Civil Engineering Reference
In-Depth Information
FIGURE 12-10
Air electrode supported type tubular solid oxide fuel cell design. (Courtesy of Westinghouse
Electric Company, A Division of CBS Corporation, Pittsburgh, PA. Reprinted with permission.)
Corporation in the U.S.A. and Mitsubishi Heavy Industries in Japan. The
cell element in this geometry consists of two porous electrodes separated by
a dense oxygen ion-conducting electrolyte as depicted in
Figure 12-10
.
It
uses ceramic tube operating at 1,000°C. The fuel cell is an assembly of such
tubes. SureCELL™ (Trademark of Westinghouse Electric Corporation, Pitts-
burgh, Pennsylvania) is a solid oxide high temperature tubular fuel cell
shown in
Figure 12-11
.
It is being developed for multi-megawatt combined
cycle gas turbine and fuel cell plants and targeted for distributed power
generation and cogeneration plants of up to 60 MW capacity. It fits well for
utility scale wind and photovoltaic power plants. Inside SureCELL, natural
gas or other fuels are converted to hydrogen and carbon monoxide by inter-
nal reformation. No external heat or stream is needed. Oxygen ions produced
from an air stream react with the hydrogen and carbon monoxide to generate
electric power and high temperature exhaust gas.
Because of the closed-end tubular configuration, no seals are required and
relative cell movement due to differential thermal expansions is not restricted.
This enhances the thermal cycle capability. The tubular configuration solves
many of the design problems facing other high temperature fuel cells. The
target for the SureCELL development is to attain 75 percent overall efficiency,
compared to 60 percent possible using only the gas turbine (
Figure 12-12
)
.
Environmentally, the solid oxide fuel cell produces much lower CO
4
, NOx
2
and virtually zero SOx compared with other fuel cell technologies.
During the eight years of failure-free steady state operation of early pro-
totypes, these cells were able to maintain the output voltage within
0.5 percent per 1,000 hours of operation. The second generation of the West-
inghouse fuel cell shows voltage degradation of less then 0.1 percent per
1,000 hours of operation, with life in tens of thousands of hours of operation.
The SureCELL prototype has been tested for over 1,000 thermal cycles with
