Anna Volkova

Methodological Approach to Determining the Effect of Parallel Energy Consumption on District Heating System

Abstract District heating (DH) offers the most effective way to enhance the efficiency of primary energy use, increasing the share of renewable energy in energy consumption and decreasing the amount of CO2 emissions. According to Article 9 section 1 of the Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the energy performance of buildings, the Member states of the European Union are obligated to draw up National Plans for increasing the number of nearly zero-energy buildings [1]. Article 2 section 2 of the same Directive states that the energy used in nearly zero-energy buildings should be created covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby. Thus, the heat distributed by DH systems and produced by manufacturing devices located in close vicinity of the building also have to be taken into account in determining the energy consumption of the building and the share of renewable energy used in the nearly zero-energy buildings. With regard to the spreading of nearly zero-energy and zero-energy houses, the feasibility of on-site energy (heat and/or electricity) production and consumption in DH areas energy (i.e. parallel consumption, when the consumer, connected to DH system, consumes energy for heat production from other sources besides the DH system as well) needs to be examined. In order to do that, it is necessary to implement a versatile methodological approach based on the principles discussed in this article.

Damages of the Tallinn District Heating Networks and Indicative Parameters for an Estimation of the Networks General Condition

Damages of the Tallinn District Heating Networks and Indicative Parameters for an Estimation of the Networks General Condition District heating networks in Estonia are mostly old and in bad condition. The state of the district heating networks of Tallinn is typical for the rest of Estonian DH networks. The paper includes an analysis of the Tallinn district heating networks. Valid data about damages in district heating systems received for the last 12 years were used for an analysis of the network damages. Different types of network damages are analysed: external corrosion, internal corrosion, defect of installation, factory defects, defect of construction and other reasons. The scale of damages for the different elements of networks is compared in the paper: armature, compensator, construction and pipes. The main factors which influence damages in district heating networks are the age of networks, the quality of construction works and the network operation conditions. The damage quantity dependence on the age of networks is also defined and analysed in the paper. The scale of damages can be diminished by reducing the average age of the networks. This is possible by replacing old pipelines and other network system elements. The pipes average age changes for a 20 year period are simulated according to different intensities of renovation works. Tallinas siltumtīklu bojājumi un tīklu stāvokła novērtējuma indikatīvie parametri Igaunijā pārsvarā ir veci siltumtīkli, turklāt sliktā stāvoklī. Tallinas centrālās apkures tīklu stāvoklis ir tipiskais Igaunijas siltumtīklu lielākajai dałai. Rakstā veikta Tallinas centrālās apkures tīklu analīze. Ticami dati tika saņemti par 12 gadiem un izmantoti tīklu bojājumu analīzei. Dazādiem siltumtīklu bojājumiem tika izanalizēti: ārējā korozija, iekšējā korozija, uzstādīšanas defekti, rūpnīcas defekti, būvniecības defekti un citi. Rakstā tika salīdzināti dazādu tīkla elementu bojājumi: armatūras, kompensatoru, caurułu un konstrukciju. Galvenie faktori, kuri ietekmē bojājumu daudzumu, ir tīklu vecums, būvniecības darbu kvalitāte un tīklu darbības apstākłi. Sajā rakstā ir noteikta un izanalizēta bojājumu daudzuma atkarība no tīklu vecuma. Bojājumu daudzumu var samazināt, nomainot vecos caurułvadus un citus tīkla elementus. Siltumtīklu caurułu vidējais vecums tuvākajiem divdesmit gadiem tika prognozēts, ņemot vērā renovācijas darbu dazādo intensitāti. Повреждения Таллинских тепловых сетей и индикативные параметры для оценка состояния сетей Тепловые сети в Эстонии главным образом старые и в плохом состоянии. Состояние сетей центрального отопления Таллинна типично для большинства эстонских теплосетей. Статья включает анализ сетей центрального отопления Таллинна. Достоверные данные были получены за последние 12 лет и использованы для анализа повреждений сетей. Различные типа повреждений сетей были проанализированы: внешняя коррозия, внутренняя коррозия, дефекты установки, фабричные дефекты, дефекты строительства и другие дефекты. Повреждения в различных элементах сетей были сравнены в статье: арматура, компенсаторы, трубы и конструкции. Главные факторы, которые влияют на количество повреждений это возраст сетей, качество строительных работ и условия работы сетей. Зависимость количества повреждений от возраста сетей определена и проанализирована в статье. Объем повреждений может быть уменьшен за счет уменьшения среднего возраста сетей. Это возможно при замещении старых труб и других элементов сетей. Средний возраст труб на ближайшие двадцать лет был спрогнозирован с учетом различной интенсивности работ по реновации сетей.

Efficiency Assessment of Support Mechanisms for Wood-Fired Cogeneration Development in Estonia

Efficiency Assessment of Support Mechanisms for Wood-Fired Cogeneration Development in Estonia There are various support mechanisms for wood-fired cogeneration plants, which include both support for cogeneration development and stimulation for increasing consumption of renewable energy sources. The efficiency of these mechanisms is analysed in the paper. Overview of cogeneration development in Estonia is given with the focus on wood-fired cogeneration. Legislation acts and amendments, related to cogeneration support schemes, were described. For evaluating the efficiency of support mechanisms an indicator - fuel cost factor was defined. This indicator includes the costs related to the chosen fuel influence on the final electricity generation costs without any support mechanisms. The wood fuel cost factors were compared with the fuel cost factors for peat and oil shale. For calculating the fuel cost factors, various data sources were used. The fuel prices data were based on the average cost of fuels in Estonia for the period from 2000 till 2008. The data about operating and maintenance costs, related to the fuel type in the case of comparing wood fuel and oil shale fuel were taken from the CHP Balti and Eesti reports. The data about operating and maintenance costs used for peat and wood fuel comparison were taken from the Tallinn Elektrijaam reports. As a result, the diagrams were built for comparing wood and its competitive fuels. The decision boundary lines were constructed on the diagram for the situation, when no support was provided for wood fuels and for the situations, when various support mechanisms were provided during the last 12 years.

Competitiveness of wood fuel in the conditions of open electricity market in Post-Kyoto period: Case study for Estonia

The goal of the paper was to evaluate competitiveness of wood fuel in comparison with oil shale taking into account Estonian renewable energy support policy, open electricity market and greenhouse gas emission allowance trading mechanisms. During the research the potential for electricity capacity and electricity production where wood is used as fuel, was calculated. The electricity production costs were evaluated for two possibilities of producing electricity from wood: for wood-fired cogeneration plants and for oil shale plants with oil shale and wood co-firing process. The options of wood utilisation were compared with the reference case when the electricity is produced using only one type of fuel - the oil shale.