Fuel exergy concept

In 2002, Wassenaar [67] made an analysis of the fossil fuel requirements of the Dutch potato industry and its main products. The products are of course, in terms of their "energy" that is, available work or exergy, of solar origin. Therefore, he introduced the concept of "fossil load factor," defined as the number of fossil fuel exergy units per exergy unit of potato-based useful... 

Exergy analyses were performed for different methanol fuel processor concepts to identify the exergy losses in the system and provide strategies for improving the efficiency of the systems. 

However, the energy of the chemical input and output is not so easily defined. At a simple level we could say that it is the chemical energy of the H2, O2, and H2O that is in question. The problem is that chemical energy is not simply defined - and terms such as enthalpy, Helmholtz function, and Gibbs free energy are used. In recent years the useful term exergy has become quite widely used, and the concept is particularly useful in high-temperature fuel cells. There are also older (but still useful) terms such as calorific value. 

The importance of the concept of exergy is that with high-temperature fuel cell systems, the system configuration should be designed in such a way that exergy loss is minimised. 

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