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.