Lab-Scale Carbonation of Wood Ash for CO2-Sequestration

Robin Koch,Gregor Sailer,Stefan Pelz,Jens Poetsch,Sebastian Paczkowski,Joachim Müller

doi:10.3390/en14217371

Robin Koch, Gregor Sailer + Show 4 more

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https://doi.org/10.3390/en14217371

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Abstract

This study evaluated the CO2 sequestration potential with combustion ashes in the aqueous phase. The aim was to provide a cost-effective carbon sequestration method for combustion unit operators (flue gas cleaning) or biogas producers (biogas upgrading). Therefore, two separate test series were executed to identify the carbonation efficiency (CE) of bottom wood ash (1) at different mixing ratios with water in batch experiments and (2) under dynamic flow conditions. It was furthermore evaluated whether subsequent use of the carbonated wood ash for soil amendment could be possible and whether the process water could be passed into the sewage. The batch test series showed that different mixing ratios of wood ash and water had an influence on the CE. The flow series showed that the mean CE varied between approximately 14% and 17%. Thus, the ash proved to be suitable for carbonation processes. The process water was dischargeable, and the carbonated wood ash has potential for chalking, as no legal thresholds were exceeded. Therefore, wood ash carbonation could be used as a low-tech CO2 sequestration technology. Compared to existing energy consuming and cost intensive carbon capture and storage technologies, sequestration with ash could be beneficial, as it represents a low-tech approach.

Highlights

Climate change will be one of the biggest challenges to face in the 21st century [1]
The bottom ash used in this study was a by-product of a grate-fired furnace from a full-scale wood combustion heat and power plant in southern Germany, using a mixture of
For batch reactor (BR) 1:20, the carbonation efficiency (CE) was at 9.9%, and for BR 1:10 it was halved (4.08%)

Summary

Introduction

Climate change will be one of the biggest challenges to face in the 21st century [1]. The European Commission proposed the European Green Deal focussing on greenhouse gas neutrality. Anthropogenic CO2 is one of the main drivers for the projected climate change, but reducing CO2 emissions is not enough to tackle this challenge. The CO2 that has already been emitted needs to be captured and stored, leading to nearly the same impact as reducing the emissions [2]. One important aspect in reaching greenhouse gas neutrality is sequestration of CO2 from exhaust gases from industrial applications or heat and power plants. Possible approaches for binding CO2 are reforestation and carbon capture storage (CCS) or bioenergy CCS technologies (BECCS) [3,4]

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