• Energy Research

This work presents the results of research connected with the flow of air through a stone battery. The research was carried out in a foil tunnel with a four-section stone battery. The battery deposit consisted of porphyry stone of 30 – 63mm granulation. The process of inlet from the inside of a tunnel to a battery (manager using an algorithm) enabled the unbundling of heat storing cycle and the cycle of delivering the stored heat to the inside of the tunnel. The amount of heat and exchanged mass was described (in relation to the unitary surface and a particular cycle). Correlational equations were formed for the found values and they enable the calculation of a unitary heat stream and the masses of stone battery exchanged cycles.

The search restrictions energy consumption in horticultural production there are in progress continually. They concern on the one hand reduce heat loss and, second, better use of available energy. Greenhouse efect in the greenhouse forced ventilation process especially in the surplus heat. The paper presents the manner of management of excess heat in the stone battery. Its structure included four segments with a volume of 13.1 m3 each. Segments of the battery were fed a stream of air in an independent manner. This enabled the work of individual segments or a few at a time. The battery can work in two stages: charging and discharging. Selecting the stage took place automatically according to the developed algorithm. This decision was dependent on the parameters of air flowing through the bed and the thermal state of the battery. During the process of charging and discharging monitored changes in air enthalpy at the inlet and outlet of the battery, and the temperature and relative humidity of air in the bed of battery. For different bed volumes increases its temperature, heat storage capacity and the ability to absorb water vapoure was determined.

The essence of the research was to model the actual energy storage system obtained from photoelectric conversion in a phase change accumulator operating in a foil tunnel. The scope of the work covered the construction of four partial models, i.e., electricity yield from solar radiation conversion for three types of photovoltaic cells (mono- and polycrystalline and CIGS), energy storage in a PCM battery, heat losses in a PCM battery and energy collection from photoelectric conversion in PCM battery. Their construction was based on modelling methods selected on the basis of literature review and previous analyses, i.e., artificial neural networks (ANN), random forest (RF), enhanced regression trees (BRT), MARSplines (MARS), standard multiple regression (SMR), standard C&RT regression trees (CRT), exhaustive CHAID for regression (CHAID). Based on the analysis of the error values (APE, MAPE, ΔESRt), the best quality models were selected and used in the further part of the work. Based on the developed models, a simulation of the influence of the size of the photovoltaic power plant and the type of cells on the process of storing energy from photoelectric conversion in a PCM battery was carried out. For the battery under study, a PV power output of 9 kWp for mono and polycrystalline panels and 13 kWp for CIGS panels is recommended for reasons of energy storage efficiency. The obtained results made it possible to develop a model determining the amount of energy stored in a phase change battery depending on the power of a photovoltaic power plant and variable solar conditions. In order to store the greatest amount of energy, we should choose a source with a capacity to produce at least 70 kWh of electricity per day. In the final stage of the work, the indicators of solar radiation energy storage in the tested phase change accumulator were determined. For the battery tested, the solar energy storage efficiency can reach 12–13% for mono and polycrystalline panels and less than 7% for CIGS panels.

The essence of the research was the modeling of a real electric energy storage system in a phase change battery operating in a foil tunnel. The scope of the work covered the construction of two partial models, i.e., energy storage in the PCM accumulator and heat losses in the PCM accumulator. Their construction was based on modeling methods selected on the basis of a literature review and previous analyses, i.e., artificial neural networks, random forest, enhanced regression trees, MARS plines, standard multiple regression, standard regression trees, exhaustive for regression trees. Based on the analysis of the error values, the models of the best quality were selected. The final result of this study was the construction of such a model of the process of storing electricity in a PCM battery, characterized by the mean absolute percentage error forecast error of 1–2%. The achievement of this goal was possible thanks to the use of the artificial neural networks model for which the input variables were the amount of energy supplied to the accumulator and the temperature of the heat storage medium.

Heat storage in systems integrated with renewable energy sources in facilities can reduce the consumption of fossil fuels, cut maintenance costs, and decrease greenhouse gas emissions from buildings and other objects. One of the possible solutions is the use of a stone heat accumulator for short-term heat storage and the use of this deposit in the ventilation process of the facility. During short-term air flow through the porous material from which an accumulator bed is made, there is an exchange of heat and mass between the flowing air and the bed particles. In the long term, the use of an accumulator can lead to an increase in dust and the development of pathogenic microorganisms, endangering human life and health. Therefore, understanding the factors influencing the efficient use of a stone deposit is very important. The aim of this study is to calculate the changes in thermal-mass parameters in the air flowing out of the stone accumulator and to assess the effect of long-term stone accumulator use on the content of microorganisms and dust concentration in bioaerosol. The application of the heat storage system in the stone bed leads to the formation of strictly controlled microclimatic conditions, and the tested air does not constitute a threat to the people staying in the object. The concentration standards of PM10 and PM2.5 exceeded the limit values (PM2.5 = 20 μg∙m−3 and PM10 = 40 μg∙m−3), and, thus, the air in the studied greenhouse was classified as polluted. The analysis also showed that, for the analyzed conditions, a 20% increase in the initial temperature of the accumulator bed results in a nearly 20% increase in the outlet air temperature.

Understanding perception about nature is paramount to understanding human behavior and decision making on the environment. We performed a survey-based study in Brazil and Poland to better understand the perception of land sparing for nature and the perceived value of nature. The countries were selected by intentional sampling and given their importance for local and global biodiversity conservation, and complex socio-ecological context of conservation versus agroforestry business. We performed an online questionnaire (N = 1030) in Brazil and face-to-face interviews in Poland (N = 322). We found that Brazilian respondents demonstrated more pro-environmental attitudes than Polish survey participants. Regarding the question: “How much nature that is left should be spared?”, nearly 51% of Brazilians answered “everything”, compared with 13% of Polish respondents. Just under half of the respondents from Poland (45.6%) indicated that half of the nature that is left should be spared. Brazilian respondents also perceived the intrinsic value of nature to a greater extent compared with Polish respondents; in total, 76% of Brazilians respondents entirely agreed that “Nature, its plants and animals have a value on their own, independent of their usefulness for us” versus 25% of Polish respondents. Our study contributes to a better understanding of the leverage points driving pro-environmental attitudes in both countries.

This paper presents the results of the analysis of thermal issues and energy efficiency of three types of accumulators; namely stone-bed; water and phase change. Research experiments were carried out during April–October 2013 in a standard commercial semi-cylindrical high plastic tunnel with tomato cultivation of 150 m2. A stone-bed accumulator; with an area of almost 75 m2 was installed in the tunnel below ground level; while a water accumulator with a volume of 4 m3 was installed outside the tunnel. A phase change material (PCM) accumulator, with a volume of 1 m3 containing paraffin, was located inside the tunnel. The heat storage capacity of the tested accumulators and the energy efficiency of the process were determined based on the analyses of the 392 stone-bed charging and discharging cycles, the 62 water accumulator charging cycles and close to 40 PCM accumulator charging and discharging cycles. Dependencies in the form of easily measurable parameters; have been established to determine the amount of stored heat; as well as the conditions for which the effectiveness of these processes reaches the highest value. The presented analysis falls under the pro-ecological scope of replacing fossil fuels with renewable energy. As a result of the analysis; it was found that; in the case of a stone-bed; such an accumulator shows higher efficiency at lower parameters; that is, temperature difference and solar radiation intensity. In turn; a higher temperature difference and a higher value of solar radiation intensity are required for the water accumulator. The energy storage efficiency of the PCM accumulator is emphatically smaller and not comparable with either the stone-bed or the water accumulator.