Policy of the Ministry of Environment in the protection of biodiversity in Lebanon

Meeting: Regional Workshop : "Biodiversity as Food", Beirut, 3-5 February, 2006PowerPoint presentatio

Design and thermo-economic evaluation of an integrated concentrated solar power-Desalination tri-generation system

In this work, a concentrated solar power (CSP) tri-generation system that is capable of the simultaneous production of steam, power and freshwater is introduced. The abundantly available direct normal irradiance can potentially allow concentrated solar power systems to become major energy contributors in the desalination market. Since CSPs can generate both thermal and electrical energy, they have been found to be excellent candidates for sustainable operation of large scale desalination systems, in the long term. This paper presents a mathematical model in the form of a Mixed-Integer Nonlinear program (MINLP), which involves a tri-generation system for combined steam and power production, primarily using solar energy to operate steam turbines. Moreover, the option of freshwater production using various desalination technology choices, such as reverse osmosis (RO) and multi-stage flashing (MSF), is also accounted for within the model. Hence, the proposed model offers a very convenient and eco-friendly tri-generation route for steam, power and water production. The proposed systematic method was tested using different feedwater salinities, as well as using different product water flowrates, and electricity prices. According to the results obtained, the water production cost (WPC) associated with a water salinity of 25 g/L resulted in a value of 1.83 USD/m3, which is significantly lower than the WPCs obtained at 35 g/L (2.09 USD/m3) and 45 g/L (2.24 USD/m3). Moreover, a large scale tri-generation system with an overall production capacity of 100,000 m3/d of freshwater resulted in a 60% reduction of the attained WPC value, when compared against a small scale system with a production capacity of 10,000 m3/d of freshwater. The option of exporting electrical energy to the grid using the proposed tri-generation system was also investigated, and a sensitivity analysis was conducted by varying the price of electrical energy. The attained breakeven energy prices were 0.74, 0.79 and 0.82 cent/kWh at 25, 35 and 45 g/L of feedwater salinity, respectively

Investigation of seasonal variations and multiple fuel options in a novel tri-generation CSP integrated hybrid energy process

This work presents a novel Mixed-Integer Non-linear Program (MINLP) that accounts for the presence of multiple fuels in tri-generation systems. The key novelty of this work pertains to the use of hybrid energy systems in tri-generation processes, which are associated with multiple energy sources. In this work, different fuel sources such as natural gas, biomass and municipal solid waste (MSW) have been considered in the model, together with concentrated solar power (CSP), as a renewable energy option. The use of the aforementioned energy sources in tri-generation systems for heat, power and water production, were assessed simultaneously by the proposed model. CSP was utilized as the sole renewable energy option, due to the ease of obtaining both heat and power from such systems. The design of optimal tri-generation systems has been studied using the proposed model, under different conditions for carbon reduction. The model has been formulated using multi-period considerations, so as to account for seasonal variations. Moreover, the effect of several different operating parameters on the land use requirements of such systems were also investigated. The results indicate that despite the high cost of CSP, it was still found to be a highly desirable choice in the presence of carbon taxation. The water production cost of a hybrid natural gas-CSP tri-generation system was estimated at 1.277 USD/m3. This value could be 16% higher in the presence of carbon taxation. Additionally, biomass and solid waste options were found to be very promising energy outlets for desalination, especially in winter and fall seasons which have the lowest DNI values. The selection of these energy streams is also highly affected by the presence of carbon taxation policy. On the other hand, the incorporation of these two energy streams along with CSP could result in a fully local energy independent system with a water production cost of 1.44 and 1.537 USD/m3, respectively

Optimization of multiple fuel utilization options in Tri-generation systems

This work investigates the design of optimal tri-generation systems for heat, power and water production via multiple fuel selections, thus aiming to reduce the reliance on fossil fuel consumption. Generally speaking, tri-generation systems are associated with high levels of carbon dioxide emissions to meet energy and water production requirements. Hence, a shift towards more renewable energy sources can assist in partially reducing the environmental damage associated with standard tri-generation operations. Since the switch from fossil fuels to renewable energy is very costly, hybrid energy systems were found an appealing solution that could allow a gradual reduction of carbon emissions. Hence, the novelty aspect of this work is the ability to generate cost-effective tri-generation systems that incorporate optimal hybrid energy selections and utility generation routes, subject to specific net carbon reduction targets (NCRT). As such, four different energy sources (natural gas, biomass, municipal solid waste (MSW) and Concentrated Solar Power (CSP) were investigated, together with five different routes for steam expansion and electricity production using a Mixed Integer Nonlinear Program (MINLP), including technical, economic and environmental constraints. In order to study the effect of different fuel selections, energy production operations, and water production routes on the performance of tri-generation systems, data from three different desalination plants (located in USA, Cyprus and Qatar) were used. The results obtained show that energy requirements for desalination greatly affects the order of selection of energy sources. In general, biomass was identified as the best alternative to replace natural gas at NCRT values below 40%. On the other hand, MSW incineration using grate-fired and fluidized bed boilers became more desirable for steam production when higher NCRT values were utilized. The water production costs (WPC) of a standalone CSP system integrated with each of the studied plants, having a feedwater salinity of 33.5, 41.8 and 45 g/L, were estimated at 1.739, 2.233 and 2.67 USD/m3, respectively. In addition, an average incremental increase of 5.5% in the WPC has been observed during seasons that provide the lowest solar availability values