High-Efficiency Bioenergy Carbon Capture Integrating Chemical Looping Combustion with Oxygen Uncoupling and a Large Cogeneration Plant

Jussi Saari,Timo Hyppänen,Esa Vakkilainen,Juha Kaikko,Petteri Peltola,Tero Tynjälä

doi:10.3390/en13123075

Abstract

Bioenergy with CO2 capture and storage (BECCS) is a promising negative emission technology (NET). When using sustainably produced biomass as fuel, BECCS allows the production of power and heat with negative CO2 emissions. The main technical challenges hindering the deployment of BECCS technologies include energy penalties associated with the capture process. This work evaluates the performance of an advanced CO2 capture technology, chemical looping with oxygen uncoupling (CLOU), in conjunction with biomass-fired combined heat and power (CHP) generation. Results from a MATLAB/Simulink reactor model were incorporated in a plant and integration model developed in a commercial process simulation software to quantify the key performance indicators of the CLOU-integrated CHP plant. Both energy and exergy analysis were conducted. The results show a remarkably low efficiency penalty of 0.7% compared to a conventional reference plant, and a high carbon capture efficiency of 97%. The low efficiency penalty is due to the high moisture and hydrogen contents of the biomass, and the separation of combustion products and excess air streams in the CLOU process; these together provide an opportunity to recover a significant amount of heat by flue gas condensation at a higher temperature level than what is possible in a conventional boiler. The condensing heat recovery yields an 18 MW generator power increase (3 MW loss in net power output) for the CLOU plant; in the reference plant with conventional boiler, the same scheme could achieve an increase of 9 MW (generator) and a decrease of 8 MW (net).

Highlights

It appears likely that, to limit the atmospheric CO2 concentration to levels compatible even with the 2 ◦ C warming goal, and the 1.5 ◦ C goal, substantially net negative CO2 emission balance must be achieved by the second half of the century [1,2]
The main operating characteristics of the reference plant and the chemical looping with oxygen uncoupling (CLOU)-combined heat and power (CHP) plant are listed in plant has slightly reduced net efficiency, the increase of thermal power is considerable, explained by low-grade heat recovered mainly in the condensation of water from the fuel reactor gas, as well as to a lesser extent the low stack temperature of the air reactor gas flow
The benefit of condensing flue gas heat recovery is much less in conventional boilers, and such equipment is still uncommon in most operational large-scale plants, recently they have started to appear in some new plants

Summary

Introduction

To limit the atmospheric CO2 concentration to levels compatible even with the 2 ◦ C warming goal, and the 1.5 ◦ C goal, substantially net negative CO2 emission balance must be achieved by the second half of the century [1,2]. Among a variety of different negative emission technologies (NETs) to remove CO2 from the atmosphere, bioenergy with carbon capture and storage (BECCS) offers a promising combination of a carbon removal potential estimated at 0.5–5 GtCO2 /year and removal cost estimated at 100–200 USD/tCO2 [3]. Energies 2020, 13, 3075 result in net negative emissions, provided that an appropriate storage option is available for the captured CO2. The significant energy penalties and equipment costs usually associated with the capture process still hinder the feasibility of BECCS technologies for widespread use, [4]

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