A framework for recognising the value proposition of CO2 capture and storage technologies
File(s)
Author(s)
Pereira Cabral, Renato Manuel
Type
Thesis or dissertation
Abstract
Carbon capture and storage (CCS) technologies are considered the most cost-effective means of curbing anthropogenic carbon dioxide (CO2) emissions from both the power and industrial sectors at a system level. Indeed, several studies consider CCS essential to limit global warming below 1.5°C by 2050 and curb the impacts of climate change. However, this technology is prohibitively expensive without government subsidies relative to unabated plants.
In this thesis, oxy-fuel combustion was used as a model CCS technology to develop cost-reduction frameworks. Process inefficiencies were analysed using the first and second laws of thermodynamics and the process was improved via a heat integration strategy. This strategy improved the efficiency of an oxy-combustion process whilst reducing its capital cost.
A solvent-based capture unit was proposed to substitute the gas processing unit (GPU) and its key performance indicators were compared with the traditional GPU. However, cryogenic methods to process the flue gas from oxy-combustion are still superior, providing comparable capture rates and CO2 purity at lower costs.
A framework to value negative emissions from bioenergy with CCS (BECCS) was proposed to simultaneously decarbonise the power and industrial sectors. However, the high CO2 price required to generate profits from auctioning negative emission credits makes this framework unlikely to be implemented.
Lastly, the flexible operation of a CCS plant to take advantage of the daily electricity price variation was evaluated. The flexible operation of a plant with liquid oxygen storage depends upon the region it operates as electricity price fluctuation plays a critical role in its profitability.
There is potential to significantly reduce CCS costs by the concurrent application of several approaches. The general nature of most of the framework developed in this thesis means that they can be applied in other CCS processes, such as post- or pre-combustion capture.
In this thesis, oxy-fuel combustion was used as a model CCS technology to develop cost-reduction frameworks. Process inefficiencies were analysed using the first and second laws of thermodynamics and the process was improved via a heat integration strategy. This strategy improved the efficiency of an oxy-combustion process whilst reducing its capital cost.
A solvent-based capture unit was proposed to substitute the gas processing unit (GPU) and its key performance indicators were compared with the traditional GPU. However, cryogenic methods to process the flue gas from oxy-combustion are still superior, providing comparable capture rates and CO2 purity at lower costs.
A framework to value negative emissions from bioenergy with CCS (BECCS) was proposed to simultaneously decarbonise the power and industrial sectors. However, the high CO2 price required to generate profits from auctioning negative emission credits makes this framework unlikely to be implemented.
Lastly, the flexible operation of a CCS plant to take advantage of the daily electricity price variation was evaluated. The flexible operation of a plant with liquid oxygen storage depends upon the region it operates as electricity price fluctuation plays a critical role in its profitability.
There is potential to significantly reduce CCS costs by the concurrent application of several approaches. The general nature of most of the framework developed in this thesis means that they can be applied in other CCS processes, such as post- or pre-combustion capture.
Version
Open Access
Date Issued
2021-03
Online Publication Date
2021-07-07T08:47:33Z
Date Awarded
2021-05
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Mac Dowell, Niall
Sponsor
Natural Environment Research Council (Great Britain)
Publisher Department
Centre for Environmental Policy
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)