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French Energy Company Dalkia acquires majority share in energy-savings company KES The company has long-term investment plans for the Bulgarian energy sector Aug 22, 2006, Sofia. Dalkia Bulgaria, subsidiary of Dalkia International, purchased 55% of the shares of the energy-saving cooperative company KES Co. Dalkia Bulgaria acquired the shares of former major stakeholder RWE Industrie-Loesungen. The other 45% of the share capital of KES Co. are owned by Stadwerke Leipzig. KES Co. is mainly pursuing various energy and energy-efficiency projects related to building facilities and production. Dalkia will provide its worldwide experience and know-how in the energy sector to KES, which realizes energy savings projects for client such as Sofia Municipality. Dalkia is acquiring the majority share of KES as part of its long-term projections for investments in the Bulgarian market. Dalkia Bulgaria will apply for qualification as a participant in the bidding procedures for privatization of the heating supply companies based in Plovdiv, Dalkia has been working in Central and East-European states, demonstrating the sustainability of its corporate business model in Hungary, Poland, the Czech Republic, Romania and Slovakia. The company provides the installations it operates increased energy performance while streamlining their management. Dalkia ensures operation and maintenance to 146 regional and local heating systems and manages 1 923 energy sites of 9 986 MW power capacity. Dalkia is supplying energy to 866 000 households in the CEEC. The above-mentioned countries take the best advantage of a long-term partner in the French energy supplier that supported them in the process of deregulation of the energy market and facilitated the reconstruction of the major heating supplying companies. Dalkia is a leading European supplier of energy services. Priority fields of the company's activity are the sectors of energy production and conversion, management of energy supplying plants and installations, and the comprehensive management of buildings, among other. The company's focus is on the optimization of variegated energy installation's performance in terms of technical efficiency, cost-effectiveness and environmental issues. In 2005 Dalkia's realized an annual turnover of Euro 6.1 billion and supplies energy services to over 5.1 mln households worldwide. Details about Dalkia: A subsidiary of Veolia Environnement and Electricite de France (EDF), Dalkia International is the leading European provider of energy services to local authorities and businesses. Since its creation, it has focused on energy and environmental optimisation. It meets customer expectations by delivering customised, end-to-end solutions to ensure comfortable living and efficient energy supply, including management of heating systems and energy and industrial fluid production facilities, energy plant engineering and maintenance services, technical services for commercial and industrial building operation, and global facility management services. With more than 47,000 employees in 38 countries, Dalkia reported 2005 managed revenue of €6.1 billion. In the CEEC, Dalkia's turnover for 2005 amounted to 674 million euros, for a total staff of 7 969. Worldwide, Dalkia operates and maintains 650 regional and local heating supply and cooling systems, managing 88.000 energy installations for a total of 81.000 MW power capacity.



The cogeneration is a process of combined heat and electric power production from one and the same basic energy source. By using of cogeneration systems we can increase the electric power generation by 30-50% to 80-90% on average. The use of cogeneration for the combined production of heat and electric power can bring about 40% savings in terms of the fuel in use. From a financial point of view that means that the consumers will pay just 60% of the fuel cost for the same amount of consumed energy.
The main advantages of this technology are its high efficiency in using of the fuel, exceeding of the regulatory ecological parameters and last but not least, autonomy of the system. It should be noted that the proper implementation of the projects requires the availability of specific knowledge and expertise. Otherwise, it is likely to fail in achieving many of the benefits provided by the cogeneration system.

The cogeneration plant consists of four main units:
Primary engine;
Electric generator;
System for receiving of the released heat - a heat exchanger;
System for control and management.

As a rule the cogeneration systems are classified according to the type of the primary engine, the generator and the fuel type used.

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Fig. 1. Comparing between the efficiencies of cogeneration and ordinary heat production.

Depending on the specific requirements, functioning as a primary engine can be:
Internal combustion engine - Two types of these are used as follows: The first type uses spark ignition and it can only operate on natural gas. The other type uses compression and it can operate on diesel or natural gas containing 5% of diesel fuel for initial ignition of the fuel mix. The total efficiency of the system is 70-92%.
Steam turbine - The electric power capacity of the system depends on the steam pressure at the inlet and outlet of the turbine. In general, the efficiency of the steam turbines used only for electric power generation is lower than that of the gas turbines and the internal combustion engines, but when working within a cogeneration system their cumulative efficiency can reach up to 84%. In order to obtain the maximum efficiency of the system, steam should be fed to the turbine at high pressure and temperature (42 bar/ 400oC or 63 bar/ 480 oC).
Gas turbine - The efficiency of the gas turbines is 25-35% depending on the performance data of the models and the specifications of the fuel used. When incorporated in a cogeneration system its efficiency reaches up to 90% and besides, it shows very good ecological features. The emissions of NOx are about 25ppm. A disadvantage of the gas turbine that it produces too much noise while in operation;
Mictoturbine - It uses natural gas but it can also be run on diesel fuel. Suitable for use in systems having horsepower ratings of less than 1MW, for which the use of gas turbines have so far proved to be unprofitable. The microturbine has some other advantages as well. Its emissions of NOx are about 10-25 ppm. Its total efficiency can reach up to 85%.
Hydrogen fuel cells - They have a number of advantages when used as a main engine in the cogeneration systems such as high efficiency, few running components which do not wear out, reliable operation, maintenance at longer time intervals, increasing twice the energy efficiency of the system.

The generators can be synchronous and asynchronous types. The synchronous generator can operate autonomously or in parallel with the power grid. The asynchronous generators can only operate in parallel with the grid. In case of malfunctions in the system the asynchronous generators trip. For that reason more frequent is the use of synchronous generators ensuring flexible operation of the cogeneration systems. The heat exchanger is an essential unit in all cogeneration plants that use the energy of the exhaust hot fumes from the electric generator engine. The operating principle is the following: the exhaust fumes flow through a heat exchanger where the hot fume heat is transferred onto a liquid heat carrier (water or glycol). Then the flue gases, which are already cool, are released into the atmosphere, their chemical and quantitative composition remaining the same.

Apart from this, a large amount of unused heat is wasted into the atmosphere. That is due to several reasons:

Efficient heat exchange can be obtained if the discharged flue gas temperature is higher that the heat carrier temperature their difference being not less than 30oC;
The discharged flue gases should not be cooled down to temperatures initiating the formation of water condensate in the flue gas stack which could prevent the normal discharge of the gas in the atmosphere;
The discharged flue gases should not be cooled down to temperatures initiating the formation of acid condensate, which causes corrosion of the materials;
The heat exchanger should be designed based on the precise calculations of the working parameters and specifications of the exhaust gas flow taking into account the type of the internal combustion engine or the turbo generator and the fuel type used.

Aimed at increasing the heat output of the cogeneration system an economizer-heat exchanger can added to the heat exchanger to ensure preheating of the heat carrier before it is fed to the main heat exchanger, where the heat carrier is heated by the hot exhaust gases of the engine. The benefit from using an economizer is that it brings about temperature reducing of the flue gases discharged downstream of the heat trap down to 120oC and lower.

What is of utmost importance for the technical efficiency of the cogeneration systems is the regular heat load ensuring the design performance of the engine and the generator. In the recent years more and more designs are being made aimed at utilization of some of the high temperature gases (up to 150 oC) for cold production in air conditioning and industrial systems using absorption, sorption and/or compressor heat equipment, the so called 'tri-generation models' (see fig. 2). They increase the regular heat load, the installed power and extend the operation time of the cogenerator.
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Fig. 2 A schematic diagram of tri-generation

CES AD carries out feasibility studies for the installation of cogeneration units and it can implement investment projects using cogeneration either as a contractor or based on a . Contract with guaranteed results.