The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Development of a Biocatalytic Fuel Cell System for Low-Power Electronic Applications
Anja Appelqvist (née Ranta, at present Ranta)
Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Automation and Systems Technology for public examination and debate in Auditorium AS1 at Helsinki University of Technology (Espoo, Finland) on the 15th of December, 2006, at 12 o'clock noon.
Dissertation in PDF format (ISBN 951-22-8494-4) [1617 KB]
Dissertation is also available in print (ISBN 951-22-8493-6)
Abstract
This thesis describes the development of a biocatalytic fuel cell which is intended for low-power electronic appliances. The operation of a biocatalytic fuel cell is based on the same principles as are metal catalyst fuel cells. The main difference between the two technologies is the catalyst material: in biological fuel cells the catalytic power is derived from a microorganism or an enzyme instead of the usual platinum-based transition metal catalysts. Activity in connection with biocatalytic fuel cells has been lively during the past decade, as has been the study of fuel cells in general. In principle, biocatalytic fuel cells offer inexpensive catalyst and component materials in contrast to metal catalyst fuel cells. However, so far the performance values of the metal catalyst fuel cells have been at least 10 times better. The essence of this study is the analysis of restrictions on electron transfer in the energy generation process of a biocatalytic fuel cell, with the emphasis being placed on the anodic process. Consequently, methods to improve functionality in respect of power and current density will be discussed.
The novel Direct Methanol Biocatalytic Fuel Cell (DMBFC) that was developed was utilised as a case to study biocatalytic energy generation. The operating principle of the DMBFC is the enzymatic breakdown of methanol by methanol dehydrogenase (MDH) from Methylobacterium extorquens. A significant increase in performance was achieved by improving the stability of the mediator, which enhances the electron transfer rate, and by introducing potassium permanganate as the terminal electron acceptor. Additionally, a first prototype of a stack-structured DMBFC was constructed and tested. Further development is required to optimise the process technology of the stack.
As a result of the research work and development of the DMBFC power source, knowledge of biological energy generation processes has deepened significantly. In addition, a novel method of fuel cell control was created. The power source that was developed, the DMBFC, is the basis for further research towards small disposable power sources based on biocatalytic energy generation.
Keywords: biofuel cells, methanol dehydrogenase, methanol, DMBFC
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© 2007 Helsinki University of Technology
Last update 2011-05-26