Maurizio Carlini

Photovoltaic Greenhouses: Comparison of Optical and Thermal Behaviour for Energy Savings

The production of energy from renewable sources, the diversification of the productive activities, and the development of photovoltaic technology and integrated systems have led to the development of solar greenhouses. The interest of the developers and designers is now to seek new approaches to combine the electricity and food production optimally. The interaction of factors as outside local climate, exposure, slope, soil, altitude, wind conditions, structural materials, or cultivated plant species, influences greatly the energy balance. This paper illustrates the comparison of optical and thermal behavior of a solar greenhouse and a similar glass greenhouse, devoted to the production of soil-less tomatoes in three different Italian areas, with computational aspects and methods of the TRNSYS simulation. Values of climatic parameters are obtained as a responce for the feasibility of the cultivation under PV modules. The results show energy savings both for heating and cooling due to PV panels, adding a new reason for the realization of these systems.

Energy Characterization and Gasification of Biomass Derived by Hazelnut Cultivation: Analysis of Produced Syngas by Gas Chromatography

Modern agriculture is an extremely energy intensive process. However, high agricultural productivities and the growth of green revolution has been possible only by large amount of energy inputs, especially those coming from fossil fuels. These energy resources have not been able to provide an economically viable solution for agricultural applications. Biomass energy-based systems had been extensively used for transportation and on farm systems during World War II: the most common and reliable solution was wood or biomass gasification. The latter means incomplete combustion of biomass resulting in production of combustible gases which mostly consist of carbon monoxide (CO), hydrogen (H2) and traces of methane (CH4). This mixture is called syngas, which can be successfully used to run internal combustion engines (both compression and spark ignition) or as substitute for furnace oil in direct heat applications. The aim of the present paper is to help the experimentation of innovative plants for electric power production using agro-forest biomass derived by hazelnut cultivations. An additional purpose is to point out a connection among the chemical and physical properties of the outgoing syngas by biomass characterization and gas-chromatography analysis.

Modelling and Simulation for Energy Production Parametric Dependence in Greenhouses

Greenhouses crops in Italy are made by using prefabricated structures, leaving out the preliminary study of optical and thermal exchanges between the external environment and the greenhouse, dealing with heating and cooling and the effects of air conditioning needed for plant growth. This involves rather significant costs that directs the interest of designers, builders, and farmers in order to seek constructive solutions to optimize the system of such emissions. This work was done by building a model of gases using TRNSYS software, and these gases then have been checked for compliance. The model was constructed considering an example of a prefabricated greenhouse, located in central of Italy. Aspects of the structural components, and thermal and optical properties are analyzed in order to achieve a representation of reality.

Stability and Control for Energy Production Parametric Dependence

The activities of plant cultivation in Italy are provided by prefabricated structures that are designed to avoid any preliminary study of optical and thermal exchanges between the external environment and the green house. Designers mainly focused on the heating and cooling system to obtain climate beneficial effects on plant growth. This system involves rather significant operating costs which have driven the interests of designers, builders, and farmers to pursue constructive solutions such as the optimization and control of energy flows in the system. In this paper we take into account a model of greenhouse for plant cultivation to be located in Central Italy. For the optimal design of a greenhouse, simulations of heat exchange and flow of energy have been made in order to maximise the cooling system consumption of energy.

Modelling the vertical heat exchanger in thermal basin

In geographical area characterize by specific geological conformations such as the Viterbo area which comprehend active volcanic basins, it is difficult to use conventional geothermal plants. In fact the area presents at shallow depths thermal falde ground water with temperatures that varies from 40 to 90°C geothermical heat pumps cannot be utilized. In these area the falde thermal can be exploited directly as hot source using vertical heat exchanger steel tubes without altering the natural bilance of the basin. Through the heat exchange that occurs between the water in the wells and the fluid that circulates inside the heat exchanger, you can take the heat necessary to meet the thermal requirements. The thermal energy used is transferred by natural convection from the thermal water to the heat exchanger in the well. The heat exchanger consists of a U-shaped tube where inside there is, as circulating fluid, water. To conduct the experiment it is necessary to examine in detail the internal temperature of the well, and the characteristics both input and output of fluid in the plant. For this reason, were inserted in the well three temperature probers for measure the temperature inside. There will be, at constant time intervals, some sampling to evaluate pH, electrical conductivity, density and salinity. These parameters are needed to evaluate the possible corrosion of the materials included in the well. The target of the project is to analyze in detail the plant for the exchange of heat with the thermal basin creating a model of heat exchange.

Energy Efficiency of a Greenhouse for the Conservation of Forestry Biodiversity

Forest biodiversity conservation is one of the most interesting and crucial problems in forestry world. Currently, the conservation methods are based on two phases: the conservation of seeds at low temperatures and the multiplication of vegetable material. This latter operation can be successfully developed in properly designed greenhouses. The aim of this paper is to define a type of greenhouse which is particularly suitable for plant material propagation in order to preserve forest biodiversity in the area of the Central Italy. Some general parameters were first defined for a correct planning of the structure, such as: the shape of the section, volume, cover material, systems for heating and cooling, and those for the control of the internal microclimate parameters (light, air temperature, and relative humidity). Considering the construction characteristics and the climatic conditions of the place, the internal microclimatic conditions have been later determined by the useful implementation in TRNSYS in order to analyse the energy efficiency of the greenhouse.

Down-Hole Heat Exchangers: Modelling of a Low-Enthalpy Geothermal System for District Heating

In order to face the growing energy demands, renewable energy sources can provide an alternative to fossil fuels. Thus, low-enthalpy geothermal plants may play a fundamental role in those areas—such as the Province of Viterbo—where shallow groundwater basins occur and conventional geothermal plants cannot be developed. This may lead to being fuelled by locally available sources. The aim of the present paper is to exploit the heat coming from a low-enthalpy geothermal system. The experimental plant consists in a down-hole heat exchanger for civil purposes and can supply thermal needs by district heating. An implementation in MATLAB environment is provided in order to develop a mathematical model. As a consequence, the amount of withdrawable heat can be successfully calculated.

Efficient energy supply from ground coupled heat transfer source

The increasing demands of Energy for industrial production and urban facilities, asks for new strategies for Energy sources. In recent years an important problem is to have some energy storage, energy production and energy consumption which fulfill some environment friendly expectations. Much more attention has been recently devoted to renewable energies [1]. Among them energy production from geothermal sources has becoming one of the most attracting topics for Engineering applications. Ground coupled heat transfer might give an efficient energy supplies for well-built construction. At a few meters below the earths surface the underground maintains a constant temperature in a approximation through the year allowing to withdraw heat in winter to warm up the habitat and to surrender heat during summer to refresh it. Exploiting this principle, heat exchange is carried out with heat pumps coupled with vertical ground heat exchanger tubes that allows the heating and refreshing of the buildings utilising a single plant installation. This procedure ensure a high degree of productivity, with a moderate electric power requirement compared to performances. In geographical area characterize by specific geological conformations such as the Viterbo area which comprehend active volcanic basins, it is difficult to use conventional geothermal plants. In fact the area presents at shallow depths thermal falde ground water with temperatures that varies from 40 to 60oC geothermal heat pumps cannot be utilized [2]. In these area the thermal aquifer can be exploited directly as hot source using vertical heat exchanger steel tubes without altering the natural balance of the basin. Through the heat exchange that occurs between the water in the wells and the fluid that circulates inside the heat exchanger, you can take the heat necessary to meet the needs. The target of the project is to analyze in detail the plant for the exchange of heat with the thermal basin, defining the technical-scientific elements and verifying the exploitation of heat in the building-trade for housing and agricultural fields.

Performance analysis of greenhouses with integrated photovoltaic modules

Thanks to the DM 19.02.2007, Italian government supported the development and the expansion of solar photovoltaic in Italy. The feed-in tariff had a great success, and like in Spain and Germany big size photovoltaic plants have been built, especially in the south of the country. The south of Italy presents high irradiation (up to 1.700 equivalent hours) and economically agriculture is an important local resource. This aspect led to the concept of the solar greenhouses, a way to match the electricity production by PV modules with an improvement of the cultivation possibilities. Solar greenhouses includes integrated PV modules mounted on the roof oriented to south and his design is new and still has to be evaluated in details. In particular important parameters like the luminance, the type of cultivations and the temperature of the PV modules must be carefully analyzed to have a real good match between the agriculture and the electricity production purpose. In the paper TRNSYS 16 has been used for the simulation of temperatures and humidity in the structure. The simulation had the goal to define the performance of the solar greenhouse during the year, with the possibility to individuate important construction parameters for the realization of a greenhouse efficient from all point of views.

Waste Wood Biomass Arising from Pruning of Urban Green in Viterbo Town: Energy Characterization and Potential Uses

The use of residual biomass arising from urban green pruning for energy production is a current and interesting subject for three main reasons: to achieve the aims of the Kyoto Protocol, to reduce the reliance on fossil fuels and to manage the urban green in a sustainable way.