Efficient Production of Clean Power and Hydrogen Through Synergistic Integration of Chemical Looping Combustion and Reforming

Mohammed N Khan,Schalk Cloete,Shahriar Amini

doi:10.3390/en13133443

Abstract

Chemical looping combustion (CLC) technology generates power while capturing CO2 inherently with no direct energy penalty. However, previous studies have shown significant energy penalties due to low turbine inlet temperature (TIT) relative to a standard natural gas combined cycle plant. The low TIT is limited by the oxygen carrier material used in the CLC process. Therefore, in the current study, an additional combustor is included downstream of the CLC air reactor to raise the TIT. The efficient production of clean hydrogen for firing the added combustor is key to the success of this strategy. Therefore, the highly efficient membrane-assisted chemical looping reforming (MA-CLR) technology was selected. Five different integrations between CLC and MA-CLR were investigated, capitalizing on the steam in the CLC fuel reactor outlet stream to achieve highly efficient reforming in MA-CLR. This integration reduced the energy penalty as low as 3.6%-points for power production only (case 2) and 1.9%-points for power and hydrogen co-production (case 4)—a large improvement over the 8%-point energy penalty typically imposed by post-combustion CO2 capture or CLC without added firing.

Highlights

Anthropogenic carbon dioxide (CO2 ) emissions to the atmosphere have risen beyond 415 ppm, causing climate change [1]
The current study presents the efficiency improvement strategies by integrating the Chemical looping combustion (CLC) plant with an additional combustor with the membrane-assisted chemical looping reforming (MA-CLR)
Hydrogen production of thereactors, 7.2%-point penalty of acycle combined cycleHowever, power plant fired by hydrogen from awith gas conventional capture is used for this added firing, the gains from higher power cycle efficiency switching reforming (GSR) process, illustrating the importance of this energy penalty

Summary

Introduction

Anthropogenic carbon dioxide (CO2 ) emissions to the atmosphere have risen beyond 415 ppm, causing climate change [1]. The Paris Climate Accord has vowed to limit the global temperature rise below 2 ◦ C of the pre-industrial level [2]. The conventional power generation technologies such as natural gas power plants (NGCC) suffer a considerable energy penalty when integrated with a carbon capture facility. An amine-based capture system reduces plant efficiency by ~8%-points [3] (all quoted efficiencies are LHV-based). The energy penalty is the primary cost driver for CO2 capture technologies due to increased fuel costs and a greater amount of plant capital required to achieve a given electricity output. The increased fuel usage is accompanied by increased emissions. The development of novel energy conversion technologies with high

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