This CAREER proposal focuses on developing an understanding of connections between fuel cell degradation and transient electrical loads, including controls that might mitigate degradation in realistic electrical environments. The project will build and validate physical models to predict degradation from the electrical terminals of an operating fuel cell, using an extensive database of proton exchange membrane transient degradation at Montana State University. Using these diagnostics, the research will develop controls for fuel cell systems to achieve acceptable trade-offs between cell degradation and measures of system performance.
Intellectual Merit: Fuel cell reliability is generally considered a materials problem, even though the electrical terminals of a fuel cell directly control the chemistry supported by the materials. This project would develop controls and diagnostics at the electrical terminals to help mitigate fuel cell degradation.
Broader Impacts: New control schemes developed through this project could enhance the extent to which fuel cells help solve future energy challenges. This project would begin to address the challenge of innovating across traditional engineering disciplines by creating a cross-disciplinary laboratory for the required undergraduate controls class in electrical engineering. Hands-on opportunities in the new lab would enhance student understanding, allow research projects to be more accessible to undergraduates, and prepare students to solve future practical problems.
Fuel cells are devices that can convert chemical energy to electrical energy with greater efficiency and less environmental impact than conventional power plants or engines coupled to generators. Fuel cells can, in principle, allow the use of both fossil and renewable chemical energy sources with much less environmental impact than the ways in which we presently use those resources. One of the challenges faced by fuel cell developers is that the cells tend to degrade with time, with the result that a fuel cell system becomes less efficient or eventually may stop working. There are several causes of fuel cell degradation that are well-known, such as impurities in the fuel, and others which are less clear. The study focussed on degradation issues in solid oxide fuel cells resulting from electrical loading conditions. In particular, we explored the hypothesis that the load connected to a fuel cell can cause it to degrade, that the load can be used to assess the state of degradation, and the possibility that cell performance can be recovered through load control. The method used to explore this hypothesis involved setting up a consist test apparatus and loading fuel cells according to different protocols until electrical performance degradation was observed. The cells were then carefully removed, stablized in epoxy, sectioned, and viewed under an electron microscope to try and understand how the smallest structures of the cell changed during the tests. We discovered that different loading conditions led to different kinds of degradation in the cell structure, including catastrophic failure. We also found that these changes could be reversed, to some degree, and cell performance could be re-established. Ultimately, these kinds of results could support new, robust fuel cell systems and allow fuel cells to be used in high-value applications such as aircraft power systems. Indeed, we've received support for further work with aerospace applications and fuel cell systems. Other outcomes of the work included supporting the education of two Ph.D. students and several masters students, initiating a collaboration to develop power electronics for fuel cell systems, and developing a number of new techniques for measuring and testing fuel cell performance. Additionally, this project supported the integration of fuel cell and control research with the teaching program at Montana State University. In particular, support from this project was paired with support from the university to develop and launch a new undergraduate laboratory in controls. This laboratory is now available students in several disciplines. Also, this project initiated work on a new text, and introduced numerous undergraduates to interdisciplinary research methods and results.
