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Isotopic Tracers for CO 2 Produced During A Planetary Impact Into Limestone Target Rocks

Terrestrial meteorite impacts have been directly linked with multiple mass extinction events throughout Earth’s history. Among these impacts, those that land in sedimentary target rocks are thought to generate large quantities of CO 2 via decarbonation. This injection of CO 2 into the atmosphere has the potential to alter the climate and threaten terrestrial habitability. The magnitude of this change depends upon the net amount of CO 2 released, which is controlled by how much CO 2 is produced by the impact, how much CO 2 is removed by back-reactions after the impact, and other post-impact CO 2 sinks. To interrogate the behavior of CO 2 release into the impact atmosphere, we present carbon (δ 13 C), oxygen (δ 18 O), and clumped (Δ 47 ) isotope results from carbonate clasts preserved within the impact breccia of the Steen River Impact Structure (SRIS) in Alberta, Canada. These clasts exhibit a ~65‰ range in δ 13 C and a ~5‰ variation in δ 18 O. However, while δ 13 C and δ 18 O are positively correlated, Δ 47 unexpectedly has a negative relationship with δ 13 C and δ 18 O. Based on prior assumptions, there would either be (1) no relationship with carbonate Δ 47 and the bulk ratios because Δ 47 would be reset at extreme impact temperatures, or (2) Δ 47 would have a positive correlation with the bulk ratios, reflecting gradual Δ 47 ‘resetting.’ To reconcile the SRIS result with these expectations, we conducted a series of in vacuo heating experiments at temperatures above calcite decomposition. As predicted by Rayleigh fractionation, these heating experiments generated depletions in δ 13 C and δ 18 O that increased with reaction time. Mimicking the SRIS results, these experiments also produced concomitant increases in Δ 47 . Using an adaptation of a mechanistic model for decomposition fractionation (Hayles & Killingsworth, 2022) we hypothesize that these exotic isotope trends are caused by Rayleigh fractionation and a Δ 47 kinetic isotope effect that results from the disproportionation of O to CaO and CO 2 during thermal decomposition. This high Δ 47 CO 2 subsequently exchanges with the residual CaCO 3 . This work highlights a potential pathway for identifying and quantifying CO 2 generation by impacts and builds on the relatively limited literature characterizing the behavior of carbonate clumped isotopes at very high geologic temperatures.

Multi-isotope systems↗

DOE OSTI2023

Microwave resonance enhanced CO 2 reduction using biochar

The conventional process for CO 2 conversion requires high energy and expensive catalysts, and shows poor product selectivity. Here, in this study, we address these challenges by investigating an environmentally friendly method for CO production through the variable frequency microwave-driven CO 2 Boudouard reaction over biochar. We hypothesized that tuning the microwave frequency to align with the dielectric properties of biochar, and thereby induce a resonance effect, could significantly enhance reaction efficiency. Experiments were conducted to explore the effect of microwave frequency on CO 2 conversion efficiency in the variable frequency microwave reactor operating within a frequency range of 2430–6000 MHz. Results reveal a significant resonance effect at 4225 MHz resulting in an outstanding CO 2 conversion of 96.3%, in sharp contrast to the complete absence of conversion observed at the conventional 2450 MHz. The resonance frequency not only facilitated exceptional conversion but also remarkably improved energy efficiency, yielding a productivity of 1427.5 µmol/kJ of CO. This represents a remarkable 474-fold increase compared to electrical heating. Furthermore, continuous microwave irradiation at this optimized frequency demonstrated remarkable stability and induced substantial enhancements in the pore structure and surface area of biochar. This innovative approach provides promising insights into sustainable and efficient CO production processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Alkali Cation Inhibition of Imidazolium-Mediated Electrochemical CO 2 Reduction on Silver

Imidazolium-based ionic liquids have led to enhanced CO 2 electroreduction activity due to cation effects at the cathode surface, stabilizing the reaction intermediates and decreasing the activation energy. In aqueous media, alkali cations are also known to improve CO 2 reduction activity on metals such as Ag, with the enhancement attributed to electrical double layer effects and trending with the size of the alkali cation. However, the effect of a mixed catholyte solution of alkali cations in the presence of an imidazolium-based ionic liquid has not been well-explored. Herein, 1-ethyl-3-methylimidazolium tetrafluoroborate, [EMIM][BF 4 ], in water was investigated with alkali salts to unravel the interaction effects for CO 2 electroreduction on Ag. Although both [EMIM] + and alkali cations have individually improved CO 2 to CO conversion on Ag in water, electrochemical results showed that alkali cations hindered imidazolium-mediated CO 2 electroreduction in most conditions. Li + , in particular, was sharply inhibitory compared to other alkali cations and strongly redirected the selectivity to hydrogen evolution. The nature of the alkali cation inhibition was investigated with spectroscopic techniques, including in situ surface-enhanced Raman spectroscopy (SERS) and dynamic electrochemical impedance spectroscopy (DEIS). Along with computational insights from density functional theory (DFT), the electrochemical and spectroscopic data suggest that alkali cations inhibit [EMIM]-mediated CO 2 reduction by competing for surface adsorption sites, preventing the potential-dependent structural reorientation of imidazolium, and promoting hydrogen evolution by bringing solvated water to the cathode surface.

cations↗

DOE OSTI2022

Monolayer Molecular Functionalization Enabled by Acid–Base Interaction for High-Performance Photochemical CO 2 Reduction

We report the development of a hybrid catalyst consisting of carbon nitride (CN x ) and cobalt phthalocyanine tetracarboxylic acid (CoPc-COOH), which converts CO 2 to CO with high reaction rate (1067 μmol/g·h) and high selectivity (over 98%), under simulated solar irradiation. The carboxylic acid substituents on the phthalocyanine ligands play a critical role as they bind to the amine groups of CN x to enable nearly ideal monolayer coverage of the molecular co-catalyst on the semiconductor surface and promote catalytic activity from the molecular complex. Specifically, the CN x /CoPc-COOH hybrid material achieves a reaction rate 16 times higher than a CN x material containing unsubstituted CoPc molecules. We further show that activation and deactivation of the CN x /CoPc-COOH composite, which are associated with the reduction and decomposition of CoPc-COOH, respectively, both proceed at a nearly constant rate regardless of the CO 2 reduction reaction rate. Here, the decoupling of charge carrier injection and CO 2 reduction catalysis has important mechanistic implications for future performance optimization and materials design of photocatalysts for CO 2 reduction.

14 SOLAR ENERGY↗

DOE OSTI2020

User’s Manual for StrmtbFlow, the Stream Tube Multiphase Flow Part of the FE/NETL CO 2 Prophet Model, Version 2

The United States (U.S.) Department of Energy (DOE) Office of Fossil Energy (FE) at the National Energy Technology Laboratory (NETL) has developed the FE/NETL CO 2 Prophet Model, which is an updated version of the CO 2 Prophet. This document is a user’s manual for StrmtbFlow, which is one part of the FE/NETL CO 2 Prophet Model. CO 2 Prophet was originally developed in the 1990s by Texaco Exploration and Production Technology Department for DOE. The FE/NETL CO 2 Prophet Model is an oil reservoir simulator that is suitable for simulating water floods and supercritical carbon dioxide (CO 2 ) enhanced oil recovery (EOR). The FE/NETL CO 2 Prophet Model uses a number of assumptions to simplify the equations describing the flow of oil, water (or brine), and CO 2 in the oil reservoir.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2024

High-throughput measurements of CO 2 permeance and solubility in ionic liquid reveal a synergistic role of ionic interactions and void fractions

The factors that govern CO 2 solubility in ionic liquids (ILs) are of great interest for the development of new materials for CO 2 capture and utilization. The cationic functional group (i.e., imidazolium, pyrrolidinium, pyridinium, etc.), alkyl chain length of cation, degree of fluorination of anion, anion size, and the void fraction in IL are known to influence CO 2 solubility. However, a comprehensive explanation of how these factors collectively affect CO 2 solubility has not been developed yet. This knowledge gap is largely attributed to the lack of CO 2 solubility data for IL structures other than imidazolium based ILs. We report here an automated high-throughput (HT) setup for the measurement of CO 2 solubility in room-temperature ILs (RTILs) combining six different anions and nine different cations for a total of 19 different specific ranges of RTILs. The HT setup first dispenses up to 200 µL of RTILs in a 96-well microtiter plate and then utilizes a robotic arm to measure cyclic voltammogram (CV) in each well using maneuverable Ag electrodes. The Cottrell analysis of the CO 2 reduction CV peak provides a direct measurement of CO 2 permeance in RTILs, which yields Henry’s constant from the estimated diffusion coefficient of CO 2 . Henry’s constants thus obtained are in very good agreement with those reported earlier. The measured CO 2 permeance and Henry’s constant of all RTILs seem to follow a first-order dependence on void fraction and a second-order dependence on electrostatic interaction between anion and cation of IL, with some synergistic dependence on the product of a void fraction and electrostatic interaction, making them two important descriptors for the design of novel ILs.

CO2 Solubility↗

DOE OSTI2023

Using high pressure solutions of polyfluoroacrylate and CO 2 to Seal cement cracks for improved wellbore integrity

Polyfluoroacrylate (PFA) is a hydrophobic and oleophobic polymer that is soluble in high pressure carbon dioxide (CO 2 ). In this study, the ability of PFA-CO 2 solutions to greatly reduce the apparent permeability of split or cracked Portland cement cylindrical samples is assessed. The apparent permeability values of confined samples were determined before and after treatment with PFA-CO 2 solutions. In four tests, PFA-CO 2 solutions were continuously displacing pure CO 2 from the cracked cement and the decrease in apparent permeability due to PFA adsorption and wettability alteration was monitored. The lowest apparent permeability cracked cement sample (81 nD) was completely sealed with a very small amount of solution. Samples with initial apparent permeabilities of 89 μD and 29.4 mD exhibited 92% and 99% reductions in permeability, respectively, before the experiments had to be stopped because of the excessively large increase in pressure drop. A 50% reduction in apparent permeability was observed with a 3.80 mD sample. Four other split cement samples (bound together with tape) with an initial apparent permeability in the 9.0–70 mD range were removed from the core holder and immersed in a PFA-CO 2 solution for 24 h to allow for PFA adsorption. Then the PFA-CO 2 solution was depressurized, allowing for the deposition of additional PFA from the solution within the crack as the pressure fell below the cloud point pressure of the PFA-CO 2 solution. These four samples were then confined again in a core holder and apparent permeability reductions of 29–93% were observed. Finally, results from these eight experiments indicates that the more substantial reductions in the nD – mD apparent permeability of the cracked cement correlated to lower initial crack permeability, higher PFA concentration, and slower injection rate of the PFA-CO 2 solution into the crack.

58 GEOSCIENCES↗

DOE OSTI2025

CO 2 Adsorption and Hydrogenation on Inverse InO x /Cu(111) Catalysts: Active Role of the Oxide–Metal Interface

The direct conversion of carbon dioxide (CO 2 ) into methanol via hydrogenation is essential for industrial applications. Recent studies on catalysts that contain an inverse oxide/metal configuration have shown very good catalytic performance for the CO 2 hydrogenation to methanol process. Here, in this study, we investigated the behavior of indium oxide-Cu(111) interfaces under pure CO 2 and CO 2 /H 2 mixtures using synchrotron-based ambient-pressure X-ray photoelectron spectroscopy (AP-XPS). Initially, a single layer of copper oxide (Cu x O) was grown on the Cu(111) surface by controlled oxidation. On this surface, indium was deposited at room temperature. Oxygen atoms transferred from Cu x O/Cu(111) to the indium metal upon deposition, forming In-O-Cu bonds and active interfaces. Although Cu(111) is not very active for the binding and activation of CO 2 , the formed InO x -Cu(111) interfaces had no problem adsorbing and dissociating the molecule at room temperature. Reaction of CO 2 with H 2 on InO x -Cu(111) yielded surface-bound H 3 CO, CO 2 δ− , CO 3 , and CH x species that are typical intermediates in the production of methanol and other oxygenates. The InO x -Cu(111) interface underwent dynamic chemical changes under reaction conditions, forming In-Cu alloys at low indium coverages (< 0.05 monolayer), while at higher indium coverages a mixture of an In-Cu and InO x was detected in XPS. These findings indicate that InO x /In-Cu interfaces can play a key role in processes aimed at the trapping and valorization of CO 2 .

36 MATERIALS SCIENCE↗

DOE OSTI2025

Effect of Viscosity of a Deep Eutectic Solvent on CO 2 Capture Performance in an Energy-Efficient Membrane Contactor-Based Process

Greenhouse gas contributions to climate change have driven intense interest in the separation of CO 2 from wet flue gas streams. Deep eutectic solvents (DESs) are an emerging class of highly selective CO 2 absorbents. A prototypical DES, reline, is a mixture of choline chloride and urea. Reline is a thermally stable, nontoxic, and biodegradable solvent with negligible volatility and is inexpensive. We demonstrate a scalable and energy-efficient hollow fiber membrane contactor (HFMC)-based process using a green solvent for CO 2 capture. This process uses reline in HFMC to provide close interfacial interactions and contact between DES and CO 2 . This approach overcomes the disadvantages associated with direct absorption in DES and could potentially be applied to a variety of solvent-based CO 2 capture methods. Commercial, low-cost polymer hollow fiber membranes were evaluated for the capture of CO 2 with reline. From a mixed gas containing N 2 and CO 2 , the DES-based HFMC separated CO 2 with a purity of 97 mol %. The effect of the viscosity of reline on the CO 2 capture performance was investigated by adding water to the reline. The addition of water to reline significantly reduced its viscosity, which led to a permeate flux of 170 mmol/(m 2 ·h) at 35 °C, 4 bar, and 60 wt % water in solvent, which was approximately 8 times higher than that of the pure reline in the membrane contactor system. In situ Fourier transform infrared spectroscopy and nuclear magnetic resonance (NMR) revealed that reline absorbs CO 2 by physical absorption without forming new chemical compounds and that CO 2 separation by reline occurs via the pressure swing mechanism. This research provides fundamental insights about green physical solvent-based separation processes and a pathway toward industrial deployment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2023

Highly Tunable Syngas Product Ratios Enabled by Novel Nanoscale Hybrid Electrolytes Designed for Combined CO 2 Capture and Electrochemical Conversion

Coupling renewable energy with the electrochemical conversion of CO 2 to chemicals and fuels has been proposed as a strategy to achieve a new circular carbon economy and help mitigate the effects of anthropogenic CO 2 emissions. Liquid-like Nanoparticle Organic Hybrid Materials (NOHMs) are composed of polymers tethered to nanoparticles and are previously explored as CO 2 capture materials and electrolyte additives. Here, in this study, two types of aqueous NOHM-based electrolytes are prepared to explore the effect of CO 2 binding energy (i.e., chemisorption versus physisorption) on CO 2 electroreduction over a silver nanoparticle catalyst for syngas production. Poly(ethylenimine) (PEI) and Jeffamine M2070 (HPE) are ionically tethered to SiO 2 nanoparticles to form the amine-containing NOHM-I-PEI and ether-containing NOHM-I-HPE, respectively. At less negative cathode potentials, PEI and NOHM-I-PEI-based electrolytes produce CO at higher rates than 0.1 molal. KHCO 3 due to favorable catalyst-electrolyte interactions. Whereas at more negative potentials, H 2 production is favored because of the carbamate electrochemical inactivity. Conversely, HPE and NOHM-I-HPE-based electrolytes display poor CO 2 reduction performance at less negative potentials. At more negative potentials, their performance approached that of 0.1 molal. KHCO 3 , highlighting how the polymer functional groups of NOHMs can be strategically selected to produce value-added products from CO 2 with highly tunable compositions.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Fast Charge‐Transfer Rates in Li‐CO 2 Batteries with a Coupled Cation‐Electron Transfer Process

Li-CO 2 batteries with a high theoretical energy density (1876 Wh kg −1 ) have unique benefits for reversible carbon fixation for energy storage systems. However, due to lack of stable and highly active catalysts, the long-term operation of Li-CO 2 batteries is limited to low current densities (mainly <0.2 mA cm −2 ) that are far from practical conditions. In this work, it is discovered that, with an ionic liquid-based electrolyte, highly active and stable transition metal trichalcogenide alloy catalysts of Sb 0.67 Bi 1.33 X 3 (X = S, Te) enable operation of the Li-CO 2 battery at a very high current rate of 1 mA cm −2 for up to 220 cycles. It is revealed that: i) the type of chalcogenide (Te vs S) significantly affects the electronic and catalytic properties of the catalysts, ii) a coupled cation-electron charge transfer process facilitates the carbon dioxide reduction reaction (CO 2 RR) occurring during discharge, and iii) the concentration of ionic liquid in the electrolyte controls the number of participating CO 2 molecules in reactions. A combination of these key factors is found to be crucial for a successful operation of the Li-CO 2 chemistry at high current rates. This work introduces a new class of catalysts with potential to fundamentally solve challenges of this type of batteries.

25 ENERGY STORAGE↗

DOE OSTI2022

Reaching the equilibrium state of the frustrated triangular Ising magnet Ca 3 Co 2 O 6

Ca 3 Co 2 O 6 is a frustrated magnet consisting of a triangular arrangement of chains of Ising spins. It shows regular magnetization steps versus magnetic field every 1.2 T that are metastable with very slow dynamics. This has puzzled the community for many years and given rise to numerous potential theories. Here we approach the problem by seeking the elusive magnetic equilibrium state at T=2 K. To this end, we explore two approaches: (1) bypassing the slow dynamics produced by changing fields by instead field-cooling directly to the target temperature and (2) quantum annealing in transverse magnetic fields. While we observe no measurable effect of the quantum annealing in fields up to 7 T, which is likely due to the large Ising anisotropy of Co spins in this material, we find that for the field cooling in longitudinal fields we achieve the predicted equilibrium 1/3 magnetization. We perform Monte Carlo simulations of the ground state phase diagram and we also simulate the quantum annealing process and find good agreement between experiment and theory. Thus we present an investigation of the elusive ground state properties of the canonical frustrated triangular system Ca 3 Co 2 O 6 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2022

FECM/NETL CO 2 Transport Cost Model (2022): Description and User’s Manual

The FECM/NETL CO 2 Transport Cost Model (CO 2 _T_COM) is an Excel spreadsheet model that calculates the cost of transporting CO 2 from the beginning to the end of a pipeline. This document provides two main functions. First, the document describes the equations and algorithms that are used by the model to calculate technical quantities (such as the minimum inner pipe diameter needed to transport a user-specified CO 2 mass flow rate a specified distance) and engineering-economic quantities (such as capital costs, operating costs and cash flows). Second, the document is a user’s manual for the model that describes the procedures the user must follow to run the model. The document also describes input variables and output variables (i.e., results) for the model.

42 ENGINEERING↗

DOE OSTI2023

FECM/NETL CO 2 Transport Cost Model (2023): Description and User’s Manual

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2021

Understanding Photocarrier and Gas Dynamics to Rationally Design Heterostructured Nanocatalysts for Solar CO 2 Conversion

Recent research in CO 2 photocatalysis has largely focused on exploring new catalysts; however, details of how these materials work often remain unclear. Knowledge of these processes will allow one to rationally design highly efficient catalysts for solar CO 2 conversion. This project aims to develop new techniques and establish new capabilities in SRNL to enable the study of photocatalysts and other materials in extreme detail. In FY21, we developed two new in situ techniques that are unique to SRNL, allowing the study of reaction intermediates and adsorbed gases during photocatalysis. We also established new in-house capabilities for catalyst synthesis and transient absorption (TA) spectroscopy, which enables the study of very short-lived excited states on photocatalysts. These capabilities will be used extensively for this project and in other current projects relevant to clean energy technologies such as photovoltaic cells, providing a good return on investment in the coming years.

14 SOLAR ENERGY↗

DOE OSTI2026

The small protein SbtC is a functional component of the CO 2 concentrating mechanism in Synechocystis sp. PCC 6803

Oxygenic phototrophs fix CO 2 via the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO), which shows relatively low CO 2 affinity and specificity. To circumvent low and fluctuating CO 2 concentrations in aquatic systems, cyanobacteria and algae have evolved sophisticated inorganic carbon (Ci) concentrating mechanisms (CCMs). Bicarbonate transporters such as SbtA play a crucial role in the cyanobacterial CCM and hence display multiple layers of tight regulation. Control of sbtA gene expression and corresponding transporter activity involves the PII-like protein SbtB, whose gene is frequently co-transcribed with sbtA. A previously non-annotated gene located upstream of the sbtAB operon in the model Synechocystis sp. PCC 6803 encodes the small protein SbtC, composed of 80 amino acids. Presence of SbtC was confirmed by immunoblotting of the sbtC-coding sequence fused to a Flag-tag. Similar to sbtAB , transcription of the sbtC locus is induced by low CO 2 availability; however, it is controlled independently. Mutation of the sbtC locus in a wild-type background produced only a mild phenotype, even under low CO 2 , but impaired diurnal growth resembled that of the mutant ΔsbtB . Biochemical analysis indicated a trimeric SbtABC complex in the membrane. Bicarbonate leakage from cells was strongly elevated when either sbtB or sbtC was deleted from recombinant Synechocystis strains harboring only SbtA as single Ci uptake system. Here, our results provide evidence that SbtC contributes to the formation of the SbtAB complex, thereby regulating bicarbonate exchange at the cytoplasmic membrane. Well-conserved SbtC-like proteins encoded in the neighborhood of sbtAB exist in many cyanobacterial genomes, pointing toward an important role in the cyanobacterial CCM.

Walke, Peter [Univ. of Rostock (Germany)] (ORCID:0↗

DOE OSTI2024

Turning Normal to Abnormal: Reversing CO 2 /C2–Hydrocarbon Selectivity in HKUST–1

Metal–organic frameworks (MOFs) can efficiently purify hydrocarbons from CO 2 , but their rapid saturation, driven by preferential hydrocarbon adsorption, requires energy-intensive adsorption–desorption processes. To address these challenges, an innovative approach is developed, enabling control over MOF flexibility through densification and defect engineering, resulting in an intriguing inverse CO 2 /C2 hydrocarbon selectivity. Here, in this study, the densification process induces the shearing of the crystal lattice and contraction of pores in a defective CuBTC MOF. These changes have led to a remarkable transformation in selectivity, where the originally hydrocarbon-selective CuBTC MOF becomes CO 2 -selective. The selectivity values for densified CuBTC are significantly reversed when compared to its powder form, with notable improvements observed in CO 2 /C 2 H 6 (4416 vs 0.61), CO 2 /C 2 H 4 (15 vs 0.28), and CO 2 /C 2 H 2 (4 vs 0.2). The densified material shows impressive separation, regeneration, and recyclability during dynamic breakthrough experiments with complex quinary gas mixtures. Simulation studies indicate faster CO 2 passage through the tetragonal structure of densified CuBTC compared to C 2 H 2 . Experimental kinetic diffusion studies confirm accelerated CO 2 diffusion over hydrocarbons in the densified MOF, attributed to its small pore window and minimal interparticle voids. This research introduces a promising strategy for refining existing and future MOF materials, enhancing their separation performance.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Chemically Enabled CO 2 -Enhanced Oil Recovery in Multi-Porosity, Hydrothermally Altered Carbonates in the Southern Michigan Basin (Final Technical Report)

This is the Final Technical Report for the project "Chemically Enabled CO 2 -Enhanced Oil Recovery in Multi-Porosity, Hydrothermally Altered Carbonates in the Southern Michigan Basin." Over the course of six years of collaboration between Battelle and project partners, all stated objectives of the program have been completed, including full geological characterization of the TBR trend (See companion report for Task2), laboratory and modeling experiments to determine the optimum composition and design of CO 2 -EOR operations in the TBR trend, execution of a field test of chemically-enhanced CO 2 in a TBR well, and integration of the data and learnings gathered during these efforts into a full-trend development plan. Detailed reporting on these activities, their outcomes, and implications for trend-wide development is provided in the report. This report and encompassed data will provide TBR field operators with detailed information on what worked, what did not work, and how to proceed with production optimization of their TBR assets using chemically-enhanced CO 2 -EOR. CO 2 -EOR is a relatively well understood and broadly implemented strategy for increasing incremental production across the oil and gas industry, but its application has been primarily focused on reservoirs with limited heterogeneity. The intention of this project was show first that the same physical mechanisms that improve recovery factors in homogeneous reservoirs (namely wettability alteration, viscosity alteration, oil swelling, and mobility control) are at play in heterogeneous reservoirs. This was proven by the project’s laboratory studies and dynamic simulations, with the potential exception of mobility control, which needs further study. The second intention was to demonstrate via direct field testing that CO 2 -EOR can work in a strongly heterogeneous reservoir. While the field test strategy implemented during this project did not succeed in producing oil, data gathered during the test sheds light on what may work for field operators who try chemically-enhanced CO 2 -EOR within their own reservoirs, significantly reducing the level of uncertainty carried by first-of-a-kind commercial efforts that could (and should) follow this test. Simultaneously, the project has identified several large-volume ethanol plants and other sources of CO 2 emissions in the region and provided a handrail that CO 2 emitters and field operators can leverage to capture, transport, and inject that CO 2 into their fields. This project has also shown that, in many cases, the economics of CO 2 -EOR in the TBR are attractive. And finally, by completing a project of this scope in the southern Michigan Basin, the project has contributed to the knowledge base and operational experience of field operators, state regulatory agencies, local service companies, and state universities, with CO 2 -EOR projects which should allow follow-on projects to proceed safely and efficiently.

02 PETROLEUM↗