Compressed Air Energy Storage (CAES) is widely recognized as a viable solution for large-scale grid integrated renewable energy systems in terms of load levelling to solve/minimize the intermittency effect of renewable energy systems especially with increased penetration of renewables to the grid. This study assesses the economic value of adding compressed air energy storage (CAES) plant to a renewable energy system and how this impacts the overall financial appeal of the system at hand, taking Egyptian grid as a case in point. Numerical modelling using MATLAB was performed to analyse the benefits of adding a CAES system to planned wind farms in Egypt by 2020 for both load-levelling as well as optimizing economic benefit. The results show that the addition of a CAES system would increase the profitability for the new Tariff for wind systems set by the Egyptian government with a NPV of $306m compared to a NPV of $207m of a stand-alone wind system at the end of 25 years of operation. Also, the economic benefits increase if the government provides subsidies for new installations of renewable energy systems, or by lowering the interest rates.
Thermochemical Heat Storage (THS) systems have recently attracted a lot of attention in research and development. One of the main parameters that influence the performance of a THS system is the thermochemical materials. This paper aims to investigate thermochemical materials which are suitable for both short-term and long-term building heat storage application driven by solar energy for an open system. Innovative composite materials using MgCl2-MgSO4, CaCl2-LiCl and MgSO4- CaCl2 salts mixtures impregnated into vermiculite, and potassium formate (KCOOH) impregnated into silica gel will be presented in this study. Initial screening and characterization results of the composite THS materials based on the energy density using differential scanning calorimetry analysis, mass loss against temperature using thermo-gravimetric analysis, and moisture vapor adsorption isotherms testing are discussed. The characterization analysis suggest that the vermiculite with salts mixtures are promising candidates for thermochemical heat storage (THS) systems compared to composite materials with individual salts. Meanwhile the potential of KCOOH-silica gel as THS materials may be further investigated in the future. The performance of the materials may be further optimized in the future by changing the concentration ratio of the mixed salts.
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