Hotter fuel cells for higher effect in trucks

Fuel cells for vehicles could be more powerful, yet demand less space, if only they could be run on a higher temperature. Björn Eriksson, postdoc at KTH, who leads an SEC-funded project, is looking at what happens in a fuel cell at higher temperatures. 

Hydrogen fuel cells may be the future of sustainable heavy transportation, but to reach a breakthrough, they need to be able to deliver at a higher effect than today. One way of getting closer in the case of the proton exchange membrane fuel cell, the PEMFC, may be through increasing the heat in it. The temperature is one of the limitations of what effect can be delivered and the regular PEMFC has a maximum temperature of around 80 degrees Celsius.  

“If we manage to get the PEMFC working in temperatures up to 120 degrees Celsius, that would enable a much higher maximum effect, which may be needed in trucks in steep and hilly environments. We know that the cell performs worse when the temperature increases, but until now we didn’t know why”, says Björn Eriksson, postdoc at KTH, and leader of the project Evaluation and optimization of materials for IT-PEMFC. 

Partners in the project are KTH, Linköping University, AB Volvo, ABB, PowerCell, and Scania. The project started in 2021 and the researchers have already some interesting results. They discovered that it is not the cell in itself that loses functionality when the temperature is increased. It is rather what happens with the gases in the cell.  

A fuel cell runs on a combination of hydrogen as fuel and air as reactant. Together they produce electricity and water. But with a higher temperature in the cell, there will be more water, which reduces the concentration of available oxygen. 

“It is all about finding the right balance between oxygen and water. At 80 degrees it is easy to control this balance, but with a higher temperature we need to find ways to maintain it. Pressure is on way, keeping the cell drier is another. We are working on the perfect combination”, says Björn Eriksson.    

Another temperature-caused limitation is the cooling system that is required to keep this temperature. The lower temperature the larger cooling system.  

“The trucks have limitations in how large systems they can have and manufacturers are very interested in ways to reduce size of the cooling system”, says Björn Eriksson.  

The industrial partners of the project also need to know more about how a higher temperature influences the lifetime of the fuel cell. Later in the project ageing mechanisms will be tested.  

“It is good to know that what we are working on is really something that the industry wants. We are using commercial materials today, but we hope to learn about their limitations and then develop new materials. That is the next step within the project”, says Björn Eriksson.