Freudenberg Sealing Technologies - Fuel Cell Stacks

The eternally young talent is growing up

Fuel cells can efficiently generate electricity, making them an alternative to battery-powered vehicles. However, the market and infrastructure are not yet ready. But the technology is making enormous progress. New seals from Freudenberg Sealing Technologies are making sure that the environmentally friendly power source is ready for the masses.

Fuel cells are nothing new: The principle of producing energy through electro-chemical reactions is more than 180 years old. They have always been seen as the power source of the future, the invention is both simple and brilliant: A fuel - such as hydrogen - reacts in the cell with an oxidizing agent such as oxygen from the air. During the process, water, heat and electricity are generated and can be used very efficiently. Fuel cells can achieve efficiency rates of up to 60 percent. By comparison: Combustion engines can merely achieve 30 to 35 percent.

The technology is known for its use in the Apollo lunar mission in the 1960s, where it provided a reliable electricity supply. In the following decades, they were installed in various applications as mobile or stationary power generation systems, such as metering stations, for camping, in floor conveyors and commercial vehicles, while also enjoy growing popularity in co-generation systems. Though there are a few thousand fuel-cell cars and buses registered around the world - the technology has yet to gain broad acceptance in road transport. 

  • The new seals can be tailored to customer requirements and can be manufactured more affordably and efficiently.

The goal: lower costs

Jürgen Emig is sure this is about to change. “The market has never been readier than it is now,” says the Freudenberg Sealing Technologies project manager. “We are working on renewable energy, electromobility, and Germany’s energy transition in general, this is the future.” Fuel cells - more precisely a stack of many fuel cells - can be used to power electric vehicles and significantly expand their range. “We can also use  the technology to solve the problem of what to do with excess electricity produced in solar power plants and wind farms,” says Emig. If renewable sources are used to produce hydrogen, this could then power fuel cell vehicles and - completing the circle - this hydrogen can then be converted back into energy. 

We have several areas where we need to work and make sure that they become more affordable

Jürgen Emig, Freudenberg Sealing Technologies project manager

A challenge for the success of fuel cells is their price. They are five to six times more expensive than combustion engines. “We have several areas where we need to work and make sure that they become more affordable,” explains Jürgen Emig. So, several Freudenberg sites in Germany and the US are working hard on product and process optimization.

As a full-range supplier of important seals needed in every individual cell and to guarantee a safe media transfer and prevent any leaks, FST has an innovation in just this area - with support from other Freudenberg Business Groups and departments, such as Freudenberg Performance Materials and Freudenberg Technology Innovation: “We were able to offer a product that is truly competitive thanks to optimized materials and processes,” says Jürgen Emig.

Many improvements

The improvements to materials started off simply. The filling of the two low-viscosity elastomer components was switched to large-series containers. The developers faced greater complexity in the injection molding process, where the innovative gas diffusion layers made from nonwoven materials or bipolar plates receive their customized frame gasket. Work first focused on reducing material usage. “In the injection molding process, the material is pushed through various runners into the mold. The previous tool technology (using hot runners) a large share remained in the manifold as waste.” This was because the process placed the elastomer under heat and pressure causing it to vulcanize, after which it cannot change form. “So, we switched to a cold runner technology to prevent this. Therefore, we only injected as much elastomer as we needed.” The material consumption and thus costs sank dramatically.

Simultaneously, the processing time and, with it, the energy costs could also be reduced. As good as the elastomer functions in the application, the harder it is to remove from the mold because of its adhesive properties - similar to those of silicon. “We have automated the process and eliminated manual operations,” explains Jürgen Emig. 

If fuel cells become more affordable, the market can mature.

Jürgen Emig, Freudenberg Sealing Technologies project manager

Freudenberg Sealing Technologies offers a wide variety of seals to its customers that can be manufactured using the new processes: Simple elastomer seals for those who want to build their own fuel cells, gas diffusion layers from Freudenberg Performance Materials, where the seal is sprayed externally, or seals that can be applied to bipolar plates made from metal or graphite. Jürgen Emig sees a large market for the innovative processes and the resulting products. “If fuel cells become more affordable, the market can mature.” FST has now made an important contribution here.

  • The FST team working under project manager Jürgen Emig (right) optimized the process to manufacture seals for fuel cells.

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