Life cycle optimisation for negative emission technologies in electricity generation

Abstract

Negative emission technologies (NETs) have been identified as the key to achieve carbon dioxide (CO2) emission targets in most coutries. However, selecting the most appropriate and cost-efficient NET to meet these targets is challenging. Thus, a deeper understanding of the system impacts of NETs is necessary for effective decision-making. This work presents a life cycle optimisation (LCO) study of a set of NET technologies. LCO study combines life cycle analysis with techno-economic analysis to optimise and screen process alternatives such as bioenergy carbon capture and storage (BECCS), direct air carbon capture and storage (DACCCS), and biochar. The proposed methodology was demonstrated with a case study with five scenarios to achieve two objectives: to minimise total system cost and to minimise net CO2 emissions. The case study analysed different NET configurations to decarbonise an existing coal-fired power plant in East Malaysia (Sarawak). In this work, an existing Balingian Coal-Fired Power Plant was considered. NET configurations were assessed based on critical performance aspects such as total life cycle carbon emissions (TLCCE) and total life cycle cost input (TLCCI). However, it is worth emphasising that the proposed methodology can be revised to handle other NET configurations that were not explicitly addressed in this paper. This can be done by utilising relevant data and assumptions that are specific to each NET configuration. Results from the case study show that the minimum cost case provides an optimum NET configuration with TLCCE and TLCCI ranging from -0.02 kgCO2eq to 100.28 kgCO2eq and 23.99 USD/MWh to 1466.70 USD/MWh, respectively. In terms of life cycle analysis, DACCS shows a favourable TLCCI of 23.99 USD/MWh and TLCCE of -0.02 kgCO2eq/MWh. On the other hand, minimising CO2 emissions results in a 7% to 17% higher TLCCI in Scenario 2 and 3 but a similar trend in each sub-system can still be observed. This has proven that higher cost is required in the case when the CO2 emissions were to be minimised.