1 A PRACTICAL APPROACH TO THE CONGENERATION SYSTEM FOR RURAL APPLIANCES A. Jan Iwaszkiewicz 1 , B. Jacek Perz 1 , C. Jarosław Mikielewicz 2 1. The Electrotechnical Institute, Gdansk Branch, Poland 2. The Szewalski Institute of Fluid-flow Machinery, Poland The proposal of distributed generation system based on cogeneration Micro-Power Plants (MPP) is presented in the paper. The proposed MPP can operate using local energy resources as well as traditional fuels. The MPP power range can be from few kW up to 100 kW. The primeval fuel energy is better utilized in cogeneration MPP than in power plants producing only electricity. The efficiency of cogeneration MPP can reach the level of 90 %, while in monogeneration power plants the efficiency is below 50 %. 70 to 80 % of the produced energy is used for local heating and 10 to 20 % is used for additional production of electrical energy. The high speed steam turbine using low-temperature evaporation working fluid and an permanent magnet voltage generator directly coupled with turbine are proposed. The different configurations of power- electronic devices for converting the produced energy to one or three phase 50 Hz waveforms have been discussed. Key words – renewable energy, distributed generation, cogeneration, power converter. 1. INTRODUCTION The importance of distributed generation systems is still growing nowadays not only within UE but worldwide. They can be based on local energy resources, renewable energy sources and technologies using conventional fuels [1]. For small and medium scale plants popular are multifunctional energy production processes like cogeneration, trigeneration and poligeneration. The cogeneration process, which means simultaneous generating heat and electrical energy, is the most commonly used. The actual energy production development trend, called cogeneration energetic, is based on the distributed low power sources using cogeneration. The European Commission Directive 2004/8/UE defines the target for energy production within UE till a year 2010. The goal is to increase the contribution of small and medium scale cogeneration power plants in energy production up to 18 %. This program creates an unique opportunity for evolution of Micro-Power Plants (MPP). MPP are designed to provide heat and electricity supply for household, farm or small enterprise. The generated heat can be used locally for heating and produced electricity can be used locally or transferred to the power grid, thus lowering the costs of electrical energy supply. Depending on local potential MPP can use conventional or renewable fuel. The efficiency of power plants producing only electrical energy reaches the level of forty to fifty percent. The primeval fuel energy is better utilized in cogeneration MPP than in power plants producing only electricity. The efficiency of cogeneration MPP can reach the level of 90 %. 70 to 80 % of the produced energy is used for heating and 10 to 20 % is used for additional production of electrical energy. It means that the owners of the boilers equipped with MPP can became producers of electrical energy. Higher efficiency in utilizing the primeval fuel energy in cogeneration MPP results in lower emission of harmful substances produced by process of burning fuel. A small cogeneration MPP can be fully automatically maintained without operating personnel. The marketing study done i.e. in Great Britain showed that the market requirement for Micro-Power Plants can be enormous, in millions pieces, comparable with the requirement for i.e. refrigerators. Taking into account that the power of such kind of power plants amount from few to hundred kW it is easy to calculate that they can replace a number of big conventional power plants. If for example the requirement for heating is about 10 kW, it is possible to obtain about 2 kW of electrical energy, accompanying the heat production. If one million of users took the advantage of this process, the impact on the power system is equivalent to installation of additional big power plant with 2000 MW power. This simple calculation shows how the presented solution can provide for efficient use of primeval energy and enhancement of environment. There is a number of different concepts of MPP realization using i.e. combustion piston engine, gas turbine, steam turbine, Stirling engine, fuel cells stack and others. Some of these concepts will be put to work in the nearest future. Authors opinion is that in next 2-3 years a cogeneration MPP using steam turbine can reach the market. https://doi.org/10.24084/repqj07.444 586 RE&PQJ, Vol. 1, No.7, April 2009