Alkaline Water Electrolysers

How do alkaline water electrolysers produce hydrogen, and what role do they play in industrial decarbonisation?

Exploring Alkaline Water Electrolysis: Unlocking the Fuel of the Future

Alkaline water electrolysis (AWE) is a process that uses an electrolyser to split water molecules (H2O) into hydrogen gas (H2) and oxygen gas (O2) using electricity.

The electrolyser consists of two electrodes (one positive and one negative) immersed in an electrolyte solution, typically a potassium hydroxide (KOH) solution, separated by a diaphragm or membrane.

In this process, when an electric current is passed through the electrolyte, it causes the water molecules near the negative electrode to undergo reduction, producing hydrogen gas. Simultaneously, at the positive electrode, oxidation of hydroxyl ions occurs, generating oxygen gas.

Alkaline water electrolysis is important in industrial scale hydrogen production as it offers a cost-effective and well-proven technology for generating large volumes of low carbon hydrogen. The hydrogen produced can be used for various applications, such as fuel cell vehicles, power generation and industrial processes.

Through use of renewable energy sources like wind, tidal and solar for the electrolysis, hydrogen production can be completely carbon emission free, contributing to the global net zero efforts in combating climate change and transitioning to a sustainable energy future.

Advantages of Alkaline Water Electrolysis:

Alkaline water electrolysis offers several advantages compared to other electrolysis technologies, such as proton exchange membrane (PEM) or solid oxide electrolyser cell (SOEC), including:

  1. Cost-effectiveness: alkaline water electrolysis utilizes catalysts that are cheaper compared to those used in PEM water electrolysis and have a longer operational life. This makes alkaline electrolysis a more cost-effective option for producing hydrogen.
  2. Scalability: alkaline water electrolysis can readily be scaled-up to megawatt-range production capacities. This means that alkaline water electrolysis can be used for large-scale hydrogen production, offering flexibility for meeting increased demand.
  3. Purity of gases: alkaline water electrolysis produces high-purity hydrogen gas, which is essential for various applications, including fuel cells, due to the effective separation of the hydrogen and oxygen gases.
  4. Energy efficiency: alkaline water electrolysis has comparable energy conversion efficiency to other technologies. This means that a substantial proportion of the electrical energy input is converted into hydrogen gas production.
  5. Environmental friendliness: alkaline water electrolysis can be powered by renewable energy sources such as wind or solar power, enabling the production of green hydrogen. This results in a clean and environmentally friendly process that has a minimal contribution to greenhouse gas emissions.
  6. Safety: alkaline water electrolysis is a well-established technology with little concern of catalyst poisoning or gas crossover related issues.

It is important to consider that while alkaline water electrolysis offers several advantages, there are also other electrolysis technologies, such as PEM, which have their own specific benefits and considerations. The choice of electrolysis technology depends on factors like the desired hydrogen purity, cost, scalability and integration with renewable energy sources.

Applications of Hydrogen Produced by Alkaline Water Electrolysis:

Hydrogen is widely used as a feedstock in various industries and sectors and serves as a key component in the production of chemicals, in refineries, steel manufacturing and power generation. Producing Hydrogen through alkaline water electrolysis enables these industries to decarbonise.

Chemical industry:
Hydrogen is a crucial feedstock, serving as a building block for the synthesis of a variety of chemical compounds and used in the production of ammonia, methanol, hydrogen peroxide and various organic compounds.

Hydrogen is utilised in refineries for hydroprocessing, where it is combined with heavy petroleum fractions to remove impurities and improve the quality of fuel products.

Steel production:
Hydrogen is employed in the iron and steel industry as a feedstock to reduce iron ore in to metallic iron in a process called direct reduction. This reduces carbon emissions associated with traditional production processes.

Power generation:
Hydrogen can be used as a feedstock for power generation through the utilisation of fuel cell technologies, which convert hydrogen in to electricity, usable as a clean energy source.

The use of hydrogen in mobility applications facilitates the transition to low-carbon transportation and the reduction of greenhouse gas emissions. It offers the advantage of providing a clean and sustainable energy source for a wide range of vehicles and transportation methods such as buses, trucks, taxis, personal cars, and even trains and ships. Hydrogen fuel cell vehicles enable longer range and quicker refuelling times when compared to battery electric vehicles, crucially also reducing weight.

By converting renewable electricity into hydrogen through alkaline water electrolysis, hydrogen as a fuel can be stored and transported over long distances, buffering and balancing the intermittent nature of renewable electricity supplies. This fuel can then be used for power generation, steam production or even to replace natural gas in domestic heating applications.

Discover more: INEOS applications for hydrogen

INEOS are Europe’s largest operator of industrial electrolysis, and also supply our own electrolyser technology to other companies all across the world. We have the credibility, safety track record and experience to deliver on large scale electrolysis projects.

Alkaline water electrolysis plays a major role in the ongoing decarbonisation of industry and a new era of efficient and clean transportation and energy management. At INEOS Electrochemical Solutions we have developed, and are now operating, our own alkaline water electrolysis technology with proprietary electrode coatings and supply chain for rapid production and industrial scale-up.

Learn more: INEOS Hydrogen group, and the projects we are working on