Why Fuel Cells

The advantages of fuel cells over other generators of electrical energy such as gas turbines, steam turbines or internal combustion engines with alternators are as follows  

This impressive list of attributes has provided the incentive for much of the research that has taken place on fuel cells in recent years. Naturally, the extent to which each of these characteristics is desirable depends on the application under consideration. Against these advantages should be set the many difficulties that have been encountered in the refinement of fuel cells towards practical power devices that are commercially viable, particularly when fuelled by natural gas, oil or coal. These primary fuels must first be reformed to hydrogen or methanol and then purified, which are tasks that present obstacles when chemical engineers seek to integrate the reformer to the fuel-cell stack and balance the characteristics of the two systems in terms of reaction kinetics and thermal management. 

The potential uses for fuel cells are extremely diverse and vary greatly in their power demands, from watts to megawatts. Broadly, the applications fall into the three following categories. 

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Discuss the reasons why fuel cells are considered to be a significant... 

So the greatest challenges are in the mobile sector, but the pressure to act is much greater here as well, owing to oil scarcity, pollutants from vehicles, noise nuisance, etc. Compared with stationary applications, the alternative technologies in the mobile sector are also much poorer. This is why fuel-cell vehicles remain a possibility, despite the enormous sectoral changes that accompany this alternative. The question is when will they achieve market penetration One of the main obstacles that will have to be overcome is the attendant position of both the automobile industry and the infrastructure industry concerning the investment. Which one is prepared to... 

The bipolar plate with multiple functions, also called a flow field plate or separation plate (separator), is one of fhe core components in fuel cells. In reality, like serially linked batteries, fuel cells are a serial connection or stacking of fuel cell unifs, or so-called unif cells fhis is why fuel cells are normally also called sfacks (Figure 5.1) [2]. The complicated large fuel cells or module can consist of a couple of serially connecfed simple fuel cells or cell rows. Excepf for the special unit cells at two ends of a simple stack or cell row, all the other unit cells have the same structure, shape, and functions. 

Finding or producing a clean source of hydrogen is just one of the difficulties fuel cell researchers face. The previous sections of this chapter have discussed why fuel cells are desirable and how they have proven their reliability in the Apollo missions and elsewhere, but numerous problems remain to be solved before this frontier of science can develop cost-effective devices and achieve the promise of a clean, efficient energy source. 

There are several reasons why fuel cells have drawn this much attention, such as ... 

A logical question is Why fuel cells are not on the market if they are so good The next several sections will attempt to answer this question through an analysis of the key issues and challenges in fuel cell state-of-the-art technology, applications, and commercialization. 

And yet, for more them four years after its very successful First National Bank of Omaha project, SurePower was not able to sell a second high-reliability system. The interrelated reasons for this go to the heart of the reason why fuel cells will have difficulty using reliability problems as a path to commercialization. 

There are several reasons why fuel cells are unlikely to make it as power plants for automobiles any time soon, BMW engineer Christoph Huss asserted in his paper. For one thing, he explained, an electric traction motor for a fuel cell vehicle costs as much as a normal internal-combustion engine. 

The reasons why fuel cells are not yet established and well-developed constituents of our economy lie in the losses caused by current flow, materials problems such as lack of chemical or mechanical strength, and— not independent of these aspects— in the cost of cells, generator and balance-of-plant. 

Despite the very demanding conditions in automotive applications and the more than 100 years of optimization of the internal combustion engine, the relatively high fuel efficiency is one of the reasons why fuel cells have a real chance to be applied even in this highly competitive market. For a couple of niche markets (Uke outdoor, yachting), fuel cells are already well established. 

Air is supplied to the cell by means of a blower or a compressor (depending on operating pressure) whose power consumption is directly proportional to the flow rate. Therefore, at higher air flow rates the fuel cell may perform better, but power consumption of a blower or particularly of a compressor may significantly affect the system efficiency. There are at least two reasons why fuel cell performance improves with excess air flow rate, namely ... 

There are at least two reasons why fuel cell performance improves with excess air flow rate, namely ... 

Why Do We Need to Know This Material The topics described in this chapter may one day unlock a virtually inexhaustible supply of clean energy supplied daily by the Sun. The key is electrochemistry, the study of the interaction of electricity and chemical reactions. The transfer of electrons from one species to another is one of the fundamental processes underlying life, photosynthesis, fuel cells, and the refining of metals. An understanding of how electrons are transferred helps us to design ways to use chemical reactions to generate electricity and to use electricity to bring about chemical reactions. Electrochemical measurements also allow us to determine the values of thermodynamic quantities. 

Why is the PEM fuel cell so sensitive to CO, while the SOFC cell is not ... 

Reactions that occur in fuel cells can be thought of as being flameless combustion reactions. Explain why. 

Although the majority of authors who have investigated CNTs as supports for Pt and PtRu particles claim higher activity or performance compared to conventional catalysts, it is not clear why these enhancement arise. It seems unlikely that the CNTs provide any electronic enhancement to Pt(Ru) reactivity, so it is likely that CNTs provide benefits for catalyst layer structure. Part of this may be related to surface area because CNTs can have relatively high surface areas and are often compared to XC72 supported catalysts that have only a moderate surface area ( 250 m g ). Given the current high expense of these materials ( 10 kgr ), further benefits of their use need to be identified before fhey can be practically considered as candidates for fuel cell catalyst supports. 

Since this reaction involves ions, electrons, and gas molecules in three separate phases, the edge of the o/y interface that makes contact with the gas phase /3 is often described as the three-phase (or triplephase) boundary (TPB). The concept of the TPB actually dates to the 1920s, when workers studying the oxidation of H2 on platinum introduced this concept to explain why Pt must be exposed simultaneously to both solution and gas to get significant reaction. This type of electrode, which Schmid called die diffusiongaselektrode or gas-diffusion electrode (GDE), is still called this today by workers studying solution- or polymer-based fuel cells. As... 

Why is concentrated phosphoric acid preferred over other aqueous acid media as the electrolyte in aqueous acid fuel cells ... 

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