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

Influence of the geographical parameters on the performance of hybrid solar gas turbine

This study aims to investigate the influence of the geographical and climate parameters on the performance of the hybrid solar gas turbine with a pressurized air receiver. A number of sites located in South America (Chile, Bolivia, and Peru) and North Africa (Algeria and Libya) are considered. The geometric design parameters of the solar receiver and the tower are calculated using an in-house code. The layout and the optical performance of the heliostat field are carried out using SolarPILOT software. The simulation of the complete hybrid solar gas turbine is carried out using TRNSYS software. A 50 MWe hybrid solar gas turbine is chosen in this study. Results show that a hybrid solar gas turbine installed in North Africa performs better than that installed in South America. This is mainly due to the optical performance of the heliostat field, which are better in North Africa are than in South America. The highest annual optical efficiency of a solar field is observed at Bechar (Algeria) 56.8% while the lowest annual efficiency is observed at Antofagasta (Chile) 48.1%. The solar-to-electric efficiency at Atacama Desert is lower than in the Sahara Desert. Indeed, in Atacama region, the solar-to-electric efficiency varies from 17% at Antofagasta to about 18% in Arequipa while it is above 19% at Sabha and Bechar

Review on Solar Thermal Desalination in Libya

Libya is suffering from freshwater shortage as most of its land is semi-arid to arid with very low precipitation rates and too limited fresh water sources. Libya is in one of the driest regions of the world with an annual rainfall ranging from just 10 mm to 500 mm, and only 5% of its land receives more than 100 mm annually. This review summarizes the most important published studies related to solar thermal desalination research in Libya. Brief description of the most thermal desalination technologies is also presented. The study has shown that only few in-completed pilot projects were carried-out for desalination using renewable energy. The research activities in the field of using renewable energy especially solar thermal energy to desalinate water are limited and do not give a comprehensive idea on the potential of different thermally driven solar desalination technologies. However, most of the recent pilot studies refer to using CSP desalination in providing most of the future water demand in Libya by 2035. A lot of efforts need to be done to carry-on a genuine research to put strategic plan to tackle the deficit water issue in Libya through using desalination driven by conventional and renewable energies

Thermodynamic Analysis and Sizing of a Small Scale Solar Thermal Power System Based on Organic Rankine Cycle

This paper presents the feasibility analysis of a small-scale low-temperature solar organic Rankine cycle power system. The heat transfer fluid for running the organic Rankine cycle system is hot water with a temperature of 120 °C provided by an array of evacuated tube solar collectors. The performance of the solar organic Rankine cycle system was investigated using two different working fluids over a wide range of the evaporation temperature. Technical and economic indicators such as the required solar collector aperture area, the total heat transfer surface area of the heat exchangers and the volume flow ratio between the outlet and inlet of the expander are among the key parameters used to evaluate the solar organic Rankine cycle. Thermolib toolbox 5.2 in conjunction with MATLAB/Simulink was used to predict the variation of the system performance. The results showed that the solar organic Rankine cycle system is able to achieve an overall system efficiency of 6.75% using a relatively low-temperature heat source. The results also showed that the solar organic Rankine cycle system requires smaller evacuated tube solar collector and heat exchanger areas when R245fa is used as the working fluid

Theoretical modelling of a dynamic solar thermal desalination unit with a fluid piston engine

Results of theoretical simulations of the steady-state operation of the dynamic solar thermal desalination unit with a fluid piston are presented in this paper. A laboratory prototype of a dynamic thermal water distillation unit was developed and it was built around an engine with fluid pistons. In the calculation scheme, the internal circuit of the desalination unit was split into several control volumes, namely the evaporator, the condenser and the cylinder. The lumped parameter mathematical model was derived based on the differential energy and mass conservation equations written for each of the control volumes and describing heat and mass transfer processes taking place during water evaporation and condensation under the cyclic variation of the pressure and temperature inside the system when the engine operates. The solution of the set of governing equations produces information on the variation of temperatures and pressure inside the system over the thermodynamic cycle and on the water desalination capacity of the unit

A novel small dynamic solar thermal desalination plant with a fluid piston converter

An innovative small dynamic water desalination plant was developed and tested under laboratory conditions. The system is a combination of a heat pipe evacuated tube solar collector, conventional condenser and novel fluid piston converter. Saline water is boiled and turned into vapour in the manifold of the solar collector. A small fraction of the solar energy supplied to the plant is used to drive the fluid piston converter. Oscillations of the fluid piston periodically change the volume and pressure in the plant. For the duration of approximately half of the periodic cycle the pressure in the plant drops below the atmospheric level causing flash boiling of saline water in the manifold of the solar collector. Generated vapour is turned into fresh water in the condenser which is surrounded by a cooling jacket with saline water. The flash boiling effect improves the fresh water production capacity of the plant. Additionally, the fluid piston converter drives a pump which provides lifting of saline water from a well and pumps this through the cooling jacket of the condenser to a saline water storage tank. This tank replenishes saline water in the manifold of the solar collector. Experimental investigations demonstrated the saline water self-circulation capability of the plant and increase in the fresh water production compared to the static mode of operation. Experimental data was also used to calibrate the mathematical model of the plant. Comparison of theoretical and experimental information demonstrates that the model accurately predicts the performance of the plant. The proposed novel system with greater fresh water production capacity has a simple design and is easy to manufacture using low cost materials and therefore can be mass deployed for small scale saline water pumping and desalination across different regions with the relatively high solar radiation and shortage in the drinking water supply

Influence of the geographical parameters on the performance of hybrid solar gas turbine

This study aims to investigate the influence of the geographical and climate parameters on the performance of the hybrid solar gas turbine with a pressurized air receiver. A number of sites located in South America (Chile, Bolivia, and Peru) and North Africa (Algeria and Libya) are considered. The geometric design parameters of the solar receiver and the tower are calculated using an in-house code. The layout and the optical performance of the heliostat field are carried out using SolarPILOT software. The simulation of the complete hybrid solar gas turbine is carried out using TRNSYS software. A 50 MWe hybrid solar gas turbine is chosen in this study. Results show that a hybrid solar gas turbine installed in North Africa performs better than that installed in South America. This is mainly due to the optical performance of the heliostat field, which are better in North Africa are than in South America. The highest annual optical efficiency of a solar field is observed at Bechar (Algeria) 56.8% while the lowest annual efficiency is observed at Antofagasta (Chile) 48.1%.The solar-to-electric efficiency at Atacama Desert is lower than in the Sahara Desert. Indeed, in Atacama region the solar-to-electric efficiency varies from 17% at Antofagasta to about 18% in Arequipa while it is above 19% at Sabha and Bechar