AC-DC Converters for Electrolyzer Applications: State of the Art and Future Challenges

Abstract

The main objective of the article is to provide a thorough review of currently used AC-DC converters for alkaline and proton exchange membrane (PEM) electrolyzers in power grid or wind energy conversion systems. Based on the current literature, this article aims at emphasizing the advantages and drawbacks of AC-DC converters mainly based on thyristor rectifier bridges and chopper-rectifiers. The analysis is mainly focused on the current issues for these converters in terms of specific energy consumption, current ripple, reliability, efficiency, and power quality. From this analysis, it is shown that thyristors-based rectifiers are particularly fit for high-power applications but require the use of active and passive filters to enhance the power quality. By comparison, the association combination of the chopper-rectifier can avoid the use of bulky active and passive filters since it can improve power quality. However, the use of a basic chopper (i.e., buck converter) presents several disadvantages from the reliability, energy efficiency, voltage ratio, and current ripple point of view. For this reason, new emerging DC-DC converters must be employed to meet these important issues according to the availability of new power switching devices. Finally, based on the authors’ experience in power conversion for PEM electrolyzers, a discussion is provided regarding the future challenges that must face power electronics for green hydrogen production based on renewable energy sources.

Proton Exchange Membrane Electrolyzer Emulator for Power Electronics Testing Applications

“…High-power industrial alkaline EL supplied by the grid are usually operated in stationary conditions, hence they can be emulated simply by an equivalent resistance. Differently, PEM ELs are available also for low power and are suitable to be supplied by RES through a converter [45]; on the other hand, a more accurate model is required [46]. Even if the EL can be considered as a load, the use of a programmable load, suitable for obtaining static operation, does not reproduce the transients unless a reference model is used.…”

Potential and Economic Analysis of Solar-to-Hydrogen Production in the Sultanate of Oman

“…The technologies for water electrolysis are an alkaline electrolyser, a polymer electrolyte membrane (PEM) electrolyser, and a solid oxide electrolyser cell. Alkaline is the earliest and most mature technology; however, it faces challenges, such as losses during operation at the high current densities that result in a rise in operating temperature and lessens efficiency [20,21], and the possibility of mixing hydrogen and oxygen gases while passing through the aqueous electrolyte. The solid oxide electrolyser cell (SOEC) has the highest efficiency; however, this technology market is still in the early stages [22].…”

Design of a LLC Resonant Converter for Powering a PEM Electrolyzer

“…Alkaline and PEM technologies are available in the market; their supply needs a DC voltage (ranging from a few to hundreds of volt) and DC currents (from ten to thousands of amp). For this reason, a power converter is required [6,7]. In particular, when the supply is a power grid or a wind turbine, the AC/DC converters must be adopted; differently, solar panels can be interfaced with DC/DC converters.…”