What are Alkaline Fuel Cells?
Alkaline fuel cells (AFCs) are electrochemical cells that convert chemical energy of reactants, namely hydrogen and oxygen, directly into electrical energy through an electrochemical reaction. Like other fuel cells, AFCs do not involve combustion and provide electricity as long as the fuel is supplied. However, unlike other fuel cells, AFCs use an alkaline electrolyte, typically potassium hydroxide (KOH), instead of an acidic or solid-state electrolyte.
History and Development
One of the earliest fuel cell technologies developed was the alkaline fuel cell (AFC) in the 1930s. Commercial development began in the 1950s and Alkaline Fuel Cells were employed to power NASA space missions and early spacecraft in the 1960s. The first widespread commercial use was for remote telephone switching stations in the 1970s. However, proton exchange membrane fuel cells eventually replaced AFCs for most applications due to durability issues with the alkaline electrolyte over long periods. Recent research focuses on improving the stability of AFCs to enable broader adoption.
How do Alkaline Fuel Cells Work?
In an AFC, hydrogen gas is supplied to the anode and oxygen or air is supplied to the cathode. At the anode, hydrogen ions are formed as the hydrogen molecules react: H2 → 2H+ + 2e-. The hydrogen ions cannot pass through the membrane but the electrons are forced to flow through an external circuit, providing usable electricity. At the cathode, the hydrogen ions, electrons from the external circuit, and oxygen react to form water: 2H+ + 1/2O2 + 2e- → H2O. The electrolyte conducts hydroxide ions between the electrodes to complete the electrical circuit. This process continues as long as fuel and oxygen are supplied.
Applications of Alkaline Fuel Cells
While proton exchange membrane fuel cells have become more prominent for transportation and stationary applications, AFCs still have potential uses, especially in niche markets:
- Material Handling Equipment: AFCs can provide electric power for forklifts, tractors, automated guided vehicles in warehouses or distribution centers without emissions. Their high power density makes them suitable for these mobile applications.
- Backup Power: AFCs can serve as backup power sources for data centers, telecom towers, hospitals etc. during grid failures. Their instant start capability provides reliable emergency power.
- Military Equipment: The high energy density and quiet operation of AFCs make them usable to power certain military radios, sensors, unmanned vehicles etc where acoustic or infrared signatures need to be lowered.
- Spacecraft/Satellites: As demonstrated previously, the lack of moving parts and high energy density of AFCs remain advantages for powering instrumentation onboard spacecrafts and satellites. Their operation in extreme environments like outer space is better than batteries.
Advantages of Alkaline Fuel Cells
- Higher efficiency compared to batteries - AFCs have an efficiency of around 70-75% vs 50-70% for lithium-ion batteries. This means more power from supplied fuel.
- Instant start capability - AFCs can provide power instantly on demand without waiting times unlike combustion engines.
- Low emissions - AFCs produce only water and heat as byproducts without any harmful emissions like nitrous oxides frominternal combustion.
- Scalable power output - The power output of an AFC stack can easily be increased by adding more cells as opposed to development of an entirely new power unit.
- Long-term operation - AFCs can run continuously for years as long as fuel is available unlike batteries requiring recharge/replacement.
Challenges facing Alkaline Fuel Cell Commercialization
Despite significant advantages, AFCs face some challenges that have prevented widespread adoption:
- Durability issues of alkaline electrolyte - The corrosive nature of potassium hydroxide electrolyte degrades cell components over time limiting longevity.
- High costs - Mass production is needed to drive down costs of catalysts, membranes and balance of plant required. Batteries currently enjoy economies of scale.
- Hydrogen storage and distribution - Developing low-cost ways to store and transport gaseous/liquid hydrogen fuel remains a barrier especially for mobile uses.
- Technology improvements - Further enhancing power density, energy efficiency and dynamic response is required to outperform alternatives.
- Standardization and regulations - Agreeing on universal size/interface standards for stacks/balance of plant and addressing safety regulations will aid commercial-scale manufacturing.
While much progress is still needed, alkaline fuel cells have the potential to play an important long-term role as part of the clean energy ecosystem, especially for stationary and backup power generation as well as specialized mobile/military applications. Overcoming challenges related to materials, costs and hydrogen infrastructure can unlock their full potential. With advancements, AFCs may emerge as a more sustainable alternative to conventional power sources.
Get More Insights On- Alkaline Fuel Cells
Get this Report in Japanese Language:
Get this Report in Korean Language:
About Author:
Money Singh is a seasoned content writer with over four years of experience in the market research sector. Her expertise spans various industries, including food and beverages, biotechnology, chemical and materials, defense and aerospace, consumer goods, etc. (https://www.linkedin.com/in/money-singh-590844163)
