The Power of Ethanol Fraunhofer Team Direct Ethanol Fuel Cell
Direct Ethanol Fuel Cell The Power of Ethanol Fuel cells are the technology of the future for the supply of power to electrical appliances. They have crucial advantages over competing technologies, such as their high efficiency rating even when operated at partial load, the energy-rich fuels that power them and enable them to operate for long periods and the ease with which they can be replenished. This is why forecasts point to high growth rates for the fuel cell market in the years to come. Ethanol is the ideal fuel to give the fuel cell mass-market appeal. Ethanol is available world-wide, is a non-toxic liquid that everyone can use easily and safely, its production is environmentally friendly and the product itself is ecologically harmless and, not least, it often provides higher chemical energy density than conventional batteries. Bipolar plate with integrated seal. Fraunhofer ISE. All this means that the logistics involved with fuel cells using ethanol are significantly simpler than with other fuels and that market entry is easy since existing norms and standards are already met and storage solutions are cost-effective because the safety requirements are less stringent and the waste disposal methods are straightforward. www.defc.de Test cell for membrane characterization. Fraunhofer IGB. The direct ethanol fuel cell (DEFC) can convert ethanol electrocatalytically and directly in the electrode. Researchers and developers from six Fraunhofer Institutes are working on technological development at both component and system levels. Research is focusing on an innovative membrane as well as on new types of catalysts. These core components are brought together in a design for a cell which can be manufactured using microsystem technologies. By linking this to an adapted control strategy, it is possible to create a reliable DEFC system. Right from the start, market needs are taken into account at development stage to enable early recognition of obstacles to market entry, and to point the way to solutions.... Are you on board? As members of the, we are happy to support you in your own development work. Please get in touch with us. 2
The Power Polymer electrolyte membrane Catalysts and electrodes Cell design and microfluidics As is also the case with methanol, ethanol is transported together with the protons through the membrane from the anode to the cathode (cross over). This causes the creation of a mix-potential and reduced efficiency and performance. To minimize cross over we are developing composite membranes here at Fraunhofer. These membranes contain an anorganic component as well as the polymer. The anorganic filler materials act as a barrier against the ethanol without reducing proton conductivity. We functionalize the surface of the anorganic particles in order to ensure that they integrate well and homogeneously into the polymer matrix, to support the development of nanodomains to improve proton conductivity, to reduce membrane swelling and to improve membrane temperature stability. Catalyst composition in conjunction with the fuel has a major influence on the performance and efficiency of the fuel cell. For example, catalysts which are currently used for methanol oxidization are unsuitable for the electrochemical conversion of ethanol. This is why we are researching into innovative, binary and tertiary catalysts for anodic ethanol oxidization. We are also investigating ways of designing reaction control and the geometrical format of electrodes with a view to optimizing ethanol conversion. One of the study methods that we are using is differential electrochemical mass spectrometry (DEMS). Depending on the given power or potential, DEMS makes it possible to observe volatile substances and also to observe the influence of material concentrations on the reaction path or product yield. We are constructing the micro fuel cell with the aid of MEMS or silicon technologies. By microstructuring and optimizing the design we minimize the amount of energy needed to operate the cell. For this, we run studies to optimize the transport of materials, charges and heat. Because of its chemical stability and purity, we prefer a micropump with a silicon base for the purpose of fuel fluidics. In particular, capillary action is harnessed to stimulate the homogeneous distribution of the fuel over the electrodes. In addition, the design is intended to aid the discharge of carbon dioxide and other by-products from the anode cycle, to ensure the fuel feed is sufficient, to make it possible to set the operating temperature and to provide stable control behavior. Nanoparticle composite membrane. Fraunhofer IGB. REM photo of a fuel cell electrode. Fraunhofer ICT. Micromembrane pump. Fraunhofer IZM, Munich branch. 3
of Ethanol Fuel cell system technology Power management Market requirements We integrate the fuel cell, micropump, control engineering, battery storage and ethanol tank into a single standalone system. For this, we first simulate the heat flows of the components in order to be sure of providing reliable heat management. The isolated and the heated zones need a functional housing. Further, we create storage containers, fluid connections, condensers for recycling the water and drip collectors to catch the educts. On the test stand, we project suitable control strategies using dynamic load tests and extended-time tests. Lifetime analyses are carried out with the aid of in-situ measuring technology. We investigate the impact of different ambient temperatures and humidity levels in a climate-controlled chamber. We are developing a hybrid power supply system. In this, the direct ethanol fuel cell provides the base load supply for the required electric load and ensures that there is always sufficient accumulator or condenser capacity. This satisfies the dynamic output requirements of the electric load. A carefully thought out power management system is essential to ensure optimum operation of the electricity storage capacity. For this, we are creating an electronics system with minimum energy requirements. It is also essential to adapt output and voltage of the individual electrical components. In addition, our intelligent controls ensure that the energy capacities are distributed correctly to where they are needed. New technologies such as fuel cells need a suitable frame of reference before they can be successfully launched on the market. Developers and manufacturers are adopting uniform practices concerning the standardisation of interfaces, and safety experts are formulating standards to minimise handling risks. We are observing this standardisation process and are monitoring trends and product requirements in order to help accelerate product development and smooth the way to market launch. In this way, we can link our own developments closely to the needs of our customers. Planar self-breathing fuel cell stack. Based on printed circuit boards. Fraunhofer ISE. Universal module for battery management and monitoring. Fraunhofer IIS. Temperature profile of a fuel cell. Fraunhofer IZM. 4
Pictures on title page. The Power of Ethanol Sustainable, renewable energy Ethanol is obtained from sustainable and renewable raw materials such as rapeseed and has many applications as a liquid fuel. Ethanol is an environmentally friendly means of generating power when used in the direct ethanol fuel cell. Fraunhofer ISI, Karlsruhe Norms and standards, market analysis. Fraunhofer ICT, Pfinztal Catalysts, electrodes, electrochemistry. Fraunhofer IGB, Stuttgart Membrane development, membrane characterisation. Fraunhofer ISE, Freiburg Fuel cell development and characterisation, system engineering, control strategy. Fraunhofer IZM, Berlin Cell design, microsystem engineering. Fraunhofer IIS, Erlangen Low-power electronics, energy management system, battery charging management. Fraunhofer IZM, Munich branch Microfluidics, micropumps 5
The direct ethanol fuel cell technology of the future. Benefit from the capabilities of the Fraunhofer Institutes for successful products and market launches. We are happy to provide you with individually tailored advice and support on the realisation of your innovations. In many cases, you can draw benefit as well from the work that the Fraunhofer Institutes undertake jointly with experienced partners in industry. We work alongside you as you develop your components and develop customised system solutions related to direct ethanol fuel cells. The service we offer ranges from technology and market consultancy through component development, output and control engineering and system simulation to system integration and field test monitoring. Do you want further information? Get in touch with us. Dr. Michael Krausa Fraunhofer-Institut for Chemical Technology ICT Joseph-von-Fraunhofer-Straße 7 76327 Pfinztal (Berghausen) phone: +49 (0) 7 21/46 40-444 fax: +49 (0) 7 21/46 40-318 Michael.Krausa@ict.fraunhofer.de Secretary Mrs. Mechthild Berger phone: +49 (0) 7 21/46 40-344 www.defc.de www.energie.fraunhofer.de Fraunhofer ICT Dr. Michael Krausa Joseph-von-Fraunhofer-Straße 7 76327 Pfinztal (Berghausen) Michael.Krausa@ict.fraunhofer.de www.ict.fraunhofer.de Fraunhofer IGB Dr. Thomas Schiestel Nobelstraße 12 70569 Stuttgart Thomas.Schiestel@igb.fraunhofer.de www.igb.fraunhofer.de Fraunhofer IIS Peter Spies Im Wolfsmantel 33 91058 Erlangen Peter.Spies@iis.fraunhofer.de www.iis.fraunhofer.de Fraunhofer ISE Dr. Carsten Agert Heidenhofstraße 2 79110 Freiburg Carsten.Agert@ise.fraunhofer.de www.h2-ise.de www.ise.fraunhofer.de Fraunhofer ISI Dr. Frank Marscheider-Weidemann Breslauer Straße 48 76139 Karlsruhe mw@isi.fraunhofer.de www.isi.fraunhofer.de Fraunhofer IZM Dr. Robert Hahn Gustav-Meyer-Allee 25 13355 Berlin Robert.Hahn@izm.fraunhofer.de www.izm.fraunhofer.de Fraunhofer IZM, Munich branch Klaus Heinrich Hansastraße 27d 80686 München Klaus.Heinrich@izm-m.fraunhofer.de www.izm-m.fraunhofer.de Planar ceramic fuel cell for mobile electronics. Fraunhofer ISE. Flexible micro fuel cell. Fraunhofer IZM.. www.defc.de