Potential of mini-hydro in Malta. Application in a pipeline

This paper evaluates the potential of mini-hydro applied to an existing or a new pipeline design. High pressure pipelines may have special installations installed on it, to extract energy from the outlet side. This is demonstrated for a specific installation at the sewage treatment plant of Ta' Barkat, Malta. The paper also presents an economic plan and summarises the regulations and incentives that are adopted in Italy and Europe in the area of mini-hydro.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe

Use of photovoltaic energy storage systems in buildings and other applications

This paper illustrates the use of storage systems with stand-alone photovoltaic systems to be used in buildings of Malta for integration of electricity and energy saving and special applications in other areas. The present energy situation suggests that the future of the domestic and industrial photovoltaic systems will include storage systems, to improve resource management of feeding renewable energy into the national grid, and increase reliability at the generation site. The paper develops around the initial stages of photovoltaic integration into the grid, when the possibility of auto consumption or net-metering was used. However, increased penetration of photovoltaic systems could now reduce the existing network load, while still not solving the main limitation of renewable sources, which is the intermittent nature of the production. Especially photovoltaics, but not only, the limitations of PV electrical generation is also subject to a certain cyclical production be it daily or seasonal, and a certain amount of “unpredictability of production”. Such issues have a solution through energy storage. The production of electricity for other special applications would include on-site production of energy for stand-alone systems.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe

Field behaviour of a flat panel ground heat exchanger

An experimental plant has been devised to investigate the behaviour of a novel type of horizontal ground heat exchanger (GHX), aiming to improve the performance of ground-source heat pumps for space heating and cooling. The GHX system is composed by hollow flat panels, which have been installed edgeways in shallow trenches two meters deep in soil. The hydraulic closed loop and the surrounding soil have been equipped with several digital sensors to monitor the ground temperature distribution and the plant in real-time. The behaviour has been tested for two years in several operating carried out especially in summertime. The specific power of heat transfer for surface-unit achieves considerable values, and no over-heating conditions were measured at the soil surface. Moreover, the GHX showed to be able to involve a large soil volume, and this behaviour enables high energy performance, at least in cooling mode. After few months of inactivity, the natural ground heat transfer erased the memory of the energy exploitation carried out by the GHX. Thus, unlike with the vertical systems, long-term subsurface thermal energy build-up or depletion wouldn’t be expecting by shallow GHXs.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe

Analysis of a stand-alone hydraulic offshore wind turbine coupled to a pumped water storage facility

The concept of wind turbines operating with hydraulic transmissions is gaining popularity. With the promise of improved energy density and lower maintenance costs, a number of manufacturers are evaluating such a novel concept. In the current study an offshore-specific hydraulic wind turbine design is proposed. This is based on the use seawater as the working fluid in a large scale, open-loop transmission system. The possibility of coupling such a system to an onshore pressurized water storage facility is also evaluated. Simulation results indicate the potential for such an energy storage system, to address a supply-demand mismatch without requiring intermediate conversion to electricity, as in current pumped storage facilities used in conjunction with wind turbines.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe

The photovoltaic greenhouses : a union between sustainable development and agriculture

The purpose of this study is to show the efficiency of introducing PV systems in greenhouses from the point of view of agriculture, from the technological point of view and from the economic point of view. The nursery greenhouses are the main sector in which PV may develop. Greenhouses in fact have qualities that a photovoltaic system needs: the right exposure to direct sunlight and large areas available. If we add to this to the fact that many ornamental plants need shading systems, it is possible to understand how the use of the roofs of greenhouses like structures on which to apply the photovoltaic panels in place of traditional plastic film cover, avoids the use of shading nets or painting and is an excellent investment for the nursery. For horticulture action instead the shading action of the solar panels is a limiting factor for crop growth. Experiments of cultivation of rocket under photovoltaic greenhouse are in progress; the first results show a qualitatively higher than that grown in traditional greenhouses, even if the shelf life is less. The conclusions of this work thus tend to highlight how the technical, functional and aesthetic components of photovoltaic technology coincide with structural components and means of agricultural production, allowing to boost farm income, diversifying income: from the cultivation of vegetables, from the production of ornamental plants, and from the production of electricity.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe

Testing the potential of voltage regulation for achieving higher energy efficiency

This paper focuses on energy efficiency of household electrical loads. It concerns a commercial product that aims to lower consumption by decreasing the supply voltage. In practice, the utility voltage is variable and at certain locations it might be consistently on the high side. The potential energy saving of the VO4Home unit is experimentally tested with a real voltage profile. The VO4Home has three settings that correspond to constant voltage reductions of 13V, 16V and 24V. A mix of loads was selected to reflect a typical household load. For the load mix and operating pattern, a minimum energy saving of 7.3% increasing up to circa 8.7% was recorded. The VO4Home is supplied in Malta by CD Power Saving Ltd.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe

Control of a doubly fed induction machine in a wind energy conversion system

This paper presents research done on the closed-loop control of the Doubly Fed Induction Machine (DFIM) applied to a Wind Energy Conversion System (WECS). Basic generator configurations used in wind energy systems, mainly fixed-speed and adjustable speed generators are discussed. A suitable Stator Flux Oriented (SFO) control topology for the DFIM is shown with which it is possible to control the stator active and reactive power. The control system designed was implemented on an experimental rig which emulates the behaviour of a practical WECS. A brief overview of sensorless algorithms is also presented; these algorithms are used to provide rotor speed/position estimates in the absence of a speed sensor. Practical results in both sensored and sensorless operation are shown including measurements for rotor currents, stator active/reactive power and rotor speed/position estimates.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe

Increasing PV module output with flat reflectors – a scenario in Malta

The output of photovoltaic (PV) modules is related to the solar radiation incident on their surface. The immediate surroundings of the modules may reflect a considerable amount of radiation on to them, thus affecting their performance and output. This paper explores ways of improving the output of PV modules installed in Malta, with the aid of flat plate reflectors installed in front of the modules. This study focused on the effect that different types of reflective materials have on the PV modules’ output. Two sets of reflectors were studied. The first set consisted of reflectors that can be set at an angle to the horizontal, while the second set emulates different flat roof surfaces. The output of PV modules was measured and compared for each case. Measurements started in October 2012 and are still ongoing. The aim is to study the effect of reflecting surfaces and the PV modules output, and to determine the effect of the inclination of reflector. Results have so far shown that a potential increase of up to 15% maybe achieved by aluminium reflectors during the winter seasons.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe

Performance of a solar-assisted thermodynamic heat pump for water heating

Malta’s domestic sector predominantly consume electric energy for the provision of comfort and operation of services within households. About 30% of the total national consumption is used by households, with the potable hot water production accounting for 24% of that energy. Nowadays, the major part of households heat water using an electric boiler, with an overall efficiency of 0.75. The EU Directive on Energy Efficiency 012/27/EU and the Renewable Energy Directive 2009/28/EU, as well as the Energy Performance of Buildings Directive 2010/32/EC, have all identified energy use in buildings as the primary area where energy saving may have technically-sound and cost effective results. This paper focuses on the use of a thermodynamic heat pump for the production of potable hot water, which would reduce the electrical consumption in households. The Solar-Assisted Thermodynamic Heat Pump (SAHP) produces hot water using the primary energy source of solar energy and ambient air. Such a system is new to Malta and no local testing has been carried out to gauge its performance under local conditions. In this paper the potential application of a unitary type direct-expansion SAHP (DX-SAHP) system was examined. Testing was carried out during the most critical months between November and January.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe

The new brewhouse, Mriehel : environmental control through natural ventilation and shading devices

Beers are as much the product of their environment as the output of a process. The new Farsons Brewhouse works as a protective shell accommodating the various building services whilst simultaneously assisting the environmental control of the interiors through two primary strategies: natural ventilation in the brewhalls and shading devices in the office building. Based on a simulated model, results showed that the induced air flow reduces the temperature by 10.7 °C and 8.5 °C in the lower and upper brewhalls respectively during the summer months. Whilst the ventilation system works successfully during most of the time, air changes drop when wind forces create a higher pressure outside of the building, as a result reverse flow occurs. The office building adopts a different design strategy; it incorporates various passive measures with the main feature being an expanded aluminium shading mesh. Monitoring of the internal temperatures before and after the mesh is installed shows that the introduction of shading reduces the peak temperatures in summer whilst maintaining a well lit internal environment. A simulated energy analysis of the building shows a potential reduction in energy consumption of 24% when compared to the same building with typical construction materials. The study concludes that by introducing moderate insulation, shading and night time ventilation internal temperatures are reduced effectively. On the other hand, the type of double glazing has to be carefully weighed, so as to avoid counter-productive results given the mild climate of Malta.Alternative Technologies Ltd., Energy Investment Ltd, JMV Vibro Blocks Ltd., Solar Engineering Ltd. and Solar Solutions Ltd.peer-reviewe