Flexible mechanisms in carbon capture and storage

• Main Authors: Española, Lea Myka S., Fernandez, Lhyra Zophiya A., Lontok, Grace Emmanuelle T., Ong, Leslie Genevieve C.
• Format: text
• Language: English
• Published: Animo Repository 2021
• Subjects: Carbon sequestration; Carbon dioxide mitigation
• Online Access: https://animorepository.dlsu.edu.ph/etdb_chemeng/3; https://animorepository.dlsu.edu.ph/cgi/viewcontent.cgi?article=1001&context=etdb_chemeng
• Institution: De La Salle University

Carbon dioxide (CO2) emissions have significantly increased since the industrial era. With this, technologies such as carbon capture and storage (CCS) are being sought for emissions reduction. There are CO2 capture techniques that exist: pre-combustion, post-combustion, and oxyfuel combustion. Among others, post-combustion is the most advantageous in terms of retrofitting, as it does not require major reconstruction of the power plant despite its high energy penalty. By implementing flexible mechanism, retrofitted technology can reduce CCS parasitic load, increase net efficiency, ramp rate, and capacity. Systematic planning for flexible mechanisms and retrofit planning, which are not considered well in previous literature yet, is needed for the operation of CCS. In this study, two integer linear programming models (ILP) are developed for planning energy systems with flexible capture. The model is generic which can be used for any region or country. The first model decides whether to switch off or not a CCS facility in a power plant retrofitted with a post-combustion capture. The second model involves the decision of whether to retrofit a power plant with flexible capture, non-flexible capture or no capture at all. For the first model, two case studies were done, an illustrative case and a Mindanao grid in the Philippines. Sensitivity analyses was also done to demonstrate intermittency in renewable energy sources due to drought that limits water supply in lakes and in rivers. Results show that as available renewable energy decreases, the number of capture systems switched off increases. A model on the summer scenario in Mindanao is also done to demonstrate which hypothetical CCS facilities in the region should be switched off due to high demand and limited supply. In an extended version of the model, retrofit planning is added while considering flexible mechanisms under the conditions of normal operation, moderate drought, or severe drought. Similar to the previous optimization model, renewable energy supply decreases while the number of power plants with switched off capture system increases. By switching off the capture systems of these power plants, the power generated satisfies the power demand. For future studies, a model linking CO2 sources with geological sinks and the utilization of captured CO2 with various storage options are recommended.