Natural Gas-based Power Plants Research Articles

Particulate matter concentrations around natural gas-fired power plants and their associated health impact assessment

The quantification and prediction of particulate matter (PM) concentrations in the air are essential due to their negative impacts on human health and the environment. This study quantified PM concentrations and associated health effects at four natural gas-based power plants in Bangladesh. The measurement of PM2.5 and PM10 using the respirable dust samplers APS-113NL and APS-113BL, respectively from the year of 2015 to 2021 revealed that the concentration of both types of particles fluctuated over the years. The highest recorded levels of particles were in 2019, with PM2.5 at 126 µg/m3 and PM10 at 283 µg/m3 and the lowest recorded levels of particles were in 2017, with PM2.5 at 76.3 µg/m3 and PM10 at 203.3 µg/m3. In 2021, PM2.5 and PM10 concentrations were 88.5 and 225 µg/m3, respectively, lower than in the past two years. Statistical modeling assessed atmospheric contaminants analyzed time series data, and projected air quality. ARIMA, ETS, and ANN modeling methods have been used to predict the monthly average of PM2.5 and PM10 concentrations. RMSE, MAPE, MASE, and MAE have been utilized for model orders, time series analysis, and forecasting validation. There is a significant variation between the forecasting models and forecasts for average PM2.5 and PM10 concentrations in natural gas-fired power plants from 2022 to 2024. This study also conducted a face-to-face interview with over 100 employees using a structured questionnaire to assess the health effects they are facing due to poor air quality in the power generation complex and found that 2 and 13 % of employees had respiratory and skin issues, respectively. Nonetheless, regular health checks, air filtration, and renewable energy consumption may benefit residents and the environment.

Systematic analysis of dual-functional catalysts for simultaneous CO-NOx reduction: Toward an effective catalyst design strategy

The development of a multifunctional catalyst suitable for application in existing facilities with limited space, with specific emphasis on its capability to concurrently remove CO and NOx is vital for meeting stringent environmental regulations. This is particularly pertinent to industries such as liquefied natural gas-based power plants and multipollutant-emitting industrial facilities. Another important consideration is that the catalyst should operate over a wide temperature range to facilitate its application across various industrial sites. In this study, we synthesized vanadium-based catalysts with a series of noble metals (Pt, Pd, and Au). The V–W–Pd/TiO2 catalyst achieved a simultaneous CO–NOx reduction efficiency greater than 90% in the widest temperature range, 228–321 °C. The excellent catalytic activities resulted from the Pd active sites, which oxidated CO and adsorbed NOx. This enables the catalyst to easily participate in the NH3-SCR reaction and facilitates NOx reduction. Moreover, we systematically analyzed the reaction properties of each catalyst using diffuse reflectance infrared Fourier transform and temperature programmed desorption methods. This enabled the elucidation of the reaction characteristics and competitive adsorption properties of the catalysts.

Enhancing bioelectricity generation and mitigating methane emissions in paddy fields: A novel approach using activated biochar in plant microbial fuel cells

In the innovative realm of green energy solutions, plant microbial fuel cells (PMFCs) have emerged as a promising frontier, embodying a greener technological approach. However, PMFC is not yet viable for large-scale application due to its low voltage generation. This study explores the integration of PMFC technology in paddy field, using activated biochar as electrode material to enhance voltage production while reducing methane emission. According to the findings, rice PMFCs equipped with activated biochar achieved the highest power density, reaching an impressive 106.67 mW m−2 of anode area, significantly outperforming SMFCs, which peaked at 38.28 mW m−2 when integrated with a biochar anode. Additionally, rice-PMFCs emitted 38 % less methane than the normal rice plant, while the reduction was 27.1 % for rice plants equipped with activated biochar, with no significant change in plant yield observed. Furthermore, PMFCs reduced greenhouse gas emissions by 70 % and 67 % compared to traditional coal and natural gas-based power plants, respectively. In summary, activated biochar shows promise as a potent alternative to traditional graphite electrodes in PMFCs.

Petroleum’s Influence on the Aquatic Environment

Aquifer, rivers, or lakes are frequently employed as the local sources of water that the petroleum industry uses to drill and hydraulically fracture wells, refine and process petroleum, and create electricity in certain natural gas-based power plants. Oil residues, chemicals from hydraulic fracturing and drilling fluids, and naturally occurring pollutants from the rocks themselves may all be present in the water that is generated along with petroleum. It is also frequently naturally salty. The environmental effects of petroleum activities may change a range of ecological characteristics, such as biodiversity, biomass, and productivity, which may then affect specific species, populations, assemblages, or ecosystems. There are two basic types of long-term and short-term impacts of petroleum contamination in water. The difficulties produced by point pollution in aquatic ecosystems have come to light due to the impact of petroleum compounds on living organisms in aquatic environments.

Performance and Stability of Molten Carbonate Fuel Cell Cathode Electrode Under Carbon Capture Endurance Tests

Introduction The molten carbonate fuel cell (MCFC) has emerged as one of the promising alternatives for carbon capture from industrial and power generation CO2 sources. MCFC technology is less energy-intensive compared to conventional amine scrubbing that requires a significant amount of energy (steam) for solvent regeneration process.MCFC has been commercially used for distributed power generation, however its use in carbon capture applications has been limited to development activities and a few demonstrations during the past decades. The electrochemical reactions taking place during cell operation involve the CO2 transfer from cathode to anode in the form of carbonate ions resulting in a gas stream with high CO2 concentration on the anode exhaust. Therefore, MCFC stack systems can be combined with conventional combustion-powered generators (coal and/or natural gas-based power plants) for simultaneous CO2 separation, power and hydrogen generation.CO2 capture applications will typically take in flue gas from industrial furnaces, coal and gas fired combined cycle plants as the cathode inlet gas stream having low CO2 concentrations ranging from 4% to 10% by volume and high CO2 utilization (>90%). These CO2-lean conditions may pose a challenge for attaining good mass-transfer performance and life stability, therefore innovative approaches are needed in terms of hardware design and cathode structure to achieve long-term stability.FCE has tested numerous single cells (250 cm2) and technology stacks (30 kW) under carbon capture operating conditions (4-8% CO2 in the cathode inlet as opposed to >12% in baseline MCFC systems) to understand impact of design parameters on performance, life, and to investigate design solutions for further enhancement. Figure 1 highlights the effect of cathode water content on CO2 utilization. It appears that differences exist between the ideal and measured CO2 utilizations, indicating that less CO2 is transferring from the cathode to anode than expected. This CO2 transference reduction becomes more pronounced with higher water concentration, suggesting that a species other than CO3 2- ion, likely hydroxide (OH- ion), may be generated and transported through the electrolyte matrix.This paper will review the cathode material stability and electrochemical performance under long-term carbon-capture operation. The effect of parameters such as water content, gas composition, utilization, and electrolyte chemistry, as well as approaches to enhance the CO2 capture efficiency and life, will be discussed. Figure 1

Multi-objective optimization of concentrated solar power plants from an energy-water-environment nexus perspective under distinct climatic conditions – Part B: Environ-economic analysis

The objective of this study is to include environmental impact in optimization of concentrated solar power plants previously limited to techno-economic analysis only. Performance of solar towers and parabolic trough collectors equipped with dry and wet cooling is numerically investigated at 10 min interval for three climatic zones. Based on electricity generation profiles pertinent to variation of design variables of solar multiple and thermal energy storage, the water usage is quantified techno-economically, considering water scarcity levels. Besides, five different potential impacts over lifecycle of concentrated solar and natural gas-based power plants are compared after unifying them into metric of net environmental impact avoided. Additionally, utilizing techno-economic solutions and eco-friendly solutions, multi-objective ‘balanced’ solution is proposed. It is found that levelized cost of water increases five-fold for areas with extreme water scarcity and is higher for trough than solar tower. Net environmental impact of troughs is higher and lower electricity generation causes the avoided impact to be higher than solar towers, when compared with natural gas-fired power plants. For eco-friendly solutions, solar multiple varies from 3.5 to 4 with thermal energy storage of 24 h. Dry-cooled solar towers with optimal solar multiple in range of 3–3.2 and thermal energy storage of 18.8–19.9 h are evaluated for pareto-optimality based ‘balanced’ solutions for all zones. These solutions offer minimum net levelized cost of electricity, alongside maximized electricity generation, huge return on invested capital and energy, and reducing environmental impact by over 94%. Lastly, semi-arid climates are found suitable for concentrated solar power plant installation.

Sustainability analyses of CO2 sequestration and CO2 utilization as competing options for mitigating CO2 emissions

CO2 capture and sequestration (CCS) and CO2 capture and utilization (CCU) are potential alternatives to mitigate CO2 emissions. There have been concerns regarding long-term geological impact of CCS and CCU requires co-reactant(s) for converting CO2 into value-added products. In this work, sustainability of CCS and CCU are assessed by simulating three processes. Each of these processes used post-combustion amine technique to capture CO2 from flue gas stream coming out of natural gas-based power plant. In the first process (CCS), captured CO2 undergoes sequestration whereas in the other two processes (CCU) CO2 reacts with hydrogen to produce methanol and dimethyl ether. Based on our technoeconomic assessment, total annualized cost of CCS process is 7.57% and 6.55% lower than CCU-methanol and CCU-DME processes, respectively. Thus, CCS is economically favourable over CCU. DME is found to be a favourable CCU-product owing to its higher market price as compared to methanol. Our analysis suggests that hydrogen price significantly impacts the technoeconomics of CCU processes. We have also demonstrated that at current market prices of methanol and DME, CCU process can be economical compared to CCS provided hydrogen price reduces to $778.5/t and $942.6/t for CCU-methanol and CCU-DME processes, respectively.

Modelling of Coal-Biomass Blends Gasification and Power Plant Revamp Alternatives in Egypt’s Natural Gas Sector

Recently, there has been a growing research interest in the co-gasification of biomass with coal to produce syngas and electricity in a sustainable manner. Co-gasification technology do not only decrease potentially the exploitation of a significant amount of conventional coal resources, and thus lower greenhouse gases (GHG) emissions, but also boost the overall gasification process efficiency. In the present work, a rigorous simulation model of an entrained flow gasifier is developed using the Aspen Plus® software environment. The proposed simulation model is tested for an American coal and the model validation is performed in good agreement with practical data. The feedstocks used in the proposed gasifier model are dry Egyptian coal and a blend of an Egyptian coal and rice straw that is gathered locally. The proposed gasifier model mainly consists of three reactors. The first one is a yield reactor where the coal pyrolysis occurs, the second reactor is a stoichiometric reactor where the gasification reactions arise, and the third reactor is a Gibbs reactor where the water-gas and steam-methane reforming reactions take place. The influence of using a feed mixture of 90 % coal and 10 % rice straw on the gasifier efficiency is investigated. The developed model provides a robust basis for revamping of an existing Egyptian natural gas-based power plant to replace its standard fuel with a coal-rice straw blend, in case of low natural gas supply. The model is further employed to assess different revamping scenarios and alternatives within the natural gas power plant. For a dry blend of (90 % Egyptian coal and 10 % rice straw), the cold gas efficiency is estimated as 85.7 %, while for dry Egyptian it is calculated as 79.61 %. The revamped Egyptian natural gas power plant decreases the total annualized cost (TAC) by 52.7 % with respect to a new constructed integrated gasification combined cycle (IGCC) plant. Besides, the payback period decreases to 1.24 y rather than 12 y in case of the construction of a new IGCC power plant. (Less)

Effect of Carbon Capture Endurance Conditions on Performance and Stability of Molten Carbonate Fuel Cell Cathode Electrode

IntroductionThe molten carbonate fuel cell (MCFC) is one of the most advanced high-temperature and clean power generating devices. To date >8 billion kWh of electricity has been produced commercially using this new technology. The high operating temperature of MCFC (550-650 °C) dramatically improves the reaction kinetics and eliminates the need for a noble metal catalyst. The electrochemical reactions taking place during cell operation involve the CO2 transfer from cathode to anode in the form of carbonate ions (Figure 1). Therefore, MCFC stack technology can be used for power generation and simultaneously, as an effective CO2 separator. MCFC systems can be combined with conventional combustion-powered generators (coal and/or natural gas based power plants) to efficiently separate CO2 in the exhaust gas and produce additional electricity.The state of the art MCFC cathode is porous lithiated nickel oxide. The cathode stability and performance are affected by several factors such as gas composition, temperature, electrode structure and electrolyte chemistry. To ensure long-term performance and material stability against NiO dissolution, polarization loss, and carbon capture efficiency, major considerations need to be taken into account in material selection, operating conditions, and electrode structure design.FCE has tested many single cells (250 cm2) and technology stacks (30 kW) under carbon capture operating conditions (4-5% CO2 in the cathode inlet as opposed to >15% in baseline MCFC systems) to understand parameters affecting performance, life, and to investigate design solutions for further enhancement. Figure 2 highlights the effect of CO2 concentration on the cathode lithiation. These measurements were conducted using an out-of-cell test (OCT) where cathode samples were exposed to different oxidizing environments. It appears that lean-CO2 gas atmospheres (<5%CO2) lead to increased lithium content in the NiO cathode. This may impact the electrolyte distribution and the cathode microstructure. Therefore, the electrolyte inventory (fill level), the lithium content and the basicity need to be considered to achieving optimal operating conditions.This paper will review the cathode material stability, microstructure, and durability under long-term carbon-capture operations. The effect of parameters such as electrolyte fill, gas composition, and electrolyte chemistry, as well as approaches to enhance the CO2 capture efficiency and life, will be discussed. Figure 1

Transition from Coal to Natural Gas Power Plants under CO2 Consideration: A Real Options Approach

As a way to alleviate global warming, there have been major initiatives to reduce carbon dioxide (CO2) emission amount across the world. In Western Europe as well as in California, market-based permits for CO2 emission have been a major enabler of such initiatives. In this paper, under the assumption of such market-based permits where permit price is inherently uncertain, we model and analyse a transition process from coal-based to natural gas-based power plants with less CO2 emission based on a real options approach. Specifically, we apply existing real options approach to derive closed-form analytical solutions for such a transition. Subsequent managerial insights and policy implications are provided in the context of CO2 emission reduction and environmental ramifications.

An analysis of price spikes and deviations in the deregulated Turkish power market

The successful operation of a real time market is related to the planning in the day ahead market. We analyze the day ahead and real time market data for the Turkish power market for the period 2012–2015 to classify price spikes and their causes. We also focus on the levels of deviation between the day ahead market values and the real time market values. We define price deviation and load deviation ratios to measure the level of deviation both in price and demand. The analysis for the load is based on load shedding and cycling values. We analyze the mean and standard deviation in market prices and we determine the price spike as a two sigma deviation from the mean value. It is shown that 60% of the price deviation ratios are in the range of (±20%), while 44% are in the range of (±10%) and 35% are in the range of (±5%). We also show that 56.9% of the spikes are due to problems in the generation of natural gas based power plants which affect the day ahead and real time prices. A total of 29.2% of the spikes are due to power plant and system failures that affect only real time prices. The share of high temperature based spikes is 13.9% which is a result of air conditioner usage.

Techno-economic assessment of the novel gas switching reforming (GSR) concept for gas-fired power production with integrated CO2 capture

The focus of this study is to carry out techno-economic analysis of a pre-combustion capture method in Natural Gas based power plants with a novel reactor concept, Gas Switching Reforming (GSR). This reactor concept enables auto thermal natural gas reforming with integrated CO2 capture. The process analysed integrates GSR, Water Gas Shift (WGS), and Pressure Swing Adsorption (PSA) into a Natural Gas based combined cycle power plant. The overall process is defined as GSR-CC. Sensitivity studies have been carried out to understand the performance of the GSR-CC process by changing the oxygen carrier utilization and Steam/Carbon ratio in GSR. The net electrical efficiency of the GSR-CC lies between 45.1% and 46.2% and the levelised cost of electricity lies between 124.4 and 128.1 $/MWh (at European natural gas prices) for the parameter space assumed in this study. By eliminating the WGS step from the process, the net electrical efficiency improves to 47.4% and the levelised cost of electricity reduces to 120.7 $/MWh. Significant scope exists for further efficiency improvements and cost reductions from the GSR-CC system. In addition, the GSR-CC process achieves high CO2 avoidance rates (>95%) and offers the possibility to produce pure H2 during times of low electricity demands.

Energy and Economic Analysis of Improved Absorption Configurations for CO2 Capture

The shortcoming of amine-based CO2 absorption technology is the large heat demand for desorption and it requires huge capital investment. Thus, it is expedient to comprehensively and critically analyse alternative process configurations, parameters and conditions to seek for the best cost saving option. The standard process, vapour recompression and vapour recompression combined with split-stream configurations for 85% CO2 capture from exhaust gas have been simulated using Aspen HYSYS Version 8.0. The process specifications are based on CO2 capture from a natural gas based power plant project at Mongstad in Norway. Energy optimisation and economic analysis including cost optimization using negative net present value (NPV) for a calculation period of 20 years have been performed. The vapour recompression alternative with 20 absorber stages, 9 desorber stages, and 1.2bar flash pressure with a minimum approach temperature (ΔTmin) of 5°C is calculated to be the energy optimum option. But cost optimisation investigation favours the vapour recompression process with 15 absorber stages, 10 desorber stages, 1.3bar flash pressure and ΔTmin of 13°C.

Co-gasification of coal and biomass wastes in an entrained flow gasifier: Modelling, simulation and integration opportunities

Gasification processes convert carbon-containing material into syngas through chemical reactions in the presence of gasifying agents such as air, oxygen, and steam. Syngas mixtures produced from such processes consist mainly of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), and methane (CH4); this gas can be directly utilised as a fuel to produce electricity or steam. Besides, it is regarded as a basic feedstock within the petrochemical and conventional refining industries, producing various useful products like methanol, hydrogen, ammonia, and acetic acid. In this work, a rigorous process model is developed to simulate the co-gasification of coal-biomass blends through an entrained flow gasifier. The proposed model is tested originally for American coal. The model validation is made against literature data and results show good agreement with these practical data, providing a robust basis for integration and retrofitting applications. Effects of critical parameters, comprising gasification temperature, steam/O2 ratio, and feedstock variability on the syngas composition and gasifier efficiency are studied. The developed model is further applied in a project to revamp an existing Egyptian natural gas-based power plant, replacing its standard fuel with coal-rice straw blends. The revamping project integrates the existing plant with a gasification unit burning a blend of coal and rice straw to replace the conventional fuel used. The feedstock used constitutes a dry Egyptian coal and a coal-rice straw blend (10 wt% rice straw), gathered locally. Different blending scenarios are investigated and the best performance is achieved with coal to rice straw ratio of 90:10 on weight basis, attaining 85.7% cold gas efficiency and significant economic savings. Results showed that the total annualised cost of the revamped process decreased by 52.7% compared with a newly built integrated gasification combined cycle (IGCC) unit.

Parametric analysis of technology costs for CO2 storage in saline formations

Over the last decade, a substantial amount of economic, engineering, and geoscience research has focused on storing CO2 in geological formations. Of those different formations, storage in saline water-bearing formations represents the largest storage potential. Fossil fuel-based power plants in the U.S. (coal and natural gas) contributed to 40% of all CO2 emissions in 2008 and therefore represent an important factor to address atmospheric CO2 emissions.The Water, Energy and Carbon Sequestration Simulation Model (WECSsim) was developed to calculate water use and treatment options, CO2 injection volumes and the levelized cost of energy (LCOE) results for both a single representative power plant paired with a saline formation scenario, and a full power plant fleet. The details of the analysis presented here broadly demonstrate the sensitivity of CO2 capture and storage (CCS) costs in geologic saline formations with water extraction, treatment and reuse to changes in the water demands associated with implementing CCS across the power plant fleet (coal and natural gas).The majority of the coal and natural gas plants in the U.S. have an avoided cost of $70–200 per tonne of CO2. Storing 1.0Gt/yr of the nation’s 2.3Gt/yr total CO2 emissions returns an avoided (storage) cost of range 79–143 (57–81) $/t ($US 2013) under various scenarios. These scenarios include allowing competition between power plants for saline formation space to store CO2, varying the duration of the storage rights, and permitting the extraction of saline waters for treatment.Under the same 1Gt/yr captured scenario, the extracted and treated water volumes could offset 12% of the added water demand due to the parasitic energy requirements of CCS at the national level. The cost of water treatment, using a reverse osmosis system, ranges between approximately $3.20/m3 water (for larger, older coal-fired plants like the San Juan Power Generating Station) and $2.60/m3 water for natural gas combined cycle plants (such as the Oyster Creek Power Generating Station) with substantial variability in costs based on plant location and design. For context, the levelized cost of energy (LCOE) composition of the pulverized coal-based San Juan Generation Station is 52%, 43% and 5% for the base LCOE, parasitic energy requirements, and water extraction, treatment and utilization costs, respectively. Similarly, for the Oyster Creek natural gas combined cycle plant, these percentages are 64%, 33%, and 2% of the total LCOE, respectively. In both technology cases the parasitic energy requirement costs far outweigh the cost to extract, treat, transport, and utilize saline formation waters.Additional results indicate that of the 325 saline formations included in the national-level analysis, the Mt. Simon formation has an estimated capacity to hold 53% of all the CO2 generated from the U.S. coal and natural gas-based power plants without extracting and treating saline water. The St. Peter Sandstone formation could hold 43%, though with saline water extraction and treatment. These results suggest that focusing research, development and demonstration (RD&D) efforts on careful geologic site selection and reducing the parasitic energy penalty, and its respective costs, will help lower the overall cost of CCS across the U.S. coal and natural gas-based power plant fleet.

Energy penalty estimates for CO2 capture: Comparison between fuel types and capture-combustion modes

Carbon capture from power plants holds the key to any significant reduction in CO2 emissions. This work considers the energy penalty related to CO2 capture from coal, natural gas and fuel oil-based power plants. We evaluate the minimum thermodynamic work for CO2 capture, and then estimate achievable targets. All the three modes of capture-combustion: pre-combustion, post-combustion, and oxy combustion, are considered. The low CO2 concentration in natural gas-based power plants translates into the highest capture energy per ton of CO2. However, the lowest energy penalty of 10% is obtained with pre-combustion capture in natural gas-based power plants (versus 17% for coal-based power plants). The highest energy penalty of about 20% is found for oxy combustion capture from coal-based power plants. In general, pre-combustion capture seems to provide the lowest energy penalties.

Optimization of Configurations for Amine based CO2 Absorption Using Aspen HYSYS

The drawback with an absorption based CO2 capture process is the large heat consumption needed for desorption. Different absorption and desorption configurations for 85% amine based CO2 removal from a natural gas based power plant have been simulated using Aspen HYSYS. A standard process, split-stream, vapour recompression and different combinations thereof have been simulated. The simulations have been used as a basis for equipment dimensioning, cost estimation and process optimization. Of the evaluated cases, a simple vapour recompression case has been calculated to be the most cost optimum configuration.

Environmental impacts of ethylene production from diverse feedstocks and energy sources

Quantitative cradle-to-gate environmental impacts for ethylene production from naphtha (petroleum crude), ethane (natural gas) and ethanol (corn-based) are predicted using GaBi® software. A comparison reveals that the majority of the predicted environmental impacts for these feedstocks fall within the same order of magnitude. Soil and water pollution associated with corn-based ethylene are however much higher. The main causative factor for greenhouse gas emissions, acidification and air pollution is the burning of fossil-based fuel for agricultural operations, production of fertilizers and pesticides needed for cultivation (in the case of ethanol), ocean-based transportation (for naphtha) and the chemical processing steps (for all feedstocks). An assessment of the environmental impacts of different energy sources (coal, natural gas and fuel oil) reveals almost similar carbon footprints for all the fossil fuels used to produce a given quantity of energy. For most of the environmental impact categories, the GaBi® software reliably predicts the qualitative trends. The predicted emissions agree well with the actual emissions data reported by a coal-based power plant (Lawrence Energy Center, Lawrence, KS) and a natural gas-based power plant (Astoria Generating Station, Queens, NY) to the United States Environmental Protection Agency. The analysis shows that for ethylene production, fuel burning at the power plant to produce energy is by far the dominant source (78–93 % depending on the fuel source) of adverse environmental impacts.

Sensitivity analysis of the evaluation of power plants impact on the living standard using the analytic hierarchy process

Ten types of power plant were evaluated as to their impact on the living standard. Power plant evaluation incorporates a number of criteria that can be assessed either objectively or subjectively. Objective assessments are usually quantitative and are based on real data, while subjective assessments are rather qualitative and derive from decision makers’ intuition, culture and experience. Because of diversity of decision makers’ opinions, subjective assessments are due to vary. Several scenarios should therefore be examined in order to evaluate what happens under different assessments. Even objective assessments can vary because of data changes due to technology and socioeconomic evolution. This is why the application of a sensitivity analysis is required in order to examine result changes under different input data. This analysis should cover all criteria and subcriteria as well as their possible combinations in the different levels of the hierarchy tree. The results show that the five types of renewable energy based power plant rank in the first five positions regardless of criteria weight variations, due to their balanced high scores against them. Only biomass drops to the eighth position when quality of life has 100% weight. Nuclear power plants show impressive score and ranking variations between the first position for 100% quality of life weight and the tenth for 100% socioeconomic aspects weight. Natural gas based power plants rank slightly higher when quality of life importance increases while coal/lignite and oil have slightly better rankings when priority is given to socioeconomic aspects.

Integrated carbon recycling system for mitigation of CO 2 emissions utilizing degraded thermal energy

A natural gas-based power plant design with onsite methanation of CO 2 incorporated has been proposed for an option of mitigation technology of CO 2 emissions. CO 2 and NO x in the flue gas at 330°C are adsorbed/separated from the main constituent N 2 gas by oxygen-deficient Ni(II) ferrite reactor and simultaneously decomposed to carbon and gaseous N 2 at the same temperature. Then, carbon is hydrogenated to form CH 4 at 330°C and recycled to the natural gas boiler along with the process heat. This system can be applied easily to existing power plants and will contribute to mitigation of CO 2 emissions at a minimum additional cost and will be important when H 2 gas would be supplied cheaply and sufficiently. A thermochemical water-splitting to form H 2 gas using a tailor-made ceramics and degraded thermal energy at 300°C was described for an efficient utilization of fossil energy.