diagram is shown in Figure 2.…”

“…In coupling intermittent renewable energy, the electrolyzer’s operational features worth consideration include the load range, ascent and descent rates, and time for start and shutdown. 17 The alkaline electrolyzer can operate at 15% to 100% of its nominal capacity, making it incompatible with a full range of input power from renewables. 18 Indeed, frequent on-and-off practices not just shorten the life of the electrolyzer but also disrupt how a hydrogen production system powered by wind and solar utilizes energy across the board.…”

Ecological and Economic Evaluation of Hydrogen Production by Different Water Electrolysis Technologies

“…Commercial AEL plants up to 160 MW and 33 000 Nm 3 H 2 h -1 have been operated on an industrial scale for decades [13]. Recent technology improvements are focused on dynamic operation with intermittent renewable energies [14]. PEM is often recommended as the most flexible and most suitable technology for dynamic operation.…”

“…The specific energy demand varies depending on the current density and the load factor. At a low load factor or rather low current densities a high efficiency and a comparatively low specific energy demand is achieved, whereas at high load factors and high current densities the efficiency of the a) Minimum operable hydrogen production rate relative to maximum specified production rate; b) thyssenkrupp system installed at Carbon2Chem ; c) Lü ke and Zschocke [14].…”

“…In countries with highcarbon electricity and where nuclear power is phase-out, such as Germany, the dynamic operation of water electrolysis with fluctuating renewables is the only possibility to produce low-carbon hydrogen. Both AEL and PEM can be operated dynamically while, in comparison, the dynamic operation of SOEC is limited [14,15]. Therefore, AEL and PEM are important for low-carbon hydrogen production in countries with high-carbon electricity, and they are more favorable than SOEC.…”