Large-Scale Commercial Carbon Capture Retrofit of the San Juan Generating Station

Abstract

Enchant Energy, L.L.C. (Enchant) was selected to conduct a Front-End Engineering Design study (FEED) for the addition of a full-scale carbon capture system to remove carbon dioxide from the flue gas emissions of the two coal-fired generating units (total of 847 MW net) at San Juan Generating Station (SJGS), using Mitsubishi Heavy Industries Americas (MHIA) KM CDR Process™. Sargent & Lundy LLC (S&L) was selected as the primary technical lead, and along with various other organizations, were able to support Enchant’s completion of the following FEED tasks: Task 1 – Project Management & Planning; Task 2 –FEED Study; Task 3 - Final FEED Study Package. The FEED study period was between October 15, 2019 to September 30, 2022. SJGS Units 1 and 4 are already equipped with environment control equipment including wet flue gas desulfurization (WFGD) for sulfur dioxide (SO2) control, fabric filter baghouses for particulate matter (PM) control, and selective noncatalytic reduction (SNCR) for nitrogen oxide (NOx) control. MHIA’s amine based carbon capture technology will remove 95% of the CO2 from the flue gas, resulting in 20,026 metric ton per day (MTD) of CO2 removed. At an 85% capacity factor, a total of 6,212,980 metric tons per year of CO2 will be produced and transported from SJGS to either the Kinder Morgan Cortez CO2 pipeline or Class VI sequestration wells. The site boundary pressure will be at an estimated 2,800 psig to account for the required injection pressures at the Cortez pipeline and sequestration wells, as well as the estimated pressure loss through the transport pipeline. Compression of the CO2 extracted from the flue gas is accomplished by the combination of CO2 compressors and CO2 pumps. Existing SJGS Unit 1 and 4 flue gas operating data, along with recent stack testing results and future coal seam projections, were used to establish the flue gas design basis for design of MHIA’s carbon capture system. New Unit 1 and 4 flue gas ducts will tie-in between their respective WFGD outlets and exhaust stacks and will be directed to the north side of the site where the carbon capture system will be installed. Low energy steam is required as part of the amine process, and so it was determined to use steam from Unit 1 and 4, which will also be directed north to the carbon capture system. The condensed steam is returned back to the power plant. The plan to execute the project is to utilize an Engineering, Procurement & Construction (EPC) contracting strategy as this presents the least financial and technical risk to the Owner. MHIA, S&L and Kiewit would be selected as the EPC team to execute the project. MHIA would be responsible for the carbon capture process design and equipment, while S&L would provide the balance of engineering to design the BOP systems as well as some of the civil and electrical work within the carbon capture boundary. Kiewit would be responsible for all construction work. The expected duration of the project from start of detailed engineering to final completion of construction, commissioning and startup is just under 5 years. The projected capital cost for the project is $1.55 billion based on pricing through May 31, 2022. The projected O&M cost on an annual basis is $171 million. The resulting cost of capture for SJGS is projected to be $46.7 / ton of CO2 removed. The resulting net total electric power output from SJGS Units 1 and 4 after carbon capture addition is expected to be 482 MW.