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Solar parabolic trough collector (PTC) was considered for seawater desalination under various flow and thermodynamic conditions while being subjected to a diurnal solar beam with seawater directly running through the PTC absorber. PTC are more economical and cost effective as well as they may yield the simplest systems. The governing equations applied to the PTC absorber were deduced from the energy and mass conservation principles and consequently numerical solutions were obtained using finite difference method. The numerical simulations were generated utilizing an in-house developed computer programs. The PTC was coupled directly with multi flash chambers. The results revealed that fresh water generation is sensitive to the vapor content of the saturated water in the PTC absorber as well as to the operating pressure; whereby the rate was observed to vary from 1.3 m³/day to slightly above 2.7 m³/day for the same PTC aperture area and under the same solar flux in the range of operations that were considered; thus demonstrating the importance of the operational conditions. Also, the results indicated that PTC are adequate for capturing solar energy by revealing that the rate of fresh water production was uniform for significant time of the sunshine period. [ABSTRACT FROM AUTHOR]

South East Europe is the region in a part of Europe with approximately 65.5 million inhabitants, making up 8.9% of Europe’s total population. The countries concerned have distinct geographical features, various climates and significant differences in gross domestic product per capita, so the integration of their energy systems is considered to be a challenging task. Large differences between energy mixes, still largely dominated by fossil-fuel consumption, make this task even more demanding. This paper presents the transition steps to a 100% renewable energy system which need to be carried out until the year 2050 in order to achieve zero carbon energy society. Novelty of this paper compared to other papers with similar research goals is the assumed sustainable use of biomass in the 100% renewable energy system of the region considered. It is important to emphasize here that only the sustainable use of biomass can be considered carbon-neutral. The resulting biomass consumption of the model was 725.94 PJ for the entire region, which is in line with the biomass potential of the region. Modelling the zero-carbon energy system was carried out using the smart energy system concept, together with its main integration pillars, i.e. power-to-heat and power-to-gas technologies. The resulting power generation mix shows that a wide variety of energy sources need to be utilized and no single energy source has more than a 30% share, which also increases the security of supply. Wind turbines and photovoltaics are the main technologies with shares of 28.9% and 22.5%, followed by hydro power, concentrated solar power, biomass (mainly used in cogeneration units) and geothermal energy sources. To keep the biomass consumption within the sustainability limits, there is a need for some type of synthetic fuel in the transportation sector. Nevertheless, achieving 100% renewable energy system also promises to be financially beneficial, as the total calculated annual socio-economic cost of the region is approximately 20 billion euros lower in the year 2050 than in the base year. Finally, energy efficiency measures will play an important role in the transition to the zero-carbon energy society: the model shows that primary energy supply will be 50.9% lower than in the base year. [ABSTRACT FROM AUTHOR]

The penetration of intermittent renewable energy sources, for instances wind power, in the power system of isolated islands is limited, even when there is large potential. The wind power that cannot be directly injected in the power grid is usually curtailed. In addition, some islands need to desalinate seawater to produce fresh water, increasing the pressure on the power system, because desalination needs electricity. Nevertheless, the water scarcity problem of an island can be part of the solution of the problem of its integration of intermittent renewable energy sources. To tackle this issue, a system was proposed to use the excess wind power in desalination units and in a pumped hydro storage, resulting in an integrated power and water supply system that would minimize the wind power curtailed. This paper proposes a methodology to optimize the size and operational strategy of this wind powered desalination and pumped hydro storage system. The objective is to minimize the total annualized production costs, maximize the percentage of renewable energy sources in the total power production and minimize the wind power curtailed. To solve this optimization problem, a derivative free multiobjective optimization method (Direct MultiSearch) is used. This methodology is applied to the integrated power and water supply system proposed for the island of S. Vicente, in Cape Verde. The results show that the penetration of renewable energy sources can reach 84% with a 27% decrease of power and water production costs and 67% decrease of CO 2 emissions, in relation to the values foreseen for 2020. [ABSTRACT FROM AUTHOR]