12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, Estonia5. COMMENT AND DISCUSSIONThe use of CHP instead of conventional plant willalways improve energy efficiency and will reduce CO 2emissions significantly, in Latvia there is potential toreplace some of the heat plants with co-generationunits (comparing with Denmark where approximately80% of the district heating in Denmark is supplied fromCHP [6].Fig. 6. Diagram of the economical optimization[12]Results of technological optimization show that, thehigher the installed capacity, the shorter the operationtime of equipment. If assumed that operation time ofthe equipment could be 5 up to 10 years, then theinstalled capacity can be 0,5MW and higher.Hence promotion of high-efficiency cogeneration (CHP)based on a useful heat demand is a priority with regardto saving primary energy, avoiding network losses andreducing emissions, in particular of greenhouse gases[2].Of course the choice of the fuel is fundamental in orderto reach the target required from the last EU directive interms Renewable Energy Sources (RES).More use of energy from biomass in terms of woodfuel,biogas, landfilled gas and biofuels seems to be a gooddirection in order to displace the part of energy sourcesgiven by the imported natural gas.Fig. 7. Equipment operation time vs installed capacity [12]Results of the climate sub model show that the higheris installed capacity, the greater the reduction ofgreenhouse gas emissions. Besides that, it is notpossible to reach extremis by using two objectivefunctions (heat value of biogas and installed capacity),which have been used in case of economical andtechnological sub models, and it is necessary tointroduce another objective functions.The use of wood in the energy sector (through theproduction of heating and electricity) must become notonly an objective for the development of the energysupply system, but it must also become part ofstrategies for economic development and for theimprovement of the import/export balance of thecountry. These measures can succeed in not onlydeveloping local production and job creation, but if canalso stimulate and increase the potential export.It is particularly important to conduct engineer-technicaland economic analysis of the various technologicalsolutions possible to implement wood use in thecogeneration plants of the larger cities (including RigaTEC 1 and TEC 2) [13]. Any possible choice and/orscenario cannot be complete if it not references to aLife cycle assessment (LCA) that it a good tool in orderto understand the environmental load of a certainprocess strategy and in order to give a comparablecommon base.Based on the targeted indicators for Latvia the beststrategy can be identify in:Fig. 8. Diagram of the environmental optimization [12]Model of power production in landfill shows that feed-intariff stated as financial support today in Latvia allowsto reach economically feasible projects even in case ifcogeneration unit is operated in power station regime(generates only electricity). Results show that statepolicy needs corrections to improve energy efficiency ofbiogas utilization for energy production.182– Enhance the diversity and variety of the energymix.– Improve maintenance of existing energyinfrastructure.– Eliminate constraints and investment in newfacilities.– Increase the efficiency of energy supply inelectricity generation.– Increase the share of electricity produced bycombined heat and power (CHP) plants.– Increase the share of renewable and domesticenergy sources in the energy mix.