"Combined Power and Process An Exergy Approach".  firstly defines and discusses the variables, heat, energy, enthalpy, entropy, thermo-mechanical exergy and chemical exergy. Then it uses example calculations to disperse the illusions surrounding such topics as combined heat and power, isothermal oxidation in fuel cells and the basis of their efficiency, and fuel cells integrated with gas turbines.

Power comes along a shaft or a cable to a rotating machine, or down a sunray to the living photosynthesis chemical reaction. Energy is the state of agitation of molecules in a substance, vibration, rotation, and translation. The two, power and energy, have different units, and cannot be added or subtracted. Power is dissipated to produce energy, e.g. water running downhill. A flow of energy is heat.The underlying equation is 1 Ws >> irreversibly>> 1 J. (From Joule’s experiment.)

Hence the efficiency of combined heat and power cannot be calculated, as is prevalent, by adding heat and power to produce an exaggerated system output. The isothermal oxidation process in a fuel cell is illustrated in a flow diagram and is much more efficient than combustion. Combustion and the calorific value must not figure in fuel cell performance calculations.

In detailed calculations of system performance irreversibility is calculated and minimised. That is also compactly done in the successful technique “process integration” for processes involving heat exchanger networks and their pinch points. It is important that the latter technique does not apply to isothermal oxidation in fuel cells.

Some example systems looked at in terms of irreversibility, are, desalination, whisky distillation, gas turbine performance, and the manufacture of hydrogen from natural gas.

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My new book, "Fuel Cells, Engines, & Hydrogen: An Exergy Approach" (published 23rd June '06) develops the fuel cell topics of my previous published book, "Combined Power and Process An Exergy Approach"  (see adjacent column.)

Isothermal oxidation in fuel cells is examined in detail, and the maximum theoretical power of the reaction is termed the “fuel chemical exergy” and calculated numerically in Ws at about five times the calorific value in J which is the performance basis wrongly used by the world fuel cell industry today, (3).Against that background, the performance of those fuel cell types with survival capability is examined.

Most fuel cells (SOFC, MCFC, PEFC etc), are termed “incomplete” because they are not equipped with voltage generating concentration cells to enable the compressible gaseous fuel, oxidant and product concentrations to be transported and reversibly equilibrated, instead of being subject to irreversible diffusion.

One type of fuel cell “Regenesys TM”,”is “complete”, via incompressible liquid reagents, and requires mere pumps instead of concentration cells. The PEFC is doubly incomplete because there is no means of manufacturing cheap hydrogen from natural gas. "Fuel Cells, Engines, & Hydrogen: An Exergy Approach" stakes out the solution, a very large industrial development problem involving unprecedented fuel cell technology as the hydrogen manufacturing route.

The millennium revolution began with "Combined Power and Process An Exergy Approach" (see adjacent column) and the author's part in that revolution, will end with the publication of "Fuel Cells, Engines, & Hydrogen: An Exergy Approach"