This article was contributed by:
Robert Jozsa
Product Manager
Alternative Technology,
Parker Hannifin
Robert is the Product Manager of Alternative Technology in the Engine Mobile Filtration Division at Parker Hannifin. He has 10 years’ experience in the development of filtration solutions for the transportation industry. In his most recent position, he is leading the development of filtration and separation solutions for Fuel Cells and H2-ICE applications. He monitors market trends and leads projects with OEMs and R&D teams to develop new technologies and products that fulfil customers’ needs.
How to Maximize Your Fuel Cell's Performance and Durability
June 12, 2024
What is the role of Fuel Cells in securing carbon neutrality?
Decarbonisation, driven by climate change, is one of the major targets of our time. Governments around the world are introducing legislation to achieve climate neutrality by increasing renewable energy production and utilisation, electrification and reducing greenhouse gas (GHG) emissions.
To facilitate the transition to climate neutrality, the transportation sector will need to undergo a substantial transformation. In Europe, transportation represents around 25% of the EU’s total GHG emissions while in the US it’s about 28%.
In the EU heavy-duty vehicles – trucks and buses – are responsible for more than a quarter of CO2 emissions from road transportation, while accounting for less than 3% of the vehicles on the road. The adoption of zero emission solutions for this sector will have a major impact in supporting climate neutrality.
There are several Zero Emission technologies that are either in production or in development.
The Battery Electric Vehicle (BEV) is already available on the market, with significant growth in the passenger vehicle sector and implementation starting in the commercial vehicle segment. The main advantage of battery electric vehicles is their efficiency.
Fuel Cell Electric Vehicles (FCEV) can be an optimal solution for the long-haul heavy-duty applications. They have a high power-density, long range and similar refuelling time to diesel. For some applications where heavy load needs to be hauled, and long range is needed, the FCEV might be the best option.
A third solution that is in development is the Hydrogen Internal Combustion Engine, where Hydrogen is burned instead of a fossil fuel. The advantage is that it uses the backbone of the internal combustion engine with some required modifications for the hydrogen adaptation.
How does a Fuel Cell work?
A Fuel Cell system generates electricity through a chemical reaction using hydrogen and oxygen where the only byproduct is water and heat.
There are several fuel cell technologies available, however for the transportation market the Proton Exchange Membrane Fuel Cell (PEMFC), also known as the polymer electrolyte membrane fuel cell, is the frontrunner. The distinguishing features are low operating temperature and pressure ranges, high power density, quick start up time and a special proton-conducting polymer electrolyte membrane.
The fuel cell stack is composed of several fuel cells connected in series. Each fuel cell contains three primary components: two electrodes (anode and cathode) and the proton exchange membrane as a conductive electrolyte. Each electrode is comprised of a porous, high-surface area material, called gas diffusion layer (GDL) and a catalyst layer as a carbon support impregnated with a catalyst, usually platinum or a platinum alloy. The electrolyte material is a polymeric membrane and serves as an ionic conductor. The chemical reaction on both the anode and cathode side happens at the catalytic surface.
On the anode side the hydrogen spreads through the GDL until it reaches the catalytic surface where it’s split into protons and electrons through hydrogen oxidation reaction (HOR). The newly formed positively charged protons permeate through the polymer electrolyte membrane to the cathode side, while the negatively charged electrons travel along an external load circuit thus creating the current output of the fuel cell.
On the cathode side the incoming oxygen spreads through the GDL and at the catalytic surface it will react with the protons permeating through the membrane and electrons arriving on the external circuit, through the oxygen reduction reaction (ORR) and will form water molecules and residual heat.
The main function of the polymer electrolyte membrane is to conduct the hydrogen protons but not the electrons and must not allow either gas to pass to the other side. For the optimal proton transfer proper membrane humidification must be ensured.
How does hydrogen and air quality impact the performance of a Fuel Cell?
As a catalyst for both the cathode and anode side typically a platinum or a platinum alloy is used. For the optimal chemical reaction, the catalyst layer surface needs to be free of impurities.
On the anode side the quality of the hydrogen needs to be very high. Impurities and different gas contaminants need to be removed. The quality of the hydrogen is controlled at the gas stations where fuel cell grade clean hydrogen is available with 99.97% cleanliness. Filtration is still needed because contaminants can still be present during refuelling.
On the cathode side the oxygen is used from the ambient air, however due to the highly uncertain pollution of the air, filtration and conditioning is required. Fine particles in the air can block the flow paths in the gas diffusion layer that will impact the oxygen flow and reduce the water elimination.
Certain gases, such as Nitrogen Oxides, Sulphur Dioxide, Ammonia, Toluene, and others, present in the air can poison the catalytic layer. These will block the platinum catalyst and will lead to power losses due to the reduction of the electrochemically active surface. The poisoning effect of some gasses can be reversible, but others can’t. For this reason, it’s critical that these contaminants are filtered out before the air reaches the stack. Different filtration technologies need to be combined for optimal air filtration.
The polymer electrolyte membrane needs to be humid to effectively transfer the protons and to block the gasses from passing to the other side. If the membrane dries out it will impact the proton transfer and it will reduce its durability and lifetime. During the operation the fuel cell will generate a large amount of water, however this needs to be removed from the stack to avoid flooding of the GDL. Ensuring an optimal level of humidity of the incoming air with a humidifier is desired.
What are Parker’s solutions to improve performance and durability?
Parker has a broad product offering for Fuel Cell systems. Starting with the conveyance of hydrogen in a safe and reliable matter we can offer a vast range of solutions, such as hydrogen pressure regulators, hydrogen fittings (low and high pressure), hydrogen hoses and hydrogen valves with the relevant certifications. To make sure that the fuel cell stack is protected, the Parker coalescing hydrogen filter as well as the anode water separator should be implemented. Additionally, from our engineering materials group we have developed several sealing materials and technologies compatible for the high-pressure hydrogen conditions.
On the cathode side, the cathode air filter will protect the fuel cell stack from fine particles as well as all type of harmful gasses. The filters are developed and selected based on application needs since the gas adsorption performance can be influenced by several factors such as ambient air condition, environmental conditions, driving cycles.
The Parker fuel cell humidifier utilises our proprietary hollow fiber technology, with a focus on durability and humidity transfer.
The complete range of our products for the whole hydrogen economy can be found on our Hydrogen selector.