High-quality Fuels Research Articles

Catalytic Hydrodenitrogenation of Asphaltene Model Compounds

The catalytic hydrodenitrogenation of heavy petroleum fractions is important for the production of high-quality fuels, because the nitrogen-bearing compounds poison acidic catalysts and inhibit sulfur removal. Two families of synthetic nitrogen-containing model compounds representative of asphaltene molecular structures were catalytically hydrogenated over a commercial NiMo/γAl2O3 catalyst under industrial hydrotreating conditions, i.e., 370 °C and 18 MPa of hydrogen for 1 h, in a stainless steel batch reactor. The bridged compounds with pyridine as a center ring gave cracking, hydrogenation, and hydrodenitrogenation products with selectivities that depended on the position of substituents on the central pyridine ring. In contrast, a series of fused cholestane-benzoquinoline compounds gave only hydrogenation of all-carbon aromatic rings.

Energy-saving drying and its application

Superheated steam is efficiently applied as a coolant for the intensification of drying, which is an important component of many up-to-date technologies. However, traditional drying is extremely energy consuming, and many drying apparatus are environmentally unfriendly. Thus, it is important to implement the proposed drying technique using superheated steam under pressure significantly higher than the atmospheric one with subsequent steam transfer for use in a turbine for electric power generation as a compensation of energy costs for drying. This paper includes a brief thermodynamic analysis of such a technique, its environmental advantages, and possible benefits of the use of wet wastes and obtaining high-quality fuels from wet raw materials. A scheme is developed for the turbine protection from impurities that can occur in the steam at drying. Potential advantage of the technique are also the absence of heating surfaces that are in contact with wet media, the absence of the emissions to the atmosphere, and the use of low potential heat for desalination and the purification of water. The new drying technique can play an extremely important part in the implementation in the field of thermal destruction of anthropogenic wastes. In spite of the promotion of waste sorting to obtain valuable secondary raw materials, the main problem of big cities is nonutilizable waste, which makes not less than 85% of the starting quantity of waste. This can only be totally solved by combustion, which even more relates to the sewage sludge utilization. The wastes can be safely and efficiently combusted only provided that they are free of moisture. Combustion temperature optimization makes possible full destruction of dioxins and their toxic analogues.

Methane Conversion to Syngas for Gas-to-Liquids (GTL): Is Sustainable CO2 Reuse via Dry Methane Reforming (DMR) Cost Competitive with SMR and ATR Processes?

Carbon dioxide is a greenhouse gas and is obtained as a waste via burning various forms of fuels. Syngas is an intermediate in large-scale long-chain hydrocarbon (C10–C20 alkanes and alcohols) production processes via Fischer–Tropsch (FT) synthesis, typically to obtain high quality fuels. Thus, it is of particular interest to engineer syngas production processes for FT that can consume various combustion process waste CO2 in the process and thus partially contribute to the sustainable carbon neutral fuel synthesis. In this work, a quantitative economic comparison of five alternative processes is presented for the production of synthesis gas with a hydrogen-to-carbon monoxide ratio of 2, which is suitable for feeding to the Fischer–Tropsch gas-to-liquid process. Combinations of steam methane reforming (SMR), dry methane reforming (DMR), autothermal reforming (ATR) and reverse water gas shift (RWGS) are explored. An amine absorber/stripper system is used for carbon dioxide removal. The effects of the cost o...

Prospects for Obtaining High Quality Fuels from the Hydrocracking of a Hydrotreated Scrap Tires Pyrolysis Oil

The hydrocracking of hydrotreated scrap tires pyrolysis oil (HT-STPO) has been studied aiming at high-quality refinery blends for alternative automotive fuels. The hydrocracking runs have been carried out with a PtPd/SiO2-Al2O3 catalyst in a fixed-bed reactor at 440–500 °C, 65 bar and space time of 0.16 h. The catalyst has been characterized by inductively coupled plasma optical emission spectroscopy, N2 adsorption–desorption isotherms, and tert-butylamine adsorption–desorption (TPD), while coke has been studied both quantitatively and qualitatively by thermogravimetric-temperature-programmed oxidation (TG-TPO), Fourier transform infrared-TPO, and Raman spectroscopy. During the first two hours of reaction and at temperatures above 480 °C, we have been able to (1) reach ultra low sulfur levels lower than 15 ppm; (2) remove almost completely the less interesting fraction—boiling points higher than 350 °C, named as the gasoil fraction—with remaining amounts lower than 1 wt %; (3) obtain a paraffinic and isop...

One-pot catalytic hydrocracking of diesel distillate and residual oil fractions obtained from bio-oil to gasoline-range hydrocarbon fuel

Abstract Bio-oil can be fractionated into three parts according to their boiling point. Here we report that diesel distillate and residual oil fractions can be converted into high-quality fuels by catalytic hydrocracking with the combined CoMoS/Al 2 O 3 and HZSM-5 catalysts. Under the conditions of 390 °C and 6 MPa H 2 , a high yield (87.0 wt.%) of liquid products was obtained. The compositions were C 7 –C 14 hydrocarbons, including 23.3% of saturated naphthene, 23.4% of saturated chain hydrocarbons, 30.5% of aromatic hydrocarbons, and 22.8% of polycyclic aromatic hydrocarbons with one of ring saturated. The high heating value of products was 42.35 MJ/kg. The amounts of coking was only 1.15 wt.%, and the combined catalysts were recycled three times without the obvious decline of activity. Moreover, the reaction process did not need any solvent, and the products were easily separated. Based on the material balance, the net hydrogen consumption for the hydrocracking process was 38 g of H 2 /kg of bio-oil, and the energy efficiency could reach up to 84%. This approach provides a high-efficiency route for the preparation of high-quality hydrocarbon fuel from bio-oil.

More growth? An unfeasible option to overcome critical energy constraints and climate change

Growing scientific evidence shows that world energy resources are entering a period shaped by the depletion of high-quality fuels, whilst the decline of the easy-to-extract oil is a widely recognized ongoing phenomenon. The end of the era of cheap and abundant energy flows brings the issue of economic growth into question, stimulating research for alternatives as the de-growth proposal. The present paper applies the system dynamic global model WoLiM that allows economic, energy and climate dynamics to be analyzed in an integrated way. The results show that, if the growth paradigm is maintained, the decrease in fossil fuel extraction can only be partially compensated by renewable energies, alternative policies and efficiency improvements, very likely causing systemic energy shortage in the next decades. If a massive transition to coal would be promoted to try to compensate the decline of oil and gas and maintain economic growth, the climate would be then very deeply disturbed. The results suggest that growth and globalization scenarios are, not only undesirable from the environmental point of view, but also not feasible. Furthermore, regionalization scenarios without abandoning the current growth GDP focus would set the grounds for a pessimistic panorama from the point of view of peace, democracy and equity. In this sense, an organized material de-growth in the North followed by a steady state shows up as a valid framework to achieve global future human welfare and sustainability. The exercise qualitatively illustrates the magnitude of the challenge: the most industrialized countries should reduce, on average, their per capita primary energy use rate at least four times and decrease their per capita GDP to roughly present global average levels. Differently from the current dominant perceptions, these consumption reductions might actually be welfare enhancing. However, the attainment of these targets would require deep structural changes in the socioeconomic systems in combination with a radical shift in geopolitical relationships.

UPSURGE OF A NEW ALCOHOLIC FUEL ERA FOR TRANSPORT SECTOR IN INDIA, IN THEFORM OF ETHANOL

The search is on for ways to marry the twin goals of economic development and environmental protection, one of the most promising strategies could be the use of ethanol as a renewable fuel to reduce environmental pollution from India’s transport sector while creating new jobs in rural communities. Ethanol as a gasoline blend has helped to reduce dependence on oil import and harmful vehicular emission and improve the rural economy. Since ethanol is produced from biomass such as sugarcane, molasses and grains, its widespread use has led to higher biomass yield, rural economy and growth in Industry. The main aim of this paper: 1) Economic and Environmental benefits of use ethanol in India, 2) How ethanol use has helped to improve environmental quality and promote economic development, etc. So far, the discovery of fossil fuel reserves has more than kept pace with demand. Known resources now exceed a trillion (1012) tones in total compared with just over half this amount 30 years ago. Hydrocarbons get heavier, they become less volatile, and these heavier fractions make excellent liquid fuels for Cars, Lorries and Aircraft respectively. With this in mind, Ethanol, Methanol, Easter and Hydrogen are the principal renewable contenders. In the last decades, technological advances have lowered the cost of producing high quality fuels and chemical products from plant matter, while environmental regulations have raised the cost of manufacturing and using petroleum derived products, mounting evidence of the potential contribution of gasoline and diesel combustion to global climate interest in long term, sustainable fuel solutions for the transport sectors. Stakeholders, who were once adversaries, are today, working together, to move toward a “renewable energy” future. Structure of ethanol molecule that all bonds are single bonds During ethanol fermentation, glucose and other sugars in the corn (or sugarcane) are converted into ethanol and carbon dioxide. C6H12O6 → 2 C2H5OH+ 2 CO2 + heat During combustion ethanol reacts with oxygen to produce carbon dioxide, water, and heat: C2H5OH + 3 O2 → 2 CO2 + 3 H2O + heat --------------------------------------------------------------------***--------------------------------------------------------------------

Investigation on the esterification by using supercritical ethanol for bio-oil upgrading

Current global resources of fossil fuels are gradually depleting and the energy crisis induces increasing concerns on the research of new effective substitution of these fossil fuels by renewable energy, especially bio-fuels from biomass such as bio-oils. However, bio-oils, generally originated from the pyrolysis of biomass, contain a great deal of carboxylic acids such as acetic acid and these acids can easily decrease the stability and the quality of oil. Meanwhile, these acids are highly corrosive to reaction equipments. Bio-oil could be upgraded before its utilization in the feedstocks of fuels and chemicals. In this work, the removing of these carboxylic acids was investigated by esterification in supercritical ethanol. The effects of reaction temperature, the ratio of ethanol to bio-oil, and reaction time on the conversion of acids were studied as well as the addition of external acid such as H2SO4, H3PO4 or zeolite. The results showed that carboxylic acids in crude bio-oil easily esterified with ethanol in the supercritical system. More ethyl acetate was formed at higher volume ratio of ethanol to bio-oil and 100% of the selectivity was achieved at the volume ratio of 5:1 after 2h reaction, whereas more side reactions were present in lower or higher ratio of ethanol to bio-oil. The addition of external acid decreased distinctly the formation of esters, indicating that these carboxylic acids could be effectively removed under the acidic system arising from the internal ionization of ethanol. These would be very useful in the upgrading of bio-oil into high quality fuels in the future biorefinery.

Production and Application of Petroleum Oil and Its Alternatives on Internal Combustion Engines

Internal combustion engines are widely used in vehicles, ships, construction machinery, and agricultural machinery due to their reliability, durability, and high efficiency. Furthermore, they will be the main powertrains for above powerplant in the next 50 years according to the wide studies. However, the development of engines is faced with some serious challenges in the future, such as the stringent emission regulations, petroleum energy supply, and greenhouse gas emissions. Therefore, we need to develop some advanced combustion technologies to reduce the pollutant emissions. Meanwhile, to prevent global warming, we need to improve the thermal efficiencies of engines and thereby reduce CO 2 emissions and save petroleum oil. Fuel properties have remarkable effects on engine performance and emissions. High-efficiency and low-emission engines must need the cooperation of high-quality fuels. Meantime, the future advanced engines may need the improved fuel properties which are different from the current gasoline or diesel fuel. In addition, the alternative biofuels have recently gained significant political and scientific interests owing to the concerns about climate change, global energy security, and petroleum supply shortage in the foreseeable future. In this special issue, firstly, N. Li et al. from State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, present the improvement on production of petroleum oil. Secondly, C. Jin and Z.Q. Zheng from Tianjin University and B. Yang et al. from Shandong University of Technology present the need for engine fuel properties for future advanced combustionmodes such as homogeneous charge compression ignition and low temperature combustion. Finally, L. Dong et al. from Civil Aviation University of China and F. Zhang et al. from Hunan University present how to achieve high-efficiency and clean combustion based on cooperated control of fuel, oil, and engines. Finally, we hope this special issue can give you some help to understand the tight relationship between petroleum and engines and to know the future engine combustion technologies and the needs for future engine fuels and oil.

Transportation fuel production by combination of LDPE thermal cracking and catalytic hydroreforming

Fuel production from plastics is a promising way to reduce landfilling rates while obtaining valuable products. The usage of Ni-supported hierarchical Beta zeolite (h-Beta) for the hydroreforming of the oils coming from LDPE thermal cracking has proved to produce high selectivities to gasoline and diesel fuels (>80%). In the present work, the effect of the Ni loading on Ni/h-Beta is investigated in the hydroreforming of the oils form LDPE thermal cracking. h-Beta samples were impregnated with Ni nitrate, calcined and reduced in H2 up to 550°C to achieve different Ni contents: 1.5%, 4%, 7% and 10%. Larger and more easily reducible metal particles were obtained on Ni 7%/h-Beta and Ni 10%/h-Beta. Hydroreforming tests were carried out in autoclave reactor at 310°C, under 20bar H2, for 45min. Ni content progressively increased the amount of gases at the expenses of diesel fractions, while gasoline remained approximately constant about 52–54%. Maximum selectivity to automotive fuels (∼81%) was obtained with Ni 7%/h-Beta. Ni loading also enhanced olefins saturation up to Ni 7%/h-Beta. High cetane indices (71–86) and octane numbers (89–91) were obtained over all the catalysts. Regarding the different studied Ni contents, Ni 7%/h-Beta constitutes a rather promising catalyst for obtaining high quality fuels from LDPE thermal cracking oils.

The outlook for fuels for internal combustion engines

The demand for transport energy is increasing, but this increase is heavily skewed toward heavier fuels such as diesel and jet fuel while the demand for gasoline might decrease. As spark-ignition engines develop to become more efficient, abnormal combustion such as knock and preignition will become more likely. High antiknock quality fuels, those with high research octane number and preferably low motor octane number, will enable future spark-ignition engines to reach their full potential. Higher fuel antiknock quality is also likely to mitigate “superknock” resulting from preignition—an abnormal combustion problem in turbocharged spark-ignition engines. In many parts of the world, fuel antiknock specifications are set on the assumption that higher motor octane number contributes to increased knock resistance. Specifications for fuel antiknock quality have a great impact on fuels manufacture and will need to be revised as this mismatch between existing specifications and engine requirements widens. The primary challenge for diesel engines is to reduce emissions of soot and NOx while maintaining high efficiency, and this becomes much easier if such engines are run on fuels of extremely low cetane. Significant development is needed before such engines can be seen on practical vehicles. In the long term, compression ignition engines are likely to use fuels with research octane number in the range of 70–85 (cetane number<∼30) but with no strict requirements on volatility. Such fuels would require less processing in the refinery than today’s fuels. Such an engine/fuels system will be at least as efficient as today’s diesel engine but could be significantly cheaper and also open a path to mitigate the imbalance in demand growth between heavy and light fuels that is expected to arise otherwise. The review concludes with a possible long-term fuel scenario.

Life cycle assessment of algal biofuels: Influence of feedstock cultivation systems and conversion platforms

Commercial technology is available for producing high quality fuels from algae-derived feedstocks, but questions persist about the environmental implications of producing and processing algae through a range of potential routes. In this study, a life-cycle assessment approach was used to investigate the impacts of combining different algae cultivation techniques (raceway vs. effluent cultivation) and fuel conversion pathways (whole cell pyrolysis vs. oil extraction and hydrotreatment). Material and energy input data for the cradle-to-grave study was compiled from peer-reviewed literature, government reports, and confidential commercial processing studies. Results indicated that a wide range of potential greenhouse gas (GHG) emissions and life cycle fossil energy demand results are possible for different algal fuels produced with various unit operations combinations, highlighting the potential for substantial emissions reductions or increases compared to fossil petroleum fuels. The fuel conversion stage is not a large source of GHG emissions (15–20g CO2eq/MJ fuel), compared to algae cultivation (25–87g CO2eq/MJ) or dewatering (60–150g CO2eq/MJ) unit operations. Results indicate that in cases where a portion of the algae biomass is not available for internal heat and power generation, favorable environmental results can be obtained when algae cultivation operations are used to offset current nutrient management activities, such as biological nutrient removal at a wastewater treatment plant. Current estimates suggest that nutrient sources other than municipal wastewater treatment effluents will have to be explored in order for this style of algae cultivation to produce commercially significant quantities of biofuel.

PELLETIZADOS DE RESIDUOS DEL CORCHO: ANÁLISIS DE VIABILIDAD ENERGÉTICA

ABSTRACT: The production and marketing of densified biomass-products have experienced a significant growth last years. Thus, new high quality fuels are emerging for industrial or domestical use. Spain has a great number of agro-industrial and forest factories, in which large amounts of waste are generated from the processing activities. The management of this waste results an important problem for industries that lack the facilities for appropriate treatment. Therefore, the densification of solid biofuels for thermal use represents a real alternative for valorization of these wastes. In Extremadura, spanish region where this work it has been carried out, most of the cork sector companies are located in a small geographical area. In fact, San Vicente de Alcantara contains the 74% of industries in the region, in which are represented from the first to the last stage of the processing. This study aims the viability analysis of energy for the use of the major solid wastes by the cork industries. Firstly, we have determinated its physical and energetic properties, and after that we have studied the pelletizing of wastes as a product for thermal use. The results obtained in this work show the viability of a collective management of the residues that are generated, in order to be densified in a pelletizing facility.

The Carbon Footprint Analysis of Thermal Power Plants

Thermal power plant is the main CO2 emission source in China. This paper discusses the carbon footprint of a thermal power plant in Liaoning province of China based on LCA (Life Cycle Assessment. The reviewed thermal power plants total carbon footprint is about 6.52 million tons, of which 90.23% are from fuel combustion. The onsite emission is 5.91 million tons which depends on the power plants technology level and energy efficiency. In order to alleviate carbon emissions at the power enterprise level, an integrated effort should be taken, including the optimization of energy structures, improvement of energy efficiency and technology level. Recommendations for thermal power plant management are that companies should make full use of geographical advantages and adopt high-quality fuels actively.

Optimizing the Refinery Operational Configuration: Case in Taxation at CO2 Emission

A refinery is essentially a joint production process system. Due to the complex nature of the process involved, while it converts heavier oils into high quality oil products, fuels and other high value products, it also provides a way to curb carbon dioxide (CO 2 ) emissions. As refineries are profit-seeking businesses, this paper used linear programming (LP) models to assess the impact of different taxation amounts on CO 2 emissions on a refinery's operational configuration, and energy using strategies for a refining expansion project in Taiwan, and to discover what the carbon price should be in order to justify the required changes. The result reveals the necessity of developing processes, such as the Delayed Coking (DCU) process combined with hydrotreating, to produce high-quality fuels and petrochemical products in the refinery. Our findings indicate that this anticipated expansion plan reduced CO 2 emissions by 4.92%, while obtaining an efficiency of 14.46 USD/ton-CO 2 at a cost of 30 USD/ton-CO 2 , and by 10.33% and 25.22% CO 2 emission with efficiency gains of 15.22 and 78.61 USD/ton-CO 2 at a cost of 90 and 180 USD/ton-CO 2, respectively. When emission costs are over 90 USD/ton-CO 2 , the refinery opts for liquid petroleum gas (LPG) instead of burning fuel oil, since using hydrogen as a makeup fuel only proves beneficial when the CO 2 emission costs are over 150 USD/ton-CO 2 .

Effects of Fuel Ignition Quality on Critical Equivalence Ratio for Autoignition

Many advanced combustion modes utilize a premixed charge, which can vary from partially premixed to fully premixed, to simultaneously reduce emissions of nitrogen oxides (NOX) and particulate matter (PM). However, the partially premixed charge results in excessive emissions of total hydrocarbons (THC) and carbon monoxide (CO) from incomplete combustion. High ignition quality fuels, or fuels with high cetane numbers, have been in shown previous studies to enable reductions of THC and CO emissions during advanced diesel combustion operation. Many factors were suggested which contribute to the lower THC and CO emissions produced by the combustion of a high cetane fuel. Among the proposed factors was that a high cetane number fuel will have a lower combustion lean limit than a low cetane number fuel, thus resisting incomplete combustion. This theory was examined in the present work where the critical equivalence ratio (ϕ), the minimum equivalence ratio at which a fuel can autoignite, was identified for diesel, a high temperature Fischer–Tropsch (HTFT) fuel, and a low temperature Fischer–Tropsch (LTFT) fuel. The fuels were vaporized and premixed with air heated to 260 °C and then fed into a modified cooperative fuels research (CFR) octane rating engine, at compression ratios of 4, 5, 6, and 8. Equivalence ratio (ϕ) was gradually increased until the critical ϕ was determined. At the lowest compression ratio of 4, the diesel fuel did not autoignite while the HTFT and the LTFT fuels did at critical ϕ of 0.76 and 0.35, respectively. At the highest compression ratio of 8, the critical ϕ of the fuels began to converge where diesel, HTFT, and LTFT had critical ϕ values of 0.23, 0.20, and 0.17, respectively. However, in the presence of simulated EGR (O2 10.7 vol %, CO2 8 vol %, and N2 81.3 vol %) at a compression ratio of 8, the critical ϕ diverged dramatically, where the diesel, HTFT, and LTFT had critical ϕ values of 1.00, 0.77, and 0.38, respectively. n-Hexane, n-heptane, and n-dodecane were used as single-component surrogates of similar ignition quality as the diesel, HTFT, and LTFT, respectively. The single-component surrogates had leaner critical ϕ than their multicomponent counterparts did.

Hydrotreating of low temperature coal tar to produce clean liquid fuels

Clean liquid oil was obtained from low temperature coal tar (LCT) via hydrotreating in trickle-bed reactor (TBR) system filled with commercial catalysts. The effects of hydrogen pressure (10–16MPa), reactor temperature (350–410°C) and liquid hourly space velocity (LHSV) (0.25–1h−1) on hydrotreating performance were investigated while hydrogen to oil volume ratio was maintained constant at 1600LN/L in all cases. The degree of sulfur removal was greater than nitrogen removal with increasing temperature, pressure and contact time over the commercial catalyst. The TBR system was capable of removing nitrogen and sulfur from 1.14 and 0.34wt % in the feed to 63μgg−1 and 8μgg−1, respectively in the products. Gasoline (<180°C) and diesel (180–360°C) fraction were separated from the oil products and analyzed. The gasoline fraction produced from LCT by hydrotreating comply with gasoline specifications for distillation range, sulfur content, induction period and gum presence. But it did not meet the specifications for RON (Research Octane Number) specifications. Diesel fraction produced from LCT meet all quality tests as fuels which could be directly used as motor fuels without upgrading. The results indicated that the raw LCT could be considerably upgraded through catalytic hydrotreating and high-quality fuels were obtained.

Single-step Hydroconversion of Jatropha Oil to High Quality Fuel Oil over Reduced Nickel-Molybdenum Catalysts

The catalytic activities of reduced NiMo catalysts supported on Al2O3, SiO2-Al2O3, SAPO-11 and AlSBA-15 in hydroconversion of Jatropha oil were evaluated. A high deoxygenation ratio was achieved over each reduced catalyst as well as sulfided catalysts. Catalytic performance was obviously influenced by the acidity of supports, resulting in significantly different carbon number distribution in produced hydrocarbons. High yield of 74.6 % of C-11-C-18 hydrocarbon products with low cloud point of ca. -16 degrees C was obtained in single-step hydrotreating of Jatropha oil over NiMo/SiO2-Al2O3 catalyst.

Effect of Load Shedding in Chinhoyi Urban Residential Areas, Zimbabwe

This paper presents the findings of the investigation carried out to establish the effects of load shedding in Chinhoyi Residential Urban areas, Zimbabwe. A questionnaire survey to assess the effects and establish the energy pattern and usage of alternative fuels during load shedding was conducted. The survey established that 60% of residence experienced losses in perishable food stuffs due refrigerat ion failure, 15% reported production downtime in their ho me industries with 10%having their electrical appliances such as television sets being damaged as a result of the power surges fashioned by the power outage. This has accordingly contributed in thinning the living standards of the residents. The survey also established a peculiar energy pattern and usage of alternative fuels for cooking and lighting during load shedding. Households in the low density areas of Chinhoyi displayed a wide energy matrix of relatively high quality fuels for both cooking and lighting. When compared to households in the high density areas, 55% of the households in low density cook mainly with LPG whereas 93% of households in high density areas cook exclusively with firewood. Use of candles was common for lighting in both residential sectors. Inco me for the residents was disproportionately eroded as a result of load shedding. The fract ion of energy cost to income was found to increase from 16% without load shedding up to 64% for those in the low density and up to 49% for those in the high density areas. This has consequently impoverished the residents. Load shedding was also found to have coined household thieves with 65% of these being wo men who harvest wood illegally fro m farms and forests. This form of harvesting is uncontrolled and therefore unsustainable. The survey therefore concludes that wo men are unduly burdened by the power outage exercise and people in general have been reduced to poverty levels as they are left with dwindled inco me.

Hybrid clean energy technologies for power generation from sub-bituminous coals: a case of 250 MW unit

Major re-thinking is required on the conventional pulverized fuel conversion route of power generation wherein the ash and mineral burden in coals is transported through the entire flow passage of the boiler. For high-ash fuels, this has to be contained and the boiler must be clear of all mineral matter. The two independent clean coal candidate technologies for efficiency enhancement and emission controls – ultra-supercritical cycle (USC) and integrated gasification with combined cycle (IGCC) – both have limitations in adaptation to high-ash coals. While the USC is limited by the steam temperature up to 600°C (commercial scale) (700°C pilot scale) and boiler tube failure risks, IGCC is limited to high-quality fuels like diesel, naphtha, etc. (commercial scale) and high-grade coals (pre-commercial scale). The hybridization of the two technologies in their current form (ultra-supercritical cycle with gasification conversion) and carbon capture and storage (CCS) together with solar energy (solar thermal and solar photovoltaic) integration presents possibilities for immediate application to low-grade sub-bituminous coals to achieve the clean technology goals. The energy efficiency of the hybrid system is around 44.45%, which is of the order of the USC with pulverized coal combustion. But the predominant benefits of a clean operation override. The benefits are reduction in CO2 generation from 0.86 to 0.70 kg/kWh and reduction in ash expelled from 0.20–0.24 to 0.12–0.18 kg/kWh besides elimination of dispersion of ash around the power station and facilitating CCS.