Academic literature on the topic 'Underground Solar greenhouses'

The use of renewable energy resource is usually directed to solar, wind or hydroelectric stations. However, there are other sources for getting the ‘green energy’. One of them is geothermal source, the energy stored in the underground fluids. In the world, geothermal water is used mostly for heating purposes, greenhouses, agriculture, for generation of warm water, therapeutic and recreational purposes and to generate electricity in power stations. After these uses, geothermal water is usually seen as waste water. This research presents the idea for innovative energy harvesting from the salinity gradient on the basis of waste geothermal water. Two methods are analyzed to be used: capacitive mixing (CAPMIX) and reverse electrodialysis (RED). The aim of the research concept is analysis for testing the applicability of both methods in energy harvesting from mixing of saline geothermal water and RO brine with water, before its re-injection to underground reservoirs.

This scientific work presents the results of scientific research on the use and accumulation of solar energy for heat supply of a solar greenhouse. For a real assessment of the problem, the following information can be cited as an example: in a greenhouse with a total area of 234 m2 covered with polyethylene film must be installed, on the average, with 6-8 furnaces to provide a certain amount of warm air. One furnace consumes about 2448 m3/h of natural gas for four months, and during this time 8.6 kg of carbon dioxide (CO2) is emitted from one furnace. As a result, taking into account the payment for the consumption of natural gas, the problem of the cost of the obtained products, energy conservation, and also environmental protection is very urgent. To solve this problem, a solar greenhouse with an additional heating chamber was constructed at the research site of the State Energy Institute of Turkmenistan. In this structure, excess of solar and heat energy of the soil was accumulated in mountain stones, and carbon dioxide that emits soil (horse manure was used as a soil) was used to feed the Chlorella vulgaris suspension grown in the photobioreactor, which in its turn had a beneficial effect on its cultivation. To transfer heated air from the additional heating chamber to the solar greenhouse and the accumulated thermal energy of the soil, polyethylene pipes with holes were used. Due to the use of the heat capacity of the materials (rock stones), a two-layer coating of the structure, compaction of the northern side with wool and accumulated heat energy, it was possible to achieve a positive temperature in the solar greenhouse in the minus environmental values. The technologies and processes considered in this research are mainly renewable energies and technical (chemical reactions) solutions such as photovoltaic (PV) modules, phase exchange material (PCM), underground heat storage technologies, energy efficient heat pumps and facade materials for the better heat insulation. The obtained results of the research work can be applied in solar greenhouses, the construction of which is planned in the areas remote from the central power supply network, since heat supply is carried out using solar energy and electric lighting is implemented due to the solar panels with a built-in LED lamp. It should be borne in mind that the intensity of solar radiation on the territory of Turkmenistan fluctuates in the range of 700-800 W/m2, which indicates the huge possibilities of using solar energy.

This study was carried out to optimize a computational model of a new underground passive solar greenhouse to improve thermal performance, storage, and saving of heat solar energy. Optimized and conventional passive solar greenhouse were compared in regards of indoor air temperature, irradiation, and energy demand. Six different materials were used in the conventional model. In addition, TRNSYS software was employed to determine heat demand and irradiation in the greenhouse. The results showed that the annual total heating requirement in the optimized model was 30% lower than a conventional passive solar system. In addition, the resulting average air temperature in the optimized model ranged from −4 to 33.1 °C in the four days of cloud, snow, and sun. The average air temperature in the conventional passive solar greenhouse ranged from −8.4 to 24.7 °C. The maximum monthly heating requirement was 796 MJ/m2 for the Wtype87 model (100-mm lightweight concrete block) and the minimum value was 190 MJ/m2 for the Wtype45 model (50-mm insulation with 200-mm clay tile) in a conventional passive solar greenhouse while the monthly heating requirement estimated 126 MJ/m2 for the optimized greenhouse model. The predictability of the TRNSYS model was calculated with a coefficient of determination (R2) of 95.95%.

Purpose The purpose of this paper is to describe the first and novel beam splitting day-lighting system possessing highest possible solar transmission efficiency to provide illumination to the core and underground areas of any structure/building. Design/methodology/approach In this system, by using a number of individually pointable thin and light optical elements mounted on a top of structure/building, the solar light is concentrated. The concentrated beam is focussed to a secondary reflecting element which directs it to a beam splitter while passing through a Fresnel lens and a horizontal solar pipe. The beam splitter located inside the structure/building splits the solar beam into a number of secondary beams using a special arrangement of a number of inbuilt light guiding optical elements inside the beam splitter. The beam splitter produces a desired number of beams which are then redirected to the beam diffusers with the help of the solar pipe and the solar pipe joint which deflects the light at the angle of 90°. Findings The system considers the use of highly sophisticated and the highly efficient optical elements so that to attain the highest possible end-to-end efficiency of the system. The system has the highest potential to transport the solar energy to larger distances than all the available day-lighting systems and possesses the potential to be used for underground human colonisation. Research limitations/implications The widespread adoption of such a system could substantially reduce energy consumption worldwide, which would contribute to bring down the increasing slope in the graph of greenhouse gases. Originality/value The paper presents the novel beam splitting day-lighting system.

<p>Studies were conducted during 2015 and 2016 to assess the effects of storage conditions on survival of nursery plants in trans-Himalayan Ladakh region. Apple nursery plants raised under warm climatic conditions of Solan (Himachal) were lifted from nurseries in first week of January and stored upto March in cold Ladakh region. Underground cellar-stored plants showed significantly higher plant survival (92 to 94%) than greenhouse-stored plants (37 to 56% survival). Low and constant temperature (-1.5±4.1 to 10.0±1.4ºC) and absence of light inside the cellar were favorable factors for storage of nursery plants. Lower survival rates of greenhouse-stored plants could be attributed to lower and greater fluctuations in temperature (-9.3±1.7to 25.1±1.9ºC) inside the greenhouse. Cellar-stored plants were less subjected to freezing injury as reflected from shoot electrolyte leakage studies. The underground cellar was found effective for overwinter storage of apple nursery plants for 3 to 4 months. The method described is easy and cost-effective, and can be a satisfactory alternative to refrigerated cold storage in trans-Himalayan region with severe winters.<strong></strong></p><p> </p>

MESMEG
Department of Mining and Environmental Geology
Solar energy development is experiencing significant growth due to national interest in increasing energy efficiency, reducing dependence on fossil fuels, increasing domestic energy production, and curbing greenhouse gas emissions. Northern Cape is generally known to be one of the preferred areas for the generation of solar energy in South Africa, and even in the world, due to its abundant solar radiation. Although this area has abundant potential for solar power generation, not all the areas are suitable for construction of solar plant facilities especially those that are prone to sand storm and dust accumulation. Consequently, site evaluation is very crucial for planning, design and construction of the solar facility. The main objective of this study was to determine the suitability of a proposed site at Kakamas in the Northern Cape for construction of a photovoltaic solar facility. The specific objectives of this research were to assess and establish all the geotechnical aspects that may have an impact on the development of the site, to explore the surface conditions at the proposed site and to establish the soil properties and comment on the use of the on-site soils in the construction of the solar facility. Other specific objectives included to determine the variability of ground conditions and effects of such variability on the proposed development and to provide foundation recommendations for the design and construction of the solar facility. In order to obtain this information, methods such as desktop studies, geological survey, soil survey, magnetic survey and soil profiling were employed to obtain information about the geotechnical aspects of the study area and properties of the on-site soil. Field tests such as cone penetration and resistivity survey and laboratory tests such as foundation indicator test, California Bearing Ratio, pH and permeability test were also performed in order to determine the engineering, behavioral and hydraulic properties of the soil. The results of the geologic and magnetic survey indicated that the study area is underlain by mainly igneous and metamorphic rocks such as gneiss, quartzite, pegmatite, gneiss and calcrete. The results of the soil profiling and the resistivity survey showed that the study area is comprised of sandy soil with either two or three horizons while the cone penetration results revealed high variable soil consistency and stiffness which ranged from very loose to very stiff soils. The particle size distribution, atterberg limits and grading modulus indicated that the study area is characterized mainly by dry, cohesionless and non-plastic to slightly plastic coarse-grained sandy soil with sand content ranging from 71- 96%. From the CBR results, it was found that the soils in the study area generally classifies as G6 material and can be used as base, sub base and backfilling material in accordance with the TRH 14 specifications. The permeability test results indicated moderately permeable sandy silt soils with coefficient of permeability ranging between 1x10-3 to 8x10-3 cm/sec and ground water was encountered at 1.3 m depth. The material excavatability indicated variable material on site ranging from soft calcretes with soft excavation to highly competent material such as quartz and dorbank which require hard excavation while the side wall stability of trial pits indicated stable pit walls during the investigation giving an indication of stability of long pit excavations. The foundation analysis showed that driven piles and earth screws are the ideal foundation types for this site and that the site is generally suitable for construction of the solar facility provided all the recommendations are implemented.
NRF