Integrated Gasification Combined Cycle Process Research Articles

Simulation of a moving bed chemical looping system for electricity production from coal via chemical looping water splitting

AbstractCoal is a crucial energy source for modern industry and society. Because coal is one of the most CO2‐intensive carbonaceous fuels, the combustion of coal with CO2 capture is of great environmental relevance. However, the conventional coal‐based power generation processes, including the pulverized coal (PC) boiler process and the integrated gasification combined cycle (IGCC) process, suffer a significant efficiency loss when integrated with conventional CO2 capture methods. Chemical looping technology is a promising alternative pathway for coal‐based power generation with intrinsic CO2 separation and capture. Process simulation of chemical looping processes can provide an overview on the viability of the processes, thereby quantifying their advantages over conventional processes. This study presents the process simulation of a chemical looping water splitting combined cycle (CLWS‐CC) system for electricity generation. The CLWS‐CC process directly uses coal as the feedstock to produce H2, which is subsequently combusted in a combined cycle to generate electricity. The oxygen carriers used in the chemical looping process are optimized in their composition. Autothermal operation is established within the chemical looping system. Four CLWS‐CC cases that operate at different pressures are considered. In two of the four cases, an unequal pressure operating strategy is adopted to minimize the compression power consumption in order to enhance the overall process energy efficiency. The process simulation shows that the CLWS‐CC process is able to achieve an 18% increase in net plant efficiency over the conventional IGCC process.

High‐performance oxygen transport membrane reactors integrated with IGCC for carbon capture

AbstractPrecombustion carbon capture is an effective strategy to reduce large‐scale CO2 emissions, which is mainly used in the area of integrated gasification combined cycle (IGCC) power plants. Oxygen transport membranes (OTMs) were suggested as the air separation unit to produce high purity oxygen for the gasifier. However, the improvement in efficiency was limited. Here, a new IGCC process is reported based on a robust OTM reactor, where the OTM reactor is used behind the coal gasifier. This IGCC‐OTM process fulfills syngas oxidation, H2 production, and carbon capture in one unit, thus a significant decrease of the energy penalty is expectable. The membrane reactor does not use noble metal components, and exhibits high hydrogen production rates, high hydrogen separation factor (103–104), and stable performance in a gas mixture mimicking real syngas compositions from a coal gasifier with H2S concentrations up to 1,000 ppm.

Energy and exergy co-optimization of IGCC with lower emissions based on fuzzy supervisory predictive control

This paper presents an energy and exergy co-optimization method of integrated gasification combined cycle (IGCC) based on Fuzzy Supervisory Predictive Control (FSPC). Firstly, a green IGCC process is proposed which contains three principle couplings: air separation unit (ASU), heat recovery steam generator (HRSG) and CO2 capture/storage unit (CCS). From law of thermodynamics, using substance thermophysical parameters, the energy efficiency and exergy efficiency of IGCC are successively defined. The IGCC power station has features such as closed coupling, large time lag and non-linearity, however, faster response speed and lower overshoot are always the unremitting pursuits. Therefore, the Fuzzy Supervisory Predictive Control (FSPC) method is proposed to implement robust control under complex disturbances by pre-considering unmeasurable disturbance and measurable disturbance. The fuzzy rules extracted from historical bigdata are employed in supervisory layer to make the precise control decisions. Finally, the energy and exergy co-optimization model is built and solved for higher efficiency and economic effectiveness. Taking the large-scale (300MW) IGCC for example, after using FSPC, the efficiency of water recovery is increased from 40.7% to 62.1% with the ratio of 52.6% because of waste water recovery (WWR) system. The net efficiency of proposed IGCC system is increased from 37.6% to 41.7% with the ratio of 10.9%. The exergy efficiency of IGCC system is increased from 36.5% to 39.2% with the ratio of 7.4%. The proposed method has great significance for the energy-saving and Near-zero emissions (NZEC) IGCC with high safety and robust control under supercritical (SC) or ultra-super critical (USC) state.

Performance analysis of an eight-layered bed PSA process for H2 recovery from IGCC with pre-combustion carbon capture

Integrated gasification combined cycle (IGCC) plants that are also capable of CO2 capture have received significant attention as the next generation of coal-based power plants for the co-production of H2 and electrical power. Accordingly, for a cost-effective and environmentally friendly poly-generation IGCC process, efficient techniques need to be developed to recover H2 from the syngas of an IGCC plant with carbon capture.In this study, an eight-layered bed pressure swing adsorption (PSA) process using activated carbon and zeolite simultaneously was developed to produce high purity H2 from the H2-rich syngas of an IGCC plant. As a first step, the separation performance was compared between four-and eight-layered bed PSA processes. The eight-layered bed PSA process led to higher recovery of H2 at the condition of a similar H2 purity owing to a greater number of pressure equalization steps in the operational step configuration. It is noteworthy that the productivity could be greatly improved as the purge gas was replaced from the product gas to residual gas in a bed. When the adsorption bed was purged by using the residual gas after the first pressure equalization step, recovery improved by about 3 ∼ 6% at the condition of 99.99+mol% H2 purity in comparison with the product-purge PSA configuration. On the other hand, the highest H2 recovery that could be obtained for the requirement of 99.99mol% H2 purity, was ∼ 89.7% from the eight-layered bed H2 PSA process when the purge gas was provided from the residual gas of the adsorption bed after the last depressurization pressure equalization step. However, as the concentration of CO in the desired H2 product was higher in the PSA configuration when using residual gas compared to the product gas, the operational configuration of PSA needed to be decided by the desired H2 purity and impurity constraints for application. Furthermore, the tail gas from the PSA contained 45–66mol% of H2 and CO, depending on the applied PSA configurations, and could be used to drive a gas turbine without any loss of the syngas, even though the recompression energy loss required evaluation.

Comparison of CO2 Capture Approaches for Fossil-Based Power Generation: Review and Meta-Study

This work is a meta-study of CO2 capture processes for coal and natural gas power generation, including technologies such as post-combustion solvent-based carbon capture, the integrated gasification combined cycle process, oxyfuel combustion, membrane-based carbon capture processes, and solid oxide fuel cells. A literature survey of recent techno-economic studies was conducted, compiling relevant data on costs, efficiencies, and other performance metrics. The data were then converted in a consistent fashion to a common standard (such as a consistent net power output, country of construction, currency, base year of operation, and captured CO2 pressure) such that a meaningful and direct comparison of technologies can be made. The processes were compared against a standard status quo power plant without carbon capture to compute metrics such as cost of CO2 emissions avoided to identify the most promising designs and technologies to use for CO2 emissions abatement.

Integration of greenhouse gas control technologies within the energy, water and food nexus to enhance the environmental performance of food production systems

The sustainability of food production systems is inherently linked with energy, water and food (EWF) resources directly and in-directly throughout their lifecycle. The understanding of the interdependencies between the three resource sectors in the context of food production can provide a measurable account for resource requirements, while meeting food security objectives. The energy, water and food Nexus tool developed by the authors has been designed to model the inter-dependency between energy, water and food resources, whilst conducting an environmental assessment of product systems. With emphasis on the inter-linkages between EWF resources, the tool quantifies material flows, natural resource and energy consumption at component unit process level. This work integrates greenhouse gas control and waste to power technologies within the energy, water and food Nexus tool and evaluates the environmental impact of a hypothetical food product system designed to deliver a perceived level of food self-sufficiency (40%) for the State of Qatar. Multiple system configurations, representative of different pathways for the delivery of consistent food products are evaluated, transforming a once linear product system into a circular design. The sub-systems added consist of a biomass integrated gasification combined cycle which recycles solid waste into useful forms of energy that can be re-used within the nexus. In addition, a carbon capture sub-system is integrated to capture and recycle CO2 from both the fossil fuel powered and the biomass integrated gasification combined cycle energy sub-systems. The integration of carbon capture with the biomass integrated gasification combined cycle transforms the carbon neutral biomass integrated gasification combined cycle process to a negative greenhouse gas emission technology known as bio-energy with carbon capture and storage. For the different scenarios and sub-system configurations considered, the global warming potential can be theoretically balanced (reduced by ∼98%) through the integration of photovoltaics, biomass integrated gasification combined cycle and carbon capture technologies. The peak global warming potential, i.e. a fully fossil fuel dependent system, is recorded at 1.73 × 109 kg CO2 eq./year whilst the lowest achievable global warming potential is 2.18 × 107 kg CO2 eq./year when utilising a combination of photovoltaics, carbon capture integrated with combined cycle gas turbine in addition to the integrated negative emission achieving system. The natural gas consumption is reduced by 7.8 × 107 kg/year in the best case configuration, achieving a credit. In the same scenario, the photovoltaics land footprint required is calculated to a maximum of 660 ha. The maximum theoretically achievable negative emission is 1.09 × 109 kg CO2/year.

Paper mills integrated gasification combined cycle process with high energy efficiency for cleaner production

The papermaking industry has developed rapidly in recent years in China. Papermaking is a high-energy-consuming process. Consequently, large-scale paper mills usually have cogeneration systems that supply both electricity and steam for the papermaking process. In China, almost all these cogeneration systems in paper mills are powered by coal combustion, which consumes a large amount of energy and emits large amounts of greenhouse gas. The Integrated Gasification Combined Cycle (IGCC) technology is regarded as a clean and efficient method of coal utilization. In this work, an IGCC process for application in paper mills was designed and modeled. An IGCC coupled with a cascade refrigeration process (CRP) was further proposed in order to reuse the waste heat from the dryer section and improve the energy efficiency of the papermaking process. A paper with a conventional cogeneration system, one with an IGCC cogeneration system, and one with an IGCC coupled with a CRP cogeneration system were analyzed and compared in terms of energy efficiency, capital investment, operational cost, and dynamic payback period. The results showed that the integration of IGCC technology allows paper mills to be more competitive than those featuring conventional cogeneration systems in terms of energy efficiency and operational cost.

Technoeconomic Analysis of an Integrated Gasification Combined Cycle System as a Way to Utilise Bagasse

Sugar cane milling processes leave a waste solid residue, known as bagasse, which is subsequently combusted with the aim of covering the energy demands of the sugar plants. An alternative way to co-generate electricity and heat is via the integrated gasification combined cycle (IGCC) process. The main sections of this process are the gasification unit and the combined power generation cycle (Brayton-Rankine) and it is usually preferred to combustion in small scale applications due to enhanced electricity yields and lower emissions. Therefore, the aim of this study is to examine whether or not the IGCC process is more feasible than combustion for the utilisation of bagasse (large scale application). Aspen plus process simulator was employed to simulate the investigated system and based on the simulations technical and economic analyses were carried out. Consequently, the cost of electricity was calculated and compared with that derived from combustion systems. So far, to the best of our knowledge, no comparative assessment between the basic biomass-to-electricity processes was attempted. Thus, the present study focuses on integrating exhaustive process simulations along with thorough energetic and financial calculations to evaluate the feasibility of the IGCC process. This methodology provides a robust mechanism and can be used as a reliable decision making tool

Production of power using underground coal gasification

ABSTRACTUnderground coal gasification (UCG) is a process that converts deep, un-mineable coal resources into syngas, which can then be converted into valuable end products such as electric power. This paper provides a summary of the options to combine UCG with electric power production and focuses on commercial-scale applications using a combined-cycle power plant including integration options and syngas cleanup steps. Simulation results for a UCG power plant with carbon capture are compared against the results for an equivalent Integrated Gasification Combined Cycle (IGCC) plant using the same feedstock. Relative capital cost savings for a UCG power plant are estimated based on published IGCC process unit costs. The UCG power plant with carbon capture is shown to provide a higher thermal efficiency, lower CO2 intensity, and lower capital cost than an equivalent IGCC plant. Finally, the potential of UCG as a method for producing cost-effective, low-emissions electrical power from deep coal is discussed and some of the challenges and opportunities are summarized.

Environmental assessment of energy generation from agricultural and farm waste through anaerobic digestion

While Turkey is one of the world's largest producers and exporters of agricultural goods, it is also, at the same time a net importer of energy carriers. This dichotomy offers a strong incentive to generate energy from agricultural and farming waste; something which could provide energy security for rural areas. Combined with the enhanced energy security for farming areas, the production of energy in this manner could conceivably contribute to the overall national effort to reduce the Turkey's carbon footprint. This study explores the environmental benefits and burdens of one such option, that is, biogas production from a mixture of agricultural and animal waste through anaerobic digestion (AD), and its subsequent use for electricity and heat generation. A life-cycle assessment methodology was used, to measure the potential environmental impact of this option, in terms of global warming and total weighed impact, and to contrast it with the impact of producing the same amount of energy via an integrated gasification combined cycle process and a hard coal power plant. This study concentrates on an AD and cogeneration pilot plant, built in the Kocaeli province of Turkey and attempts to evaluate its potential environmental impacts. The study uses laboratory-scale studies, as well as literature and LCI databases to derive the operational parameters, yield and emissions of the plant. The potential impacts were calculated with EDIP 2003 methodology, using GaBi 5 LCA software. The results indicate that N2O emissions, resulting from the application of liquid and solid portions of digestate (a by-product of AD), as an organic fertilizer, are by far the largest contributors to global warming among all the life cycle stages. They constitute 68% of the total, whereas ammonia losses from the same process are the leading cause of terrestrial eutrophication. The photochemical ozone formation potential is significantly higher for the cogeneration phase, compared to other life cycle stages of the proposed scenario, due to NOx being emitted from the gas engine during combustion. Overall, the total environmental impact of the option was determined to be ten times lower than that of a hard coal option and 50% lower than the gasification option, since the latter does not generate digestate that is able to replace mineral fertilizer, thus mitigating the environmental footprint. Finally, the sustainability of energy production from agricultural and farm waste, via AD, was further enhanced by eliminating it from conventional waste management system practiced in the region, i.e. landfilling.

Economic assessment of integrated coal gasification combined cycle with sorbent CO2 capture

An integrated gasification combined cycle process with sorbent CO2 capture (IGCC-SCC) using lime (CaO) was developed to assess the application of the gasification process to the power generation industry. Aspen Plus was used to simulate the detailed heat and material balance of the process. The process modeling results, including the composition, flow rate, temperature, pressure and enthalpy of different streams, were used to determine the sizes of the process units and related equipment.A high-level economic model was prepared to evaluate the economic viability of an IGCC-SCC plant and to compare it to GE Energy and Shell Convective gasification plants for converting coal to power. The results show that the proposed process would produce 560MW of power with a net plant efficiency of 46.4% compared to those of the GE Energy and Shell Convective plants, which are 39.2% and 42.0%, respectively. The total capital investment required for an IGCC-SCC facility having a coal capacity of 3000tpd was estimated to be $1082million, which translates to a specific annual capital expenditure (CAPEX) of 1889$/kW. It was estimated that an IGCC-SCC plant could generate an after-tax internal rate of return (IRR) of 14.4%, which is equivalent to a payback period of 9.1years. This represents an improvement over the IRR and payback period of the GE Energy and Shell Convective plants at the same capacity.A sensitivity analysis was also conducted in order to identify the relative importance of key economic variables driving the project returns and to quantify the impact of any changes to the assumptions used in the project economics.

Energy and exergy analysis of chemical looping combustion technology and comparison with pre-combustion and oxy-fuel combustion technologies for CO2 capture

Carbon dioxide (CO2) emitted from conventional coal-based power plants is a growing concern for the environment. Chemical looping combustion (CLC), pre-combustion and oxy-fuel combustion are promising CO2 capture technologies which allow clean electricity generation from coal in an integrated gasification combined cycle (IGCC) power plant. This work compares the characteristics of the above three capture technologies to those of a conventional IGCC plant without CO2 capture. CLC technology is also investigated for two different process configurations—(i) an integrated gasification combined cycle coupled with chemical looping combustion (IGCC–CLC), and (ii) coal direct chemical looping combustion (CDCLC)—using exergy analysis to exploit the complete potential of CLC. Power output, net electrical efficiency and CO2 capture efficiency are the key parameters investigated for the assessment. Flowsheet models of five different types of IGCC power plants, (four with and one without CO2 capture), were developed in the Aspen plus simulation package. The results indicate that with respect to conventional IGCC power plant, IGCC–CLC exhibited an energy penalty of 4.5%, compared with 7.1% and 9.1% for pre-combustion and oxy-fuel combustion technologies, respectively. IGCC–CLC and oxy-fuel combustion technologies achieved an overall CO2 capture rate of ∼100% whereas pre-combustion technology could capture ∼94.8%. Modification of IGCC–CLC into CDCLC tends to increase the net electrical efficiency by 4.7% while maintaining 100% CO2 capture rate. A detailed exergy analysis performed on the two CLC process configurations (IGCC–CLC and CDCLC) and conventional IGCC process demonstrates that CLC technology can be thermodynamically as efficient as a conventional IGCC process.

Dynamic modelling and simulation of IGCC process with Texaco gasifier using different coal

Integrated gasification combined cycle (IGCC) is considered as a viable option for low emission power generation and carbon dioxide sequestration. As a part of the process of IGCC plant design and development, modelling and simulation study of the whole IGCC process is important for thermodynamic performance evaluation, study of carbon capture readiness and economic analysis. The work presented in the paper is to develop such a whole system model and simulation platform. A simplified dynamic model for the IGCC process is developed, in which Texaco gasifier is chosen to give the basic representation for the IGCC process. The chemical equilibriums principle is used to predict the syngas contents in the modelling procedure. The influences of key parameters to regulate the input such as oxygen/coal ratio and water/coal ratio to syngas generation are studied. The simulation results are validated by comparing with the industry data provided by the Lu-nan fertilizer factory. Water-shift reactor, gas turbine and heat recovery steam-generation modules are modelled to study the dynamic performance with respect to the variation from the input of syngas stream. The simulation results reveal the dynamic changes in the plant outputs, including gas temperature, power output and mole percentages of hydrogen and carbon dioxide in the syngas. The process dynamic responses with three types of coal inputs are studied in the paper and their dynamic variation trends are presented via the simulation results.

CaO-Based Energy and CO2 Storage System for the Flexibilization of an IGCC Plant with Carbon Capture

Integrated gasification combined cycle (IGCC) plants have significant potential for efficient power generation with carbon capture and storage (CCS). The IGCC process with CCS, however, has multiple temperature and flow constraints which severely limit its flexibility to meet the dynamic demands of the current grid. A novel energy and CO2 storage system based on the reversible reaction of CaO with CO2 has therefore recently been proposed, to enable a temporary increase in the IGCC peak power output. This is achieved by (1) providing additional high quality heat for electricity production and (2) providing temporary CO2 storage, thus reducing the parasitic load of the CCS system by reducing the energy requirements for acid gas removal (AGR) and CO2 compression. In contrast to existing concepts, the carbonation–calcination loop herein is operated in a cyclic mode; the CaCO3 produced during carbonation is not regenerated immediately, but stored until off-peak periods during which the CaCO3 is regenerated res...

Dynamic modeling of Shell entrained flow gasifier in an integrated gasification combined cycle process

The Shell coal gasification system is a single-stage, up-flow, oxygen-blown gasifier which utilizes dry pulverized coal with an entrained flow mechanism. Moreover, it has a membrane wall structure and operates in the slagging mode. This work provides a detailed dynamic model of the 300MW Shell gasifier developed for use as part of an overall IGCC (integrated gasification combined cycle) process simulation. The model consists of several sub-models, such as a volatilization zone, reaction zone, quench zone, slag zone, and membrane wall zone, including heat transfers between the wall layers and steam generation. The dynamic results were illustrated and the validation of the gasifier model was confirmed by comparing the results in the steady state with the reference data. The product gases (H2 and CO) began to come out from the exit of the reaction zone within 0.5s, and nucleate boiling heat transfer was dominant in the water zone of the membrane wall due to high heat fluxes. The steady state of the process was reached at nearly t=500s, and our simulation data for the steady state, such as the temperature and composition of the syngas, the cold gas efficiency (81.82%), and carbon conversion (near 1.0) were in good agreement with the reference data.

Gas and particle flow characteristics in the gas reversing chamber of a syngas cooler for a 300 MWe IGCC process

The gas reversing chamber (GRC) is the top part of a syngas cooler in the Shell coal gasification process, in which the quenched syngas flowing from the gasifier is turned downward into evaporator channels. Using computational fluid dynamics (CFD), this study investigated the detailed gas/particle flow and heat transfer characteristics in the GRC of an integrated gasification combined cycle (IGCC) process with 300 MWe capacity for operational loads between 50 and 100%. The gas flow rapidly changed its direction to downward after impinging onto the wall opposite to the inlet. This led to the formation of a higher velocity region along the opposite side, increasing the gas flow rate in the outer channel of the evaporator. In contrast, a region with low velocity below 2 m/s developed towards the inlet side above the evaporator, which may lead to the significant deposition of fly slag particles onto the structural elements. Larger wall heat flux appeared along the main gas stream with a maximum of 180 kW/m2 at full load. Convection accounted for about 70% of the total heat transfer rate, of which the coefficient was correlated to Nu = 8.778 Re0.435Pr0.3. Many particles impinged onto the wall along the main gas stream, especially at the joint connecting the transfer duct and the GRC. However, erosion by fly slag was not expected to be significant, mainly due to the reduced gas velocity at the high operating pressure (43 bar).

Economic evaluation of pre-combustion CO2-capture in IGCC power plants by porous ceramic membranes

Pre-combustion-carbon-capture is one of the three main routes for the mitigation of CO2-emissions by fossil fueled power plants. Based on the data of a detailed technical evaluation of CO2-capture by porous ceramic membranes (CM) and ceramic membrane reactors (WGSMR) in an Integrated-Gasification-Combined-Cycle (IGCC) power plant this paper focuses on the economic effects of CO2-abatement. First the results of the process simulations are presented briefly. The analysis is based on a comparison with a reference IGCC without CO2-capture (dry syngas cooling, bituminous coal, efficiency of 47.4%). In addition, as a second reference, an IGCC process with CO2 removal based on standard Selexol-scrubbing is taken into account. The most promising technology for CO2-capture by membranes in IGCC applications is the combination of a water gas shift reactor and a H2-selective membrane into one water gas shift membrane reactor. For the WGSRM-case efficiency losses can be limited to about 6%-points (including losses for CO2 compression) for a CO2 separation degree of 90%. This is a severe reduction of the efficiency loss compared to Selexol (10.3% points) or IGCC–CM (8.6% points). The economic evaluation is based on a detailed analysis of investment and operational costs. Parameters like membrane costs and lifetime, costs of CO2-certificates and annual operating hours are taken into account. The purpose of these evaluations is to identify the minimum cost of electricity for the different capture cases for the variation of the boundary conditions. Fixing 90% CO2 separation the analysis identifies clearly that the economic minimum for cost of electricity and maximum thermodynamic efficiencies do not coincide. The cost of electricity for the reference case was 67€/MWh and for the WGSMR integration with 90% CO2 separation 57€/MWh, if certificate costs of 30€/tCO2, membrane costs of 300€/m2 and 8000 operating hours/year are considered. Further studies on the sensitivity of cost of electricity on the technical and commercial boundary conditions will be presented.

CO2emissions reduction technologies in IGCC: ELCOGAS's experiences in the field

This paper introduces the main research, development and innovation (R&D&I) activities of ELCOGAS related to CO2 emissions reduction. The largest R&D&I investment in the last decade focused on CO2 capture, with the aim of (i) demonstrating the feasibility of CO2 capture and H2 production in an integrated gasification combined cycle (IGCC) that uses solid fossil fuels and residues as feedstock and (ii) obtaining representative economic data. Its main milestone was the commissioning in 2010 of a carbon capture pilot plant integrated in Puertollano IGCC power plant which captured 100 t/d of CO2 while producing 2 t/d of high purity H2, using proven and commercial technology. In this paper, technical results obtained, lessons learnt during the project, as well as, economic data using this pilot plant are reported. ELCOGAS is also acquiring relevant knowledge in the field of co-gasification of biomass. The most recent milestone in this subject is the execution in 2012 of real tests at two levels (2 and 4% in weight) and with two different kinds of biomass (olive oil residue and grape seed meal) pointing at assessing the influence of biomass in the IGCC process including CO2 capture within FECUNDUS (RFCR-CT-2010–00009). ELCOGAS S.A. is a Spanish company which operates the Puertollano 335MWISO IGCC demonstration power plant. © 2013 Society of Chemical Industry and John Wiley & Sons, Ltd

An Integrated Framework for Modeling, Synthesis, Analysis, and Optimization of Coal Gasification-Based Energy and Chemical Processes

A framework is proposed for integration of unit modeling, process synthesis, analysis, optimization, and process design of coal gasification-based energy and chemical processes. The conceptual models of these processes are built by the modeling and synthesis blocks in the framework, which are the bases of analysis and optimization. A number of analysis techniques are employed in the framework to fully understand the characteristics of the processes and their performances from technical, economic, and environmental points of view. Life cycle assessment and sustainability analysis are also included in the framework. According to these multilayer analyses, optimization is included in this framework to explore the best process or the best operational parameter set. Because of the systematic integration of the above techniques, the proposed framework could provide a comprehensive study for coal gasification-based processes. Three coal gasification-based processes are selected as the study cases in this Article. They are an integrated gasification combined cycle process, a methanol production, and a coproduction process combining the first two processes. The exergy efficiencies and economic investments of the three processes are analyzed and compared. The key parameters for material distribution in the coproduction process are optimized from the exergy efficiency and the investment points of view.

Economic evaluation of IGCC plants with hot gas cleaning

This paper investigates whether coal-fired Integrated Gasification Combined-Cycle (IGCC) power plants can be an economically viable future technology for providing less carbon-intensive electricity and heat energy in Germany than today. In the context of CO2 emission mitigation in power generation, energy conversion technologies enabling the implementation of Carbon Capture and Storage (CCS) need to be considered. IGCC is such a technology, as it utilizes coal but does not necessarily emit CO2. In our study we investigate, from an economic perspective, whether IGCC plants can be an alternative to nuclear and/or conventional coal-fired power plants. The research is based on scenario analysis. The starting point is the expected shut-down of nuclear power stations and outdated coal-fired power plants, as well as the projected evolution of the CO2 price. The hot gas cleaning option in IGCC plants is of particular interest, as it allows a significant enhancement of the efficiency of the IGCC technology and the use of combined heat and power production (CHP). Corresponding supplementary earnings (incl. subsidies) are compared with an increase in specific investment costs. Besides hot gas cleaning, we also investigate the economic impact of injecting pure CO2 (separated from the IGCC process) into oilfields, as Enhanced Oil Recovery (EOR) can help to reduce the costs of CO2 transport and storage. Based on the results from our analysis we find that the replacement of currently operating power plants by IGCC facilities is only reasonable under certain circumstances, e.g. for locational reasons. Furthermore, from today’s perspective, and due to its various advantages, a complete abandonment of the IGCC technology seems rather unlikely. Our analysis of NPVs of total costs indicates that some IGCC designs exist that are less expensive to set up and operate than a conventional reference power plant. The option of injecting CO2 sequestered from the power plant process into almost depleted oil fields appears attractive for a utility investing in IGCC technology, rendering such a plant configuration as likely cost-competitive. However, with regard to climate change mitigation, the least-cost investment alternative is not necessarily the one with the lowest GHG emissions. Significant cost reductions can be achieved by improving the efficiency or the availability of the plant. Finally, the NPV changes markedly when the heat-to-power ratio is altered, and high ratios are found to be incompatible with NPV minimization.