Hydrogen Production Processes

Hydrogen is a clean and renewable fuel that has the potential to play a significant role in the transition to a sustainable energy future.?

Hydrogen production will be done by steam methane reforming, coal gasification, oil reforming, and electrolysis process.?

Steam Methane Reforming?

SMR (Steam Methane Reforming) is a conventional method to produce hydrogen. The steam methane reforming process produces syngas (hydrogen and carbon monoxide) through the reaction of hydrocarbons with water. The feed for the SMR reaction is methane/natural gas. The main goal of the process is to produce hydrogen.?

The main disadvantage of the SMR reaction is the formation of a huge amount of CO2, which was found to be 8.47kg of CO2/Kg H2.?

The produced hydrogen is mainly used in refining petroleum, treating metals, producing fertilizer, and processing foods. SMR is accountable for the maximum production of hydrogen to meet market demand. The high use of SMR technology for hydrogen production is due to its low cost of hydrogen production. The cost of hydrogen from SMR ranges between $1 and $1.3/Kg.?

Electrolysis Process?

Electrolysis is the technique used to produce hydrogen by breaking the water molecules using an electric current in an electrolyzer in order to extract the H2. The main advantage of the electrolysis process is zero emissions of greenhouse gases.?

Although the electrolysis process was invented in 1789, its development has been limited due to economic constraints. However, the world has undergone a transformation toward sustainability in the last few decades, making this process more appealing. The present contribution of electrolysis to hydrogen production is around 4%; by the year 2050, it is estimated to reach around 60% of the total hydrogen production.?

Alkaline water electrolysis (AEL), polymer electrolyte membrane electrolysis (PEME), solid oxide electrolyser (SOEL), and anion exchange membrane electrolysis (AEM) are the most common electrolysis technologies. While SOEL and AEM are at lab scale, alkaline water electrolysis is the only method that is economically feasible for green hydrogen at the present time.?

Alkaline Water Electrolysis?

Alkaline water electrolysis is the only commercially viable electrolytic process. Hydrogen is produced in a cell comprising an anode, a cathode, and a membrane. The cells are usually assembled in series to produce more hydrogen and oxygen at the same time.?

When the current applies to the electrolysis cell stack, hydroxide ions move through the electrolyte from the cathode to the anode of each cell, generating bubbles of hydrogen gas on the cathode side of the electrolyzer and oxygen gas at the anode. The purity of the AEL is lower compared to other electrolysis processes, which have a purity of 70%. oldest and best-established electrolyte technology.?

The demand for the alkaline water electrolysis process is increasing because of its low-cost utilisation of catalysts and commercialization feasibility, and the global alkaline water electrolysis market size was $116.05 million in 2021.?

Polymer Electrolyte Membrane Electrolysis?

PEM electrolyzers use a proton exchange membrane and a solid polymer electrolyte. The proton exchange membrane acts as both the gas separator and the electrolyte. In the electrolysis process, only deionized water is injected into the cell without any electrolytic additives. There are a variety of advantages of PEM electrolysis, such as high current density, greater energy efficiency, low gas permeability, wider operating temperatures (20–80°C), and easy handling and maintenance.?

The Purity of the PEM electrolysis process is around 99% and the process is expensive due to the precious metals as catalysts.?

The technology is new and only partially established, with high component costs and an acidic environment reducing its durability. But due to its high purity feature, cost optimization is being developed for this project. High-production projects are establishing themselves on PEME.?