Optimizing Fuel Cell Efficiency with Precision-Rolled Alloy Materials
As countries and industries prioritize reducing greenhouse gas emissions and fossil fuel markets remain volatile, fuel cells are becoming an increasingly popular alternative to combustion engines for clean power generation.
In 2020, the global fuel cell market was valued at nearly $4 billion, and research projects it will reach $32 billion by 2030. The transportation and power sectors have been early adopters of fuel cells and are expected to drive a significant growth percentage. This includes major automakers like Toyota and Hyundai, who have fuel-cell-powered cars on the market. Others, including GM, are investing in fuel-cell systems that could charge fully electric vehicles.
Compared to conventional combustion-power cars, fuel cell vehicles' advantages include increased efficiency and zero pollutants or greenhouse gas emissions while boasting a longer driving range than all-electric vehicles.
In the power sector, fuel cells provide energy for industrial, commercial, and residential buildings, as well as long-term energy storage for the grid in reversible systems.
As demand for this innovative technology increases, so will the demand for advanced materials that enable fuel cells to achieve peak performance.
What are Fuel Cells?
A fuel cell is an electrochemical cell that generates electricity using only chemical fuel and an oxidizing agent. Fuel cells that use hydrogen as chemical fuel are completely carbon-free, and their only byproducts are electricity, heat, and water.
Fuel cells vary significantly in size and applied technologies based on the end application. Some fuel cells are smaller, almost battery-like, and used to power warehouse forklifts. Others are large towers that could supplant existing energy sources and help provide electricity (or backup power generation) for an entire facility.
How Do Fuel Cells Generate Electricity?
A fuel cell is primarily two bipolar (anode & cathode) plates separated by catalyst and electrolyte material.
In a hydrogen fuel cell, hydrogen gas is fed into the negatively-charged anode plate, while the positively-charged cathode plate is filled with oxygen.
The hydrogen in the anode wants to react with the oxygen in the cathode to form water, but it cannot get to the other side of the fuel cell because of the electrolyte; electrolyte materials only let positively charged ions through (hydrogen atoms are neutral with one proton and one electron).
This is where the catalyst comes in. The catalyst splits the hydrogen atoms apart, separating the electrons from the protons. The protons can now get through the electrolyte, leaving the electrons behind.
A wire is connected to allow the electrons to flow through and react with the protons. Once the electrons travel through the wire, they create water that drains from the system.
Electricity is simply moving electrons, so we now have an electrical current in that wire that can power vehicles, facilities, or even satellites.
Fuel cells will continue to produce electricity for as long as there is a supply of fuel (in this case, hydrogen) and oxygen.
What Materials Are Used to Manufacture Fuel Cells?
As mentioned, fuel cell technologies can vary significantly based on the required application and power output. A basic rule of thumb is the more power that's needed, the bigger the fuel cell must be.
For this article, let's focus on polymer electrolyte membrane (PEM) fuel cells, a popular fuel cell type for powering vehicles.
The two main parts of a PEM fuel cell are the membrane electrode assembly (MEA) and the hardware around it.
The MEA includes the electrolyte membrane, the catalyst layers, and the gas diffusion layers, where the chemical reactions occur that create electricity.
Materials used in the MEA include polymers, ionomers, platinum powder (as the catalyst), and coated carbon paper (to diffuse gas and prevent water buildup rapidly).
The hardware around the MEA includes the bipolar plates and gaskets. Each individual MEA produces less than 1 V, so they are typically stacked to reach the required voltage, with each cell separated by bipolar plates and gaskets to create a tight seal.
These bipolar plates are the most common fuel cell component manufactured with Ulbrich precision alloys, but we also supply other assorted metal parts.
What are the Key Material Properties Needed to Optimize Fuel Cell Applications?
Fuel cells get very hot during operation, and their environments are very corrosive. The durability of materials under these challenging conditions is key for this market.
Therefore, austenitic stainless-steel alloys, which contain at least 8% nickel and are resistant to corrosion and high temperatures, are often used in fuel cell applications. Secondary processing by parts fabricators is typical to impart alloy fuel cell parts with even more corrosion resistance.
Corrosion and temperature-resistant special metals like Nickel 200 & 201 are also commonly used in fuel cell designs.
Alloys:
Alloy thickness is another critical component. The thinner the bipolar plates, the more power-generating fuel cell membranes that can be stacked, creating a more efficient system that can meet higher voltage needs.
Because these alloy plates are stacked, tight tolerances (and flatness) are critical to ensure the system operates at peak performance. The slightest inconsistencies are magnified exponentially with each stack, and if you're not precise, the fuel cell stack could look like Pisa's leaning tower. Tight tolerances are also critical for the secondary processing done by fuel cell parts manufacturers.
Finally, careful consideration is given to how specific surface finishes will affect the efficiency and reliability of the fuel cell — different applications and different fuel cell technologies require different bi-polar plate finishes.
The significant impact surface finishes can have on corrosion resistance alone highlights the importance of sourcing fuel cell material from suppliers with advanced surface control capabilities.
Precision re-rollers offer far more control over surface finishes than you would have sourcing directly from a melt mill. For example, Ulbrich works with many of our customers to provide many types of specialized, customized, and application and process-specific finishes.
Typically measured in RA, RY, and RZ (examining different aspects of the peaks and valleys of a surface), precision is vital to keep these numbers consistent throughout the length and width of the material. This results in a uniform, consistent surface finish that creates predictable performance for engineers and fuel cell manufacturers.
While each fuel application is different, various considerations must be considered for each alloy. The temper, finish, and gauge of all alloys used can affect gas diffusion, electrical conductivity, longevity, and other key performance factors.
What Should I Look for When Choosing a Fuel Cell Materials Supplier?
Capability and availability are essential in the fuel cell market.
Fuel cell applications can be wildly different, so look for a precision re-roller with the technical capabilities and metallurgical expertise to match their alloy solutions to the specific needs of your application. If needed, they should be equipped to assist your technical team with research and development as different properties and material variables are tested.
When it comes to availability, choosing a material supplier that offers a wide selection of readily available alloys will also help ensure you’re utilizing an optimal grade for your application.
At Ulbrich, technical collaboration with our metallurgists and product development team is what sets our customers up for success. Once optimal material characteristics are determined, our tight tolerance control, a wide variety of finishes, vast alloy selection, and efficient manufacturing processes enable us to consistently produce a custom-built product for the precise needs of each different fuel cell application.
Our service center distribution hubs allow us to augment our precision re-roll capabilities and provide our fuel cell customers with a consistent supply of material, including wide-width and light-gauge products from our Ulbrich of California location.
If you’re a fuel cell manufacturer or a parts fabricator, Contact Us
to learn how our advanced fuel cell materials expertise and manufacturing capabilities can advance your application.
