RCN Poster Abstracts
From Monday, April 14 until Wednesday April 16 the following posters will be on display outside of Davis Auditorium in the CEPSR/Schapiro Center. On Wednesday at 12:30-1:30 there will be a poster session for presenters to talk more about their work.
To expand the abstracts, click on the + next to the title.
+ Capturing CO2 from Air: Low temperature regeneration of NaOH using Fe2O3 James Campbell, John Grace, and Jim Lim
Direct capture of CO2 from air could conceivably help mitigate emissions from small and distributed sources which are not amenable to end-of-pipe capture. Wet scrubbing using NaOH has the potential to make CO2 capture from air a feasible process. The Na2CO3 formed can be separated by crystallization and calcined with Fe2O3(s) in the solid state producing NaFeO2(s) and a stream of pure CO2. The NaFeO2(s) can be leached with hot water to recover NaOH(aq) and precipitate Fe2O3(s). However the temperature at which the calcination occurs is high (>850°C), requiring a kiln probably fired by natural gas. The extra CO2 produced by burning natural gas must then be captured, adding to the complexity of the process and possibly nullifying the carbon savings. We have found that ball milling of Na2CO3 and Fe2O3 prior to calcination, can reduce the temperature of CO2 release to 600°C. This is thought to be due to intimate contacting rather than simply the reduced particle size. These lower temperatures also help to avoid Fe3O4 formation, which is detrimental to the process. If the milling process could be replicated at larger scales, then the low-temperature calcination could facilitate integration with renewables or industrial waste heat, significantly increasing the carbon negativity of the process.
+ Feasibility of using depleted shales as a repository for permanent storage of CO2
Andres F. Clarens, Zhiyuan Tao
Civil and Environmental Engineering
351 McCormick Road, Thornton Hall
University of Virginia, Charlottesville, VA, 22904
Oil and gas production from hydraulically fractured shale formations is an abundant new source of domestically available energy for the United States. It will also result in significant CO2 emissions with important climate implications. Several studies have suggested that fractured shale formations could be used to permanently store CO2 once they are depleted of hydrocarbons. Many of the largest shale formations being developed in the United States have temperature and pressure profiles that are similar to those of saline aquifers being widely studied for geologic carbon sequestration. Here a modeling framework was developed that can be used to estimate the sequestration capacity for a shale formation based on historical CH4 production. The model is applied to those portions of the Marcellus formation found in Pennsylvania because reliable data on well production is readily available for this state. Production data from over 300 wells was compiled and used to estimate historical production and to extrapolate projected production. In shale formations, much of the CO2 would be sorbed to the pore and fracture surface and so this model considers sorption kinetics as well as total sorption capacity.
The results suggest that shale formations could represent a significant repository for geologic carbon sequestration. The Marcellus shale in Pennsylvania alone could store between 10.4 and 18.4 Gigatonnes of CO2 between now and 2030. This would be over 50% of total annual US CO2 emissions from stationary sources. The mass transfer and sorption kinetics results indicate that CO2 injection proceeds several times faster than CH4 production. Even though most unconventional production wells generate economically relevant amounts of natural gas for over 10 years, the injection of CO2 would proceed much faster, on the order of one to two years before the well could be retired. Model estimates were most sensitive to the permeability of the formation and assumptions about the ultimate ratio of adsorbed CH4 to CO2. CH4 production is a useful basis for calculating sequestration capacity because gas mass transfer out of the formation will be impacted by the same factors (e.g., temperature, pressure, and moisture content) influencing gas injection. CH4 production data is also readily available for production wells in many locations, which facilitate calculations. The differences between horizontal and non-horizontal wells were taken into account to understand how well structure would influence gas transport kinetics. It was assumed that only the sorbed CO2 would stay in the formation over time. The MATLAB source code used to calculate sequestration potential from natural gas production logs in a region is open source and available from the author’s website.
Beyond the scale of CO2 that could be stored in these formations, there is an opportunity to leverage existing infrastructure, such as pipelines and wells, to couple shale gas production with carbon sequestration that would improve the economics of both. Other synergies could exist in terms of long-term site monitoring. Related impacts associated with induced seismicity and leakage would need to be explored to understand the full potential of this approach. Geomechanical stresses in the post-fracture post-extraction shale could limit permeability in a way that would need to be quantified to fully understand the storage capacity of a depleted formation in the field. But as a first approximation this method for calculating sequestration capacity developed here supports continued exploration into this pathway for producing carbon neutral energy.
+ Modifications to cost curves of geologic CO2 storage caused by reservoir leakage and the policy implications
Hang Deng1, Jeffrey M. Bielicki2,3, Michael Oppenheimer4, Jeffrey P. Fitts1, Catherine A Peters1
1Department of Civil and Environmental Engineering, Princeton University
2Department of Civil, Environmental, and Geodetic Engineering, The Ohio State University
3The John Glenn School of Public Affairs, The Ohio State University
4Department of Geosciences, Princeton University
Carbon dioxide (CO2) Capture Utilization and Storage (CCUS) faces several challenges, including high cost, the lack of a CO2 emissions price, and uncertainties regarding the long-term security of storage. Among the CCUS technologies, geologic storage of CO2 has large capacity, but the potential is clouded by the risk of CO2 or brine leakage from the storage reservoir and related financial consequences (Bielicki et al, 2014). These risks and associated costs of prevention and remediation will affect the deployment of geologic storage, and more importantly, regulatory decisions that shape the role of CCUS in our future energy system.
Integrated Assessment Models (IAMs) have been used extensively to assess the technical and economic viability of energy technology deployment in the context of satisfying both future energy demand and climate objectives. However, current IAMs fail to adequately account for leakage risks of geologic storage. In some cases, leakage is simply included as an additional source of CO2 emissions into the atmosphere, while the costs that arise from leakage interfering with other valuable subsurface resources (e.g., natural gas and groundwater) are overlooked.
In this work, we have determined cost curves that comprehensively account for the financial consequences of reservoir leakage. We build on a previously developed evaluation framework – the Risk Interference of Subsurface CO2 Storage (RISCS) model (Bielicki et al., 2013, Bielicki et al, 2014). We use the costs estimated by the model to modify cost curves for geologic CO2 storage from the Global Change Assessment Model (GCAM) (Kim et al., 2006).
Consideration of leakage risks not only causes upward shift of cost curves, but also changes the shape of the curves. As CO2 storage increases, the risks of leakage and subsequent financial costs are expected to increase due to higher injection rates, larger CO2 plumes and exploitation of less suitable storage sites. We applied the evaluation framework under different injection scenarios, and examined the geospatial variability of leakage risks, using the Michigan sedimentary basin as an example, as well as the corresponding financial consequences.
The ultimate goal of our study is to apply the modified cost curves to GCAM to investigate policy implications. For instance, how CCUS deployment will be affected by regulations intended to protect groundwater and competing subsurface activities and by the allocations of financial responsibility for leakage.
Bielicki, J., Pollak, M., Wilson, E., Fitts, J., and Peters, C. (2013). “A Methodology for Monetizing Basin-Scale Leakage Risk and Stakeholder Impacts.” Energy Procedia. 37, 4665-4672.
Bielicki, J., Pollak, M., Fitts, J., Peters, C., and Wilson, E. (2014). “Causes and Financial Consequences of the Impacts of Leakage from Geologic CO2 Storage Reservoirs.” International Journal of Greenhouse Gas Control. 20. 272–284
Kim, S.H., J. Edmonds, J. Lurz, S. J. Smith, and M. Wise (2006) The ObjECTS Framework for Integrated Assessment: Hybrid Modeling of Transportation Energy Journal (Special Issue #2) pp 51-80.
+ Methane fuel production by catalytic hydrogenation of CO2 over Ru/(gamma)-Al2O3 catalyst for renewable energy storage, Melis S. Duyar1, Robert J. Farrauto2
Earth and Environmental Engineering Department, Columbia University in the City of New York, New York, New York, 10027
The production of synthetic natural gas from carbon dioxide using renewable energy sources can result in significant reductions in CO2 while allowing renewable energy sources to be dispatchable and hence more reliable. The Sabatier reaction (1) is a chemical route that allows for methane to be synthesized from CO2. This reaction can be performed catalytically to convert CO2 directly into a valuable fuel resource.
CO2 + 4H2 -> CH4 + 2H2O ΔH0 = -164 kJ/mol (CO2) (1)
By converting CO2 into synthetic natural gas (SNG), two problems concerning global warming prevention efforts are simultaneously addressed. The first major problem is that renewable energy sources are intermittent, and fluctuations in output create problems when integrating these energy sources into the existing grid. Since a viable storage option does not yet exist, electricity produced in excess of consumer demand is wasted. In the proposed approach, electricity from renewables is first converted to hydrogen (which has its own difficulties in transportation and handling) via electrolysis of water, and then used to hydrogenate CO2 in a two step process. In this manner, energy that cannot be used in the electricity grid is integrated into the natural gas grid. The second problem addressed by this approach is that CO2 is a greenhouse gas, which is continuously created through all industrial operations, and residential energy needs around the world. Hydrogenation of CO2 to SNG can result in significant decrease in annual CO2 emissions because it enables the recycling of carbon directly in industry.
CO2 methanation has been evaluated as a means of storing intermittent renewable energy in the form of synthetic natural gas. A range of process parameters suitable for the target application (4720 h-1 to 84000 h-1 and from 160oC to 320oC) have been investigated at 1 bar and H2/CO2 = 4 over a 10 % Ru/γ-Al2O3 catalyst. Thermodynamic equilibrium was reached at T ≈ 280oC at a GHSV of 4720 h-1. Cyclic and thermal stability tests specific to a renewable energy storage application have also been conducted. The catalyst showed no sign of deactivation after 8 start-up/shut-down cycles (from 217oC to RT) and for total time on stream of 72 h, respectively. In addition, TGA-DSC was employed to investigate adsorption of reactants and suggest implications on the mechanism of reaction. Cyclic TGA-DSC studies at 260oC in CO2 and H2, being introduced consecutively, suggest a high degree of short-term stability of the Ru catalyst, although it was found that CO2 chemisorption and hydrogenation activity were lowered by a magnitude of 40 % after the first cycle. Stable performance was achieved for the following 19 cycles. The CO2 uptake after the first cycle was mostly restored when using a H2-pre-treatment at 320oC between each cycle, which indicated that the previous drop in performance was not linked to an irreversible form of deactivation (sintering, permanent poisoning, etc.). CO chemisorption on powder Ru/(gamma)-Al2O3 was used to identify metal sintering as a mechanism of deactivation at temperatures higher than 320oC.
+ Acqueos MG(OH)2 Carbonation and its Application to the water gas shift reaction , Kyle Fricker
Mg-bearing materials, specifically solid or aqueous Mg(OH)2, derived from silicate minerals or industrial wastes, can directly capture and store CO2 without incurring the energy intensive sorbent regeneration penalty. Since calcium is naturally abundant in CaCO3 mineral, Ca-based sorbents must be regenerated and reused, and therefore only represent an energy intensive carbon capture solution. Instead, single-use Mg-based sorbents capture CO2 and store it in permanent and environmentally benign magnesium carbonates. Through integration of in-situ mineral carbonation with various energy conversion systems, the CO2 can be removed as it is generated. In the water-gas shift (WGS) reaction, for example, Mg(OH)2 carbonation has the added benefit of enhancing H2 production as the CO2 is converted to MgCO3 and the equilibrium is shifted. The WGS and carbonation reactions synergistically utilize steam, as both a H2 source and carbonation promoter.
The poster investigates the pathways of Mg(OH)2 carbonation at elevated temperatures and CO2 pressures (up to 400 ºC and 15 atm) in the presence of steam as well as in the slurry phase. Generally, gas-solid carbonation experiences kinetic and mass transfer issues which limit conversion, though the extent of carbonation increases dramatically with increasing PH2O. Steam’s effect on carbonation is attributed to ffundamental mechanisms, and the reaction parameters driving the formation of hydrated and anhydrous carbonate phases are determined. The results indicated that the presence of H2O enables an alternate pathway through an intermediate hydrated magnesium carbonate species. Those hydrated carbonates form relatively quickly (compared to the anhydrous carbonate) and can transform into the anhydrous carbonate depending on the experimental conditions, namely at greater H2O loading, higher temperature, and/or longer reaction time.
Slurry phase carbonation of Mg(OH)2 (very high H2O loading) proceeds to completion via a homogeneous precipitation reaction between carbonate ions and dissolved Mg2+. The metastability of various hydrated magnesium carbonates is governed by the reaction temperature. Methods for preferentially forming anhydrous carbonate—desirable from end product stability and process efficiency standpoints—at unsuitable conditions (T < 200 °C) are proposed and evaluated. Solution additives like NaCl and bicarbonate can inhibit hydrated carbonate formation by reducing the activity of H2O and increasing carbonation reaction kinetics. The use of magnesite (MgCO3) seed particles to direct precipitation of anhydrous carbonate at 150 °C is also demonstrated.
The carbonation reaction is integrated with the WGS reaction in a semi-batch slurry reactor to investigate the effect of in-situ carbonation on water-gas shift reaction characteristics, namely enhanced H2 yield. The presence of a bulk aqueous phase complicates the traditional gas phase WGS as CO can combine with hydroxide ions to create formate ions which may remain in solution or react and decompose into H2. The presence of the slurry shows an enhanced hydrogen yield with and without the presence of catalyst. The system is under continued investigation and optimal reactor arrangements are proposed.
+ H2 from biomass using alkaline thermal treatment, Tom Ferguson, Maxim Stonor
With the ever-increasing demand for energy and the depleting supplies of fossil fuels, focus has been placed on producing renewable and sustainable energy. Biomass sources such as agricultural and food waste are excellent feed-stocks, which contain a large proportion of lingo-cellulosic material that can be transformed into useful energy, specifically H2 gas. Although H2 from biomass is not a new subject, many processes require high temperatures, pressures in order to achieve reasonable H2 yields. Furthermore, waste biomass never comes from a centralized location so the transportation of such low energy feedstocks is impractical. Therefore, the alkaline thermal treatment (ATT) of lingo-cellulosic material to H2 is of great interest since the reaction can take place at moderate temperatures of 573K and ambient pressure. The use of NaOH as a reagent in the ATT process results in a COx free stream of H2 that can be fed directly into a PEM fuel cell.
Understanding the effects of various process parameters in the production of hydrogen from the alkaline thermal treatment of cellulose is crucial to process design. Key parameters such as mixing method, hydroxide concentration, hydroxide type, vapor flow-rate, and the use of catalyst have been investigated. Sodium hydroxide was found to suppress COx formation from cellulose while enabling hydrogen and hydrocarbon formation. The addition of water vapor to the sodium hydroxide and cellulose system enhanced hydrogen formation while suppressing hydrocarbon side product formation. Analysis of the solid products remaining after the alkaline thermal treatment of cellulose showed significant inorganic carbon content, indicative of the formation of carbonate, and demonstrative of the carbon management potential of the alkaline thermal treatment technology.
Other types of hydroxides were also investigated as alternatives to NaOH. It was found that the amount of H2 produced was highly dependent on the type of hydroxide used, and followed the following trend when referring to H2 yield: K>Na>>Ca>Mg. Group II hydroxides performed more poorly than their Group I counterparts due to their low solubility, thus making them weak bases. For this reason it was important to investigate methods by which the activity of these cheaper hydroxides could be ameliorated through catalysis. Two catalysts were investigated, Nickel and Platinum, with Platinum acting as the representative metal of the noble metals, known for their catalytic properties. It was found that Nickel at 10% coverage supported on ZrO2 performed better than 1.67% Platinum. Utilizing higher loadings of platinum was not feasible due to the increased cost, thus Nickel proved to be an ideal candidate. It was found that 10% Ni/ZrO2 promotes the yield of H2 in the Ca(OH)2 and cellulose reaction, to levels comparable to the non-catalytic reaction of NaOH and Cellulose. The conversion of cellulose to H2 in both cases was 29% and 33% respectively, which are fairly close, although NaOH is still marginally more effective.
+ Geo-Chemo-Physical Studies of Carbon Mineralization for Natural and Engineered Carbon Storage Greeshma Gadikota1, Ah-hyung Alissa Park1, Peter Kelemen2 and Juerg Matter2,3
1Department of Earth and Environmental Engineering & Chemical Engineering,
Lenfest Center for Sustainable Energy, Columbia University, NY
2Department of Earth and Environmental Sciences, Columbia University, NY
3Department of Ocean and Earth Science, University of Southampton, UK
Rising concentration of CO2 in the atmosphere is attributed to increasing consumption of fossil fuels. One of the most effective mechanisms to store CO2 captured from power plants is via geological injection of CO2 into formations that contain calcium and magnesium silicate and alumino-silicate minerals and rocks. The mechanism that ensures the permanent storage of CO2 within rocks is mineral carbonation. When CO2 is injected into mineral or rock formations rich in calcium or magnesium silicates, they react with CO2 to form calcium or magnesium carbonates, which is also known as carbon mineralization. Calcium and magnesium carbonates are stable and insoluble in water. However, the kinetics of in-situ mineral carbonation involve CO2 hydration, mineral dissolution and formation of carbonates, and the relative rates of these phenomena when coupled, are not very well understood.
In this study, the coupled interactions of CO2-reaction fluid-minerals were investigated to determine the optimal conditions for carbon mineralization, and to identify the chemical and morphological changes in the minerals as they react to form carbonates. Carbon mineralization in various minerals and rocks such as olivine and basalt were studied at high temperatures (Tmax = 185 oC) and high partial pressures of CO2(PCO2, max = 164 atm), which are relevant for in-situ conditions. Systematic comparisons of the effects of reaction time, temperature, partial pressure of CO2, and fluid composition on the conversion of these magnesium and calcium bearing minerals and rocks were conducted. Overall the results of these studies demonstrate the effect of various parameters on carbon mineralization, and how these parameters can be connected to predict CO2 storage in mineral formations. Sensitivity analyses of the effects of various parameters were performed to determine their effects on the rates of carbon mineralization.
+ Storing Electricity and CO2 as Synthetic Hydrocarbon Fuels by High Temperature Electrolysis, Graves et. al
Christopher Graves , Sune D. Ebbesen , Søren H. Jensen , Peter V. Hendriksen , Mogens B. Mogensen
Department of Energy Conversion and Storage, Technical University of Denmark, Risø campus, Frederiksborgvej 399, DK-4000 Roskilde, Denmark
Today’s major sustainable energy efforts are (i) reduction of CO2 emissions and (ii) increasing the share of renewable energy. One way of CO2 emissions reduction is CO2 sequestration, which can be pursued independently of renewable energy. Another way is CO2 utilization, which at large scale means conversion of CO2 into synthetic hydrocarbon fuels for use in existing infrastructure. This conversion must be driven by energy sources that do not produce CO2 emissions, e.g. renewable or nuclear energy sources. Advantageously, using renewable energy to convert CO2 to fuels also helps increase the share of renewable energy because the most abundant renewable sources, solar and wind, provide fluctuating energy supplies which must be stored. Synthetic hydrocarbon fuels are excellent energy storage media.
Solar energy can be used to convert CO2 and H2O into fuels in a variety of ways. The most common way is by growing biomass, but also many artificial processes are actively researched, including photoelectrochemical, photovoltaic+electrolytic, solar thermochemical, solar thermolytic, and solar thermoelectric+electrolytic conversions. Wind energy, on the other hand, is collected exclusively as electricity, and therefore electrolysis is the most appropriate and direct type of conversion.
Our group at the Technical University of Denmark (formerly Risø National Lab) has been researching high temperature electrolysis of CO2 and H2O using solid oxide electrolysis cells (SOECs) for more than 10 years. The ceramic cell technology that was developed most actively for fuel cell application (solid oxide fuel cells) can be simply run in the reverse by applying electrical energy. Besides using the cells optimized for fuel-cell mode operation, new types of cells optimized for electrolysis mode operation are also under development. Compared with conventional low temperature electrolysis, operating at high temperature has several advantages that lead to higher efficiency as well as potentially lower capital cost. First, high reaction rates are achieved without expensive electrocatalysts such as platinum. Second, the electrolysis reaction becomes increasingly endothermic with increasing temperature and the inevitable resistive losses in the cell can be used as heat in driving the reaction. The combination of these two advantages enable operation at high throughput (>1 A/cm2) at the thermoneutral voltage (100% electrical-to-chemical energy conversion efficiency; in a real system, heat-exchanger losses will make the efficiency slightly lower).
However, the high temperature reactive environment also poses challenges for long-term stability: the fine porous microstructures of the electrodes can coarsen over time, the local gas composition and electrical potential can induce detrimental structural or phase changes, the component materials can react with each other, and operating errors can lead to sudden thermal transients or exposure of certain materials to oxidizing or reducing conditions which damages the material. Despite all the possible degradation mechanisms, the large effort in materials design that has been undertaken for many years has brought 5 to 10 year operating lifetimes with reach. SOEC research therefore entails a combination of fundamental studies of materials with long-term testing of pre-commercial devices for thousands of hours, as well as investigating the integration of the devices into the larger energy system.
When operated at atmospheric pressure, high temperature electrolysis of CO2 and H2O yields CO and H2 at the cathode and O2 at the anode. The CO/H2 mixture (syngas) is subsequently converted with well-known catalytic reactors used in the fossil fuel industry to produce liquid or gaseous hydrocarbons such as methane, methanol, gasoline and diesel. By pressurizing the SOEC device instead of only pressurizing the catalytic hydrocarbon synthesis reactor, it is possible to directly produce hydrocarbons like methane in the cathode chamber. Pressurized operation can therefore reduce the electrolysis system cost and increase the efficiency for production of synthetic hydrocarbon fuels.
We will describe our latest experimental findings about performance and stability of SOECs and present recent results of pressurized SOEC operation.
+ Air capture and CO2 sequestration in remote locations
, David S. Goldberg1 and Klaus S. Lackner2
David S. Goldberg1 and Klaus S. Lackner2
1Lamont–‐Doherty Earth Observatory of Columbia University USA2
Dept of Earth and Environmental Engineering,
Strategies for stabilizing atmospheric greenhouse gas concentrations need to consider future CO2 emissions from an enormous resource of worldwide fossil fuel supplies and a diverse range of mitigation technologies. It is likely that global CO2 concentrations in the Earth’s atmosphere will increase for decades. This research considers an option for the secure sequestration of CO2 in basalt formations, vast geological repositories that could mitigate
Carbon release to the atmosphere and environment for many centuries and remain well away from material and human risks. Remote basalt reservoirs minimize difficult problems for conventional sites related to their potential for leakage, groundwater safety, land access, proximity to private property, storage permanence, and human inconvenience.
Geological sequestration of the captured CO2 requires a stable and high capacity storage reservoir with low risk of leakage (IPCC, 1). Specifically, locating CO2 storage reservoirs in remote locations reduces the potential of real property damages near populated areas, mitigates the risk of induced earthquakes, and minimizes concerns about produced/expelled fluids in groundwater aquifers after CO2 injection. Large Igneous Provinces (Coffin, 2) consists of large volumes of extrusive rocks, such as basalt, can be found around the globe, and have been proposed as secure CO2 reservoirs (Oelkers 3; McGrail, 4). Goldberg (5) suggested that CO2 injected in basalt reservoirs would ultimately be sequestered in the form of thermodynamically stable and environmentally benign minerals. Because mineralization would strengthen these reservoir rocks (Yarushina, 6), the consequences of small pressure increases due to injection are unlikely to cause faulting or major earthquakes. Furthermore, if injected CO2 were to migrate through a basalt reservoir, low–‐permeability sediment caprocks present above it in many locations could provide additional trapping and protective capacity. Collection of CO2 from ambient air is a new technology that may play a pivotal role in controlling global emissions and, in principle, in reducing atmospheric concentrations to pre–‐industrial levels. Because CO2 mixes rapidly in the atmosphere, air capture systems can operate anywhere around the globe. To have a large impact on atmospheric build–‐up of CO2, an associated reservoir with vast storage capacity will be required. This research advances the notion that remote basalt reservoirs provide more than sufficient capacity, by outfitting them with ambient air capture systems, these remote locations become viable CO2 collection points. An important advantage of siting these technologies together, and remotely, is that long–‐term mitigation of global CO2 emissions may be implemented in an environmentally secure and publically acceptable manner, and thus, present a much greater likelihood of worldwide CO2 stabilization in the future. Lackner (7) suggested direct capture of CO2 from ambient air as an energetically and economically viable climate mitigation technology. Laboratory studies have indicated that the partial pressure of CO2 in the outflow from air capture largely determines its energy requirements (Wang, 8). Experiments in the laboratory have demonstrated the efficiency of CO2 capture under various weather and wind conditions, which are often more extreme in remote locations. Extreme conditions are of interest, for example, because high wing speeds can provide an important renewable energy resource that is available using current technology. Goldberg (9) suggests co–‐location of these technologies to allow for CO2 air capture and geological sequestration at sites where renewable energy resources (e.g. wind) are large and sufficient to power and sustain both activities (Figure 1). Estimates of 50 TWh or more of electrical energy output annually from wind could translate into a production of 75 Mt CO2 or more per year by direct air capture. Possible locations with large wind resources and potential basalt reservoirs include Iceland and Greenland, the Kerguelen plateau in the south Indian Ocean, Siberia and Morocco. Basalt reservoirs in these regions could sequester a large fraction of 21st century CO2 emissions, and potentially, provide sufficient sequestration capacity or the reduction of atmospheric carbon to preindustrial levels. Mobilizing the industrial infrastructure in these areas would be costly, however. Using he available wind energy resource at a site in combination with CO2 air capture also enables synfuel production from the CO2 feedstock using electrolysis and Fischer–‐Tropsch processes. An additional and practical benefit of evaluating substitute synfuels is that it puts forward a means of establishing a price for the combined technologies at a given site, helping to identify locations where implementation could be economical. The reduction of atmospheric CO2 concentrations by co–‐location of ambient air capture and CO2 sequestration in remote locations presents a powerful tool for carbon management. Renewable wind resources would provide power for an energetically sustainable CO2 collection/sequestration point at remote locations. To help launch evaluation of potential sites and begin economic assessment of scaling up these new technologies over the long term, implementation of global carbon management strategies through collective regulation by inter–‐ governmental agencies, public–‐private partnerships, and energy, resource, environmental experts will be needed. Considering a global CO2 management approach such as this will require considerable investment and long–‐term commitments to scientific research, engineering development, and new regulatory policy. 1 Intergovernmental Panel on Climate Change (2005) Special report on carbon dioxide capture and storage, Prepared by Working Group III of the IPCC, Metz B, Davidson O, DeConinck HC, Loos M, Meyer LA (Eds.), Cambridge Univ.Press,UK,NewYork, pp. 442. 2 Coffin MF,EldholmO(1994) Large Igneous Provinces – Crustal structure, dimensions, and external consequences, Rev. Geophys.32, 1, 1–‐36. 3 Oelkers EH, Gislason SR, Matter JM (2008) Mineral carbonation of CO2, Elements 4, 333–337. 4 McGrail BP, Schaef HT, Ho AM, Chien Y–‐J, Dooley JJ, Davidson CL(2006) Potential for carbon dioxide sequestration in flood basalts. J. Geophys. Res.111, B12201 doi:10.1029/2005JB004169. 5 Goldberg DS, Takahashi T, Slagle AL (2008) Carbon dioxide sequestration in deep–‐ ea basalt, Proc. Nat. Acad. Sci. USA 105, 29, 9920–‐9925. 6 Yarushina YM, Bercovici D (2013) Mineral carbon sequestration and induced seismicity, Geophys. Res. Lett. 40 (1–5), doi:10.1002/grl.50196. 7 Lackner KS (2009) Capture of carbon dioxide from ambient air, Eur Phys J Special Topics 176,93-106. 8 Wang T, Lackner KS, Wright A (2011) Moisture swing sorbent for carbon dioxide capture from ambient air, Environ. Sci. Technol. 45 (15), 6670–‐75; doi: 10.1021/es201180v. 9 Goldberg DS, Lackner KS, Han P, Slagle AL, Wang T (2013) Co–‐location of air capture, sub–‐ocean CO2 sequestration, and energy production on the Kerguelen plateau, Environ. Sci. & Tech., 47(13), 7521–‐7529, doi:10.1021/es401531y. Figure 1. Schematic of potential wind energy resource use, CO2 capture, sequestration and synfuel production. With ∼50 TWh/year from wind energy, 75 Mt of CO2 or more could be sequestered in basalt reservoirs or produce ∼750 million gal of diesel fuel annually using electrolysis and Fischer−Tropsch processes. Figure from (Goldberg, 9).
+ Ad and Desortion CO2, Marco Holzer, Andreas Züttel
Abstract: CO2 may be harvested via ad- and desorption from a solid sorbent. Conventional CO2 desorption is realized by increasing the temperature of the sorbent and/or lowering the partial pressure of the adsorbate. Alternatively, the sorbent may be purged with hot H2 gas resulting in a mixture of CO2 and H2, a precursor for Syngas. Desorption is enhanced by convective heat and mass transport, leading to faster and more efficient regeneration and thus higher productivity. The schematic process is presented.
+ Tagging Carbon Dioxide to Enable Quantitative Inventories of Geological Carbon Storage, Yinghuang Ji
Abstract: This US Department of Energy award project works on developing a tracer technology, which tags carbon dioxide with carbon-14 at atmospheric level before being injected underground for geological storage. Since reservoirs below 800 meters in depth are practically carbon-14 free, carbon-14 is an extremely sensitive tag for anthropogenic carbon. The quantitative inventories can help to gain public trust and confidence in safe and permanent geological carbon dioxide storage, therefore, are important in risk assessments of large-scale CCUS projects. Our system includes a filling station to make the carbon-14 supply units, an injection system to evaluate the tracer injecting and mixing, and a detection system to enable the carbon-14 counting. In order to demonstrate the effectiveness and accuracy of this technology, we conducted both laboratory-scale evaluation and field test in Carbfix carbon sequestration site in Iceland.
The poster will consist of four sections. Section 1 gives the introduction and background of this project. Sections 2-4 give quantitative results we achieved in each part of this project; errors between expected and experimental values will be provided.
1. Online 14CO2 monitoring in geological carbon storage
This part contains background in geological carbon storage; the need of monitoring, verification and accounting; the reason why carbon-14 tracer is good for this purpose; and one diagram to illustrate the concept of online 14CO2 monitoring in geological carbon storage.
2. Filling Station to generate 14CO2 tracer supply units
This part contains one diagram of membrane system to illustrate the its design; photos of 14CO2 tracer loops and membrane system; and one graph of test results to present the characterization of membrane system, i.e. CO2 concentrations achieved in tracer solutions made at different set temperatures.
3. Injection System to conduct laboratory-scale evaluation
This part contains one photo of high-pressure flow loop to illustrate its design and functions; two graphs of test results from SF6 tracer injection and 14CO2 tracer injection into supercritical CO2, respectively.
4. Field Test in Carbfix carbon sequestration site in Iceland
This part contains several photos to describe Carbfix site and our setup for injecting and sampling during our field test.
+ Practical Supported Amine Adsorbent Materials for CO2 Capture from Air
Watcharop Chaikittisilp, Sumit Bali, Miles Sakwa-Novak, Stephanie A. Didas, Hyung-Ju Kim, Thomas Chen and Christopher W. Jones*
Sumit Bali – email@example.com
Miles Sakwa-Novak – firstname.lastname@example.org
Stephanie Didas – email@example.com
Hyung Ju Kim – HyungJu.Kim@chbe.gatech.edu
Thomas Chen – firstname.lastname@example.org
Christopher Jones – email@example.com
School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332, United States
Solid supported amine materials have been shown to be a promising class of adsorbents for the removal of CO2 both from dilute streams similar to flue gas, as well as ultra-dilute streams such as air. In the context of air capture, our group, in collaboration with Global Thermostat LLC, has identified steam stripping as a potentially practical regeneration method for these materials. However, the stability of the materials to the conditions imposed by such a process will impact the potential for large scale deployment. Thus, our group has focused on developing a fundamental understanding of such degradation processes in order to engineer more stable materials. Additionally, the development of scalable preparation methods for amine incorporation into practical sorbent contactors, such as monoliths or hollow fibers, is an additional barrier to commercialization. As such, we have also been interested in novel functionalization techniques. Here, we provide an overview on our recent work on these topics. Highlighted will be specific work in 3 areas:
i. Development of a novel procedure for the in-situ polymerization of polymeric amines on several potentially steam stable support materials, based on monomer transport in the vapor phase.
ii. Investigation of steam induced structural changes to sorbents prepared with both mesoporous silica and -alumina as amine supports.
iii. Investigation of oxidative degradation to -alumina supported amine sorbents.
In section (i) we describe the preparation of supported amine sorbents based on the in-situ polymerization of polymeric amines on several potentially steam stable supports based on the vapor phase transport of the reactive amine containing monomer. Post-synthetically aluminated SBA-15 mesoporous silica and mesoporous -alumina were contacted in the vapor phase by two reactive amine containing monomers, aziridine and azetidine, resulting in the surface grafting and in-situ polymerization of the monomers in the porous supports. It is demonstrated that surface acidity of the porous support plays a large role in the extent of polymer surface grafting. Finally, comparisons are drawn to the conventional liquid phase preparation method.
In section (ii) we show that extended steam treatment causes structural changes to sorbents using both mesoporous silica and mesoporous alumina as amine supports, but that the changes induced on silica cause much a severe loss in CO2 capacity, whereas for alumina the materials are more stable. A detailed investigation of -alumina sorbents exposed to steam for various times revealed that the -alumina partially hydrates to a hydrated mineral phase, boehmite. Evidence is provided that this change in the crystal phase does not directly impact the CO2 capacity of the material under simulated air capture conditions.
In section (iii) we show that extended oxygen exposure at temperatures above 70 oC causes significant degradation to poly(ethyleneimine) supported on mesoporous -alumina. However, when poly(allylamine), an all primary amine containing polymer, was used, the oxidative degradation was significantly reduced. This further asserts the importance of the development of such primary amine containing polymers.
+ Post-Combustion CO2 Capture using Polymer Supported Amine Hollow Fibers in Rapid Temperature Swing Adsorption
Christopher W. Jones,* William J. Koros, Yoshiaki Kawajiri, Matthew J. Realff, Ryan P. Lively, David S. Sholl, Fateme Rezaei, Yanfang Fan, Ying Labreche, Swernath Subramanian, Grace Chen
Christopher W. Jones – firstname.lastname@example.org
William J. Koros – email@example.com
Yoshiaki Kawajiri – firstname.lastname@example.org
Matthew J. Realff – email@example.com
Ryan P. Lively – firstname.lastname@example.org
David S. Sholl – email@example.com
Fateme Rezaei – firstname.lastname@example.org
Yanfang Fan – email@example.com
Ying Labreche – firstname.lastname@example.org
Swernath Subramanian – email@example.com
Grace Chen – firstname.lastname@example.org
School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia 30332, United States
The use of novel polymeric hollow fiber contactors loaded with CO2 adsorbents has been recently demonstrated as a new and scalable process configuration for post-combustion CO2 capture. The hollow fiber morphology allows coupling of efficient heat transfer with effective gas contacting, potentially giving lower parasitic loads on the power plant compared to traditional contacting strategies using solid sorbents. The focus of this study is the development of a process based on hybrid amine-functionalized – polymeric hollow fibers for use as contactors in a rapid temperature swing adsorption (RTSA) carbon dioxide capture process. In particular, poly(ethyleneimine) (PEI) was infused into cellulose acetate/mesoporous silica hollow fiber sorbents using a novel post-fiber-spinning amine-infusion technique. When exposed to a humid flue gas containing 14% CO2 with 100% RH at 35 °C, the first generation hollow fiber sorbents showed the CO2 breakthrough capacity of 1.16 mmol/g upon the removal of the heat of adsorption by flowing cooling water in the bores of the fiber sorbents. The CO2 adsorption and desorption rates were found to be very rapid, with CO2 breakthrough occurring in less than 72 s and the majority of the adsorbed CO2 desorbing in 5 min. Extensive cycling studies demonstrated that the amine-based hollow fiber sorbents have the good dynamic swing capacities, stabilizing over 60 cycles. In addition, numerical modeling of the hollow fiber RTSA system was performed and validated against experimental breakthrough profiles. A good agreement was found between experimental and numerical data indicating that our proposed model can describe experimental observation very well. The numerical results obtained from RTSA cycle modeling indicate that under operating conditions considered here, it is possible to achieve high purity and recovery within a cycle time of shorter than 3 min.
+ CO₂ as an asset – Potentials and Challenges for Society An assessment of the policy and business framework of CCU technologies in Germany and its possible societal benefits H. Naims, B. Olfe-Kraeutlein
1. Introduction – Carbon Capture and Utilization (CCU) in Germany
For some time already, German universities and research centers have been working on transforming CO2 into valuable substances such as fuels or carbon based materials of the chemical industry. While many projects are still in a research and development phase, first breakthroughs have been achieved and a CO2-based production at an industrial level can become a reality soon. Moreover, the utilization of CO₂ could soon contribute to reducing prospective CO₂ emissions and fulfilling Germany’s policy targets on emission reductions.
Currently, despite the rising significance of renewable energy, Germany’s highly developed industrial and energy sectors are still strongly dependent on fossil sources of carbon. Since Germany is lacking sufficient own fossil reservoirs there is a high regional interest in exploring alternative carbon sources for the future. Consequently, the German government has taken a favorable and supportive position towards the CCU research field and has invested a total of 100 million Euro (approximately 137m USD) between 2010 and 2016. In the program’s 33 collaborative research projects, overall an additional 50 million Euro (approximately 68,5m USD) were invested through the industry. Traditionally, the chemical and automotive industries play a strong role in the German economy. In order to lower dependencies from volatile resource markets and meet climate protection expectations
the industry is increasingly investigating their CCU options. Due to the industry’s motivation and the government’s supportive role the future development of CCU technologies in the region seems very promising.
2. The Institute for Advanced Sustainability Studies (IASS) at a glance The Institute for Advanced Sustainability Studies (IASS) is a new and unique type of institute in Germany, combining the characteristics of a research institute and a think tank. It was founded on the basis of the Potsdam Memorandum of the 2007 Nobel Laureate Symposium “Sustainability – A Nobel Cause”. Conceptualized as an advanced study institute for sustainability research, the IASS provides an open and encouraging space to think in novel ways and address niche or taboo topics. By providing an infrastructure for inter- and transdisciplinary research, the IASS addresses the challenges
of a society transitioning towards global sustainability.
The institute’s objective is to scope out critical aspects of the challenges faced by societies today and in the future, and to envision, assess, and support implementation of transition pathways to help solve these challenges. In order to achieve this, the IASS approach involves convening researchers from a broad range of disciplines together with stakeholders from all sectors of society, to co-generate knowledge and co-develop transition pathways together (see figure 1). Accordingly, the research on CCU is rooted in academic science but conducted according to the transdisciplinary approach of the IASS. Therefore, societal stakeholders outside academia are engaged throughout the project in order to foster transformative societal action towards sustainability.
3. Research on CCU at the IASS The perspective of CO₂ utilization bears an important ecological and economic potential. Beside the availability of specific technologies, more general knowledge needs to be generated. Especially transdisciplinary research projects need to accompany the ongoing development of technologies and
products to make sure that society will fully benefit from the sustainability potential of CCU.
Consequently, the interdisciplinary research teams of the IASS address a multitude of research questions along the entire chain of knowledge generation (see figure 2).
The project “Recovery of CO₂ for the production of methanol“ of the cluster Earth, Energy and Environment (E3) focuses on the assessment of the catalytic conversion of captured CO2 to methanol, examining and the potential of existing industrial, state-of-the-art and future technology as well the associated economics and energy demands considering at each process step. Furthermore, in the project “Environmental side effects of CO₂ separation technologies” of the cluster Sustainable Interactions with the Atmosphere (SIWA) possible environmental side effects of CO2 separation technologies on a large scale which are not covered by the existing environmental characterization methods are analyzed. Finally, the project “CO₂ as an asset” of the platform Enabling Technologies for Sustainability (ETS) assesses how an implementation of different CO₂ utilization technologies could affect the three pillars of sustainability economy, environment and society.
4. Project “CO₂ as an asset – potentials and challenges for society”
The project was set up with an interdisciplinary team in February 2013 in partnership with the University RWTH Aachen and the company Bayer Material Science. It aims at drafting a comprehensive value chain of CO₂ and evaluating the technologies’ benefits and risks for society as well as their possible contribution to a circular economy in three sub-projects:
a. Sub-project Ecology
Focusing on the evaluation of the impact of CCU technologies on carbon emissions, the life cycle analysis of CO₂ utilization processes and products is assessed and developed in comparison to conventional products. This sub- project is conducted in close cooperation with the university RWTH Aachen. Its specific aims are to identify and classify possible CO2 based products, develop a general LCA methodology, perform an LCA of the project case studies and to extend LCA by integrating market effects and improving the LCA result communication.
b. Sub-project Economy
This sub-project aims to evaluate the economic potential of CO₂ utilization technologies and their impacts on industries and value chains in the German and European economy. First, the current economic state of existing and emerging technologies for an industrial CO2 utilization is determined.
Then, a scenario evaluation of the market potential of CO₂ utilization technologies will be designed and implemented on a case study basis for the German and European economy.
c. Sub-project Communication
Once a reality, a successful implementation of innovative technologies is often inhibited by their perception. This could for example be caused by a lack of information or trust in the available information, but also by a distribution of “pseudo knowledge” or other emotional obstacles. In the case of CO2 utilization technologies, this effect could even be reinforced because with the greenhouse gas CO₂, a potentially “harmful” substance is involved. Furthermore, the association of CCU technologies with Carbon Capture and Storage (CCS) needs to be considered in particular since CCS experienced a strong public rejection in Germany. Main targets of the sub-project are the analysis of challenges and obstacles in the communication of CO₂ utilization and the development of communication strategies to enhance the acceptance of CO₂ utilization technologies and products
among different stakeholder groups.
5. Contents of the poster
During the Annual Meeting of the NSF Research Coordination Network CCUS, the authors intend to
present the following on a poster related to topic 7 – business and policy:
Firstly, the key questions that are addressed by the IASS project “CO₂ as an asset – potentials and challenges for society” and a brief project overview (see no. 4) will be presented (box no. 1). Following, the focus of the poster will be on the assessment of the policy and business framework of CCU technologies in Germany and its possible societal benefits. Accordingly, the current business and policy framework in Germany in regard to CCU technologies will be illustrated by a SWOT analysis (box no.2).
An overview on the basic concept of CO2 utilization will be presented by the graphical representation of the industrial CO2 cycle (sources, utilization, end of life) that was developed in the IASS project for the German public (see fig. 3).
Moreover, selected results of the subprojects Economy and Communication will be presented in two further representations. Concerning communication (box no. 3), statements regarding CCU in the media and obstacles in communicating CCU will be made and first steps for a strategic communication for CCU will be proposed in order to “get the message through”. For the economic perspective (box no. 4), the current state of CCU technologies in industrial applications will be represented. Moreover some economic case study illustrations of the envisaged utilization of CO2 in the production of polyurethanes will be presented.
+Power to Liquid and Power to Gas technologies: an option
for the German Energiewende.
The Integrated Energy and Climate Programme of the German Federal Government
gives the right impetus to climate policy in the upcoming decades. The German
Government has declared that it adheres to the European target of a GHG emissions
reduction of 40% by 2020 and of 80-95% by 2050. The share of power from renewable energy sources shall reach at least 35% by 2020 and 80% by 2050.
Recent Reports from German AgenciesI shows that both electricity supply system based completely on renewable energies and future greenhouse gas reduction in Germany by 2050 are technically as well as ecologically feasible. These studies are mainly based on three main premises:
No use of fossil or nuclear energy carriers
No cultivation of biomass crops for energy purposes
No CCS (Carbon Capture and Storage)
In this context, synthetic fuels such as methanol (CH3OH), dimethyl ether (DME), methane (CH4) and liquid hydrocarbons are being promoted as substitute final energy carriers and raw materials that could help cut CO2 emissions while satisfying the energy demand. Indeed, these fuels can be produced using renewable inputs: green electrical power from perennial energy sources (wind, solar, etc.) and carbon from biomass or captured CO2. These factors, as well as the inherent proprieties oF methanol, have led Nobel Laureate George A. Olah to develop the
concept of the “Methanol Economy®” as a more practical alternative to, for instance,
a “Hydrogen Economy” II . The use of hydrogen (H2) as final energy carrier is interesting because of its clean combustion, but in practice the storage, transport and distribution of H2 raises many technological and safety concerns (e.g. it is a highly explosive gas), while the cost of transforming the whole energy infrastructure is likely to prove economically prohibitive.
Due to the most recent development in the sector of H2O and CO2 reduction via electrolysis – with a sensible growth of the process efficiency and the improvement of material durability and robustness – the process of transforming the electric power in liquid – or gaseous – form, indicates the PtL and PtG (Power to Liquid and Power to Gas) technologies as an important player in the future energetic scenarios.
Moreover, synthetically produced fuels can represent a convenient storage media for surplus power from renewable energy sources (RES), thereby buffering their natural intermittency and alleviating one of the major constraints to large scale RES deployment. Based on PtL and PtG schemes all components of the final energy mix – electricity, liquid and gaseous fuels, feedstocks – can be successfully covered whilst greatly reducing CO2 emissions. In this framework a sensible increment of RE power production could lead to a scenario where the quasi-total energetic supply of a country could be covered from renewable resources.
In fact, if the total electric load could be theoretically covered from RE generated electric power (RES-E) the remaining leftover part of energy consumption, that inevitably cannot be covered by the electric production, must be satisfied by the PtL and PtG fuels production.
The aim of this work is to is to raw quantifying a pathway for a German energy system for 2050, moving towards a strong enhancement of the renewable installed power – mainly wind and PV – coupled with the PtL and PtG technologies for the ”sustainable” recycled fuel production.
For this purpose, has been set-up a simple numerical model – based on official German electric load and renewable energy production data – and able to produce qualitative forecast of the future energetic scenarios. In the extreme scenario, where we are supposed to be able to indefinitely increase the installed renewable power without technical, geographical and political
constraints, RES-E should cover almost entirely the national electric load, while the huge residual load would drive the electro-catalytic processes for converting the power to fluid energy carriers.
In a more realistic scenarios, the gradual increase of installed renewable power is supposed to be shared amongst an instantaneous use, finalized to meet the network load, and the conversion via Ptl and Ptg technologies to a storable energy carrier, to be used for industrial applications, in the transportation sector, or to be eventually converted again into electricity by exploiting the reversibility of electrolyte systems.
Energy target 2050: 100 % renewable electricity supply, UBA (2010),
Germany 2050 – A Greenhouse Gas-Neutral Country, UBA (2013)
Wege zur 100% erneuerbaren Stromversorgung. Sondergutachten, SRU(2011).
Energiesystem Deutschland 2050, Frauhnofer Institut für Solare Esergiesysteme ISE.
George A. Olah, Alain Goeppert, G. K. Surya Prakash, Beyond Oil and Gas: The Methanol
Economy, Wiley-VCH, 2009.
+ Adsorption Isotherm Measurements of Gas Shales for Subsurface Temperature and Pressure Conditions
Authors: Beibei Wang, Reza Haghpanah, Hassan Aljama, Jennifer Wilcox*
Address: 367 Panama Street, 065, Stanford, CA 94305
The global atmospheric carbon dioxide concentration, primarily related to fossil fuel combustion, has increased significantly compared to pre-indsutrial levels, resulting in a rise in the global average temperature. To stabilize the atmospheric CO2 concentration, one possible approach is to inject and store CO2 into gas shale, where significant amounts of methane are present and can be exploited and recovered. Experimental studies indicate that CO2 has a stronger likelihood of being adsorbed over CH4, thus the injected CO2 may displace the adsorbed methane inside the gas shale, thereby potentially enhancing methane recovery efficiency. However, the adsorption properties of CO2 and methane on gas shale are not fully understood, and need to be investigated both experimentally and theoretically.
In our recent work, the excess adsorption isotherms of CO2 and CH4 on gas shale samples have been measured under subsurface temperature condition, using a Rubotherm magnetic suspension balance. The samples used in this study are from the Eagle Ford reservoir and Barnett formations. Both core chip and powdered forms of sample have been investigated. According to our preliminary results, the shale sample in powder form gives higher gas capacity than the same sample in chip form. Reduced macropore mass-transfer resistance and more accesible pore space in the powdered sample are possible explanations for its higher gas capacity.
Since kerogen and clay are the major constituents that contribute to the adsorption behavior in gas shale, adsorption isotherm measurements for isolated kerogen and illite (used as reference clay) are performed to determine the roles that each component plays in the overall shale adsorption mechanism and capacity estimates.
In addition, Grand Canonical Monte Carlo has been used to study the adsorption behavior of carbon-based materials with different pore sizes and functional groups. Results from simulation and experiment are compared to further investigate the adsorption properties of gas shale and to predict the adsorbed phase densities as a function of temperature, pressure, and pore size.
+ Adhesion of CO2 on hydrated mineral surfaces and its implications to geologic carbon sequestration
Shibo Wang1,2, Zhiyuan Tao2, Sara M. Persily2, Andres F. Clarens2
Lawrence Berkeley National Laboratory, Berkeley
1 Cyclotron Road, Berkeley, CA, 94720
2Civil and Environmental Engineering
351 McCormick Road, Thornton Hall
University of Virginia, Charlottesville, VA, 22904
Most mineral surfaces are water wetting, which has important implications for the transport of non-aqueous phase liquids, such as CO2, through porous media. In this work, contact angle experiments were carried out wherein unusual wetting behavior was observed between mineral surfaces and liquid or supercritical CO2 under certain geochemical conditions. This behavior can be understood in the context of adhesion between the CO2 and the mineral surface. When adhesion occurs, the wettability characteristics of the surfaces are significantly altered. More importantly, the CO2 exhibits a strong affinity for the surface and is highly resistant to shear forces in the aqueous phase. A static pendant drop method was used on a variety of polished mineral surfaces to measure contact angles. The composition of the aqueous phase (e.g., pH, ionic strength) and the characteristics of the mineral surface (e.g., composition, roughness), were evaluated to understand their impact on the prevalence of adhesion. Pressure and temperature conditions were selected to represent those that would be prevalent in geologic carbon sequestration (GCS) or during leakage from target repositories.
Adhesion was widely observed on phlogopite mica, silica, and calcite surfaces with roughness on the order of ~10 nanometers. CO2 exhibited little adhesion on mineral surfaces with higher roughness (e.g., quartz). On smoother surfaces, the CO2 is thought to have more contact area with the mineral, enabling the weak van der Waals forces that drive most adhesion processes. Brine chemistry also had an important role in controlling CO2 adhesion. Increases in CO2 partial pressure and ionic strength both increased the incidence of adhesion. The addition of strong acid or strong base permanently inhibited the development of adhesion. These results suggest that the development of adhesion between the CO2 and the mineral surface is dependent on the integrity and thickness of the hydration layer between the CO2 and the mineral. N2 control experiments were carried out under the same pressure and temperature conditions and adhesion was also observed. The wettability hysteresis phenomena were quantified under adhesion
conditions by means of advancing/receding contact angle measurements. The experimental results indicated that adhesion could cause an increase in the contact angle by a factor of three.
These results support an emerging understanding of adhesion of nonpolar non-aqueous phase fluids on mineral surfaces influenced by the relative thickness of the electrical double layer of the hydration layer between CO2 or N2 and the mineral surface. These findings could have important implications in certain geological formations for estimating residual trapping, capillary entry pressure, and a number of other processes that are strongly dependent on the wetting behavior of mineral surfaces.
Keywords: geologic carbon sequestration, CO2 adhesion, hydration layer, wettability alteration and hysteresis, aqueous chemistry, surface roughness
+ Sustainable Iron Making Technology Integrated with Carbon Capture, Utilization and Storage Xiaozhou Helios Zhou
A number of commercial fluidization processes such as FINEX® iron making technology involve binary or quaternary particulate systems with different particle sizes and densities. During the operation of multiphase systems such as fluidized beds, electrostatic charges are generated primarily via triboelectric or frictional charging due to the dielectric nature of the materials. The accumulation of electrostatic charge within the system can impact the fluidization behavior and in some cases can be operationally hazardous. In this study, the electrostatic charge generation and accumulation are investigated for binary and quaternary particulate systems using a faraday cup system and an on-line electrostatic probe system. Specifically, the effect of addition of two different fine iron ores (i.e., hematite and magnetite) in fluidized beds is studied in terms of particle-particle interactions and entrainment rates. The behaviors of different particulate systems are found to highly depend on the chemical and physical properties of particles such as size, density, hydrophobicity, surface roughness and even magnetism. The results suggest that the enhanced electrostatic forces between fine and coarse particles due to significant electrostatic charging phenomenon during fluidized bed operation can retain the fines to some extent.
Limestone and dolomite are utilized as flux materials during iron and steel making. Calcined limestone and dolomite (CaO or MgO) are bonded with SiO2 and ended up as slag in order to remove the impurities from the molten iron. Iron and steel slag have been used as cement raw material, road construction material or fertilizer, however, not all of them could be reused since the environmental concern of heavy metals (i.e., Cr) contained in some kinds of slag. Recently, iron/steel slags have been thought as one of the alternative for carbon sequestration considering that 30~60 wt% of the slag are CaO and MgO in total. Therefore this study assesses two options of treating the slag in terms of its overall carbon footprint: recycle the slag as flux material internally vs. convert the slag into environmentally benign cementitious material. CaO and SiO2 can form calcium silicate in various crystal structures with different Ca/Si ratio thus conditions of forming differed calcium silicate have been evaluated in order to investigate the maximum loading of SiO2 onto CaO which will help explore the potential of recycling the slag during iron and steel making. On the other hand, cement making is mixing crushed stone and calcined limestone with other additives such as aluminum silicate which is also a large CO2 emitting industry. Converting the slags into quality assured cement material could save the carbon emission from burning equivalent amount of limestone. Compressive, flexural and leaching tests have been conducted for the slag-based cementitious material in order to evaluate its mechanical propeties and environmental safety.