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Gasification reactions of Thar coal chars with CO2 and H2O have been investigated, using pressurized thermo-gravimetric analyzer (PTGA). A quartz fixed-bed reactor was used to prepare coal char at 900 °C with a nitrogen environment. Dynamic heating segments were maintained with a constant heating rate during all experiments. The temperature was raised from room temperature to 1000 °C, at different pressures 1 atm., 5 atm., and 10 atm. using pure reacting gases (CO2 and H2O). The weight loss data obtained from PTGA results were used to study the kinetic behavior of Thar lignite char for gasification reactions with CO2 and H2O as gasifying reacting species. It was observed that gasification reactions of char with reacting gas CO2 and char with reacting gas steam (H2O) initiated at 750 °C and completed after reaching 950 °C, at atmospheric pressure, but the occurrence of reactions was slightly delayed at high pressures. Volumetric Model and Grain Model were used to develop a kinetic model for Thar lignite. The direct plot and integral methods were used to calculate Arrhenius parameters such as the pre-exponential factor (A) and activation energy (E). An increase of A and E was also observed in increasing pressures. The activation energy (E) was investigated from 244.64 to 317.6 kJ/mol at atmospheric pressure; whereas, it is lying in the range of 286.13–356.67 kJ/mol at a pressure of 10 atm.

Gasification is one of the prominent and technically efficient technologies for converting solids like coal, biomass or solid waste into useful gas known as “syngas.” Several configurations are in use today among which entrained flow gasifiers have several advantages over other configurations. Presently research is more focused on micro-level modifications in the configurations which have a significant impact on overall performance of gasification. Scant, literature is available for comparison of slurry over dry form of feedstocks, especially with low-grade coals. Hence, present research aims to establish a concrete finding regarding the impacts of slurry versus the dry condition of coal on the overall performance of gasification. To achieve this goal, a two-dimensional computational fluid dynamic (CFD) model of downdraft gasifier was developed in commercial CFD software FLUENT for performing numerical simulations with indigenous coal feedstock. Rich oxidant conditions (95% oxygen and 5% nitrogen) were maintained in the gasifier for the gasification. The performance of gasification was measured by comparing efficiencies of gasification and the quality of syngas produced with different coal forms. As per simulation results, coal forms and operating conditions caused a significant effect on overall gasification performance. In syngas composition, H2 mol fraction reached at maximum, when the slurry form of coal was used for gasification. This effect is remarkable for generating hydrogen-rich fuel from lignite without consuming steam externally.

Thermochemical conversion of biomass is an encouraging way for the production of syngas. In the present research, four different biomass materials were used for gasification which includes rice husk, cotton stalks, sugarcane bagasse, and sawdust. These biomass sources were selected because they are common Pakistani feedstocks. Gasification of selected biomasses was performed using concentric tube entrained flow gasifier. Three-dimensional computational fluid dynamics model was used to investigate the impacts of kinetic rate and diffusion rate on the gasification performance. The Euler–Lagrange method was used for the development of entrained flow biomass gasifier using commercial computational fluid dynamics code ANSYS FLUENT®14. Discrete phase model was used to predict the movement of particles, whereas the gas phase was treated as the continuous phase with a standard k–ε turbulent model to predict the behavior of gas phase flow. Finite rate/Eddy dissipation model was applied for the calculation of homogenous and heterogeneous reaction rates. Oxygen was used as a gasifying agent. Cotton stalks and sugarcane bagasse produced higher mole fractions of hydrogen (H2) and carbon monoxide (CO) than sawdust and rice husk. Regarding carbon conversion efficiency, cold gas efficiency, and higher heating value cotton stalks and sugarcane bagasse produced better syngas quality as compared to sawdust and rice husk. The oxygen/fuel (O/F) ratio is a key operating parameter in the field of gasification and combustion. The O/F ratio above 0.42 favored combustion reactions and increased mole fraction of water vapor (H2O) and carbon dioxide (CO2) in syngas composition, whereas gasification reactions dominated below 0.42 O/F ratio, resulting increased mole fraction of H2 and CO in syngas composition.

Pakistan has remained an energy-deficient country, and most of the industrial sectors are closed due to the loading shedding of electricity. Even though Pakistan is located on the “solar belt” and receives over 2 MWh/m2 solar irradiation per year with 1500–3000 h of sunshine, unfortunately solar energy is not harnessed to fulfill the energy needs of the country. Solar flat plate collectors (SFPC) are widely employed for collecting solar radiations from the sun. Currently, worldwide solar thermal energy is widely used in household and commercial equipment for energy collection and utilization. The working fluid selected for this research work is water; numerical simulations were performed using Ansys FLUENT. On selected geographical coordinates, solar ray tracing model was employed to incorporate solar heat flux. Nawabshah (NWB), Hyderabad (HYB), Jacobabad (JCB), and Mirpurkhas (MPK) cities were selected for the measuring of performance of SPFC. Firstly, parallel to ground (at a 0° tilt angle) orientation of SFPC was performed. Furthermore, the performance of SFPC was measured using tilt angles of 15°, 30°, and 45°, respectively. The maximum exit water temperature in JCB at a tilt angle of 30° was 97.8 °C in March and a minimum of 88.09 °C in June. In HYD, at a tilt angle of 45°, the maximum temperature rise was recorded at 98.01 °C in November and the minimum was noticed at 76.37 °C in June. While in JCA, at an angle of 30°, the highest temperature was recorded at 97.83 °C in February and a minimum of 78.54 °C in June. The specific aim of this research study was to measure the performance of the SFPC at different tilt angles and at varying geographical coordinates through numerical simulations.

The aim of this study involves establishing a three-dimensional computational fluid dynamic (3D-CFD) model of solar flat plate collector (SFPC) in order to investigate the effect of operating and geometric parameters on thermal efficiency. In this research work, commercial CFD code ANSYS FLUENT®14.0 version was used for the development of a model of solar plate collector. The single circular tube geometry was created using ANSYS DesignModeler®14.0. The general continuity equation along with Navied–Stokes equations was solved for tracking motion of the working fluid. The general k–e turbulence modeling approach was used for solving the turbulence in the flow. Solar ray tracing was activated for calculating solar load in the model. The latitude and longitude of the Hyderabad region were inserted in the solar ray-tracing model for calculating solar intensity as per local conditions. Two fluids i.e., water and air were circulated with different flow rates in the developed model of SFPC. It was observed that water gave higher efficiency due to high density and thermal conductivity. The simulation results gathered revealed that the temperature of water and air was raised by almost 79 °C and 73 °C respectively.

In this study 2D numerical simulation for two-stage entrained flow dry feed coal gasification performance was developed. The detailed operational characteristics of O/C distribution between the two stages of the gasifier were examined in standard CFD software FLUENT®14 to analyze their effects on the gasification performance. Furthermore the different reaction mechanisms were investigated for validation of the model with experimental results. The results show that H 2 and CO composition at the exit of gasifier are increased at O/C ratio 0.8 as compared to other simulation cases, and the temperature gradually decreases from 2nd injection level because of water-shift reaction. Maximum CO% was observed when 40% of oxygen injected at the lower level, overall range of H 2 % at the exit of gasifier was 10–45% but maximum H 2 % was found when 50% O 2 % and 30% of coal injected at a lower level. The maximum temperature about 2300 K when 40% O 2 and 40% of coal was injected at a lower level. Overall optimized results for CO, H 2 , and minimum CO 2 formation was observed when 60% O 2 and 40% of coal was injected at a lower level of the gasifier. The gasification performance can be controlled with the optimized coal/oxidant distribution between the stages.

Pakistan is very rich in coal reserves specifically after exploration of Thar coal reserves. At the same time country is facing energy crises due to shortage or unavailability of sustainable fuel supply at a cheaper rate. One potential solution is coal gasification which gives clean synthetic gas usually called syngas for use as an alternative fuel source for electricity production at a cheaper rate as well as a source of recovering different chemicals used as basic raw materials in other industries. Numerical simulations have been performed in this work for the gasification process of indigenous coal on a 2D computational fluid dynamic (CFD) model of downdraft entrained-flow gasifier using commercial CFD software FLUENT®6.3.26. Navier-stokes equations along with transport equations for species have been solved using eddy-dissipation combustion model. The compositions of indigenous coals (Thar, Lakhra, and Sonda) were used in simulations as gasification feedstock. Rich oxidant conditions 95 % O2 and 5 % N2 were set for gasification. The gasification performance was studied by comparing efficiencies of gasification and quality of syngas produced for three types of coal feedings. The temperature and pressure profiles inside the gasifier were also studied. From simulation results, the great influence of coal composition was observed in the performance of gasification. Lakhra coal produced syngas with a maximum heating value of 20.55 MJ/kg whereas sonda coal produced syngas with a minimum heating value of 17.96 MJ/kg.

A 3D CFD model for two-stage entrained flow dry feed coal gasifier with multi opposite burners (MOB) has been developed in this paper. At each stage two opposite nozzles are impinging whereas the two other opposite nozzles are slightly tangential. Various numerical simulations were carried out in standard CFD software to investigate the impacts of coal and oxidant distributions between the two stages of the gasifier. Chemical process was described by Finite Rate/Eddy Dissipation model. Heterogeneous and homogeneous reactions were defined using the published kinetic data and realizable k–e turbulent model was used to solve the turbulence equations. Gas–solid interaction was defined by Euler–Lagrangian frame work. Different reaction mechanism were investigated first for the validation of the model from published experimental results. Then further investigations were made through the validated model for important parameters like species concentrations in syngas, char conversion, maximum inside temperature and syngas exit temperature. The analysis of the results from various simulated cases shows that coal/oxidant distribution between the stages has great influence on the overall performance of gasifier. The maximum char conversion was found 99.79% with coal 60% and oxygen 50% of upper level of injection. The minimum char conversion was observed 95.45% at 30% coal with 40% oxygen at same level. In general with oxygen and coal above or equal to 50% of total at upper injection level has shown an optimized performance.

Pakistan is gas rich but power poor country. Conventional approach is always directed toward power plants using fossil fuel. Some trials have also taken place demonstrating wind and other nontraditional energy source for generating electricity. A pragmatic and feasible unexploited resource is the potential energy from high-pressure natural gas. Currently, this energy is being wasted at gas pressure reducing stations in Pakistan. At present there are two integrated gas companies (transmission and distribution), i.e., Sui Southern Gas Company Limited (SNGPL) and Sui Northern Gas Pipelines Limited (SSGCL). The gas is transmitted through the transmission pipelines in the pressure ranges of 800–1,000 psig. The gas is distributed by reducing from the transmission pressure into distribution pressure up to a maximum level of 150 psig at the city gate stations normally called “sales metering station (SMS).” There are almost more than 200 SMSs in SNGPL and SSGCL. This study highlights real possibilities to utilize the energy lost in gas reducing stations (SMSs) as a source of electrical power. The present study shows that with average pressure ratio (ratio of upstream to downstream pressure) of 10 and average gas flow of 35 MMSCFD from any gas metering station, more than 2 MWe power could be generated without consumption of any fuel.

The strong challenges of sustainable development are as diversified and complex as the human societies and natural ecosystems around the world. Sustainable development requires the participation of diverse stack holders, with the idea of reconciling different and sometimes opposing values and goals toward a coordination of mutual action to achieve required goals. Energy sector issues and developments continued to severely constrain Pakistan’s economy in 2009–2010. Against a backdrop of a sharp increase in the international price of oil through the calendar year 2009, which put enormous upward pressure on the cost structure in the power generation (and transport) sector, in particular, large domestic supply shortages of electricity and gas occurred. Lower accumulation of water reserves in dams compounded the severity. The cumulative effect of the energy crisis on the economy is estimated at upward of 2% of gross domestic product (GDP) during 2009–2010 alone. Brundtland Commission and others provide the background for the approach we have chosen to structure the indicators. Sustainability indicators are generally designed to illustrate the economic, environmental, and social dimensions of sustainable development. Policymakers need methods for measuring and assessing the current and future effects of energy use on human health, human society, air, soil, and water. Energy indicators for sustainable development: guidelines and methodologies, IAEA (Energy indicators for sustainable development: guidelines and methodologies, Vienna, 2005) are focused here. Some guidelines are recommended for the sustainable development of energy in Pakistan.

Sugar industry, being the major consumer of water, discharges its effluents into the outside environment mostly as untreated. However, besides knowing about the pollution strength of these effluents, knowledge about the mode of disposal of these effluents into the surroundings is also crucial. Thus, an intensive investigation was carried out to know the disposal patterns adopted by three selected sugar mills, namely, Habib Sugar Mills, Nawabshah, Matiari Sugar Mills, Matiari, and Fauji Sugar Mills, Tando Mohammad Khan, along with the obvious problems people were facing as a result. The study concluded that the disposal of untreated effluents into the surroundings had a negative impact on the resources such as land and water (both surface and ground) in particular and on the health of people and their livestock in general.