It is important to understand the maximum possible thermal efficiency a device is capable of obtaining and then what of this it actually achieves. In this paper it is shown that the thermal efficiency is a product of the voltage efficiency and the maximum possible thermal efficiency. One can mathematically demonstrate that for any elemental direct anodic oxidation reaction for a simple hybrid system, any fuel cell, and any operating temperature, any pressure, the maximum reversible work is equal to the free energy of reaction at the standard state. This is useful in defining an intrinsic fuel cell exergetic efficiency. An equation for thermal efficiency as a product of exergetic efficiency and maximum possible thermal efficiency is developed and presented for loosely integrated fuel cell turbine hybrids. From these simple studies alone one would conclude that the efficiency potential of fuel cells is expanded through simple fuel cell turbine hybrids.

1.
Fuel Cell Handbook, 1988, US DOE.
2.
Williams
,
M. C.
, 2007, “
Electrochemical Thermodynamic Analysis and Exergetic Studies of Intermediate Temperature Electrolytes
,” Japan Society for the Promotion of Science Report.
3.
Winkler
,
W.
, 2003,
High Temperature SOFCs
,
S.
Singhal
and
K.
Kendall
, eds.,
Elsevier
,
New York
.
4.
Winkler
,
W.
, 1994, “
SOFC-Integrated Power Plants for Natural Gas
,”
Proceedings of the First European Solid Oxide Fuel Cell Forum
, Ulf Bossel. Lucerne, Oct. 3–7, pp.
821
848
.
5.
Minh
,
N.
, and
Takahashi
,
T.
, 1995,
Science and Technology of Ceramic Fuel Cells
,
Elsevier
,
New York
.
6.
Wark
,
K.
, 1977,
Thermodynamics
,
McGraw-Hill
,
New York
.
7.
Goodisman
,
J.
, 1987,
Electrochemistry: Theoretical Foundations, Quantum and Statistical Mechanics, Thermodynamics, the Solid State
,
Wiley
,
New York
.
8.
Virkar
,
A.
,
Singhal
,
S.
,
Zhao
,
F.
, and
Williams
,
M. C.
, 2007, “
Concepts for Ultra-High Power Density Solid Oxide Fuel Cells
,”
ECS Trans.
1938-5862,
5
(
1
), pp.
401
422
.
9.
Williams
,
M. C.
, and
Hawkes
,
G.
, 2008, “
Development of Reversible SOFCs for Hydrogen Production
,”
Hydrogen Production, Transport, and Storage
,
2
, pp.
7
22
.
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