Hall G, 2nd pm, Day 4 Thursday Abstracts

Session S7. Carbon capture, utilization, and storage (CCUS)

Mineral carbonation (MC) is the only recognized form of permanent CO₂ storage options with no concerns regarding its long term stability. Industrial waste alkaline residues are utilized in mineral carbonation transforming them into useful products. The waste usually requires at least one pre-treatment step to make it more reactive. Pre-treatment is usually an energy-intensive process and involves the use of extraction agents which are not environmentally friendly. This translates into numerous environmental and economic concerns that hider the applicability of MC using industrial wastes. In this study, steel-making waste has been mineralized by CO₂ to produce valuable calcium and magnesium carbonates and capture CO₂ as illustrated in Figure 1. The study investigates an environmentally friendly and economical approach for MC by reacting electric arc furnace (EAF) baghouse dust (BHD) in a reject brine medium with CO₂ in a novel reactor system, specially designed for contacting gases and liquids. This approach eliminates the need for pre-treatment chemicals and its associated cost which is estimated to be 0.4 €/kg of steel waste. Response surface methodology was used to optimize the MC process. At optimum operating parameters, the optimum CO₂ uptake was 0.22 g CO₂ /g BHD. A higher CO₂ uptake performance of 0.98 g CO₂/g BHD was achieved at ambient temperature and pressure of 5 bar. In addition, the concentration of the dissolved solids in the reject brine was reduced hence reducing its salinity. Thermal gravimetric analysis (TGA) of the solid products revealed that a variety of carbonate products being produced, particularly, calcium and magnesium carbonates.

A technology for converting CO₂ recovered from a power plant into fuels or chemicals like methane or methanol is attracting attention as a CO₂ effective utilization technology. We have been developing phase separation solvent for the purpose of energy saving of CO₂ recovery. The absorbent consists of amine / ether / water and is characterized by low temperature regeneration. In this presentation, we will report on the prospect of significant energy savings by integrating CO₂ recovery in the first stage and conversion in the second stage.

The following carbon capture, storage and investigation of potential CO₂ storage sites projects are being conducted in Japan.
1. Tomakomai CCS Demonstration Project
Full-chain CCS demonstration Project
2. Investigation of Potential CO₂ Storage Sites
Identify potential CO₂ storage sites in waters surrounding Japan by 2021.
3. Sustainable CCS Project
Demonstration of capture facilities and comprehensive studies to introduce CCS
4. Osaki Coolgen Demonstration Project
Step 1: Oxygen-blown IGCC, Step 2: IGCC+CO₂ Capture, Step 3: IGFC+CO₂ Capture
The description of Tomakomai CCS Demonstration Project is as follows.
CO₂ Capture Facility: The CO₂ source is a hydrogen production unit (HPU) of an adjacent oil refinery, which supplies off gas containing approximately 50% CO₂ from a Pressure Swing Adsorption (PSA) hydrogen purification unit. In the capture facility, gaseous CO₂ of 99% purity is recovered by a commercially proven amine scrubbing process. A two-stage absorption system reduces the amine reboiler duty in the capture system.
CO₂ Injection Wells: The CO₂ is compressed and injected into shallow and deep offshore reservoirs by two separate deviated wells. The cumulative injected CO₂ volume is 230,000 tonnes as of March 20, 2019.
Monitoring Facilities: An important objective of the project is to confirm the safety and stability of CO₂ injection. As Japan is highly susceptible to earthquakes, natural earthquakes and micro-seismicity are also monitored to verify that natural earthquakes do not affect the stored CO₂, and that CO₂ injection does not cause any noticeable tremors. An extensive monitoring system comprising 3 observation wells with bottomhole temperature & pressure sensors and seismometers, 4 ocean bottom seismometers (OBSs), 1 ocean bottom cable (OBC) and 1 onshore seismometer was established. Monitoring was commenced one year prior to the start of CO₂ injection and has been conducted continuously. In addition, seismic surveys are conducted to delineate the subsurface CO₂ distribution.