11 Jun 2019

Optimizing Fuel Cells | Heated Platens

Proton-exchange membrane fuel cells, also known as polymer electrolyte membrane fuel cells (PEFMCs), show great promise as an energy-dense, efficient and portable power source. Generating hydrogen fuel using renewable power has the potential to make fuel cell systems a practical alternative to internal combustion engines running on non-renewable hydrocarbon fuel.

PEMFCs produced via hot-pressing methods have been shown to be sensitive to temperature, pressure, and press-time during the manufacturing process. Specac’s range of precision heated platens and laboratory hydraulic presses offer a compact and affordable way to accurately control these parameters for optimal fuel cell performance. 

As global fossil fuel reserves grow closer to depletion, research into alternative fuels is increasing in intensity. Global power infrastructure is reliant on chemical fuels for their energy density, relative ease of use, and, at least for now, abundance. This is especially true of the transport sector, which accounts for around 25% of global power consumption.1Development of alternative fuel sources is vital in order to meet future energy demands.

Fuel cells that run on hydrogen offer a particularly promising alternative to combustion engines that run on petroleum-derived fuels. Electrolysis of water (producing hydrogen and oxygen) is a common method for hydrogen production which requires an external power source. 

Powering hydrogen production with renewable energy sources such as solar or wind could potentially make hydrogen fuel cells an incredibly energy-dense and efficient store of completely renewable energy. An energy infrastructure based on hydrogen fuel cells would remove carbon oxide emissions from the equation of energy production entirely, emitting only water, and using water as the primary precursor to fuel.

solar fuel cells

Proton-exchange membrane fuel cells (PEMFCs) are a particularly promising form of fuel cell which offers a number of advantages.2At the core of a PEMFC is a membrane electrode assembly (MEA) containing an electrolytic polymer membrane which conducts protons but, crucially, not electrons. Catalysts are used to facilitate the splitting of hydrogen into protons and electrons at the anode. The resulting protons are then conducted through the polymer membrane – typically Nafion – to the cathode. Meanwhile, electrons (unable to travel through the membrane) are conducted through an external circuit (e.g. an electric motor in a vehicle) to provide power. Electrons and protons then recombine with protons and Oxygen at the cathode to produce water.

PEMFCs offer very short start-up times compared to other fuel cell architectures – typically a few seconds. They also operate at much lower temperatures than many other fuel cell types, typically below 120C (much colder than the hundreds of degrees reached inside a typical internal combustion engine).3These two features make PEMFCs well suited to application in vehicles. 

PEMFCs have found application in automobiles, buses, backup power systems and larger scale power generation, however, issues to do with cost and deterioration still prevent widespread adoption.4,5,6,7Optimizing the performance of PEMFCs is the subject of ongoing research, with the eventual goal of producing a fuel source capable of displacing the internal combustion engine with a carbon-free renewable energy source.

Optimising Proton Exchange Membrane Efficiency

The MEA is the primary functional component in a fuel cell; comprising a proton exchange membrane, catalyst layers and gas diffusion layers (GDL). They are often assembled via a hot press method, in which a thin film of catalyst is spread over either the GDL or the membrane, then the two layers are sandwiched together in a heated hydraulic press.

In an effort to improve fuel cell performance, researchers have identified a number of ways in which the manufacturing conditions of the membrane electrode assembly (MEA) can affect the performance of PEMFCs.8The temperature, pressure and time of press have all been shown to play an important role in the performance of the fuel cell.

The IV characteristics and maximum power output of PEMFCs are all sensitive to these factors. Maximum power output can be particularly sensitive to the temperature used during manufacturing – Researchers at the University of The Basque Country found that a change of only 10C during hot pressing almost doubled the maximum power output of a fuel cell under certain conditions.

It’s clear that fine control over temperature, pressure and press time is crucial for the construction of effective PEMFCs via hot pressing. Specac’s range of benchtop hydraulic presses and heated platens are a compact solution to tightly controlled hot-press manufacture of fuel cell MEAs.9,10

Specac hydraulic presses are designed for laboratory and industrial use alike, offering unparalleled precision and compactness. They are available in manual, powered and fully automated configurations.

Specac’s heated platens incorporate digital temperature controls to provide exceptional temperature control, with a stability of 1C and a maximum temperature of 300C. Platens are easily installed into Specac hydraulic presses and feature water-cooling of the connecting blocks to isolate the press from any heating effects and enable efficient heating and cooling of the platens.

References and Further Reading

1.        International Energy Outlook 2016 | U.S. Energy Information Administration. Available at: https://web.archive.org/web/20170727110053/https://www.eia.gov/outlooks/ieo/pdf/0484(2016).pdf. (Accessed: 8th March 2019)
2.        Peighambardoust, S. J., Rowshanzamir, S. & Amjadi, M. Review of the proton exchange membranes for fuel cell applications. Int. J. Hydrogen Energy35, 9349–9384 (2010).
3.        Reguera, G. et al.Biofilm and Nanowire Production Leads to Increased Current in Geobacter sulfurreducens Fuel Cells. Appl. Environ. Microbiol.72, 7345–7348 (2006).
4.        AC Transit orders 4 more UTC Power fuel cell systems for public transport buses in California | News Center | News | United Technologies. Available at: http://www.utc.com/News/News-Center/Pages/AC-Transit-orders-4-more-UTC-Power-fuel-cell-systems-for-public-transport-buses-i.aspx. (Accessed: 15th March 2019)
5.        Craven, W. B. Common Fuel Cell Project23, (2013).
6.        PEMFC Lifetime and Durability an overview.
7.        Stationary | Nedstack. Available at: http://www.nedstack.com/pem-powerplants/. (Accessed: 15th March 2019)
8.        Barrio, A., Parrondo, J., Lombraña, J. I., Uresandi, M. & Mijangos, F. Influence of Manufacturing Parameters on MEA and PEMFC Performance. Int. J. Chem. React. Eng.6, (2008).
9.        Hydraulic Press | Laboratory Presses - Specac. Available at: https://www.specac.com/en/products/sample-preparation/hydraulic-press. (Accessed: 18th March 2019)
10.      Heated Platens | Electrically Heated - Specac. Available at: https://www.specac.com/en/products/sample-prep/platens/electric/platens. (Accessed: 18th March 2019)

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