PEM vs. alkaline electrolyzer: Which hydrogen production technology is more suitable for your needs?

In the selection of hydrogen production technology, the choice between proton exchange membrane (PEM) electrolyzer and alkaline electrolyzer requires a comprehensive consideration of many factors. The following comparison will help you make a decision:

I. Technical performance

1. Current density and energy consumption

• Alkaline electrolyzer: The current density is usually 0.2–0.4 A/cm², and the system energy consumption of the two is similar.

• PEM electrolyzer: The current density reaches 1–2 A/cm², and the system energy consumption of the two is similar.

2. Load range and response speed

• Alkaline electrolyzer: Load adjustment range 40-100%, slow start and stop speed (hot start 1–5 minutes, cold start 1–5 hours), not suitable for intermittent energy such as wind power/photovoltaic power - pressure balance is required to avoid gas leakage.

• PEM electrolyzer: Load range 0%–120%, fast start and stop (hot start <5 seconds, cold start 5–10 minutes), very suitable for matching fluctuating renewable energy.

2. Cost factors

1. Equipment cost

• Alkaline electrolyzer: low cost, electrodes do not contain precious metals. The domestic market share is high, and the equipment price is only 1/4–1/6 of PEM.

• PEM electrolyzer: high cost (overseas price is 1.2–1.5 times that of alkaline, and 4–6 times that of domestic), because the catalyst requires precious metals such as iridium and platinum. However, overseas price performance is better, and domestic production is reducing costs through localization and scale.

2. Operating cost

• Alkaline electrolyzer: low equipment cost, high energy consumption, and energy consumption optimization in the future.

• PEM electrolyzer: low energy consumption can reduce costs, but equipment and precious metal expenses push up overall operating costs, and cost reduction depends on increasing current density, reducing iridium usage and localization.

3. Application scenarios

1. Alkaline electrolyzer applicable scenarios:

• Large-scale industrial hydrogen.

• Scenarios with low water quality requirements: ordinary deionized water can be used, suitable for areas with limited high-purity water supply.

2. PEM electrolyzer applicable scenarios:

• Renewable energy coupling scenario (wind power/photovoltaic): fast response, wide load range, suitable for off-grid distributed hydrogen production (such as islands, mining areas).

• High-purity hydrogen scenario (such as hydrogen refueling station): directly produce high-purity hydrogen without additional separation.

IV. Future trends

• Alkaline electrolyzer: focus on reducing energy consumption (upgrading diaphragms/catalysts) and improving current density to further optimize cost performance.

• PEM electrolyzer: through technological breakthroughs (reducing the use of precious metals), localization and scale-up cost reduction, it is expected that the market share will expand after the cost reduction.

Summary

• Choose alkaline electrolyzer: if the demand is large-scale low-cost hydrogen production, and the purity of the water source needs to be taken into account.

• Choose PEM electrolyzer: if you focus on fast response, adapt to the fluctuations of renewable energy, pursue high-purity hydrogen, and can accept a higher initial investment.