Water Electrolysis for Green Hydrogen Production
Hydrogen is an important fuel source that can be used in various applications, including transportation, power generation, and industrial processes. However, the majority of hydrogen production today comes from fossil fuels, which generates significant greenhouse gas emissions. To address this issue, researchers and industry professionals have been exploring alternative methods for hydrogen production, such as water electrolysis.
Types of Hydrogen Production:
Hydrogen can be produced using various methods, and the color of the hydrogen refers to the environmental impact of the production process. Here are the different types of hydrogen production:
- Grey Hydrogen: is produced by steam methane reforming (SMR) of natural gas, which releases carbon dioxide into the atmosphere. It is the most commonly produced type of hydrogen and accounts for around 95% of the global hydrogen production.
- Blue Hydrogen: is produced using SMR or auto-thermal reforming (ATR) of natural gas, but with carbon capture and storage (CCS) technology to capture the carbon dioxide and store it underground. This process significantly reduces the carbon emissions associated with hydrogen production.
- Green Hydrogen: is produced using water electrolysis powered by renewable energy sources, such as wind, solar, or hydropower. It is the cleanest and most sustainable type of hydrogen, as it does not release any carbon emissions during the production process.
- White Hydrogen: is produced using water electrolysis powered by nuclear energy. It is a relatively small-scale method of production and is currently only used in a few countries.
Each type of hydrogen production has its own advantages and disadvantages in terms of cost, efficiency, and environmental impact. However, the increasing demand for clean energy sources and the urgent need to reduce carbon emissions are driving the development and adoption of green and blue hydrogen production technologies.
Water and Alkaline Electrolysis Process:
Water electrolysis is a process that involves the separation of water molecules into hydrogen and oxygen gas by applying an electrical current in an electrolysis cell. The cell consists of a cathode and an anode separated by a porous membrane. The cathode is usually made of nickel, while the anode is typically made of a metal oxide such as nickel oxide or iron oxide.
During the process, water molecules are dissociated into hydrogen ions (H+) and hydroxide ions (OH-) as an electric current is passed through the cell. The positively charged hydrogen ions are attracted to the cathode where they combine with electrons to form hydrogen gas (H2), which is collected at the cathode. At the same time, the negatively charged hydroxide ions move towards the anode, where they lose electrons to form oxygen gas (O2), which is collected at the anode.
Alkaline water electrolysis is one of the most widely used methods for hydrogen production. This process uses an alkaline electrolyte, such as potassium hydroxide (KOH), to increase the electrical conductivity of the water and allow for the splitting of water molecules. Alkaline water electrolysis operates at a relatively low temperature and pressure, making it an efficient and cost-effective method for hydrogen production.
Overall, water and alkaline electrolysis offer a clean and sustainable method for producing hydrogen gas. With the increasing demand for clean energy sources, the development of more efficient and cost-effective electrolysis technologies has become a priority for the industry.
At FabLab Bangkok, We have developed a hydrogen engine prototype that is based on alkaline water electrolysis. The prototype uses a carbon rod as both the cathode and anode to produce hydrogen and oxygen gas. We collaborated with Dr. Nutthapol Wongyao, a hydrogen energy researcher from King Mongkut’s University of Technology Thonburi (KMUTT), to test and validate the prototype.
We applied potassium hydroxide (KOH) to the electrolyte solution, which is a known method for hydrogen production that is both efficient and low-cost. This approach presents a promising alternative to traditional fossil fuel engines, and we are thrilled to demonstrate the potential of this technology in contributing to a more sustainable future.
Efficient Hydrogen and Oxygen Production:
Efficient hydrogen and oxygen production in alkaline water electrolysis requires careful control of the operating conditions, such as the temperature, pressure, and electrolyte concentration. Higher temperatures and pressures can increase the reaction rate and improve the efficiency of hydrogen production, but also require more energy input. The electrolyte concentration affects the electrical conductivity and can influence the cell voltage and efficiency.
To improve the efficiency and reduce the cost of alkaline water electrolysis, various research efforts have focused on developing new electrode materials, optimizing the cell design, and integrating renewable energy sources. Using advanced catalysts such as platinum-group metals or non-noble metals can enhance the hydrogen evolution reaction and reduce the overpotential required for water splitting.
In conclusion, water electrolysis, and specifically alkaline water electrolysis, is a promising technology for green and blue hydrogen production. Advances in material science, process optimization, and renewable energy integration can further enhance the performance and reduce the environmental impact of this technology.