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AbstractThis paper presents the experimental plans and designs as well as examples of predictive modeling of a pilot-scale CO2 injection experiment at the Heletz site (Israel). The overall objective of the experiment is to find optimal ways to characterize CO2 -relevant in-situ medium properties, including field-scale residual and dissolution trapping, to explore ways of characterizing heterogeneity through joint analysis of different types of data, and to detect leakage. The experiment will involve two wells, an injection well and a monitoring well. Prior to the actual CO2 injection, hydraulic, thermal and tracer tests will be carried out for standard site characterization. The actual CO2 injection experiments will include (i) a single well injection-withdrawal experiment, with the main objective to estimate in-situ residual trapping and (ii) a two-well injection-withdrawal test with injection of CO2 in a dipole mode (injection of CO2 in one well with simultaneous withdrawal of water in the monitoring well), with the objective to understand the CO2 transport in heterogeneous geology as well as the associated dissolution and residual trapping. Tracers will be introduced in both experiments to further aid in detecting the development of the phase composition during CO2 transport. Geophysical monitoring will also be implemented. By means of modeling, different experimental sequences and injection/withdrawal patterns have been analyzed, as have parameter uncertainties. The objectives have been to (i) evaluate key aspects of the experimental design, (ii) to identify key parameters affecting the fate of the CO2 and (iii) to evaluate the relationships between measurable quantities and parameters of interest.

AbstractWe measured dissolved inorganic carbon (DIC) stable isotopes (813CDIC in ‰) of brine from an observation well within the first aquifer above the CO2 reservoir at the Ketzin pilot site, to test weather these can detect potential CO2 leakage. The monitoring revealed that DIC concentrations and 813CDIC values were masked by the used high alkaline drilling mud, even eight months after well development. However, subsequent changes in 813CDIC and DIC from of -27 ‰ and 165mg L−1 to -23.5 ‰ and 116mg L−1 reflect most likely a shift towards pristine values of the aquifer.

Abstract The complete cycle of specific processes related to the geological storage of CO 2 is investigated in detail at Ketzin since 2004. The scientific monitoring program targets different depths of the involved area and addresses the safety and reliability of the storage. The surface monitoring comprises long-term soil CO 2 flux measurements and soil gas analyses. Annual mean values of soil CO 2 fluxes ranged from 2.4 to 3.4 µmol m -2 s -1 before the injection started (2005-2008) and from 2.3 to 3.5 µmol m -2 s -1 during and after CO 2 injection (2009-2016) and thus do not indicate an upward migration of the injected CO 2 .

AbstractA high-pressure/high-temperature reactor has been used to lead PVT and H2-solubility experiments in saline solutions covering conditions for which no data are available in literature: salinity up to halite concentration, pressure up to 200bar and temperature up to 373K. The hereby presented preliminary results show significant deviations from theoretical models. Further analysis and more measurements are needed to assess precision and reproducibility of these measurements; however they pinpoint the importance of experimental work to reliably constrain predictive models.

AbstractFly ash entering a CO2 capture plant in the incoming coal-fired flue gas is a potential source of metals which support as catalysts the formation of degradation products in the MEA solvent. This study presents an assessment of the accumulation of absorbed particulate matter and an evaluation of the impact on the CC process. The particulate matter which is absorbed inside the CC plant and the ratio of flue gas flow to the installed liquid inventory determine the rate of accumulation. Filtration or settlement of particulate matter inside the process does not avoid leaching. The results of one ash sample from an European power station are presented leached with fresh 30 wt% lean MEA at different ratios (1:10 to 1:2000g/g, ash/solvent) The results show that mobility of the trace elements Cu, V, Mn increases significantly to lower ash concentrations compared to the Fe mobility values. Dissolved Fe concentrations of 0.5-1.0mg/L derive from leached fly ash after approximately 500hours of operation provided that 1mg/m3 is absorbed and a high ratio of flue gas flow to liquid inventory is installed. Small dissolved Fe concentrations might still trigger the formation of degradation products.

AbstractThe migration of CO2 stored in deep saline aquifers depends on the morphology of the top of the aquifer. Topographical highs, such as anticlines, may trap CO2 and limit the distance migrated, or elevated ridges may provide pathways enabling CO2 to migrate further from the injector. For example, seismic data of the Utsira formation at the Sleipner storage site indicates that a branch of the CO2 plume is moving to the north [1]. It is therefore important to study the interface between the aquifer and the caprock when assessing risk as CO2 storage sites.Undulations in the top surface of an aquifer may either be caused by sedimentary structures [2], or by folding. In addition, irregularities may be generated by faulting [2]. Large-scale features are detected using seismic data (i.e. structures with amplitudes greater than 10 m), and such structures will generally be included in reservoir or aquifer models. However, smaller- scale features could also have an effect on a CO2 plume migration, and this is the topic of our study. We have conducted simulations in models with a range of top-surface morphology, and have examined the distance migrated and the amount of dissolution.The results from this study suggest that the effects of sub-seismic variations in the topography of the aquifer/caprock interface are unlikely to have a significant impact on the migration and dissolution of CO2 in a saline aquifer, compared with tilt or permeability anisotropy. The results were most sensitive to the kv/kh ratio during the injection period.

Abstract In binary geothermal power plants based on the Organic Rankine Cycle (ORC) typically shell-and-tube heat exchangers are used as evaporators. In the shell-side, nucleate boiling of the working fluid takes place on the outer surface of the tubes. For the replacement of fluids with high global warming potential (GWP) or selection of efficient working fluids, a comprehensive evaluation has to be performed. Therefore, the knowledge about the nucleate boiling heat transfer coefficient (HTC) in combination with the electrical power output is necessary. In this study, the focus is led on the investigation of the replacement of R245fa by the low GWP fluid R1233zd(E) in geothermal applications. The nucleate boiling HTC on a horizontal tube and the electrical power of a 1 kW scroll expander are simultaneously measured with an ORC test rig for both fluids. The thermal input is provided by an electrically heated preheater and evaporator. Nucleate boiling takes place on a plain copper tube with an outer diameter of 32 mm and a heated length of 822 mm. The surface temperature of the copper tube is determined by thermocouples within the tube in consideration of thermal conduction. The obtained results, regarding power output as well as heat transfer characteristics, show that the working fluid R245fa performs better at equal saturation temperatures due to the higher density and pressure, and the lower viscosity. The HTC of R245fa is exemplarily up to 43.2 % increased in comparison to R1233zd(E).

AbstractThe tail gas from the barley straw to transport liquid production processes contains light hydrocarbons, N2, CO2, H2, and CO. It could combust as the fuel in the utility system for steam and power generation. Another tail gas treatment method is tail gas recovery to recycle H2 and CO back to the production process for more liquids production. In this work, four tail gas treatment scenarios are investigated to address quantitative correlation among H2 and CO recovery, product outputs, utility fuel selection, utility system performance, and CO2 emission. The production processes and utility systems are optimized simultaneously to reach the optimal production and utility system operation. From the research results, tail gas recovery by reforming would lead to the optimal economic performance for the whole process site system. However, the tail gas combustion as fuel in the utility plant can achieve a similar economic profit, but reduce CO2 emission about 20%.