Introduction

As the world shifts toward renewable energy, green hydrogen—produced using electrolysis powered by clean electricity—has emerged as a key player in decarbonizing industries like transportation, steelmaking, and chemicals. Among the different electrolyzer technologies, alkaline electrolyzers (ALK) currently dominate the market. But why?

In this blog, we’ll explore the advantages of alkaline electrolyzers, their role in green hydrogen production, and why they remain the preferred choice for large-scale projects.

 

What Are Alkaline Electrolyzers?

Alkaline electrolyzers have been around for decades and are one of the most mature technologies for hydrogen production. They use an alkaline solution (typically potassium hydroxide, KOH) as an electrolyte and nickel-based electrodes to split water (H₂O) into hydrogen (H₂) and oxygen (O₂) through an electrochemical reaction.

Key Reaction:

At the cathode: 2H₂O + 2e⁻ → H₂ + 2OH⁻
At the anode: 2OH⁻ → ½O₂ + H₂O + 2e⁻

 

Why Alkaline Electrolyzers Dominate the Market

1. Proven Technology & Reliability

Alkaline electrolyzers have been used for industrial hydrogen production since the early 20th century. Their long track record makes them a low-risk choice for large-scale projects compared to newer technologies like PEM (Proton Exchange Membrane) or SOEC (Solid Oxide Electrolyzers).

2. Lower Capital Costs

One of the biggest advantages of ALK systems is their cost-effectiveness. They use non-precious metals (e.g., nickel instead of platinum or iridium), making them significantly cheaper than PEM electrolyzers, which rely on expensive catalysts.

3. Scalability for Industrial Use

Alkaline electrolyzers are ideal for large-scale hydrogen production, such as ammonia plants or refineries.

4. Longer Lifespan & Durability

With fewer degradation issues than PEM systems, ALKs often have lifespans about 20 years, reducing long-term operational costs. Their robust construction makes them suitable for harsh industrial environments.

5. Compatibility with Renewable Energy

While ALKs traditionally required stable power inputs, advancements in dynamic operation have improved their ability to work with intermittent renewable sources like wind and solar.

 

Challenges & Future Improvements

Despite their advantages, alkaline electrolyzers face some limitations:

Lower Efficiency at Partial Loads – They perform best at steady, high-capacity operation.

Slower Response Times – Less flexible than PEM electrolyzers for rapid start-stop cycles.

Liquid Electrolyte Maintenance – Requires periodic refilling and corrosion management.

 

However, innovations such as:
Advanced electrode materials (improving efficiency)
Zero-gap configurations (reducing energy losses)
Hybrid systems (ALK + PEM)
are helping ALKs stay competitive.

 

Conclusion: Alkaline Electrolyzers Lead the Green Hydrogen Race

While newer electrolyzer technologies are gaining attention, alkaline electrolyzers remain the market leader due to their cost efficiency, scalability, and proven reliability. As green hydrogen demand grows, ALKs will continue playing a crucial role in the energy transition—especially for large industrial applications.

For now, they are the go-to solution for cost-effective, large-scale green hydrogen production.

As the world shifts toward clean energy, green hydrogen—produced using renewable electricity—has emerged as a key player in decarbonizing industries like transportation, steel, and chemicals. However, a major barrier to widespread adoption is high production costs. Among the available electrolysis technologies, alkaline electrolyzers (ALK) present a promising path to cost reduction.

 

In this blog, we explore:

Why hydrogen production costs need to decrease

How alkaline electrolyzers work and their cost advantages

Recent advancements making ALK more competitive

The future outlook for affordable green hydrogen

 

The Challenge: High Costs of Green Hydrogen

Currently, most hydrogen is produced from fossil fuels (gray hydrogen), which is cheap but emits CO₂. Green hydrogen, made via water electrolysis powered by renewables, is clean but expensive due to:

High electricity costs (if not from surplus renewables)

Capital expenditures of electrolyzers

Maintenance and efficiency losses

For green hydrogen to compete, electrolyzer costs must drop significantly—and alkaline electrolyzers are leading the charge.

 

Why Alkaline Electrolyzers (ALK)?

Alkaline electrolyzers are one of the oldest and most mature electrolysis technologies. Compared to alternatives like PEM (Proton Exchange Membrane) and SOEC (Solid Oxide Electrolysis Cells), ALK offers:

1. Lower Capital Costs

No expensive materials: Unlike PEM electrolyzers, which require platinum and titanium, ALK uses nickel-based electrodes and liquid alkaline electrolytes (KOH or NaOH), reducing material costs.

Simpler construction: ALK operates at lower pressures and temperatures, avoiding costly high-performance components.

2. Longer Lifespan & Durability

Proven reliability: ALK systems often exceed 60,000–100,000 hours of operation with proper maintenance.

Less sensitivity to impurities: Unlike PEM, ALK tolerates varying water quality better, reducing pretreatment costs.

3. Scalability for Industrial Use

Large-scale hydrogen production: ALK systems are already used in ammonia plants and refineries, benefiting from economies of scale.

Compatibility with intermittent renewables: While PEM responds faster to variable power, newer ALK designs are improving flexibility.

Recent Innovations Driving Costs Down

 

While ALK has traditionally lagged behind PEM in efficiency, recent advancements are closing the gap:

1. Advanced Electrode Materials

Nanostructured nickel catalysts improve efficiency, reducing energy consumption.

Coating technologies enhance durability, lowering replacement costs.

2. Dynamic Operation for Renewable Integration

New ALK designs allow rapid load-following, making them better suited for wind and solar power fluctuations.

3. Manufacturing Scale-Up

Mass production of ALK stacks reduces per-unit costs.

4. Hybrid Systems (ALK + PEM)

Some projects combine ALK’s low cost with PEM’s responsiveness, optimizing performance.

 

The Future: Can ALK Make Green Hydrogen Affordable?

With continued R&D and scaling, alkaline electrolyzers could help reduce the cost of green hydrogen, making it competitive with fossil-based hydrogen. Key steps include:

✔ Further efficiency improvements (targeting <45 kWh/kg H₂)

✔ Automated manufacturing to cut production costs

✔ Integration with cheap renewable power (e.g., excess solar/wind)

 

While PEM electrolyzers often steal the spotlight for their high efficiency and flexibility, alkaline electrolyzers remain a cost-effective workhorse for large-scale green hydrogen production. With ongoing innovations, ALK could play a crucial role in making clean hydrogen affordable—accelerating the transition to a zero-emission energy future.

Alkaline electrolyzers have been a cornerstone of hydrogen production for decades, offering a reliable and cost-effective method for water electrolysis. However, their efficiency—defined as the ratio of energy input to hydrogen output—can vary significantly depending on several factors. Understanding these factors is crucial for optimizing performance, reducing costs, and improving the feasibility of green hydrogen production.

In this blog, we'll explore the key factors that influence the efficiency of alkaline electrolyzers and how they can be managed to enhance overall system performance.

 

1. Electrolyte Concentration and Composition

The alkaline solution (typically potassium hydroxide, KOH, or sodium hydroxide, NaOH) plays a critical role in ion conductivity and reaction kinetics.

Higher concentrations (20-30% KOH) improve ionic conductivity but can increase corrosion risks.

Lower concentrations reduce corrosion but may decrease efficiency due to higher ohmic losses.

Additives (e.g., inhibitors) can help mitigate degradation while maintaining performance.

 

2. Temperature Effects

Operating temperature significantly impacts reaction kinetics and overall efficiency:

Higher temperatures (70-90°C) reduce the thermodynamic voltage required for water splitting, improving efficiency.

Excessive heat (>90°C) may accelerate material degradation and increase gas crossover risks.

Optimal thermal management is essential to balance efficiency gains with system durability.

 

3. Current Density

The current density (A/cm²) directly affects hydrogen production rate and efficiency: 

Higher current densities increase hydrogen output but also raise ohmic losses and overpotentials.

Lower current densities improve efficiency but reduce production capacity.

Finding the optimal operating range is key to balancing efficiency and throughput.

 

4. Electrode Materials and Catalysts

The choice of electrodes influences overpotentials and longevity:

Nickel-based electrodes are common due to their stability and catalytic activity.

Advanced coatings (e.g., Ni-Mo, Ni-Fe, or Ni-S) can reduce overpotentials, improving efficiency.

Degradation over time (e.g., passivation, erosion) must be managed to sustain performance.

 

5. Separator/Membrane Performance

The diaphragm (traditionally asbestos, now often composite materials) must allow ion transport while minimizing gas crossover:

Thinner separators reduce ohmic resistance but may increase gas permeation.

Pore size optimization is critical to balance conductivity and gas purity.

Degradation (e.g., fouling, chemical attack) can reduce efficiency over time.

 

6. Pressure Conditions

Operating pressure affects gas evolution and system efficiency:

Higher pressures (>30 bar) reduce downstream compression needs but may increase gas crossover and energy losses.

Atmospheric pressure systems are simpler but require additional compression for storage.

 

7. System Design and Stack Configuration

Optimal electrode spacing reduces ohmic losses.

Flow field design ensures uniform electrolyte distribution and gas removal.

Bipolar vs. unipolar configurations impact voltage efficiency and scalability.

 

8. Power Supply and Load Variability

DC power quality (ripple, stability) affects electrolyzer performance.

Renewable energy integration (solar/wind) requires dynamic operation strategies to maintain efficiency under variable loads.

 

Conclusion

Improving alkaline electrolyzer efficiency requires a holistic approach, considering electrolyte properties, temperature, current density, materials, and system design. Ongoing research into advanced catalysts, durable separators, and optimized operating conditions continues to push the boundaries of efficiency, making alkaline electrolysis a competitive solution for large-scale green hydrogen production.

By addressing these key factors, operators and manufacturers can enhance performance, reduce energy consumption, and drive down the cost of hydrogen—bringing us closer to a sustainable energy future.

 As the world transitions to a more sustainable energy system, green hydrogen has emerged as a crucial solution to decarbonize industries, power grids, and transportation. Among the various technologies used to produce green hydrogen, alkaline electrolyzers stand out as a key player. Their efficiency, scalability, and cost-effectiveness make them an essential component in the green energy revolution.

 

1.The Growing Importance of Green Hydrogen

Green hydrogen, produced through water electrolysis using renewable energy sources, is gaining global attention as a clean alternative to fossil fuels. Unlike grey and blue hydrogen, which are derived from natural gas and generate carbon emissions, green hydrogen is entirely emission-free, making it a pivotal solution in the fight against climate change. Countries and industries are increasingly investing in hydrogen infrastructure to meet decarbonization targets and secure energy independence.

 

2.What Are Alkaline Electrolyzers?

 Alkaline electrolyzers are one of the most established and widely used technologies for hydrogen production. They operate by passing an electric current through an alkaline solution (usually potassium hydroxide or sodium hydroxide) to split water into hydrogen and oxygen. The electrodes, separated by a diaphragm, allow the generation of high-purity hydrogen at scale.

 Compared to other electrolysis technologies, such as proton exchange membrane (PEM) and solid oxide electrolyzers, alkaline electrolyzers offer several advantages:

Lower Cost: Alkaline electrolyzers use abundant and cost-effective materials, such as nickel-based catalysts, which reduce capital expenditure compared to PEM electrolyzers that rely on expensive platinum-group metals.

Proven Technology: With decades of industrial use, alkaline electrolysis is a mature and reliable technology, making it a preferred choice for large-scale hydrogen production.

Scalability: Alkaline electrolyzers can operate at large capacities, making them suitable for industrial applications and integration with renewable energy sources like wind and solar power.

Longer Lifespan: Due to their robust design and durable materials, alkaline electrolyzers have longer operational lifetimes compared to other electrolysis technologies.

 

3.Challenges and Innovations in Alkaline Electrolysis

Despite their advantages, alkaline electrolyzers also face challenges that require ongoing innovation:

Dynamic Operation: Unlike PEM electrolyzers, which can quickly respond to fluctuations in renewable energy supply, traditional alkaline electrolyzers are less flexible. Advances in design, such as improved catalysts and power electronics, are helping to make alkaline systems more adaptable to intermittent renewable energy sources.

System Size and Footprint: While alkaline electrolyzers are scalable, they tend to be bulkier than PEM electrolyzers. Innovations in modular design and compact systems are addressing this limitation to enable broader deployment.

 

4.The Future Outlook: Scaling Up Green Hydrogen with Alkaline Electrolyzers

As the demand for green hydrogen continues to rise, alkaline electrolyzers are poised to play a central role in scaling up production. Governments and industries are investing heavily in hydrogen infrastructure, with initiatives like the European Green Hydrogen Strategy and the U.S. Department of Energy’s hydrogen programs driving advancements in electrolysis technology.

With improvements in efficiency, flexibility, and integration with renewable energy, alkaline electrolyzers will remain a cornerstone of the hydrogen economy. As manufacturing scales up and production costs continue to decline, green hydrogen generated by alkaline electrolyzers will become a mainstream energy source, accelerating the global transition to a low-carbon future.