S. M. Shaahid

Techno-Economic Potential of Retrofitting Diesel Power Systems with Hybrid Wind-Photovoltaic-Diesel Systems for Off-Grid Electrification of Remote Villages of Saudi Arabia

Recent climatic anomalies such as hot summers, cold winters, hurricanes, and cyclones are all reflections of global warming due to burning of fossil fuels. To combat unprecedented global warming and to mitigate future energy challenges, there is worldwide interest in utilization of renewable sources of energy such as solar-photovoltaic (solar-PV) and wind energy. Other driving forces paving avenue for renewable energy include rapid escalation in oil prices, growing concerns regarding depletion of oil/gas reserves, etc. Retrofitting of diesel systems with hybrid wind-PV-diesel systems is being widely disseminated to reduce diesel fuel consumption and to minimize atmospheric degradation. One of the potential market for deployment of hybrid systems is in remote locations which are driven by diesel generators. The Kingdom of Saudi Arabia (KSA) has a number of remote villages scattered all over the Kingdom. The aim of this study is to analyze wind speed and solar radiation data of Rafha, KSA, and to assess the technical and economic potential of hybrid wind-PV-diesel power systems to meet the load requirements of a typical remote village Rawdhat Bin Habbas (RBH) with annual electrical energy demand of 15,943 MWh. Rafha is located near RBH. The monthly average wind speeds range from 2.99 m/s to 4.84 m/s at 10 m height. The monthly average daily global solar radiation ranges from 3.04 to 7.3 kWh/sq.m. The hybrid systems simulated consist of different combinations of 600 kW wind machines, PV panels, supplemented by diesel generators. National Renewable Energy Laboratorys (NREL) Hybrid Optimization Model for Electric Renewables (HOMER) software has been used to perform the techno-economic study. The simulation results indicate that for a hybrid system comprising of 1.2 MW wind farm capacity (two 600 kW units, 50 m hub-height) and 1.2 MW of PV capacity together with 4.5 MW diesel system (three 1.5 MW units), the renewable energy fraction with 0% annual capacity shortage is 24% (10% wind + 14% PV). The cost of generating energy (COE) from this hybrid wind-PV-diesel system has been found to be 0.118

Wind Measurements and Energy Potential for a Remote Village in Saudi Arabia

/kWh (“assuming diesel fuel price of 0.1

Experimental Study on the Flow Regimes and Pressure Gradients of Air-Oil-Water Three-Phase Flow in Horizontal Pipes

/l”). The study exhibits that for a given hybrid configuration, the number of operational hours of diesel generators decreases with increase in wind farm and PV capacity. Attention has also been focused on wind/PV penetration, unmet load, excess electricity generation, percentage of fuel savings and reduction in carbon emissions (relative to diesel-only situation) of different hybrid systems, cost breakdown of wind-PV-diesel systems, COE of different hybrid systems, etc.

Jet Impingement Cooling in Gas Turbines for Improving Thermal Efficiency and Power Density

Site specific wind speed measurements are critical for techno-economical development of wind energy applications. This paper presents the wind power potential at Rawdat Ben Habbas village where meteorological measurements were made using a 40 meter tall wind tower for a period of one year. The wind speeds were recorded at 20, 30 and 40 meters above ground level (AGL) and the wind direction at 30 and 40 meters AGL. The other meteorological parameters like ambient temperature, pressure, relative humidity and global solar radiation were measured at 2 meters AGL. The wind exponent was obtained using wind speed at different height and found to vary between 0.28 and 0.36 corresponding to February 2006 and December 2005, respectively. The air density varied between 1.076 kg/m3 in the month of August 2006 and 1.187 kg/m3 in January 2006. Annual mean wind speed was noted as 4.6, 5.23 and 5.57 m/s at 20, 30 and 40 meters AGL, respectively. A wind farm of 30 MW installed capacity assumed to be developed using 30 wind turbines of 1 MW rated capacity each could generate 88,096 MWh of electricity each year at an average plant capacity factor of 33.5% at the site of wind measurements.

Role of Cooling Techniques and Fuels in Enhancing Power and Efficiency of Gas Turbine Plants

An experimental investigation has been carried out to study the flow regimes and pressure gradients of air-oil-water three-phase flows in 2.25 ID horizontal pipe at different flow conditions. The effects of water cuts, liquid and gas velocities on flow patterns and pressure gradients have been studied. The experiments have been conducted at 20°C using low viscosity Safrasol D80 oil, tap water and air. Superficial water and oil velocities were varied from 0.3 m/s to 3 m/s and air velocity varied from 0.29 m/s to 52.5 m/s to cover wide range of flow patterns. The experiments were performed for 10% to 90% water cuts. The flow patterns were observed and recorded using high speed video camera while the pressure drops were measured using pressure transducers and U-tube manometers. The flow patterns show strong dependence on water fraction, gas velocities, and liquid velocities. The observed flow patterns are stratified (smooth and wavy), elongated bubble, slug, dispersed bubble, and annular flow patterns. The pressure gradients have been found to increase with the increase in gas flow rates. Also, for a given superficial gas velocity, the pressure gradients increased with the increase in the superficial liquid velocity. The pressure gradient first increases and then decreases with increasing water cut. In general, phase inversion was observed with increase in the water cut. The experimental results have been compared with the existing unified Model and a good agreement has been noticed.

Heat Transfer in a Channel With Inclined Target Surface Cooled by Single Array of Impinging Jets

The gas turbine is an engine which produces a great amount of energy depending upon its size and weight. Gas turbines are used for aircraft propulsion and land based power generation. Thermal efficiency and power output (power density) of gas turbines increase with increasing turbine rotor inlet temperatures (RIT). Today there are gas turbines, which run on natural gas, diesel fuel, naphtha, methane, crude, low-Btu gases, vaporized fuel oils, and biomass gases. The last 20 years has seen a large growth in gas turbine technology which is mainly due to growth of materials technology, new coatings, and new cooling schemes. In a simple gas turbine cycle (Figure 1), low pressure air is drawn into a compressor (state 1) where it is compressed to a higher pressure (state 2). Fuel is added to the compressed air and the mixture is burnt in a combustion chamber. The resulting hot products enter the turbine (state 3) and expand to state 4 and the air exhausts. Most of the work produced in the turbine is used to run the compressor and the rest is used to run auxiliary equipment and to produce power. Figure 2 shows schematic of cross section of a small gas turbine.

Economic analysis of retrofitting existing gas turbine power plants with cogeneration facility

Performance analysis of different gas turbine power plant configurations is presented in this paper. The work includes the effect of humidity, ambient inlet air temperature and types of fuels on gas turbine plant configurations with and without cooling technologies. Investigation also covers economic analysis. 20 MWe GE 5271RA and 40 MWe GE-6561B frames are selected for the present study. GT PRO software has been used for carrying out the simulations for a given location of Saudi Arabia. The relative humidity and temperature have been varied from 30 to 45 % and from 80 to 100° F, respectively. Fuels considered in the study are natural gas, diesel and heavy bunker oil. Results show that variation of humidity does not affect the gas turbine performance for all types of fuels. For GT only situation, for a decrease of ambient inlet air temperature by 10 °F, plant net output and efficiency have been found to increase by 4%, 1 % respectively, for all fuels. However, with addition of, fogger, plant net output and efficiency further increase by 3 %, 1% respectively. For all GT frames with fogger, the net plant output and efficiency are relatively higher as compared to GT only case for all fuels. The net plant output and efficiency for natural gas are higher as compare to other fuels for all GT scenarios. For 40 MWe frame with and without fogger, break even fuel price and electricity price have been found to vary from 2.03 to 2.22 USD/MMBTU and from 0.024 to 0.026 USD/kWh respectively.

Impact of Gas Turbine Frame Size on Efficiency of Gas Turbine Power Plants

An experimental investigation has been carried out to study the heat transfer characteristics in a channel with heated target plate inclined at an angle cooled by single array of centered impinging jets. The target plate forms the leading edge of a gas turbine blade. The work includes the effect of various exit outflow orientations and crossflow and feed channel aspect ratios on the heat transfer characteristics for a given orifice-jet plate configuration. Three feed channel aspect ratios (H/d = 5, 7, 9) and have been examined. In general, it has been observed that Nu is high for higher aspect ratios. This increase can be attributed to increase in strength of impinging jets due to increase in feed channel aspect ratio. Additionally, for a given jet-orifice plate with centered holes and for a given Re = 18800, the heat transfer is almost the same through out the target surface for the outflow passing out in both the directions.Copyright

Effect of Viscosity on the Pressure Gradient in 4-Inch Pipe

Cogeneration refers to the generation of combined heat and power (CHP), which is more efficient than a central power plant generating only electricity. The proportion of power generation using CHP is growing world-wide due to efficiency improvements and environmental benefits. Exhaust heat from GT power plants can be fed to boilers for producing steam. Steam is used for reservoir flooding, petrochemical industries, food processing etc. Operational gas turbine power generation plants can be retrofitted to co-generation power plant to produce steam in addition to electrical power. A computational preliminary economic feasibility study of retrofitting a given existing gas turbine power generation plant into a co-generation power plant is presented in this paper. A 80 MW GE-6111FA frame has been selected for the present study. The work includes the effect of relative humidity (RH), ambient air temperature, etc., on economics of the power plant. GTPRO/PEACE software has been used for carrying out the analysis. The RH and temperature have been varied from 30 to 45 % and from 80 to 100° F, respectively. For a decrease of inlet air temperature by 10 °F, net plant output and efficiency have been found to increase by 4.3 and 1.4 %, respectively for GT only situation. However, for GT with cogeneration scenario, for a decrease of inlet air temperature by 10 °F, net plant efficiency has been found to be increased from 33.3 % (GT only) to 63.4 % (cogeneration). For situations with and without cogeneration, break even fuel price has been found to vary from 2.6 to 3.0 USD/MMBTU respectively and break even electricity price have been found to vary from 0.018 to 0.022 USD/kWh respectively. For the simulation conducted, emission has been found to be 344352 ton/year.

EFFECT OF INCLINATION ON THE AIR-WATER FLOW IN 4-INCH PIPE

A computational study to assess the effect of gas turbine (GT) frame size on efficiency of gas turbine power plant configurations is presented in this paper. The work includes the effect of relative humidity (RH), ambient inlet air temperature and frame size on gas turbine plant configurations with and without fogger unit. Investigation also covers economic analysis. 20 MWe GE 5271RA, 40 MWe GE-6561B and 70 MWe GE-6101FA frames are selected for the present study. GT PRO software has been used for carrying out the analysis including; net plant output and net efficiency, break even electricity price (BEEP) and break even fuel LHV price (BEFP), etc. The relative humidity and temperature have been varied from 30 to 45 % and from 80 to 100° F, respectively. Fuels considered in the study are natural gas, diesel and crude oil. Results show that variation of humidity does not affect the gas turbine performance appreciably for all GT frame size regardless of type of fuel. For a decrease of inlet air temperature by 10 °F, net plant output and efficiency have been found to increase by 4 and 1.7 %, 4.2 and 1.3 %, 4.7 and 1.8 %, respectively for 20 MW,40MW and 70MW for crude oil and for GT only situation. However, for GT with Fogger scenario, for a decrease of inlet air temperature by 10 °F, net plant output and efficiency have been found to further increase by 3.1 and 1.3 %, 3 and 0.9 %, 3.2 and 1.1 %, respectively for 20 MW,40MW and 70MW. For situations with and without fogger for crude oil, BEFP have been found to vary from 1.3968 to 1.3916, 2.13 to 2.0948, 2.387 to 2.4642 USD/MMBTU respectively for 20 MW, 40MW and 70MW and BEEP have been found to vary from 0.03142 to 0.0313, 0.02488 to 0.02504, 0.0229 to 0.0233 USD/kWh respectively for 20 MW, 40MW and 70MW.