The fate of potassium and ash from biomass combustion and their impact on the degradation of monoethanolamine (MEA) for carbon capture

Bioenergy with carbon capture and storage (BECCS) is expected to play an important role in mitigating the effects of climate change due to its ability, if done correctly, to remove CO2 from the atmosphere. Many future greenhouse gas emission scenarios rely on BECCS to offset sectors that will struggle to cut emissions. The focus of this work is to examine the impact of combusting biomass on the amines used to capture CO2 in a carbon capture plant. Biomass fuels were selected that are likely to be used by a BECCS power plant. These fuels were characterised to determine their fundamental composition and combusted under various conditions to examine the release of species volatile under combustion temperatures. Potassium is an element present in high quantities in biomass and highly volatile under combustion. A single particle combustion rig was employed to examine the release of potassium during biomass combustion and the impacts of an additive on potassium release were examined. Whilst combustion of biomass at different temperatures enabled an examination of the ashes which may encounter a carbon capture facility.

Biomass and coal ashes were used to examine the effects on the degradation of 30 wt% w/w MEA in laboratory and pilot scale experiments. Solvent samples were analysed by 1H nuclear magnetic resonance (NMR) and gas chromatography mass spectrometry (GC-MS) for the formation degradation products. This work characterised degradation products previously identified in literature and a degradation product that had not been previously identified, which is present in significant quantities. The analysis of laboratory and pilot scale results in this thesis suggest that carbon capture solvents are likely to encounter high quantities of potassium from biomass combustion. However the degradation of MEA, and thus the associated regeneration cost, may be less when carbon capture is used with biomass flue gases rather than coal. The important findings of this work provides initial evidence for the installation of post-combustion carbon capture technologies working well with gases produced from biomass combustion.