Bernard Franković

New high profitable wind turbines

To generate more quantities of electric energy from wind it is necessary to use a new type of wind turbine built in the regulable mantles nozzle. This wind turbine type replaces the free air stream from wind by a programmed, i.e. regulated, and partially concentrated stream of air. The nozzle shell is designed as an aerodynamically shaped ring with wings with its lower pressure side pointed towards the centre so that the lift force on each part of the wing is directed radially towards the centre. This induces centrifugal reaction force in the airflow that causes the stream field to expand strongly downstream of the rotor and includes a greater number of streamlines in the active stream in front of the rotor (upstream). Thus the nozzle forces a higher mass flow rate of air through the turbine. The higher mass flow and higher velocity reduction behind the rotor result in a higher energy output from the wind turbine in the nozzle. In this way the wind turbine efficiency is multiplied. New turbines induce more power from weaker and medium winds and their lasting time, because of the relation P=f(v3) (i.e. the power corresponds to wind velocity raised to third power). Wind turbine nozzle produces three times more energy than conventional wind turbine. Short economic analysis for conditions of the island of Lastovo indicates that profit gained by new turbines is up to five times higher than by conventional turbines. The new wind turbine nozzle should generate interest and demand on an international market, even for regions with weaker winds.

Solar energy demonstration zones in the Dalmatian region

The energy consumption in the Dalmatian region was estimated for residential and public sector, tourism, commercial sector and industry. The national energy program for the use of solar energy, SUNEN, assessed solar energy potential in Croatia. Energy from fossil fuels and electricity consumption in the region, which is mostly used in households for preparing hot water and space heating, could be economically substituted by renewable energy. The situation is most promising for the islands of the Adriatic, where solar thermal collectors, PV modules and wind generators could substitute conventional energy sources in satisfying the present thermal and electric demand. The Dalmatian Islands, characterised by a small density of energy consumption, are proposed as unique candidates in Europe for renewable zones, which could demonstrate the full potential of the renewable energy option. As a practical demonstration, the island of Lastovo and the planned tourist village and yacht marina in the Bay of Jurjeva Luka are proposed as a first solar demonstration project on the islands. Technical, economic, legal and institutional barriers, as well as shortages of financing the project identification process produced hereto an adverse environment for solar applications in Croatia. This paper is an initiative for eliminating the barriers and intensify the solar energy use in Croatia providing the clean environment and activation of indigenous energy resources in the region.

Thermal utilisation of solar energy: Croatian National Energy Program SUNEN, 1998 – 2010

In the paper, thermal use of solar energy as well as prospects and problems of its utilisation in Croatia have been given. The National Solar Energy Program, SUNEN, has been established to stimulate the usage of solar energy. The main goals of the program are the assessment of technical and economically viable solar potential in order to define real objectives and tasks to provide use of exploitable indigenous clean and renewable energy potential. The Program addresses benefits, the most promising solar applications and solar potential. Much attention has been given to identification of obstacles and barriers in the process of solar technology dissemination. SUNEN is an initiative to increase solar energy use and to become more compatible with the present renewable energy sources policy in EU and Mediterranean countries. The program proposes twelve different types of thermal solar energy systems, which could be multiplied up to 28 000 installations until the year 2010 with annual heat recovery of approximately 1,5 TWh (5,4 PJ).