Design And Performance Analysis Of A Parabolic Trough Power Plant Under Tamanrasset Climatological Conditions
Benhadji Serradj, Djamal Eddine
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In this study the current status of the energy resources, supply and demand in Algeria is reviewed. The different sources of renewable energy and their contribution to the present and future electricity supply of the country are also analyzed. Low electricity price in Algeria is one of the major challenges facing the development of renewable energies in the country. Since the energy prices are low, country’s energy consumption is one of the highest in Africa at 1277 kWh per capita per annum where the average per capita energy consumption for Africa is 543 kWh . Conventional resources, especially natural gas are the primary sources exploited for electricity production. However, the latter resources emit a great amount of greenhouse gases. The huge solar energy potential in Algeria and its different applications can be utilized to meet the escalating energy demand with minimal greenhouse gases. In this study, the site of Tamanrasset was taken as the case study because of the high direct normal irradiation (DNI) received in the city. Tamanrasset is an oasis city and capital of Tamanrasset province in southern Algeria, in the Ahaggar Mountains. In summer there is an escalation of power demand due to the cooling load. The capacity of the existing transmission infrastructure cannot meet this additional load and hence there is periodic shortage of electricity. The most suitable technology for harvesting (DNI) is concentrating solar power (CSP) and has been chosen for this project. To support the existing installed power capacity connected to Tamanrasset, the electricity demand of the city was initially determined for two critical periods in the year (winter and summer), where the winter peak load was found during the night at a value of 73 MW and in summer peak load was in the afternoon and late in the evening at 87 MW. A parabolic trough power plant of 100 MWp with 6 hours of storage was designed and simulated to assess the city’s load demand portion that power produced from the designed power plant could meet. Different parameters were taken into account during the design to minimize the impact of the environmental conditions on the performances of the plant. Initially Meteonorm weather resource assessment software was used to generate the annual weather data file at a suitable site in Tamanrasset (Latitude: 22.79, longitude: 5.526). Using this file System Advisor Model software was then used to simulate the designed parabolic trough power plant considering two different condensers types; evaporative and air-cooled in consideration of water constraint in the selected location. The two different cooling technologies were compared based on the power plant electricity production and water consumption. The results have shown that for the whole year, energy produced from the one using water for cooling was higher than the one using air cooling system. Therefore, the capacity factor of the evaporative cooling power plant was higher by 4% more than the opponent technology. However, water consumption was very high for water cooling power plant reaching almost 14 times more than the air cooled technology. Since the water consumed in evaporative cooled power plant was enormous comparing to its availability in Tamanrasset the load, economic and greenhouse analysis was done only for dry cooled power plant. The electricity production was compared after to the real load of the city during the month of January and August. It was found that during the month of January (winter) the power plant was able to cover 78% from the needs of the city. On the other hand, during the month of August (summer) even with the high electricity production the power plant provided the city with only 60% of the needs and that was due to the high demand of the city. On the other hand, the energy losses of the power plant were analyzed and it was found that the biggest share of energy losses was in form of parasitic losses in the power plant heat transfer pumps and also in the receiver in form of thermal losses. Economic analysis of the power plant was undertaken and the levelized cost of electricity was found as 8.19 DA/kWh with a payback period of 8.78 years and benefit-cost ratio of 1.73. Sensitivity analysis when varying the solar multiple of the power plant and also the size of the thermal energy storage was done and shown for each solar multiple process an optimum number of hours of storage that gives the optimum LCOE. Moreover, it was found also that whenever the storage hours increase the Levelized cost of electricity increases too. A cash flow analysis was performed also to analyze the assets of project. Environment impact analysis of the power plant was done and established, the designed power plant avoided greenhouse gas emissions were estimated using the emissions that could be released if the power plant was using natural gas in a combined cycle plant.