G.C. Bakos

Feasibility study of a hybrid wind/hydro power-system for low-cost electricity production

This paper deals with the operation of a hybrid wind/hydro power system aiming at producing low cost electricity. A specific application on the island of Ikaria in Greece is analysed and typical results are presented and compared to the results produced from a simulation program. The simulation program, which is based on the stochastic behaviour of the weather conditions, uses as input data the monthly wind-speed distribution and, to a smaller extent, which is determined from the use of an appropriate weighting factor, the rate of rain water which is stored in the hydro reservoir. Useful conclusions were drawn regarding the feasibility of these applications in Greek islands and the expected electric energy saving.

Technoeconomic assessment of a building-integrated PV system for electrical energy saving in residential sector

This paper describes the installation, technical characteristics, operation and economic evaluation of a grid-connected building-integrated photovoltaic system (BIPV) installed in Northern Greece, and in particular in the city of Kastoria. The technical and economical factors are examined using a computerized renewable energy technologies (RETs) assessment tool. A number of different economic and financial feasibility indices are calculated for different financing scenarios in order to assess the gross return of the investment. Useful conclusions were drawn regarding the feasibility of BIPV systems and their potential for increased energy market penetration.

Design, optimisation and conversion-efficiency determination of a line-focus parabolic-trough solar-collector (PTC)

PTCs are the preferred type of collector used for steam generation, due to their ability to work at high temperatures with high efficiencies. The results produced from a simulation program, showing the variation of collectors efficiency as a function of heat transfer fluid flux, pipe diameter, solar radiation intensity and active area of the PTC, are presented.

Techno-economic assessment of a stand-alone PV/hybrid installation for low-cost electrification of a tourist resort in Greece

This paper reports on the techno-economic assessment of an autonomous hybrid PV/diesel system installed in a bungalow complex in Elounda, Crete. Technical and economic factors are examined using a computerized renewable-energy technologies assessment tool. Several different economic and financial feasibility indices are calculated, such as the Internal Rate-of-Return (IRR), Year-to-positive cash flow, Net Present Value (NPV) and the simple Pay-Back Period (PBP) for different financing scenarios, in order to assess the gross return on the investment.

Greenhouse heating using geothermal energy

Abstract This paper describes the use of a low enthalpy geothermal source in Northern Greece to heat a greenhouse where flowers could be grown, especially roses. The different parts of the developed greenhouse, the heat loss calculation and the heating system are described. An analysis is given of different greenhouse heating approaches, and a description of the selection procedure, following low-cost and high-efficiency criteria. An analysis is also made of an extended heating system, which uses low temperature water or direct geothermal fluid to heat a second greenhouse similar to the first. The second greenhouse could be used for strawberry cultivation, where an inside temperature of 15°C is required. The existing greenhouse, described in this paper, proved to be very important and beneficial for this area of Northern Greece, with its numerous low enthalpy geothermal sources.

Direct energy generation from γ-radiation

Abstract In this paper theoretical and experimental calculation of direct heat generation from the penetration of 6.12 MeV photons energy through single layer concrete, steel and lead shields is described. Also, the direct heat generation for various thickness for single layer concrete shield with ducts of different diameters is calculated.

Direct energy generation and energy conservation in radiation shielding facilities

Abstract In this paper, the experimental and theoretical calculation of direct heat generation from the penetration of 6.20 MeV photons energy through double layer combinations of concrete (Al), steel (Fe) and lead (Pb) shields is described. The results are displayed in curves to show the distribution of heat generation in the shield thickness. The results show good agreement between the measured and calculated values and show also that the heat generation has its maximum value in the first layer of the shield thickness.

Technical feasibility and economic viability of a small-scale grid connected solar thermal installation for electrical-energy saving

This paper reports on the techno-economic assessment of a grid-connected solar thermal system used for electrical-energy saving in the residential sector. The technical characteristics of the solar thermal system, based on a line-focus parabolic-trough concentrator, are given and its useful electrical and thermal-energy production is estimated using a simulation program based on a Monte Carlo method for reading solar radiation data. The economic assessment is performed using the Life-Cycle Savings (LCS) method and the payback period (PBP) of the investments initial capital cost is determined.

Direct heat generation and corresponding energy saving in nuclear reactors due to optimum synthesis of shielding materials

Abstract In this paper the calculation of direct heat generation and energy savings due to the penetration of 1.37 and 2.75 MeV energy photons, emitted from a Na-24 radiation facility, through double layer shielding slabs of aluminium, steel and lead is described. A comparison is being made among six different shielding material combinations in order to assess the optimum shield related to the maximum energy captured due to γ-rays penetration through the combined shielding materials.

A systematic techno-economic assessment of a WEC system installation for low-cost electrification of a habitable dwelling

This paper deals with the technical feasibility and economic viability of a grid connected wind-energy conversion system (WECS) used to cover the energy demand of an average habitable dwelling. The various parts of the wind-energy system are described and the useful electrical energy production is determined using a simulation program based on the Monte Carlo method. An economic analysis of the WEC system is performed using a computerized assessment tool. Important financial indices are calculated and financial scenarios investigated.