O objetivo deste trabalho é aplicar a metodologia do Planejamento Integrado de Recursos energéticos (PIR) dentro do ambiente corporativo. Para estudo de caso foi escolhida uma indústria de papel e celulose, por se tratar de uma das indústrias de maior consumo energético, e a região onde ela está instalada, o município de Suzano. Inicialmente, procurou-se descrever o processo produtivo em uma indústria de papel e celulose. Para este trabalho foi analisado somente os recursos do lado da oferta. Além dos recursos tradicionais, que são a caldeira de biomassa, a caldeira de gás natural/óleo combustível e as caldeiras de recuperação, foi incluída uma nova tecnologia, a gaseificação de biomassa. Foram descritas as tecnologias de gaseificação disponíveis e mostrado o seu estado da arte. Dentro dessas tecnologias, há uma aplicação que busca substituir as tecnologias atuais de caldeira de recuperação, a gaseificação de licor negro. / The purpose of this study was to apply the Integrated Resources Planning for Energy (IRP) methodology within corporate environment. A study of case of pulp and mill industry was chosen, because it is one of largest energy consumption industries, and the region that was studied was Suzano. Initially we described the industrial process of pulp and mill factory. This study we will analyze only the features of Supply Side Resources. In addition to the traditional power supplies which are biomass boiler, natural gas/fuel oil boiler and recovery boiler, we include a new technology, biomass gasification. We described the technologies available for gasification and show the state of art of this technology. Within these technologies, we have an special application the seeks to replace currently technology of recovery boiler, Black Licor Gasification.

<p>U okviru istraživačkog rada formiran je matematički model za simulaciju<br />procesa transformacije energije u postrojenju gasne turbine pri<br />sagorevanju gasova srednje ili niže toplotne moći. Data je analiza procesa<br />kosagorevanja gasa iz gasifikacije kukuruznog oklaska i prirodnog gasa u<br />postrojenju gasne turbine, za tri različite konfiguracije postrojenja.<br />Analiza je rađena na primeru osnovnog Joule-ovog ciklusa sa vazduhom<br />hlađenim lopaticama.</p> / <p>This paper presents mathematical model for simulation of energy<br />transformation process in gas turbine facility with combustion of medium<br />and low calorific gases. The basis of the mathematical model is the<br />M&uuml;ller&rsquo;s method. Analysis of co-firing the corn cob gas and natural gas for<br />different gas turbine facility configurations is presented. The basic Joule<br />cycle with blade cooling was analyzed.</p>

Le démantèlement des réacteurs Uranium Naturel Graphite-Gaz (UNGG), tous arrêtés depuis 1994, génèrera 23 000 tonnes de déchets de graphite de Faible Activité et Vie Longue (FAVL), contenant notamment du 14C. Le but de ce travail de thèse est d’étudier un procédé original d’extraction sélective de ce radionucléide par carboxy-gazéification. L’organisation multi-échelle des graphites vierge et irradié a été étudiée par un couplage entre microspectrométrie Raman et microscopie électronique à transmission. Avec la fluence neutronique, la structure se dégrade et la nanostructure peut être fortement modifiée. Dans les cas extrêmes, la nanostructure lamellaire du graphite nucléaire est devenue nanoporeuse. En outre, ces dégâts sont systématiquement hétérogènes. Un effet d’orientation des « cristallites », mis en évidence expérimentalement par implantation ionique, pourrait être une cause de ces hétérogénéités. Cette étude a également montré qu’à partir d’une certaine fluence, l'apparition importante de zones nanoporeuses coïncide avec une augmentation spectaculaire de la concentration en 14C. Ce radionucléide pourrait donc être préférentiellement concentré dans ces zones nanoporeuses qui sont potentiellement plus réactives que les zones restées lamellaires et a priori moins riches en 14C.Ce procédé par carboxy-gazéification a d'abord été testé sur des matériaux « analogues » non radioactifs (graphites broyés mécaniquement). Ces essais ont confirmé, pour des températures entre 950 et 1000 °C, l’élimination sélective et complète des zones nanoporeuses. Des tests ont alors été réalisés sur des déchets de graphite provenant des réacteurs Saint-Laurent-des-Eaux A2 et G2. Les résultats sont prometteurs avec notamment un quart du 14C extrait pour seulement quelques pourcents de perte de masse. Jusqu’à 68 % du 14C a pu être extrait, mais au prix d’une gazéification plus importante. Ce traitement permettrait donc d’extraire sélectivement une part du 14C (mobile ou lié à des zones nanoporeuses) et d’imaginer des scénarios alternatifs de gestion de ces déchets de graphite. / The decommissioning of French gas cooled nuclear reactors (UNGG), all arrested since 1994, will generate 23,000 tons of graphite waste classified Low Level and Long Lived and notably containing 14C. The aim of this thesis is to study a new method for selective extraction of this radionuclide by CO2 gasification.The multiscale organization of virgin and irradiated graphite has been studied by a coupling between microspectrometry Raman and transmission electron microscopy. With the neutron fluence, the structure degrades and the nanostructure can be greatly changed. In extreme cases, the lamellar nanostructure nuclear graphite has become nanoporous. Furthermore, these damages are systematically heterogeneous. An orientation effect of "crystallites", shown experimentally by ion implantation, could be a cause of these heterogeneities.This study also showed that from a specific fluence, there is an important development of nanoporous zones coinciding with a dramatic 14C concentration increase. This radionuclide could be preferentially concentrated in the nanoporous areas which are potentially more reactive than the remaining laminar areas which could be less rich in 14CThis process by CO2 gasification was firstly tested on "analogous" non-radioactive materials (mechanically milled graphite). These tests confirmed, for temperatures between 950 and 1000 °C, the selective and complete elimination of nanoporous areas.Tests were then carried out on graphite waste from Saint-Laurent-des-Eaux A2 and G2 reactors. The results are promising with notably the quarter of 14C inventory extracted for a weight loss of only few percent. Up to 68 % of 14C inventory was extracted, but with an important gasification. Thus, this treatment could allow extracting selectively a share of 14C inventory (mobile or linked to nanoporous areas) and allows imagining alternative scenarios for graphite waste managing.

Coal is a very prominent energy source in the world, but it is environmentally unattractive due to its high sulfur and ash content as well as its alleged contribution towards climate change, but it is affordable, abundant, and has high energy content. Thus, utilizing coal in a cleaner and more efficient way has become necessary. One promising clean coal technology involves fully gasifying coal into synthesis gas, cleaning it, and feeding it into a high-efficiency combined cycle, such as an Integrated Gasification Combined Cycle (IGCC). Inspired by the recent success of warn gas cleanup (WGCU), mild and partial gasification are proposed as less energy intensive options. This Integrated Mild/Partial Gasification Combined Cycle (IMPGC) could significantly save energy and improve efficiency. The objective of this study is to investigate the capabilities of IMPGC as both a new plant and a retrofit option for traditional coal power plants with and without carbon capture. I MPGC relies on the principles of mild and partial gasification and the recently available WGGU technology with the following benefits: a.) completely negate the need for syngas cooling; b.) significantly reduce the energy needed to fully thermally crack the volatiles and completely gasify the char as in the IGCC system; c.) preserve the high chemical energy hydro-carbon bonds within the feedstock to allow more efficient combustion in the gas turbine; d.) reduce the size of gasifier and piping to reduce the costs; and e.) enable retrofitting of an old coal power plant by preserving the existing equipment. The software used (Thermoflex®) was first validated with established cases from the U.S. Department of Energy. For new plants, the results show that IMPGC’s efficiency is 8 percentage points (20%) higher than IGCC, 8 points higher than a modern subcritical Rankine cycle, and 3-4 points higher than an ultra-supercritical (USC) cycle. When retrofitting older plants, a minimum improvement of over 4 points is predicted. When carbon capture is involved, IMPGC’s efficiency becomes 10 points better than a subcritical plant and 8 points better than a USC plant. Emissions wise, IMPGC is better than IGCC and much better than Rankine cycle plants.

<p>Black liquors are presently combusted in recovery boilers where the inorganic cooking chemicals are recovered and the energy in the organic material is converted to steam and electricity. A new technology, developed by Chemrec AB, is black liquor gasification (BLG). BLG has more to offer compared to the recovery boiler process, in terms of on-site generation of electric power, liquid fuel and process chemicals. A prerequisite for both optimization of existing processes and the commercialization of BLG is better understanding of the physical and chemical processes involved including interactions with the refractory lining. The chemistry in the BLG process is very complex and to minimize extensive and expensive time-consuming studies otherwise required accurate and reliable model descriptions are needed for a full understanding of most chemical and physical processes as well as for up-scaling of the new BLG processes. However, by using these calculated model results in practice, the errors in the state of the art thermochemical data have to be considered. An extensive literature review was therefore performed to update the data needed for unary, binary and higher order systems. The results from the review reviled that there is a significant range of uncertainty for several condensed phases and a few gas species. This resulted in experimental re-determinations of the binary phase diagrams sodium carbonate-sodium sulfide (Na2CO3-Na2S) and sodium sulfate-sodium sulfide (Na2SO4-Na2S) using High Temperature Microscopy (HTM), High Temperature X-ray Diffraction (HT-XRD) and Differential Thermal Analysis (DTA). For the Na2CO3-Na2S system, measurements were carried out in dry inert atmosphere at temperatures from 25 to 1200 °C. To examine the influence of pure CO2 atmosphere on the melting behavior, HTM experiments in the same temperature interval were made. The results include re-determination of liquidus curves, in the Na2CO3 rich area, melting points of the pure components as well as determination of the extent of the solid solution, Na2CO3(ss), area. The thermal stability of Na2SO3 was studied and the binary phase diagram Na2SO4-Na2S was re-determined. The results indicate that Na2SO3 can exist for a short time up to 750 °C, before it melts. It was also proved that a solid/solid transformation, not reported earlier, occurs at 675 ± 10 °C. At around 700 °C, Na2SO3 gradually breaks down within a few hours, to finally form the solid phases Na2SO4 and Na2S. From HTM measurements a metastable phase diagram including Na2SO3, as well as an equilibrium phase diagram have been constructed for the binary system Na2SO4-Na2S. Improved data on Na2S was experimentally obtained by using solid-state EMF measurements. The equilibrium constant for Na2S(s) was determined to be log Kf(Na2S(s)) (± 0.05) = 216.28 – 4750(T/K)–1 – 28.28878 ln (T/K). Gibbs energy of formation for Na2S(s) was obtained as ΔfG°(Na2S(s))/(kJ mol–1) (± 1.0) = 90.9 – 4.1407(T/K) + 0.5415849(T/K) ln (T/K). The standard enthalpy of formation of Na2S(s) was evaluated to be ΔfH°(Na2S(s), 298.15 K)/(kJ mol–1) (± 1.0) = – 369.0. The standard entropy was evaluated to be S°(Na2S(s), 298.15 K)/(J mol–1 K–1) (± 2.0) = 97.0. Analyses of used refractory material from the Chemrec gasifier were also performed in order to elucidate the stability of the refractory lining. Scanning electron microscopy (SEM) analysis revealed that the chemical attack was limited to 250-300 μm, of the surface directly exposed to the gasification atmosphere and the smelt. From XRD analysis it was found that the phases in this surface layer of the refractory were dominated by sodiumaluminosilicates, mainly Na1.55Al1.55Si0.45O4.</p>

Black liquors are presently combusted in recovery boilers where the inorganic cooking chemicals are recovered and the energy in the organic material is converted to steam and electricity. A new technology, developed by Chemrec AB, is black liquor gasification (BLG). BLG has more to offer compared to the recovery boiler process, in terms of on-site generation of electric power, liquid fuel and process chemicals. A prerequisite for both optimization of existing processes and the commercialization of BLG is better understanding of the physical and chemical processes involved including interactions with the refractory lining. The chemistry in the BLG process is very complex and to minimize extensive and expensive time-consuming studies otherwise required accurate and reliable model descriptions are needed for a full understanding of most chemical and physical processes as well as for up-scaling of the new BLG processes. However, by using these calculated model results in practice, the errors in the state of the art thermochemical data have to be considered. An extensive literature review was therefore performed to update the data needed for unary, binary and higher order systems. The results from the review reviled that there is a significant range of uncertainty for several condensed phases and a few gas species. This resulted in experimental re-determinations of the binary phase diagrams sodium carbonate-sodium sulfide (Na2CO3-Na2S) and sodium sulfate-sodium sulfide (Na2SO4-Na2S) using High Temperature Microscopy (HTM), High Temperature X-ray Diffraction (HT-XRD) and Differential Thermal Analysis (DTA). For the Na2CO3-Na2S system, measurements were carried out in dry inert atmosphere at temperatures from 25 to 1200 °C. To examine the influence of pure CO2 atmosphere on the melting behavior, HTM experiments in the same temperature interval were made. The results include re-determination of liquidus curves, in the Na2CO3 rich area, melting points of the pure components as well as determination of the extent of the solid solution, Na2CO3(ss), area. The thermal stability of Na2SO3 was studied and the binary phase diagram Na2SO4-Na2S was re-determined. The results indicate that Na2SO3 can exist for a short time up to 750 °C, before it melts. It was also proved that a solid/solid transformation, not reported earlier, occurs at 675 ± 10 °C. At around 700 °C, Na2SO3 gradually breaks down within a few hours, to finally form the solid phases Na2SO4 and Na2S. From HTM measurements a metastable phase diagram including Na2SO3, as well as an equilibrium phase diagram have been constructed for the binary system Na2SO4-Na2S. Improved data on Na2S was experimentally obtained by using solid-state EMF measurements. The equilibrium constant for Na2S(s) was determined to be log Kf(Na2S(s)) (± 0.05) = 216.28 – 4750(T/K)–1 – 28.28878 ln (T/K). Gibbs energy of formation for Na2S(s) was obtained as ΔfG°(Na2S(s))/(kJ mol–1) (± 1.0) = 90.9 – 4.1407(T/K) + 0.5415849(T/K) ln (T/K). The standard enthalpy of formation of Na2S(s) was evaluated to be ΔfH°(Na2S(s), 298.15 K)/(kJ mol–1) (± 1.0) = – 369.0. The standard entropy was evaluated to be S°(Na2S(s), 298.15 K)/(J mol–1 K–1) (± 2.0) = 97.0. Analyses of used refractory material from the Chemrec gasifier were also performed in order to elucidate the stability of the refractory lining. Scanning electron microscopy (SEM) analysis revealed that the chemical attack was limited to 250-300 μm, of the surface directly exposed to the gasification atmosphere and the smelt. From XRD analysis it was found that the phases in this surface layer of the refractory were dominated by sodiumaluminosilicates, mainly Na1.55Al1.55Si0.45O4.

Für die Modellierung der Hochdruck-Partialoxidation von Heiz- und Schweröl werden zunächst Untersuchungen des Einsatzstoffes durchgeführt, um deren Verdampfungs- und Pyrolyseverhalten zu bestimmen. Dazu wird das Verfahren der Hochdruck-Thermogravimetrie verwendet. Mit Hilfe der numerischen Strömungsmechanik unter Anwendung von detaillierten Reaktionsmechanismen und eines umfangreichen Partikelmodells werden die Zustände im Reaktor modelliert. Die Validierung mit Verweilzeitmessungen wird demonstriert und damit verbundene Probleme aufgezeigt. Anhand von Untersuchungen am Vergasungsrückstand kann die Existenz von Cenosphären (Tropfenrückstände) und von in der Flamme gebildetem Ruß nachgewiesen werden.

The need for effective disposal of huge volumes of industrial waste is becoming more challenging due to expected imposition of stringent pollution control regulations in the near future. Thermochemical conversion, particularly gasification of organics in the waste is considered the best route from the perspective of volume reduction and prevalent eco-friendly concept of waste-to-energy transformation. It is considered imperative to have adequate understanding of basic combustion features as a part of the thermochemical conversion process, leading to gasification. The aim of this thesis is to understand the fundamental combustion processes associated with one of the top listed hazardous wastes from distilleries (Biochemical Oxygen Demand (BOD) ~ 40,000 - 50,000 mg/L), commonly known as vinasse, stillage or spent wash, through experiments and modeling efforts. Specially designed experiments on distillery effluent combustion and gasification are conducted in laboratory scale reactors. As an essential starting point of the studies on ignition and combustion of distillery effluent containing solids consisting of 62 ± 2 % organics and 38 ± 2 % inorganics (primarily sugarcane derivatives), the roles of solids concentration, drop size and ambient temperature were investigated through experiments on (1) liquid droplets of 65 % and 77 % solids (remaining water) and (2) spheres of dried effluent (100 % solids) of size 0.5 mm to 20 mm diameter combusted at ambient temperatures of 773 to 1273 K. The investigation reveals that the droplets burn with two distinct regimes of combustion, flaming and char glowing. The ignition delay ‘t1’ of the droplets increased with size as is in the case of non-volatile droplets, while that of bone-dry spheres was found to be independent of size. The ‘t1’ decreased with increase in solids concentration. The ignition delay has showed an Arrhenius dependence on temperature. The initial ignition of the droplets and the dry spheres led to either homogeneous (flaming) or heterogeneous (flameless) combustion, depending on the ambient temperature in the case of sphere and on solid concentration and the ambient temperature, in the case of liquid droplets. The weight loss during the flaming combustion was found to be 50 - 80 % while during the char glowing it was 10-20 % depending on the ambient temperature. The flaming time tc is observed as tc~ d2c , as in the case of liquid fuel droplets and wood spheres. The char glowing time tc' is observed as tc ~ d2c as in the case of wood char, though the inert content of effluent char is as large as 50 % compared to 2 - 3 % in wood char. In the case of initial flameless combustion, the char combustion rate is observed to be lower. The heterogeneous char combustion in quiescent air in controlled temperature conditions has been studied and modeled using one-dimensional, spherico-symmetric conservation equations and the model predicts most of the features of char combustion satisfactorily. The measured surface and core temperatures during char glowing typically are in the range of 200 to 400 K and are higher than the controlled temperature of the furnace. Based on the results of single droplet combustion studies, combustion experiments were conducted in a laboratory scale vertical reactor (throughput ranging from 4 to 10 g/s) with the primary aim of obtaining sustained combustion. Spray of effluents with 50 % and 60 % solids (calorific value 6.8 - 8.2 MJ/kg), achieved by an air blast atomizer, was injected into a hot oxidizing environment to determine the parameters (ambient temperature and air-fuel ratio) at which auto-ignition could occur and subsequently studies were continued to investigate pre-ignition, ignition and combustion processes. Effluent with lower solids concentration was considered first from the point of view of the less expensive evaporator required in the field conditions for concentration and a spin-off in terms of better atomization consequently. Three classes of experiments were conducted: 1) Effluent injection from the wall with no auxiliary heat input, 2) Effluent injection with auxiliary heat input and 3) effluent injection within kerosene enveloping flame. Though individual particles in the spray periphery were found to combust, sustained spray combustion was not achieved in any of the three sets of experiments even with fine atomization. While conducting the third class of experiments in an inclined metallic reactor, sustained combustion of the pool resulting of accumulated spray seemed to result in large conversion of carbon. This led to the adoption of a new concept for effluent combustion in which the residence time is controlled by varying reactor inclination and the regenerative heat transfer from the product gases supplies heat for endothermic pre-ignition process occurring on the bed. Combustion and gasification experiments were conducted in an inclined plate reactor with rectangular cross section (80 mm x 160 mm) and 3000 mm long. A support flame was found necessary in the injection zone in addition to the regenerative heat transfer. Effluent with 60% solids was injected as film on the reactor bed. This film disintegrated into fine particles due to induced aerodynamic stretching and shear stripping. Combustion of individual particles provided exothermic heat profile and resulted into high carbon conversion. However, effluent clogging in the cold injection zone hindered system from attaining steady state. Effluent injected directly on the hot zone caused it to remain mobile due to the spheroidal evaporation and thus assuaging this problem. Improved mass distribution was achieved by displacing nozzle laterally in a cycle, actuated by a mechanism. Consistent injection led to sustained effluent combustion with resulting carbon conversion in excess of 98 %. The typical gas fractions obtained during gasification condition (air ratio = 0.3) were CO2 = 14.0 %, CO = 7.0 %, H2 = 12.9 %, CH4 - 1 % H2S = 0.6 - 0.8 % and about 2 % of saturated moisture. This composition varied due to variation in temperature (± 30 K) and is attributed to combined effect of local flow variations, shifting zones of endothermic processes due to flowing of evaporating effluent over a large area. In order to minimize this problem, experiments were conducted by injecting effluent at higher solids (73 % solids is found injectable). The effluent was found to combust close to the injection location-due to the reduced ignition delay and lower endothermic evaporation load helped raising the local temperature. This caused the pyrolysis to occur in this hottest zone of the reactor with higher heating rates resulting in larger yield of devolatilized products and improved char conversion. Effluent combustion was found to sustain temperature in the reactor under sub-stoichiometric conditions without support of auxiliary heat input and achieved high carbon conversion. These results inspired the use of higher concentration effluent, which is also known in the case of wood to have improved gasification efficiency due to reduction in moisture fraction. In addition, the recent studies on the sulfur emission in the case of black liquor combustion in recovery boilers have revealed that with increase in solids concentration, release of sulfur in gas phase is reduces. The required concentration can be carried out using low-grade waste heat from the reactor itself. It was found through experiments that, even though spray ignition occurred at this concentration, the confined reactor space prevented the spray from attaining sustained combustion. This led to the conduct of experiments in a new vertical reactor with adequate thermal inertia, essential to prevent variations in local temperature to reach a steady state gasification and required space to accommodate the spray. The results of the experiments conducted in the vertical reactor in which effluents with 73 % solids, heated close to the boiling point and injected as fine spray in a top-down firing mode are consolidated and reported in the thesis in detail. Single particle combustion with enveloping faint flame was seen unlike stable flame found in coal water slurry spray combustion. Sustained gasification of gas-entrained particles occurred at reactor temperature in the range of 950 K - 1000 K and sub-stoichiometric air ratio 03 - 0.35 without the support of auxiliary fuel. The typical gas fractions obtained during gasification condition (air ratio = 0.3) were CO2 = 10.0 -11.5 %, CO - 10.0 - 12.0 %, H2 - 6.7 - 8.0 %, CH4 = 1.75 % H2S = 0.2 - 0.4 % and about 2 % of saturated moisture. The carbon conversion obtained was in the range of 95 - 96 %. These experiments have provided the conditions for gasification. The extraction of potassium salts (mostly sulfates, carbonate and chloride) from the ash, using a simple water leaching process, was found to recover these chemicals to as high an extent as 70 - 75 % of total ash. In summary it is concluded that increasing the solid concentrations to as high levels as acceptable to the system (~ 75 %) and introducing as a fine spray of heated material (~ 363 K) into furnace with air at sub-stoichiometric conditions in a counter current combustion reactor will provide the frame work for the design of a gasification system for vinasse and similar effluent material. The thesis consists of seven chapters. Chapter 1 introduces the problem and motivation of the work presented in the thesis. Literature review is presented in Chapter 2. The Chapter 3 deals with the single particle combustion studies. The results of effluent spray combustion experiments conducted in a laboratory scale vertical reactor are presented in Chapter 4. The results of combustion and gasification experiments conducted in another variant of a reactor, namely, inclined flat plate rectangular reactor is consolidated in Chapter 5. The results of gas-entrained spray gasification experiment of higher concentration effluent injected as spray in the vertical reactor are presented in Chapter 6. The general conclusions and scope for the future work are presented in the concluding chapter 7.

Vergasungsprozesse, bei denen kohlenstoffhaltige Ausgangsstoffe in ein vorwiegend aus Wasserstoff und Kohlenmonoxid bestehendes Synthesegas umgewandelt werden, stellen eine Schlüsseltechnologie für eine zukünftige nachhaltige Rohstoffnutzung dar. Der Grund für den Einsatz von Hochdruckverfahren liegt in der Steigerung der Wirtschaftlichkeit. Die numerische Simulation der Hochdruckvergasung hat große Schnittmengen mit der Verbrennungssimulation. So kann die Flammenzone mit Hilfe von Verbrennungsmodellen beschrieben werden. In der Arbeit wurden Simulationen einer Versuchsanlage für Hochdruckvergasung mit Hilfe kommerzieller CFD-Codes und mit Hilfe des quelloffenen Codes OpenFOAM durchgeführt. Eine Analyse des Verbrennungsmodells ergab, dass die wesentlichen Reaktionen im Reformierungsbereich, wo kein freier Sauerstoff mehr vorhanden ist, nur unzureichend abgebildet wurden. Durch die Verwendung eines alternativen Ansatzes konnte der Modellierungsfehler deutlich reduziert werden.

Renewable Natural Gas (RNG) is a low-carbon fuel source that is derived from the anaerobic digestion (AD) or thermal gasification (TG) of biomass, or produced using renewable electricity through the methanation of carbon dioxide. This thesis uses a thermodynamic balance to determine the total technical potential of RNG in the United States, as well as the future technical potential of methanation-derived RNG based on growth curves for renewable electricity. Furthermore, this work establishes an analytic decision-making framework for determining on a rolling basis, from an economic standpoint, whether to sell electricity directly to the grid, or produce and sell methanation-derived RNG. This framework is used to establish the economic potential of RNG, based on Texas wind resources. This work details the formulation of a model that determines which production option generates more marginal profit, based on fluctuating electricity and gas prices. The model also aggregates the total amount of electricity and RNG sold, assuming that the main objective is to maximize the marginal profit of integrated wind- and methanation facilities. This work concludes that the annual technical potential of methanation-derived RNG nationally was 1.03 Quads in 2011. The technical potential of biomass-derived RNG was 9.5 Quads. Thus, the total 2011 technical potential of RNG in the United States was 10.5 Quads, or equal to roughly 43% of the total US consumption of natural gas that year. Assuming a constant, 80% electrolyser efficiency, the technical potential of methanation-derived RNG is expected to rise at an average rate of 1.4% per year, following growth curves for renewable power, until the year 2040, when it will be 1.54 Quads. The 2011 economic potential of methanation-derived RNG in Texas was between 2.06×10⁷ MMBTU and 3.19×10⁷ MMBTU, or between 19.4% and 30.1% of the corresponding annual technical potential. Furthermore, the total marginal profit increase from introducing the option of producing and selling methanation-derived RNG was around $366 million, given a ‘best case scenario’ for the state of Texas. / text