Polyamide solutions for viable hydrogen fuel cell vehicles
The sustainable mobility revolution is gaining momentum, with close to 10 million electric vehicles (EVs) on the road today, and a tenfold increase expected over the next 10 years. And the scope of alternative drivetrain solutions goes beyond battery EVs and hybrids. It also includes fuel cell electric vehicles (FCEVs), which produce their own electricity through a hydrogen fuel cell. Key components of the fuel cell, including the stack and storage, require demanding material performance and Technyl® delivers with specially-formulated PA solutions.
In fuel cell technology, hydrogen (H2) reacts with oxygen in a process known as reverse electrolysis. The hydrogen comes from one or more tanks built into the fuel cell EV, while the oxygen comes from the outside air. This reaction creates electrical energy, along with heat and water vapor, which is expelled as clean exhaust.
While a hydrogen FCEV shares many of the same attributes of a battery EV, such as silent operation, instant power and zero emissions, it has certain other advantages over a BEV. These include a quick, 5-minute refueling process compared to the charging time of between 30 minutes and several hours for a BEV. FCEVs also generally have a longer range than purely electric cars and this range is not affected by cold weather.
That said, BEVs are at a much more advanced stage of market development in terms of available charging infrastructure and declining prices. FCEVs face the challenges of limited hydrogen refueling stations and the relatively high purchase price of the vehicles, because of limited demand at this stage. Yet, a number of manufacturers see sufficient potential in hydrogen FCEVs for sustainable mobility to pursue the technology, alongside BEVs, including Toyota, Hyundai and Honda.
State-of-the-art storage solutions
Hydrogen storage is a key factor for FCEVs, requiring the development of advanced storage methods to handle higher energy density. Storage of hydrogen as a gas typically requires high-pressure tanks (350–700 bar). The compressed hydrogen is stored in a tank composed of a polymer liner and a composite structure that supports the severe mechanical forces.
Technyl® is at the forefront of polymer liner technology for H2 tanks, with its specially-formulated PA6 offering, Technyl® C 550BCR. This polyamide is the ideal compound for H2 storage applications of 700 bars pressure, because it can handle the high temperatures of up to 120°C created by the pressure. It also guarantees low permeability, good processing ability and great impact resistance.
“We already have approval from Toyota for using Technyl C 550BCR in the fuel cell storage tanks of its Mirai hydrogen FCEV vehicle, which gives us good market traction,” says Tobias Epple, Business Development New Mobility.
Stacked with advantages
The other key application for Technyl® polyamides in hydrogen FCEVs is for fuel cell stack components, where high purity is the key. Here, another special formulation, Technyl® ONE J 219HT V35 Black, has been developed for fuel cell stack components, including the water trap along with the manifold, humidifier and end plates. Most applications in fuel cell stacks can be made using one grade material, which gives a big advantage for the customer when using this Technyl ONE grade.
For this application, purity is the main challenge. The Polymer Electrolyte Membrane (PEM), must be kept extremely pure regarding metallic ions for optimal performance of this key component for the electrolysis. To achieve this high level of purity, a clean formula, with no chance of polluting the clean water, and good manufacturing practices as well as clean room facilities are necessary. This includes raw material control for cleanliness, clean water and packaging process purity.
Dimensional stability and weldability are also key requirements for this application, which the Technyl® ONE grade delivers admirably.
Diversified PA portfolio
“We have been working with OEMs in Asia for a number of years to develop the PA solutions that meet their specific requirements for hydrogen fuel cell vehicles,” adds Tobias. “European OEMs are also looking to fuel cells for sustainable mobility diversification, with priority given to commercial vehicles, and new the EU hydrogen strategy will give a boost to this promising technology. At Technyl, we will keep pursuing innovative developments in our expanding polyamide portfolio to make sustainable mobility a reality.”