(341d) Integration of Solid-Oxide Fuel Cells and Compressed Air Energy Storage for Peaking Power with Zero Carbon Emissions | AIChE

(341d) Integration of Solid-Oxide Fuel Cells and Compressed Air Energy Storage for Peaking Power with Zero Carbon Emissions



In recent years, sustainable
production of environmentally friendly electricity has become a major topic of
discussion and research worldwide. One promising technology is the solid-oxide
fuel cell (SOFC) power generation system [1]-[4]. An SOFC utilizes a
carbonaceous fuel gas (synthesis gas, for example) and an oxidant (typically
air) to efficiently produce electrical power through an electrochemical
reaction across a solid oxide barrier. There are key advantages to using SOFCs
for power production. For example, the anode exhaust is mainly H2O
and CO2, which are easily separated if the anode and cathode streams
are not mixed downstream, and the cathode exhaust is mostly N2,
which can be used for additional power generation or heat recovery and then
safely vented. However, a significant disadvantage of the SOFC system is that
there are currently cost-prohibitive operational challenges associated with its
dynamic use, which limits the usefulness of an SOFC system for following a typical
diurnal demand profile for electrical power.

This work investigates a novel system that integrates a
natural gas fuelled SOFC system for base load power production (Adams and
Barton (2010)) with a compressed air energy storage (CAES) plant for
load-following capabilities [1]. This new system takes advantage of the already
hot and compressed cathode exhaust by temporarily storing it underground with a
relatively low parasitic energy penalty. The SOFC/CAES plant may be switched
from storage mode (where the CAES system consumes power to store compressed
cathode exhaust) to expansion mode (where the CAES system generates power by
releasing stored compressed exhaust through a turbine). The plant operates in
storage or expansion mode depending on whether the current power demand is
lower or higher than the base power output provided by the SOFC system,
respectively. The cathode and anode exhaust streams of the SOFC system are not
mixed, and thus 100% CO2 capture from the anode exhaust can be maintained
at all times. Simulations of the combined system under a variety of charging
and discharging conditions are performed in Aspen-Plus and dynamic simulations
of the load-following scenarios and dynamic mass balances on the storage cavern
are executed in MATLAB.

Simulation results based on real scaled market demand and
pricing data show promising results for the SOFC/CAES system with regard to both
its ability to provide peaking power as well as improve gross revenues due to
hourly variations in electricity pricing. Moreover, the addition of CAES turbomachinery allows for effective load-following
capabilities to be added to the SOFC system with very minor reductions in
overall plant efficiency (~1% HHV). Furthermore, unlike other standalone CAES
plants, the SOFC/CAES hybrid plant does not require any additional air or fuel
in order to operate the CAES section; all of the required electricity, heat,
and compressed air can be obtained from the SOFC and its waste streams.
Therefore, the SOFC/CAES system provides load-following power generation from
fossil fuels with essentially zero CO2
emissions at high efficiencies. A techno-economic analysis of the combined
SOFC/CAES system is also performed, and its profitability is discussed and
compared to other systems.

References

[1]        Adams T.A.
II, Barton, P.I. High-efficiency power production from natural gas with carbon
capture. Journal of Power Sources. 2010, 195, 1971.

[2]        Adams T.A.
II, Barton P.I. High-efficiency power production from coal with carbon capture.
AIChE J. 2010, 56, 3120.

[3]        Duan, L.; Yang, Y.; He, B.; Xu,
G. Study on a novel solid oxide fuel cell/gas turbine hybrid cycle system with
CO2 capture. Int. Journ. of Energy Res. 2012, 36, 139-152.

[4]        Becker,
W.L.; Braun, R.J.;
Penev, M.; Melaina, M.
Design and technoeconomic performance analysis of a 1
MW solid oxide fuel cell polygeneration system for combined production of heat,
hydrogen, and power. Journal of Power
Sources
. 2012, 200, 34-44.

See more of this Session: Energy Systems Design II

See more of this Group/Topical: Computing and Systems Technology Division