Fuel cell performance Future directions

Stability of fuel cell performance. Intense R D is going on in regard with novel material development and formation of new membranes to fulfill the above goals. In particular, the following snbjects are highlighted as indicating the directions in the future R D activities. 

Another important parameter that has to be taken into account when choosing the appropriate diffusion layer is the overall cost of the material. In the last few years, a number of cost analysis studies have been performed in order to determine fuel cell system costs now and in the future, depending on the power output, size of the system, and number of xmits. Carlson et al. [1] reported that in 2005 the manufacturing costs of diffusion layers (for both anode and cathode sides) corresponded to 5% of the total cost for an 80 kW direct hydrogen fuel cell stack (assuming 500,000 units) used in the automotive sector. The total value for the DLs was US 18.40 m-, which included two carbon cloths (E-TEK GDL LT 1200-W) with 27 wt% P ILE, an MPL with PTFE, and Cabot carbon black. Capital, manufacturing, tooling, and labor costs were included in the total. 

Another important future area for diffusion layers is the use of three-dimensional catalyzed diffusion layers for liquid-based fuel cells. This allows the three-phase active zone to be extended into the diffusion layer to increase performance and utilization and reduce crossover [276,277]. Recent work by Lam, Wilkinson, and Zhang [278] has shown the scaleable use of this concept to create a membraneless direct methanol fuel cell. In other work by Fatih et al. [279], the... 

The review is organized as follows. Section 2 defines a systematic framework for fuel cell modeling research, called computational fuel cell dynamics (CFCD), and outlines its four essential elements. Sections 3—5 review work performed in the past decade on PEFCs, DMFCs, and SOFCs, respectively. Future research needs and directions of the three types of fuel cells are pointed out wherever applicable and summarized separately at the end of each section. 

The Direct Methanol Fuel Cell, DMFC, (see Fig. 7-6 in section 7.2.2.4.) is another low temperature fuel cell enjoying a renaissance after significant improvements in current density. The DMFC runs on either liquid or, with better performance but higher system complexity, on gaseous methanol and is normally based on a solid polymer electrolyte (SPFC). R-Ru catalysts were found to produce best oxidation results at the anode, still the power density is relatively low [5, 29]. Conversion rates up to 34 % of the energy content into electricity were measured, an efficiency of 45 % is expected to be feasible in the future. SPFC in the power order of several kW to be used in automobile applications are currently in the development phase. 

Direct methanol fuel cells (DMFCs) are attracting much more attention for their potential as clean and mobile power sources for the near future [1-8], Generally, platinum (Pt)- or platinum-alloy-hased nanocluster-impregnated carbon supports are the best electrocatalysts for anodic and cathodic fuel cell reactions. These materials are veiy expensive, and thus there is a need to minimize catalyst loading without sacrificing electro-catalytic activity. Because the catalytic reaction is performed by fuel gas or fuel solution, one way to maximize catalyst utilization is to enhance the external Pt surface area per unit mass of Pt. The most efficient way to achieve this goal is to reduce the size of the Pt clusters. 

Technology Validation Validate component R D in a systems-context under real-world operating conditions to quantify the performance and reliability, document any problem areas, and provide valuable information to researchers to help refine and direct future R D activities related to fuel cell vehicles. 

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