Gasification-based Power Generation Research Articles

Sustainability assessment of gas based power generation using a life cycle assessment approach

PurposeIndia is a developing economy along with an increasing population estimated to be the largest populated country in about seven years. Simultaneously, its power consumption is projected to increase more than double by 2020. Currently, the dependence on coal is relatively high, making it the largest global greenhouse gas emitting sector which is a matter of great concern. The purpose of this paper is to evaluate the environmental impacts of the natural gas electricity generation in India and propose a model using a life cycle assessment (LCA) approach.Design/methodology/approachLCA is used as a tool to evaluate the environmental impact of the natural gas combined cycle (NGCC) power plant, as it adopts a holistic approach towards the whole process. The LCA methodology used in this study follows the ISO 14040 and 14044 standards (ISO 14040: 2009; ISO 14044: 2009). A questionnaire was designed for data collection and validated by expert review primary data for the annual environmental emission was collected by personally visiting the power plant. The study follows a cradle to gate assessment using the CML (2001) methodology.FindingsThe analysis reveals that the main impacts were during the process of combustion. The Global warming potential is approximately 0.50 kg CO2 equivalents per kWh of electricity generation from this gas-based power plant. These results can be used by stakeholders, experts and members who are authorised to probe positive initiative for the reduction of environmental impacts from the power generation sector.Practical implicationsConsidering the pace of growth of economic development of India, it is the need of the hour to emphasise on the patterns of sustainable energy generation which is an important subject to be addressed considering India’s ratification to the Paris Climate Change Agreement. This paper analyzes the environmental impacts of gas-based electricity generation.Originality/valuePresenting this case study is an opportunity to get a glimpse of the challenges associated with gas-based electricity generation in India. It gives a direction and helps us to better understand the right spot which require efforts for the improvement of sustainable energy generation processes, by taking appropriate measures for emission reduction. This paper also proposes a model for gas-based electricity generation in India. It has been developed following an LCA approach. As far as we aware, this is the first study which proposes an LCA model for gas-based electricity generation in India. The model is developed in line with the LCA methodology and focusses on the impact categories specific for gas-based electricity generation.

Evaluating the Electricity Supply in Turkey Under Economic Growth and Increasing Electricity Demand

The growing economy and residential consumption cause an increasing trend in the demand for electricity in Turkey. The country imports a quite ratio of its energy resources and heavily depend on the fossil fuels. On the other hand, the demand for the electricity that needs to be provided using resources that have minimum cost, sustainable supply and long term cycle is increasing parallel to the economic growth in the country. The long term investments on the renewable energy resources and hydroelectric plants affect the electricity supply. The country is planning to have a nuclear power plant in near future. Turkey stills provides the large part of its electricity from coal and natural gas. The natural gas based power generation is still expensive and that affect the power prices. In this research, the Turkish electricity market is analysed first, then the relationship between economic growth and electricity demand are analysed. The annual electricity demand and supply are also discussed.

Thermo-economic investigation: an insight tool to analyze NGCC with calcium-looping process and with chemical-looping combustion for CO2capture

In this work, three kinds of natural gas-based power generation processes for CO2 capture and storage, that is, natural gas-combined cycle with pre-combustion decarburization (NGCC-PRE), NGCC-PRE with calcium-looping process, and NGCC-PRE with chemical-looping combustion (NGCC-CLC), are analyzed by Aspen Plus. The effects of two decisive variables (i.e., steam-to-natural gas (S/NG) ratio and oxygen-to-natural gas (O/NG) ratio) on the thermodynamic performances of individual process, such as energy and exergy efficiencies, are investigated systematically. Based on simulation outcomes, all the three processes are favored by operating at S/NG = 2.0 and O/NG = 0.65. Furthermore, comparisons of individual system efficiencies and exergy destruction contributor are herein involved. The results show that the highest system efficiencies and lowest exergy destruction are achieved in the NGCC-CLC process. In addition, capital investment, dynamic payback period, net present value, and internal rate of return are used for deciding the economic feasibility and surely are involved in this work for comparison purpose. Copyright © 2016 John Wiley & Sons, Ltd.

Gas based power generation in India: Lessons from a transaction cost analysis

We use a transaction cost framework to analyze the performance of gas-based private investments in two coastal Indian states – Andhra Pradesh and Gujarat. These states have a similar regulatory set-up and have seen bulk of the initial gas-based private investment being made. Yet they differ greatly in terms of actual generation. Andhra Pradesh's lack of success can be attributed to upstream regulation and arm's length contractual design. This created a weak demand response giving rise to high transaction costs. Whereas in Gujarat, upstream contractual design has ensured that demand response is strong enough to minimize transaction costs for utilities downstream. Our cases reiterate that alternative governance structures (competitive markets and hierarchical systems) need to be subjected to a comparative analysis of transaction cost minimization. Hence, the general policy of promoting competition may not be a strategic solution for India where adequate investment for annual supply of electricity is the real problem.

Industry experience in deriving updated emission factors to characterize methane emissions for select emission sources in natural gas systems

Natural gas production is rapidly expanding globally using advanced techniques that are opening new areas to exploration and development. New techniques and practices, including those involving hydraulic fracturing, have spurred growth in natural gas based power generation that is credited with reducing greenhouse gas (GHG) emissions with the co-benefit of improved air quality. These new operating practices necessitate a thorough review of existing quantification methods for methane emissions. This paper addresses the wide ranging efforts undertaken by the American Petroleum Institute over the past decade, or more, to provide robust data for characterizing methane emissions from natural gas operations. Industry efforts to characterize emission sources that are unique to natural gas production operations are also described. In order to inform the public debate on natural gas use and its role in mitigating overall GHG emissions this paper includes a comparison of new methane emission factors derived by industry to those used for the US National GHG Inventory.

Thermo-Economic Evaluation of Solar Thermal and Photovoltaic Hybridization Options for Combined-Cycle Power Plants

The hybridization of combined-cycle power plants with solar energy is an attractive means of reducing carbon dioxide (CO2) emissions from gas-based power generation. However, the construction of the first generation of commercial hybrid power plants will present the designer with a large number of choices. To assist decision making, a thermo-economic study has been performed for three different hybrid power plant configurations, including both solar thermal and photovoltaic hybridization options. Solar photovoltaic combined-cycle (SPVCC) power plants were shown to be able to integrate up to 63% solar energy on an annual basis, whereas hybrid gas turbine combined-cycle (HGTCC) systems provide the lowest cost of solar electricity, with costs only 2.1% higher than a reference, unmodified combined-cycle power plant. The integrated solar combined-cycle (ISCC) configuration has been shown to be economically unattractive.

Life cycle assessment of rice straw-based power generation in Malaysia

This paper presents an application of LCA (Life Cycle Assessment) with a view to analyzing the environment aspects of rice straw-based power generation in Malaysia. It also compares rice straw-based power generation with that of coal and natural gas. GHG (Greenhouse gas) emission savings were calculated. It finds that rice straw power generation can save GHG (greenhouse gas) emissions of about 1.79 kg CO2-eq/kWh compared to coal-based and 1.05 kg CO2-eq/kWh with natural gas based power generation. While the development of rice straw-based power generation in Malaysia is still in its early stage, these paddy residues offer a large potential to generate electricity because of their availability. Rice straw power plants not only could solve the problem of removing rice straw from fields without open burning, but also could reduce GHG emissions that contribute to climate change, acidification, and eutrophication, among other environmental problems.

Full Chain Analysis and Comparison of Gas-Fired Power Plants with Co2 Capture and Storage with Clean Coal Alternatives

This paper presents the new models developed for the natural gas fuelled power generation chain, involving various natural gas production methods, gas processing routes, gas transport options, and alternative gas based power generation with/without CO2 capture. The comprehensive and quantitative Life Cycle Inventory (LCI) database developed models inputs/outputs of processes at high level of detail, allowing to account for technical and geographic differences in the power generation value chain scenarios analysed. With the advantage of LCI models developed at unit process level, this work successfully identified the key operational parameters for alternative gas-fuelled power plants and the key component processes that emit the majority of GHGs across the gas supply chains.

Perspectives on CCS Cost and Economics

Summary Focus on carbon capture and storage (CCS) has grown over the past decade with recognition of CCS's potential to make deep CO2-emission reductions and that fossil fuels will continue to be needed to supply much of the world's energy demands for decades to come. How CCS will compare with other options in the future depends critically on the cost of CCS (the focus of this paper) and resolution of barriers to CCS deployment and costs and barriers for other emission-reduction options. This paper provides a comparison of the cost of electricity of five power-generation options—gas combined cycle gas turbine (CCGT) and supercritical coal with and without CCS and nuclear—and shows regions of carbon price and fuel prices where each can be economically viable. Current cost estimates for coal CCS for nth-of-a-kind power-generation plant are in the USD 60 to 100/t of CO2 avoided, which is higher than some of the earlier CCS estimates, and higher than the generally accepted range of expected carbon prices in the next 2 decades. The high cost of coal CCS suggests that Gas-based power generation is significantly more economical than coal CCS at carbon prices less than USD 60 to 100/t CO2.Even after carbon prices reach USD 60 to 100/t CO2, gas CCS produces lower-cost electricity than coal CCS, as long as natural-gas prices remain less than USD 9/MBtu.Nuclear has a lower cost of electricity than coal CCS. Although coal or gas CCS is unlikely to be economical in power generation over the next 2 decades, subsidized demonstrations of CCS are likely to occur. In addition, components of CCS technologies will continue to be economically practiced in early-use segments [e.g., natural-gas processing and enhanced-oil-recovery (EOR) operations]. In the natural-gas-processing industry, CO2 separation cost is a fraction of the cost of CO2 capture in power generation because of its higher gas pressure, and the CO2 separation is typically necessary to monetize the natural-gas resource. In contrast, CCS for most refinery and industrial emissions is expected to be significantly more costly than in power generation because the CO2 streams are typically smaller scale and more distributed than those from large power plants. Realistic cost estimates for CCS and for other greenhouse-gas (GHG) mitigation options are an important input for focusing research, development, and demonstration addressing barriers to applications that show the greatest promise and for development of sound policy.

Comparing the greenhouse gas emissions from three alternative waste combustion concepts

Three alternative condensing mode power and combined heat and power (CHP) waste-to-energy concepts were compared in terms of their impacts on the greenhouse gas (GHG) emissions from a heat and power generation system. The concepts included (i) grate, (ii) bubbling fluidised bed (BFB) and (iii) circulating fluidised bed (CFB) combustion of waste. The BFB and CFB take advantage of advanced combustion technology which enabled them to reach electric efficiency up to 35% and 41% in condensing mode, respectively, whereas 28% (based on the lower heating value) was applied for the grate fired unit. A simple energy system model was applied in calculating the GHG emissions in different scenarios where coal or natural gas was substituted in power generation and mix of fuel oil and natural gas in heat generation by waste combustion. Landfilling and waste transportation were not considered in the model. GHG emissions were reduced significantly in all of the considered scenarios where the waste combustion concepts substituted coal based power generation. With the exception of condensing mode grate incinerator the different waste combustion scenarios resulted approximately in 1Mton of fossil CO2-eq. emission reduction per 1Mton of municipal solid waste (MSW) incinerated. When natural gas based power generation was substituted by electricity from the waste combustion significant GHG emission reductions were not achieved.

Operational experience on a grid connected 100 kWe biomass gasification power plant in Karnataka, India

The paper reports the operational experience from a 100 kWe gasification power plant connected to the grid in Karnataka. Biomass Energy for Rural India (BERI) is a program that implemented gasification based power generation with an installed capacity of 0.88 MWe distributed over three locations to meet the electrical energy needs in the district of Tumkur. The operation of one 100 kWe power plant was found unsatisfactory and not meeting the designed performance. The Indian Institute of Science, Bangalore, the technology developer, took the initiative to ensure the system operation, capacity building and prove the designed performance. The power plant connected to the grid consists of the IISc gasification system which includes reactor, cooling, cleaning system, fuel drier and water treatment system to meet the producer gas quality for an engine. The producer gas is used as a fuel in Cummins India Limited, GTA 855 G model, turbo charged engine and the power output is connected to the grid. The system has operated for over 1000 continuous hours, with only about 70 h of grid outages. The total biomass consumption for 1035 h of operation was 111 t at an average of 107 kg/h. Total energy generated was 80.6 MWh reducing over 100 t of CO 2 emissions. The overall specific fuel consumption was about 1.36 kg/kWh, amounting to an overall efficiency from biomass to electricity of about 18%. The present operations indicate that a maintenance schedule for the plant can be at the end of 1000 h. The results for another 1000 h of operation by the local team are also presented.

HCN and NH3Formation during Coal/Char Gasification in the Presence of NO

Understanding the conversion of coal-N during gasification is an important part of the development of gasification-based power generation technologies to reduce NO(x) emissions from coal utilization. This study investigated the conversion of coal-N in the presence of NO during the gasification of three rank-ordered coals and their chars in steam and low-concentration O(2). Our results show that NO can be incorporated into the char structure during gasification. The inherent char-N and the N incorporated into the char from NO-char reactions behave very similarly during gasification. During the gasification in steam, significant amounts of HCN and NH(3) can be formed from the incorporated N structure in char, especially for the relatively "aged" chars, mainly due to the availability of abundant H radicals on the char surface during the gasification in steam. During the gasification in 2000 ppm O(2), the formation of HCN or NH(3) from the N structures in char, including those incorporated into the char from the NO-char reactions, was not a favored route of reaction mainly due to the lack of H on char surface in the presence of O(2).

Turbine Airfoil Aerothermal Characteristics in Future Coal—Gas-Based Power Generation Systems

Most promising operating cycles being developed for future coal– gas-based systems are hydrogen-fired cycle and oxy–fuel cycle. Both cycles will likely have turbine working fluids significantly different from those of conventional air-based gas turbines. The oxy–fuel cycle, with steam and CO2 as a primary working fluid in the turbine section, will have a turbine inlet temperature target at approximately 1750 o C, significantly higher than the current level of utility turbine systems. Described in this paper is a CFD-based simulation of the transport phenomena around the gas side of a turbine airfoil under realistic operating conditions of future coal–gas-based systems. The relatively high concentration of steam in the oxy–fuel turbine leads to approximately 40% higher heat transfer coefficient on the airfoil external surface than its hydrogen-fired counterpart. This suggests that advances in cooling technology and thermal barrier coatings (TBC) are critical for the developments of future coal-based turbine systems. To further explore this issue, a comparative study on the internal cooling effectiveness between a double-wall or skin-cooled arrangement and an equivalent serpentine-cooled configuration is performed. The contribution of thermal barrier coatings (TBC) toward overall thermal protection for turbine airfoil cooled under these two different cooling configurations is also evaluated.

D109 DRY GAS CLEANING SYSTEM FOR BIOMASS GASIFICATION POWER GENERATION : PERFORMANCE VERIFICATION BY TESTS WITH PILOT PLANT AND FEASIBILITY EVALUATION(Biomass-3)

Gasification power generation plant has significant potential for highly efficient utilization of biomass and refuse derived materials. This work evaluates the performance of the dry gas cleaning system for the power generation plant and to examine its feasibility in commercial scale. Sorbents for impurity removal was prepared as copper based mercury sorbent, glass fiber reinforced halide sorbent and zinc oxide sulfur sorbent. Performance evaluation in the demonstration plant showed sufficient performance for various impurities. Power generation test with the molten carbonate fuel cell (MCFC) was also successful in accomplishing stable power generation with the MCFC. The commercial scale plant of dry and wet system was designed and compared, which showed large advantage of the dry system. These results confirmed that the dry gas cleaning system is sufficiently feasible to establish the biomass gasification based power generation system.

Progress in carbon dioxide capture and separation research for gasification-based power generation point sources

The purpose of the present work is to investigate novel approaches, materials, and molecules for the abatement of carbon dioxide (CO 2) at the pre-combustion stage of gasification-based power generation point sources. The capture/separation step for CO 2 from large point sources is a critical one with respect to the technical feasibility and cost of the overall carbon sequestration scenario. For large point sources, such as those found in power generation, the carbon dioxide capture techniques being investigated by the Office of Research and Development of the National Energy Technology Laboratory possess the potential for improved efficiency and reduced costs as compared to more conventional technologies. The investigated techniques can have wide applications, but the present research is focused on the capture/separation of carbon dioxide from fuel gas (pre-combustion gas) from processes such as the Integrated Gasification Combined Cycle (IGCC) process. For such applications, novel concepts are being developed in wet scrubbing with physical sorption, chemical sorption with solid sorbents, and separation by membranes. In one concept, a wet scrubbing technique is being investigated that uses a physical solvent process to remove CO 2 from fuel gas of an IGCC system at elevated temperature and pressure. The need to define an “ideal” solvent has led to the study of the solubility and mass transfer properties of various solvents. Pertaining to another separation technology, fabrication techniques and mechanistic studies for membranes separating CO 2 from the fuel gas produced by coal gasification are also being performed. Membranes that consist of CO 2-philic ionic liquids encapsulated into a polymeric substrate have been investigated for permeability and selectivity. Finally, processes based on dry, regenerable sorbents are additional techniques for CO 2 capture from fuel gas. An overview of these novel techniques is presented along with a research progress status of technologies related to membranes and physical solvents.

Power sector scenarios for Thailand: An exploratory analysis 2002–2022

Power sector scenarios for Thailand are constructed in this paper to represent the range of opportunities and constraints associated with divergent set of technical and policy options. They include Business-As-Usual (BAU), No-New-Coal (NNC), and Green Futures (GF) scenarios over a 20-year period (2002–2022). The results from the BAU scenario show that fossil fuels will continue to dominate electricity generation in Thailand during the study period. Similar results are obtained for the NNC option, although the dependence shifts from coal and oil towards natural gas-based power generation. This may represent a better environmental pathway but an all out shift from coal to natural gas is likely to increase Thailand's dependence on imported fuel, making it more vulnerable to unstable global oil and gas prices. The GF scenario offers a more optimistic route that allows the country to confront its energy security dilemma whilst fulfilling its environmental commitments by giving renewable energy technologies a prominent place in the country's power generation mix. Over the study period, our result showed little difference between the three scenarios in terms of financing new generation plants despite an early misgiving about the viability of an ambitious renewable energy programme. This paper also goes beyond the financial evaluation of each scenario to provide a comparison of the scenarios in terms of their greenhouse gas emissions together with the comparative costs of emissions reductions. Indeed, if such externalities are taken into account to determine ‘viability’, the GF scenario represents an attractive way forward for the Thai power sector.

Integration of Gas Turbines Adapted for Syngas Fuel With Cryogenic and Membrane-Based Air Separation Units: Issues to Consider for System Studies

The purpose of this paper is to aid systems analysts in the design, modeling, and assessment of advanced, gasification-based power generation systems featuring air separation units (ASUs) integrated with gas turbines adapted for syngas fuel. First, the fundamental issues associated with operating a gas turbine on syngas will be reviewed, along with the motivations for extracting air from the turbine-compressor and/or injecting nitrogen into the turbine expander. Configurations for nitrogen-only and air-nitrogen ASU integration will be described, including the benefits and drawbacks of each. Cryogenic ASU technology will be summarized for both low-pressure and elevated-pressure applications and key design and integration issues will be identified and discussed. Finally, membrane-based ASU technology will be described and contrasted with cryogenic technology in regard to system design and integration.

Liquid metal systems for gasification-based power generation

A closed-loop liquid metal system is proposed for the simultaneous quenching and desulphurization at elevated temperature of raw fuel gas from commercial gasifiers. Besides its origins in a recently conceived liquid metal transport gasifier, application to the oxygen-blown Shell gasifier and the air-blown Mitsui-Babcock gasifier is discussed. The quenched fuel gas is filtered at relatively low temperature before being reheated to 750 °C or above by direct contact heat exchange with liquid metal in advance of partial precombustion to raise the temperature (1735 and 1194 °C respectively). Ammonia is reduced and equilibrium established prior to massive superheated steam injection, utilizing all available steam, and then rapid transmission to the can-annular combustors of a 1500 °C Class gas turbine at 870 °C, where autoignition of the highly preheated fuel gas is predicted. NOx emissions as low as 2 ppmv are anticipated. Mercury is projected to be recovered in elemental form, while other air toxics are prevented from discharging into the environment. Water recovery at 99 per cent appears feasible in a low-pressure drop system, and visible plume discharge is avoided by reheating the condenser off-gas in direct contact with a passivated liquid metal surface. Parallels are drawn with the molten tin based float glass process.

04/00762 Method and apparatus for gasification-based power generation: Bryan, B. and Rabovitser, I. U.S. Pat. Appl. Publ. US 2003 106,266 (Cl. 48-197FM; C10J3/00), 12 Jun 2003, Appl. 13,224

04/00762 Method and apparatus for gasification-based power generation: Bryan, B. and Rabovitser, I. U.S. Pat. Appl. Publ. US 2003 106,266 (Cl. 48-197FM; C10J3/00), 12 Jun 2003, Appl. 13,224

Strategic considerations for clean coal R&D

While present interest in coal-fired power generation is centred on the developing countries, with new natural-gas-fired power stations predominating in the developed world, in the long term coal will return to being the fuel of choice for power generation for much of the world. To minimise the global impact of coal use it is essential, therefore, that coal technologies are developed that are efficient, clean and economically attractive. Techno-economic analyses of the options for coal are presented together with a strategic overview of potential lines of development. The broad conclusions are that new coal plant will not be truly competitive with natural gas until the price of gas increases to about 3.3 EURO/GJ, compared with a coal price of 1.3 EURO/GJ. Present state-of-the-art pulverised coal-fired plant is close to its optimum techno-economic performance and further improvements depend on the development of cost-effective super-alloys. However, there are good opportunities to increase the efficiency of coal use to greater than 50% (LHV basis) using gasification-based power generation cycles. Unless credit is given for the much lower emissions provided by these cycles, the pulverised coal and pressurised fluidised bed combustion will remain the most economic options.