Optimal solar radiation utilization: concentrated solar power versus photovoltaics and photosynthesis
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620.9+621.311.24 (1)
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BOSHNYAGA, Yu. A., AGARWAL, Elena, BOLOGA, M.. Optimal solar radiation utilization: concentrated solar power versus photovoltaics and photosynthesis. In: Materials Science and Condensed Matter Physics, Ed. 9, 25-28 septembrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Fizică Aplicată, 2018, Ediția 9, p. 317.
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Materials Science and Condensed Matter Physics
Ediția 9, 2018
Conferința "International Conference on Materials Science and Condensed Matter Physics"
9, Chișinău, Moldova, 25-28 septembrie 2018

Optimal solar radiation utilization: concentrated solar power versus photovoltaics and photosynthesis

CZU: 620.9+621.311.24

Pag. 317-317

Boshnyaga Yu. A.1, Agarwal Elena2, Bologa M.1
 
1 Institute of Applied Physics,
2 State University „Dimitrie Cantemir”
 
Disponibil în IBN: 14 februarie 2019


Rezumat

Solar radiation is the main primary source of energy on the Earth. Intermittence of solar radiation (especially - seasonal one) and its relatively low energy density are the fundamental impediments for plentiful energy supply. Both mentioned shortcomings are partially attenuated in a natural way - due to accumulative (storage) ―abilities‖ of the photosynthesis‘ products. This refers especially to high-quality deposits of fossil fuels (unfortunately, non-sustainable), and less - to the sustainable, but distributed in space - low-density ―current‖ products of photosynthesis (biomass). We elaborated a powerful tool for optimization, based on Thermodynamics (inclusively - for energy management optimization). It is based on thermodynamic analysis and ensures obtaining of optimal solutions (technologies) - with the extreme indices, which are maximally close to the respective thermodynamic limitations. The main parameter for optimization is the increment (gain) of free energy ΔG (Gibbs‘s energy). Maximal gain of free energy ΔG, ensured by the technology, corresponds to the optimal solution. Our conclusion is - advanced concentrating solar power (CSP) system will be one the main pylons of the sustainable energy development (we prove that it disposes of potential for maximal final gain of free energy ΔG). Presently are in progress Generation-3 Concentrating Solar Power Systems (point-focus systems). Novel Brayton cycles (that use supercritical carbon dioxide (sCO2) as the working fluid) can operate efficiently at temperatures above 700°C [1]. Respectively, the advanced sCO2 power cycle has the potential for significantly lower costs and thermodynamic efficiencies of over 50%. Such CSP plants can operate efficiently only in desert-like environments - their thermal energy storage (TES) systems ensure several days of functioning without solar energy afflux. Our Generation-3+ CSP System ensures year-round functioning - mainly due to integration with energy-absorbing technologies, which possess very high energy-accumulative potential and ensure significant synergy effects. The main (base) such a technology - it is pyrolysis (decomposition due to application of high temperatures) of biomass and other biological (organic) wastes. As a result of organic material pyrolysis, we obtain solid structured carbon (―activated carbon‖, carbon tubes, wires, etc.), liquid fuel and gas-phase fuel. In fact, all three components are fuels, but usually on site it is sufficient to storage and use (burn) only a certain part of the liquid fuel and some undesirable (for storage and export) gas-phase components. Pronounced positive energy balance of biomass pyrolysis permits to accumulate the quantity of liquid and gas fuel, which allows functioning of the CSP plant all year round with the desirable (predictable and flexible) power generation. Presently the easily accessible reserves of biomass wastes (at least - for Moldova) are cheap and unlimited. The ―communal‖ biologic wastes are even of ―negative‖ price. Respectively, the added value of the produced chemicals is comparable (or even overcomes) the value of the generated electric power. In conditions of the ―extra solar energy‖ (during long solar days in summer) - it is used additionally another thermal energy accumulation technology - thermolysis of the limestone (CaCO3), approximately at the same temperature range 8250C - 10000C: CaCO3 = CaO + CO2 (1) Both products of the above endothermic reaction are utilized as thermoaccumulators and chemicals (carbon dioxide CO2 could be used as chemical - inclusively directly on the site). Calcium oxide (CaO - burnt lime) furthermore should be used as a long-term solar energy thermoaccumulator - due to its powerful exothermic reaction with water: CaO (solid) + H2O (liquid) = Ca(OH)2 (aq), ΔHr = −63.7 kJ/mol of CaO (2)