Solar thermal and photovoltaic electrical generation in Libya

This thesis investigates the application of large scale concentrated solar (CSP) and photovoltaic power plants in Libya.Direct Steam Generation (DSG) offers a cheaper and less risky method of generating electricity using concentrated solar energy than Heat Transfer Fluid (HTF) plant. However, it is argued that the location of a DSG plant can be critical in realising these benefits, and that the South-East part of Libya is ideal in this respect. The models and calculations presented here are the result of an implementation of the 2007 revision of the IAPWS equations in a general application based on Microsoft Excel and VBA. The hypothetical design for 50MW DSG power plant discussed in this thesis is shown to yield an 76% reduction in greenhouse gas emissions compared to an equivalent gas-only plant over the ten-hour daily period of operation. Land requirement is modest at 0.7km2.A new method for improving the distribution of heat within the absorber tube wall was developed. Internal helical fins within the absorber tube have been proposed to provide a regularly pitched and orderly distribution of flow from the ‘hot’ to the ‘cold’ side of the absorber tube. Note that the irradiance profile on the absorber tube is highly asymmetric. A CFD simulation using FLUENT software was carried out for three types of pipes with different internal helical-fin pitch, and an aluminium pipe without fins. The results show that the thermal gradient between the upper and lower temperature for the pipe without a helical fin is considerably higher compared with the pipes with helical fins. Also, the thermal gradient between the two halves for the aluminium pipe (without a helical fin) is much lower when compared to the result for the traditional steel pipe (without a helical fin).A 50MW PV-grid connected (stationary and tracking) power plant design in Al-Kufra, Libya has been carried out presently. A hetero-junction with intrinsic thin layer (HIT) type PV module has been selected and modelled. The effectiveness of the use of a cooling jacket on the modules has been evaluated. A Microsoft Excel-VBA program has been constructed to compute slope radiation, dew-point, sky temperature, and then cell temperature, maximum power output and module efficiency for this system, with and without water cooling for stationary system and for tracking system without water cooling. The results for energy production show that the total energy output is 114GWh/year without a water cooling system, 119GWh/year with a water cooling system for stationary system and 148GWh/year for tracking system. The average module efficiency with and without a cooling system for the stationary system is 17.2% and 16.6% respectively and 16.2% for the tracking system. The electricity generation capacity factor (CF) and solar capacity factor (SCF) for stationary system were found to be 26% and 62.5% respectively and 34% and 82% for tracking system. The payback time for the proposed LS-PV power plant was found to be 2.75 years for the stationary system and 3.58 years for the tracking system.The modelling that was carried was based on the measurements conducted on the experimental system set in a city in the southern part of Turkey. Those measurements are recorded by a Turkish team at Iskanderun. As well as the current, voltage and cell temperature of the photovoltaic module, the environmental variables such as ambient temperature and solar irradiance were measured. These data were used for validation purposes. The correlation for the conversion of solar irradiation from horizontal to sloped surface indicated that the presently used model is highly successful reflected by the goodness of fit parameters: the coefficient of determination is 0.97, and the mean bias error -2.2W/m2. Similarly, the cell temperature model used in the present thesis is validated by the following correlation parameters R2 = 0.97 oC, while MBE is 0.7 and RMSE = 2.1 oC

Review on Solar Thermal Electricity in Libya

Libya is facing an increasing deficit in electrical energy supply which needs great efforts to find new and renewable alternative sources of power. Solar thermal electricity is one of the most promising and emerging renewable energy technologies to substitute the conventional fossil fuel systems. A review of the research literature of solar thermal electricity in Libya is presented in this article. The state of the art of these technologies including design, operation principles and global market is demonstrated. Detailed reviews of research activities that have been conducted by Libyan researchers or institutions are presented. It has been found that Libya as a country needs a strategic plan and more research efforts in order to adopt these new technologies and put them in production mode

Inter-relationship between mean-daily irradiation and temperature, and decomposition models for hourly irradiation and temperature

Terrestrial temperature records have existed for centuries. These records are available for very many locations. Temperature is indeed the most widely measured meteorological parameter. In contrast, solar radiation being a parameter of secondary importance and also in view of the excessive measurement cost and the associated due care, it is recorded very infrequently. This article presents evaluation of a new type of model for mean-daily and hourly solar radiation based on temperature. The proposed model is of a very simple constitution and does not require any secondary meteorological parameters as required by other group of models that are available in literature. Furthermore, hourly temperature models are also presented that only require mean-daily temperature data. A comparison was undertaken regarding the performance of the presently proposed and previous models. It was found that the present models are able to provide reliable irradiation and hourly temperature estimates with a good accuracy

Modeling and Experimental Verification of Solar Radiation on a Sloped Surface, Photovoltaic Cell Temperature, and Photovoltaic Efficiency.

This article presents modeling and experimental verification of conversion of solar irradiation from horizontal to sloped surfaces and photovoltaic cell temperature and an analysis of photovoltaic conversion efficiency. Modeling and validation of the models are carried out on the basis of measurements conducted using the experimental system set in a city in southern Turkey. In addition to current, voltage, and cell temperature of the photovoltaic module, environmental variables such as ambient temperature and solar irradiance were measured and used for validation purposes. Correlation of conversion of solar irradiation from horizontal to sloped surfaces indicated that the presently used model is highly successful because of the fitting parameters: the coefficient of determination (R 2 )=0.97 , and the mean bias error (MBE)=−2.2 . Similarly, the cell temperature model used in the present article is validated by the following correlation parameters: (R 2 )=0.97 , MBE=0.7 , and root-mean-square error (RMSE)=2.1

Modeling and Experimental Verification of Solar Radiation on a Sloped Surface, Photovoltaic Cell Temperature, and Photovoltaic Efficiency.

This article presents modeling and experimental verification of conversion of solar irradiation from horizontal to sloped surfaces and photovoltaic cell temperature and an analysis of photovoltaic conversion efficiency. Modeling and validation of the models are carried out on the basis of measurements conducted using the experimental system set in a city in southern Turkey. In addition to current, voltage, and cell temperature of the photovoltaic module, environmental variables such as ambient temperature and solar irradiance were measured and used for validation purposes. Correlation of conversion of solar irradiation from horizontal to sloped surfaces indicated that the presently used model is highly successful because of the fitting parameters: the coefficient of determination (R 2 )=0.97 , and the mean bias error (MBE)=−2.2 . Similarly, the cell temperature model used in the present article is validated by the following correlation parameters: (R 2 )=0.97 , MBE=0.7 , and root-mean-square error (RMSE)=2.1

Modeling the behavior of a 50MW DSG plant for southern Libya based on the thermodynamic and thermophysical properties of water substance

This paper presents arguments for the use of direct steam generation (DSG) in preference to other forms of generation in particular locations according to the prevailing environmental and economic conditions. In addition, the paper describes the development of a software tool based on Microsoft Excel and Visual Basic for Applications (VBA), which draws upon established physical relationships in the heat transfer literature to perform plant capacity calculations in a fast and convenient manner. The results of the VBA program determine the solar fraction of the plant, assuming that the plant is in operation for 10 h per day (07:30–17:30 hours), the solar fraction is shown to be 76% and the DSG plant achieves a 76% reduction in emissions. Construction costs are also estimated based on formulae from previous work