At the heart of the Green Hydrogen revolution lies a crucial technology: the electrolyser. This device, often overlooked but immensely powerful, is transforming how we produce clean energy. But what exactly is an electrolyser and why is it so important?

What is an Electrolyser?

An electrolyser is an electrochemical device that uses electricity to split water (H2O) into its constituent elements: hydrogen (H2) and oxygen (O2). This process, known as electrolysis, is the cornerstone of green hydrogen production. Unlike traditional hydrogen production methods that rely on fossil fuels, electrolysers powered by renewable energy sources create hydrogen with zero carbon emissions.

The basic form of an electrolyser unit contains an electrolytic cell with two electrodes – a cathode (negative charge) and an anode (positive charge) – and a membrane. An electrolyser system contains the electrolyser cell stacks, pumps, vents, storage tanks, a power supply, a separator and other operating components.

Electrolysis occurs within the cell stacks when an electric current is applied across the electrolytes. The anode attracts the negatively charged hydroxide ions (OH-), releasing oxygen gas (O2). The cathode attracts the positively charged hydrogen ions (H+) and releases hydrogen gas (H2).

What are the kinds of Electrolysers?

There are three main types of electrolysers, each with its own unique characteristics:

1. Alkaline Electrolysers: The most mature and widely used technology, alkaline electrolysers use a liquid electrolyte solution of potassium or sodium hydroxide. They are known for their durability and lower cost but have slower response times.
2. Proton Exchange Membrane (PEM) Electrolysers: These use a solid polymer electrolyte and offer higher efficiency and faster response times. PEM electrolysers are compact and ideal for applications requiring pure hydrogen, but they are currently more expensive.
3. Solid Oxide Electrolysers: Operating at high temperatures (700-800°C), these are the most efficient but are still in the early stages of commercialization. They can use waste heat from industrial processes, potentially increasing overall system efficiency.

The cost trade-off between alkaline and PEM is not direct as the latter operates better under varying power conditions, reducing battery storage cost in the system. This could make capex for PEM lower than alkaline in certain cases, especially since alkaline requires higher space as well.

What are the applications of Electrolysers?

Electrolysers are mostly used to produce hydrogen gas. This gas is essential for industrial processes, including ammonia production for fertilizers and fuel for fuel cell applications for the mobility sector (buses, trucks and trains). They can be used for energy storage by converting excess electricity from renewable energy sources, such as wind, solar and hydropower, into hydrogen gas. The gas can then be compressed, stored and used as needed. Hydrogen can also be used for blending into natural gas networks for residential and commercial heating. Electrolysers can help balance electrical grids by converting excess renewable energy into storable hydrogen.

They are playing a critical role in meeting India’s decarbonization goal of net zero emissions by 2070, as they are used for producing green hydrogen.  Globally, by 2050, green hydrogen has the potential to reduce CO2 emissions by 20%. The Green Hydrogen production capacity in India is projected to reach 5 MMTPA, reducing the reliance on import of fossil fuels and curtailing the cumulative imports of fossil fuels worth INR 1 trillion (US$12.03 billion) by 2030.

Who are the key manufacturers in India?

The Strategic Interventions for Green Hydrogen Transition (SIGHT) program is a key component of the National Green Hydrogen Mission set up by the government in January 2023. It promotes research and development to accelerate technological advancements in Green Hydrogen production. The tender for selection of Electrolyser Manufacturers (EM) for setting up manufacturing capacities for Electrolysers in India under SIGHT Scheme (Tranche-I), was awarded on 12th January 2024 to 8 companies for a total capacity of 1,500 MW per annum.

Most of the above players are rapidly developing their electrolyser manufacturing capabilities. John Cockerill, L&T Electrolysers, Reliance Electrolyser Manufacturing and Adani New Industries see their manufacturing units ready by 2025. Reliance has entered into a technology licensing agreement with Norway's Nel ASA for its alkaline electrolysers in India. L&T Energy GreenTech commissioned its first indigenously manufactured hydrogen electrolyser at the green hydrogen plant in Hazira, Gujarat on March 1, 2024. The company used alkaline electrolyser technology from McPhy Energy, France. Adani New Industries is developing an electrolyser facility in Mundra, Gujarat to produce green hydrogen.

What are the manufacturing costs?

The cost of manufacturing electrolysers in India is a crucial factor in the country's green hydrogen ambitions. The manufacturing cost of electrolysers can range from $350–$1000 per kilowatt (kW). The cost depends on the type of electrolyser, the scale of production and the materials used. 

According to a September 2024 study by The Council on Energy, Environment and Water (CEEW) the bottom-up manufacturing cost of a PEM electrolyser is approximately $359 per kW. For alkaline electrolysers, the cost is around $400 per kW and for Solid oxide electrolyser systems it is about $344 per kW. A research report by SBI Caps (December 2024) puts the CAPEX requirements for an alkaline electrolyser at USD 300-350/kW (China has the lowest) to USD 750-1000/kW (standard). The study estimates PEM CAPEX at USD 600-1250/kW. 

The Indian government's National Green Hydrogen Mission aims to reduce costs and increase domestic manufacturing capacity.

What are the challenges in using electrolysers?

Despite their potential, electrolysers face several challenges. Some of these include high initial costs of electrolyser systems, improving efficiency of electrolysis, enhancing lifespan of electrolyser components to reduce maintenance costs, ensuring consistent supply of high-purity water for electrolysis.

However, as India and the world move towards a cleaner energy future, electrolysers stand at the forefront of the green hydrogen revolution. Ongoing research and development, coupled with supportive policies, are paving the way for more efficient, affordable and widely adopted electrolyser technology. The future of clean energy is bright, and electrolysers are lighting the way.

Sources

• https://www.accelerazero.com
• https://www.ceew.in/publications/how-can-india-indigenise-hydrogen-electrolyser-manufacturing
• https://renewablewatch.in/wp-content/uploads/2024/05/Indias-Green-Hydrogen-Revolution-Booklet-1.pdf
• https://renewablewatch.in/wp-content/uploads/2024/05/Indias-Green-Hydrogen-Revolution-Booklet-1.pdf
• https://renewablewatch.in/wp-content/uploads/2024/12/here.pdf