Fixation of carbon dioxide by producing carbonates from minerals and steelmaking slags

Capture and storage of carbon dioxide (CO2) is internationally considered to be one of the main options for reducing atmospheric emissions of CO2. In Finland, no suitable geological formations are known to exist for storing captured CO2. However, fixing CO2 as solid carbonates using silicate-based materials is an interesting alternative. The magnesium silicate deposits in Eastern Finland alone could be sufficient for storing 10 Mt CO2 each year during a period of 200-300 years. Finnish steelmaking slags could also be carbonated, but the amounts produced provide a much smaller potential for CO2 storage (0.5 Mt CO2 per year) than magnesium silicates provide. The aim of this thesis was to study the possibility of reducing CO2 emissions by producing calcium and magnesium carbonates from silicate materials for the long-term storage of CO2 using multi-step processes. The production of carbonates from steelmaking slags and serpentinite, a magnesium silicate ore available from a metal-mining site, was studied both experimentally and theoretically. On the basis of the results, process concepts were developed and evaluated. Finally, the stability of synthetic calcium and magnesium carbonates as a medium for CO2 storage was assessed. Experiments with aqueous extraction and precipitation processes showed that magnesium and calcium can easily be extracted from steelmaking slags and natural silicate minerals using acids. Natural minerals seem to demand stronger acids for extraction than slags. Relatively pure calcium carbonate (80-90% calcite) was produced at room temperature and a CO2 pressure of 1 bar by adding sodium hydroxide to acetate solutions made from slag. Similarly, serpentinite was successfully converted into 93-100% pure hydromagnesite (a magnesium carbonate), using nitric acid or hydrochloric acid for the dissolution of serpentinite and sodium hydroxide for precipitation. The conversion of raw material to carbonate ranged from 60-90%. Although the results show that pure carbonates can be produced from industrial by-products and mining residues, the process concept suggested requires the recycling of large amounts of sodium hydroxide and acid, as well as low-grade heat for solvent evaporation. The methods suggested for recovering the spent chemicals were found to be expensive and cause more CO2 emissions than the amount of CO2 stored

Development of chemical looping combustion technology for bio-CCS application

Carbon capture and storage (CCS) is acknowledged as an important technology in cost-efficiently achieving the required greenhouse gas emission reductions this century. Combining biomass combustion with CCS (Bio-CCS; BECCS) offers the possibility of “negative” CO2 emissions. In the latest IPCC assessment, bio-CCS was found to have an important role to play in climate change mitigation. Many scenario models were not able to achieve the necessary reduction in greenhouse gas concentration in the atmosphere to 450 ppm CO2eq by 2100 if key technologies, such as bioenergy, CCS, and their combination were limitedly available (IPCC, 2014). Chemical looping combustion (CLC) is a new technology being developed that could be promising both for biomass combustion and as a bio-CCS application. In chemical looping combustion, the fuel is oxidized in two separate reactors with solid metal oxide particles, called “oxygen carriers”, transporting the oxygen between the two reactors. In the air reactor, the metal oxide particles react with the oxygen in air, after which the particles are transported to the fuel reactor, where they react with the fuel. It is expected that high-temperature corrosion problems can be significantly reduced in a bio-CLC reactor as compared to a conventional biomass furnace. This is because heat will be extracted mainly in the exothermic air reactor, in which there will be no alkali compounds present and very little fly ash. This should in turn allow the use of higher steam parameters in comparison to conventional biomass combustion, which would improve the power generation efficiency. In order to test and verify the benefits of bio-CLC, a new dual fluidized bed (DFB) test rig applicable for biomass was converted into a 10-50 kWth scale bio-CLC test rig. The test rig is located at VTT’s new piloting centre Bioruukki in Finland and consists of a circulating fluidized bed (CFB) air reactor interconnected with a bubbling fluidized bed (BFB) fuel reactor. A set of tests is currently being carried out using ilmenite as oxygen carrier and wood pellets as fuel. The main objectives are to study and optimize operation and process parameters for CLC using biomass-based fuels with both high and low volatile contents. In addition, deposit formation and corrosion will be evaluated in order to evaluate the possibility for improving power generation efficiency by using enhanced steam parameters. The research is carried out in the framework of two research projects: the Carbon Capture and Storage R&D Program (CCSP) with financial support from Tekes - the Finnish Funding Agency for Innovation, and Nordic Energy Research’s flagship project ”Negative CO2 Emissions with Chemical Looping Combustion of Biomass”

Spectrum, Volume 12, Number 20

Highlights include: 1994 was the first year in which any member of the University community could be awarded the 30 year honor. Last year. Registrar Douglas Bohn and Professor Maria Toiriera were handed medals for their service. This year Professor of Mathematics Raoul DeVilliers and Professor of Art Virginia Zic will receive 30 year medals -- Twelve faculty members, representing all disciplines, have become involved in a new Writing Advisory Board. Director of Freshman Communications Dr. Alison Warriner formed the board with the future of writing instruction at Sacred Heart University in mind. The Writing Advisory Board is currently discussing options to bring a writing-across-the-curriculum (WAC) program to SHU --Four professors take sabbatical: professors will be involved in projects designed to enhance their effectiveness as university faculty. Associate Professor of philosophy, Dr. Edward A. Papa, in his eighth year with the University will be writing. Dr. Gary L. Rose, professor of political science, will be completing his fourth book The American presidency under siege. After 29 years with the University, Associate Professor of biology. Dr. Carol Schofield will undertake the task of redesigning the University’s anatomy and physiology laboratories, using a multi-media interactive approach to learning. Ninth year history professor Dr. Thomas Curran will be involved in several research projects. His primary focus will be on revising his dissertation, “Education and Society in Republican China,” which deals with the changing status of intellectuals --Professor Jonathan Matte makes Math magnificent

Implications of the New EU Maritime Emission Monitoring Regulation on Ship Transportation of CO2

In the framework of the CCSP R&D program, the regulatory gaps have been assessed at VTT using the current monitoring rules for capture, pipeline transportation and geological storage of CO"sub"2"/sub" as a benchmark. The scope of the presented work includes: (i) definition of CO"sub"2"/sub" emissions from ship transportation of CO"sub"2"/sub"; (ii) review of EU regulations on MRV of maritime CO"sub"2"/sub" emissions; and (iii) review of the MRV regulation on capture, transport and geological storage of CO"sub"2"/sub" under the EU-ETS. The considered activities related to ship transportation of CO"sub"2"/sub" are liquefaction and intermediate storage with recirculation loop for boil-off CO"sub"2"/sub", loading and unloading facilities and CO"sub"2"/sub" transportation and handling during the ship voyage. Identification of the regulatory gaps, based on the above, shows what is needed to enable ship transportation of CO"sub"2"/sub" for geological storage in Europe. Based on the results, maritime transportation for CCS could be made possible with very limited new emission monitoring and verification practices. Also the trade-offs of using an MRV regulation analogous to pipeline transportation of CO"sub"2"/sub" is discussed in the results