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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Best Practices in Underground Coal Gasification

Underground coal gasification (UCG) converts coal in-situ into a gaseous product, commonly known as synthesis gas or syngas through the same chemical reactions that occur in surface gasifiers. Gasification converts hydrocarbons into a synthesis gas (syngas) at elevated pressures and temperatures and can be used to create many products (electric power, chemical feedstock, liquid fuels, hydrogen, synthetic gas). Gasification provides numerous opportunities for pollution control, especially with respect to emissions of sulfur, nitrous oxides, and mercury. UCG could increase the coal resource available for utilization enormously by gasifying otherwise unmineable deep or thin coals under many different geological settings. A 300-400% increase in recoverable coal reserves in the U.S. is possible. For developing countries undergoing rapid economic expansion, including India and China, UCG also may be a particularly compelling technology. UCG has been tested in many different experimental tests in many countries. The U.S. carried out over 30 pilots between 1975 and 1996, testing bituminous, sub-bituminous, and lignite coals. Before that, the Former Soviet Union executed over 50 years of research on UCG, field tests and several commercial projects, including an electric power plant in Angren, Uzbekistan that is still in operation today after 47 years. Since 1991, China has executed at least 16 tests, and has several commercial UCG projects for chemical and fertilizer feedstocks. In 2000, Australia began a large pilot (Chinchilla) which produced syngas for 3 years before a controlled shut-down and controlled restart. As present, multiple commercial projects are in various stages of development in the U.S., Canada, South Africa, India, Australia, New Zealand, and China to produce power, liquid fuels, and synthetic natural gas.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2014

Advanced geophysical underground coal gasification monitoring

Underground Coal Gasification (UCG) produces less surface impact, atmospheric pollutants and greenhouse gas than traditional surface mining and combustion. Therefore, it may be useful in mitigating global change caused by anthropogenic activities. Careful monitoring of the UCG process is essential in minimizing environmental impact. In this paper, we first summarize monitoring methods that have been used in previous UCG field trials. We then discuss in more detail a number of promising advanced geophysical techniques. These methods – seismic, electromagnetic, and remote sensing techniques – may provide improved and cost-effective ways to image both the subsurface cavity growth and surface subsidence effects. Active and passive seismic data have the promise to monitor the burn front, cavity growth, and observe cavity collapse events. Electrical resistance tomography (ERT) produces near real time tomographic images autonomously, monitors the burn front and images the cavity using low-cost sensors, typically running within boreholes. Interferometric synthetic aperture radar (InSAR) is a remote sensing technique that has the capability to monitor surface subsidence over the wide area of a commercial-scale UCG operation at a low cost. It may be possible to infer cavity geometry from InSAR (or other surface topography) data using geomechanical modeling. The expected signals from these monitoring methods are described along with interpretive modeling for typical UCG cavities. They are illustrated using field results from UCG trials and other relevant subsurface operations.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2016

Chemical looping coal gasification with calcium ferrite and barium ferrite via solid--solid reactions

Coal gasification to produce synthesis gas by chemical looping was investigated with two oxygen carriers, barium ferrite (BaFe2O4) and calcium ferrite (CaFe2O4). Thermo-gravimetric analysis (TGA) and fixed-bed flow reactor data indicated that a solid–solid interaction occurred between oxygen carriers and coal to produce synthesis gas. Both thermodynamic analysis and experimental data indicated that BaFe2O4 and CaFe2O4 have high reactivity with coal but have a low reactivity with synthesis gas, which makes them very attractive for the coal gasification process. Adding steam increased the production of hydrogen (H2) and carbon monoxide (CO), but carbon dioxide (CO2) remained low because these oxygen carriers have minimal reactivity with H2 and CO. Therefore, the combined steam–oxygen carrier produced the highest quantity of synthesis gas. It appeared that neither the water–gas shift reaction nor the water splitting reaction promoted additional H2 formation with the oxygen carriers when steam was present. Wyodak coal, which is a sub-bituminous coal, had the best gasification yield with oxygen carrier–steam while Illinois #6 coal had the lowest. The rate of gasification and selectivity for synthesis gas production was significantly higher when these oxygen carriers were present during steam gasification of coal. The rates and synthesis gas yields during the temperature ramps of coal–steam with oxygen carriers were better than with gaseous oxygen.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2023

Coal gasification operations with carbon capture (CCS)

Hydrogen production through coal gasification, with carbon capture. To access the model referenced in the report, please visit https://www.netl.doe.gov/energy-analysis/details?id=e20c7c55-0123-48e2-a97f-0b967f214767

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2015

Underground coal gasification: An overview of groundwater contamination hazards and mitigation strategies

Underground coal gasification is the in situ conversion of coal into an energy-rich product gas. It takes place deep underground, using chemical reactions to consume the coal and grow a cavity. Gas wells, drilled into the coal seam, inject reactant air, oxygen, and/or steam to sustain the reactions. Production wells then extract the product gas. Careful analysis and understanding of likely failure modes will help prevent and minimize impacts. This document provides a general description of the relevant processes, potential failure modes, and practical mitigation strategies. It can guide critical review of project design and operations.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2022

Utilizing lowly-reactive coal gasification fly ash (CGFA) to stabilize aggregate bases

This study explored the feasibility of utilizing lowly-reactive coal gasification fly ash (CGFA) for stabilizing road aggregate bases. Three types of aggregate stabilizers including the ordinary Portland cement (OPC)-CGFA, hydrated lime (CH)-CGFA and alkali-activated CH-CGFA were evaluated based on the performances of compacted base specimens. It was found that the OPC-CGFA stabilized bases showed better mechanical and durability properties while the CH-CGFA samples had low water stability and freeze-thaw durability due to the dissolution of unreacted CH. However, the reaction degree of CGFA associated with the performances of CH-CGFA stabilization could be considerably enhanced by the alkali-activation. The sustainability and economic feasibility analyses showed the use of CGFA could significantly reduce the CO 2 emissions and costs, highlighting the synergy between the recycling of CGFA and the construction of sustainable road bases. Here, a framework of selecting CGFA-based stabilizers for road bases was proposed considering the performance ratings of the material properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Hydrogen Production by Steam Oxidation of Reduced CaFe 2 O 4 during Chemical Looping Coal Gasification: Equilibrium and Kinetic Analysis

CaFe 2 O 4 reduced during chemical looping coal gasification can be oxidized with steam for production of hydrogen. The conversion and equilibrium data of the oxidation of reduced CaFe 2 O 4 with steam were analyzed using steam concentrations of 10–25 vol % with a balance of helium and the temperature range of 1023–1123 K. Experimental data were evaluated to characterize H 2 production rates and oxidation isotherms. The film diffusion was the controlling step for the oxygen uptake process, and its parameters were determined on the basis of the uptake rate model. The steady-state oxygen uptake data were also evaluated with Langmuir, Temkin, Freundlich, and Dubinin–Radushkevich isotherms. The Langmuir isotherm model correlated the oxidation isotherms best, and the peak uptake capacity decreased with increasing temperatures, which suggests an exothermic process. In conclusion, the negative Gibbs free energy values (–Δ G °) implied the spontaneous nature of the uptake process at 1023–1123 K.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2019

Application of Chemical Looping with Spouting Fluidized Bed for Hydrogen-Rich Syngas Production from Catalytic Coal Gasification

The goal of this final project report is to comprehensively summarize the work conducted in project DE-FE0024000. In accordance with the Statement of Project Objectives (SOPO), the University of Kentucky Center for Applied Energy Research (UKy-CAER) developed a multifaceted particle as a catalyst-oxygen carrier (catalyst-OC) for chemical looping gasification. The project also included the design, fabrication, commissioning and performance evaluation of a novel spouted bed approach to gasifiers in conjunction with chemical looping concepts to significantly reduce the capital cost associated with typical gasification technologies. Specifically, UKy-CAER investigated red mud (RM) with and without Cu additives for catalytic and stability benefits in a bench scale reactor, provided the detailed front-end design of a 50 kWth chemical looping gasification (CLG) plant and completed a 70+ hour long experimental campaign to evaluate the coal feed system and the performance and flexibility of the 50 kWth facility with various coal and OCs. Project results verified UKy-CAER’s proposed approach to catalytic coal gasification technology using a chemical looping process with three reaction zones to provide in-situ separated oxygen for coal partial-combustion (e.g. gasification) with water-gas shift reaction. Central to the project was kinetically facile red mud OC and a spouted bed gasifier configuration that enabled the success of the following operation, performance and economic objectives: (1) Low-temperature gasifier operation (as low as 600°C); (2) Avoidance of ash and OCs aggolmeration; (3) Elimination of methane formation; and (4) Promotion of water-gas shift (WGS) reactions and syngas reforming. The red mud OC is economical and the novel spouted bed reducer shows promise, as summarized in this report, as an effective means for improved plant efficiency with reduced process complexity.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2017

A Review of Underground Coal Gasification Research and Development in the United States

An intense and productive period of research and development on underground coal gasification (UCG) took place in the United States from the mid-1970’s through the late 1980’s. It began with the translation and review of Soviet literature and ended with the Rocky Mountain 1 field test. This demonstrated the feasibility of newly-developed technologies that form the basis of many UCG projects around the world today. This period began with little domestic understanding of UCG and ended with an accurate observation-based conceptual model and a corresponding predictive multi-physics mathematical model of the process. The many accomplishments of this period form the main content of this report. This report also covers recent U.S. activities and accomplishments during the period 2004-2015, and touches briefly on the Bureau of Mines efforts between 1948 and 1963. Most of the activities were funded by the United States Department of Energy and its predecessors. While private/commercially-funded activities are reviewed here, the emphasis is on government-funded work. It has a much greater extent of publicly available reports and papers, and they generally contain much greater technical detail. Field tests were the marquis activities around which an integrated multi-faceted program was built. These are described in detail in Section 4. Highlights from modeling efforts are briefly covered, as the program was integrated and well-rounded, with field results informing models and vice-versa. The primary goal of this report is to review what has been learned about UCG from the U.S. experience in aggregate. This includes observations, conclusions, lessons-learned, phenomena understood, and technology developed. The latter sections of this report review these things.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2017

Performance and Cost Assessment of a Coal Gasification Power Plant Integrated with a Direct-Fired sCO 2 Brayton Cycle

The objective of this study is to develop a cost and performance baseline for a coal syngas-fueled, direct-fired supercritical carbon dioxide (sCO2) power plant using coal gasification, and to analyze the sensitivity of its cost and performance to variations in operating parameter and cost assumptions. The study results yield a sCO2 baseline plant efficiency of 37.7% (HHV), with 97.6% carbon capture at 99.8% purity, much higher than the reference integrated gasification combined cycle (IGCC) plant using the same Shell gasifier (31.2% efficiency, 90% carbon capture). The economic analysis estimates a cost of electricity (COE) of $137/MWh for the mature, commercial-scale sCO2 plant (without CO2 transport and storage costs), yielding a 10% reduction in COE from the reference IGCC case. These results demonstrate the significant potential of direct sCO2 power cycles for achieving DOE’s transformational power generation goals for coal-fueled power plants with carbon capture and storage.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2019

Breakthrough Hybrid CTL Process Integrating Advanced Technologies for Coal Gasification, Natural Gas Partial Oxidation, Warm Syngas Cleanup and Syngas-to-Jet Fuel

The objective of this research and development effort was to develop a breakthrough hybrid CTL process integrating advanced coal gasification (R-Gas) and natural gas partial oxidation technologies from Gas Technology Institute (GTI) (previously developed by Aerojet Rocketdyne (AR)) with advanced warm syngas cleanup (WDP) and advanced syngas-to-liquids (STL) technologies from RTI International to produce cost-competitive jet fuel compared to conventional refining routes and having a greenhouse gas emissions footprint that meets EISA 2007 §526 requirements.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2015

Advanced Hydrogen Transport Membrane for Coal Gasification

A pilot-scale hydrogen transport membrane (HTM) separator was built that incorporated 98 membranes that were each 24 inches long. This separator used an advanced design to minimize the impact of concentration polarization and separated over 1000 scfh of hydrogen from a hydrogen-nitrogen feed of 5000 scfh that contained 30% hydrogen. This mixture was chosen because it was representative of the hydrogen concentration expected in coal gasification. When tested with an operating gasifier, the hydrogen concentration was lower and contaminants in the syngas adversely impacted membrane performance. All 98 membranes survived the test, but flux was lower than expected. Improved ceramic substrates were produced that have small surface pores to enable membrane production and large pores in the bulk of the substrate to allow high flux. Pd-Au was chosen as the membrane alloy because of its resistance to sulfur contamination and good flux. Processes were developed to produce a large quantity of long membranes for use in the demonstration test.

08 HYDROGEN↗
DOE OSTI2019

Chemical Looping Coal Gasification Sub-Pilot Unit Demonstration and Economic Assessment for IGCC applications (Final Report)

The Ohio State University (OSU) coal to syngas (CTS) technology is an advanced air separation process that can be applied for electricity production via an integrated gasification combined cycle (IGCC). The objective of the proposed project is to enable the OSU CLG technology for a commercially relevant demonstration by 2020. In order to accomplish this objective, small pilot scale demonstration of the CLG reactor system was performed. The small pilot test unit incorporates commercially scalable non-mechanical gas sealing and solids flow control components for extended operations of the integrated reactor system. A cumulative demonstration of greater than 100 hours was performed to confirm the reliability of the reactors (reducer and oxidizer) and non-mechanical devices in maintaining controlled solid circulation, gas sealing, and coal distribution in the reactor (reducer) as well as to confirm sustained syngas product performance. A comprehensive techno-economic analysis (TEA) of the OSU CLG process for IGCC application was conducted with the support of WorleyParsons, Ltd. (WP) and compared to the Department of Energy (DOE) baseline IGCC report. Using the data gained from the small pilot demonstration, a complete comprehensive techno-economic analysis (TEA) of the CLG process was conducted. The evaluation was used as basis to attract utilities and coal industries in Ohio. The project duration lasts 30 months (6 months of no cost extension). Ohio coal was used in the integrated CLG small pilot unit to convert to high hydrogen syngas. A demonstration of the integrated chemical looping reactor system at the 15 kW th scale accelerates technology commercialization in the near term. The 15 kWth demonstration addressed several major technology gaps, such as coal injection and distribution in the reducer, controllable solids circulation with the desired fuel to solids ratio, system pressure distribution for proper gas sealing, effects of contaminants and fuel/oxygen carrier residence time requirements. The fates of impurities, such as SO x and NO x was also investigated in unit demonstrations. WP conducted a comprehensive system TEA to optimize the OSU CLG process design for efficient electricity generation with greater than 90% CO 2 capture in IGCC applications. The conclusion of this project supports the further scale-up of the technology to a commercially applicable large pilot scale test unit for operation by 2020. More importantly, it benefits Ohio as it provides an economically competitive mean for power generation with carbon capture. Given the rise of natural gas usage and strict environmental regulations, the use of Ohio coal is expected to decrease and thus impact the coal economy in Ohio. The conclusion of this project provided way for Ohio coal to compete in the future and secure jobs in the energy sector.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2023

Performance of hydrophobic physical solvents for pre-combustion CO 2 capture at a pilot scale coal gasification facility

Here, in this paper, we present the first pilot plant data for hydrophobic physical solvents for CO 2 and H 2 S removal from coal-derived H 2 -rich syngas. Four physical solvents were tested under pre-combustion CO 2 capture conditions at bench scale and pilot plant scale: one baseline hydrophilic solvent and three hydrophobic solvents. The solvents were: (1) polyethylene-glycol-dimethyl ether (PEGDME), a hydrophilic solvent analog for the commercial process Selexol, (2) tributyl- phosphate (TBP), a commercially available hydrophobic solvent, (3) polyethylene glycol-poly(dimethylsiloxane) (PEG-PDMS-3), and (4) diethyl sebacate (CASSH-1), a novel, computationally screened hydrophobic solvent developed by the National Energy Technology Laboratory (NETL). All solvents were studied under pure gas (CO 2 /N 2 /H 2 /CH 4 ) equilibrium conditions at NETL followed by pilot plant testing with syngas at the University of North Dakota Energy & Environmental Research Center (UND EERC). Long term performance of CASSH-1 and PEDGME was then assessed with results compared to process simulation predictions. Within experimental uncertainties, all solvents showed comparable CO 2 absorption performance at above room temperature operation while the hydrophobic solvents had limited water uptake and low vapor pressure, which alleviates concerns related to corrosion, water absorption, and solvent loss to evaporation. These results indicate low viscosity, low vapor pressure hydrophobic solvents are a promising option for lower cost CO 2 capture from high pressure syngas applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗