Andra Blumberga

System Dynamic Model for the Accumulation of Renewable Electricity using Power-to-Gas and Power-to-Liquid Concepts

Abstract When the renewable energy is used, the challenge is match the supply of intermittent energy with the demand for energy therefore the energy storage solutions should be used. This paper is dedicated to hydrogen accumulation from wind sources. The case study investigates the conceptual system that uses intermitted renewable energy resources to produce hydrogen (power-to-gas concept) and fuel (power-to-liquid concept). For this specific case study hydrogen is produced from surplus electricity generated by wind power plant trough electrolysis process and fuel is obtained by upgrading biogas to biomethane using hydrogen. System dynamic model is created for this conceptual system. The developed system dynamics model has been used to simulate 2 different scenarios. The results show that in both scenarios the point at which the all electricity needs of Latvia are covered is obtained. Moreover, the methodology of system dynamics used in this paper is white-box model that allows to apply the developed model to other case studies and/or to modify model based on the newest data. The developed model can be used for both scientific research and policy makers to better understand the dynamic relation within the system and the response of system to changes in both internal and external factors.

Non-thermal Plasma for VOC Treatment in Flue Gases

Non-thermal Plasma for VOC Treatment in Flue Gases The paper discusses non-thermal plasmas, their generation and characteristics, formation mechanisms of ozone and the treatment of volatile organic compounds (VOCs). In the experimental part, undecane (C11H24 as model VOCs) was treated with assistance of low temperature plasma at an atmospheric pressure which was generated in the so-called stack reactor. The gas composition was 13% of oxygen in nitrogen with impurities of carbon dioxide, carbon monoxide and undecane. The formation of by-products, as well as the removal efficiency, were investigated. Zemas temperatūras plazma GOS attīrīšanai dūmgāzēs Šī darba galvenais mērķis bija veikt izpēti zemas temperatūras plazmas lietojumam dūmgāzu attīrīšanā no gaistošajiem organiskajiem savienojumiem (GOS). GOS tiek minēti kā prekursori - vielas, kas veicina piezemes ozona veidošanos, noārda stratosfēras ozona slāni un uzkrājas apkārtējā vidē, kā arī piedalās fotoķīmiskās reakcijās, veido toksiskus un kancerogēnus savienojumus. Tiek uzskatīts, ka zemas temperatūras plazmas tehnologijas nākotnē varētu samazināt emisijas ļoti efektīvi un par saprātīgām izmaksām. Plazma gaisā veido ozonu, kas ir viens no labākajiem oksidētājiem, ar kuru ir iespējams attīrīt GOS līdz CO2 un ūdenim, tāpēc tika apskatītas GOS attīrīšanas iespējas ar plazmu. Tika pētīti galvenie procesi, kas norisinās plazmā. Eksperimentālais stends tika izveidots INP institūtā Greifsvaldē Vācijā. Pētījumā, analizējot plazmas reaktora darbību un ozona veidošanos, tika konstatēts, ka ozona veidošanās procesā slāpekļa oksīdu formēšanās gāzu sastāviem ar un bez GOS bija atšķirīga. Tika noteikts, ka plazmā veidojas ne tikai CO2 un H2O, bet arī daudz dažādi blakusprodukti. Kā galvenos var minēt N2O un skudrskābi. Nepilnīgi oksidējoties rodas arī citi GOS, tomēr izmantojot FTIR spektrometru, to nebija iespējams noteikt, jo notika spektru pārklāšanās. Tika sasniegta 27 % GOS attīrīšanas efektivitāte un piedāvāti risinājumi, kā palielināt šo efektivitāti, nepalielinot reaktora jaudu. Citu GOS veidošanās apstākļu izpētei, kā arī attīrīšanas efektivitātes paaugstināšanai, ir nepieciešami plašāki eksperimentāli pēt ījumi.

Research of Woody Biomass Drying Process in Pellet Production

Abstract This paper presents results of experimental research on wood chips and sawdust drying in a rotary dryer. Empirical models for the assessment of two dependent parameters of the drying process were created based on the results of experimental data. The mathematical description of the relationship between the independent variable - reduced sawdust moisture content - and dependent variable - specific fuel consumption - is represented by a linear equation.

Energy Consumption and Indoor Air Quality of Different Ventilation Possibilities in a New Apartment Building

Energy Consumption and Indoor Air Quality of Different Ventilation Possibilities in a New Apartment Building The paper focuses on natural ventilation systems in new buildings. There is particular interest in heat energy consumption and indoor air quality with different ventilation possibilities. Indoor air quality measurements during different ventilation solutions were conducted in a new apartment building. The results of this paper show that, by applying some common ventilation solutions, the consumption of heat energy for heating the cold incoming air can reach up to 0,86 MWh/month in a 10 m2 room in the coldest months of winter.

Thermal Bridge Impact on the Heating Demand in a Low-Energy House

Thermal Bridge Impact on the Heating Demand in a Low-Energy House Thermal bridges typically occur at the junction of different building components where it is difficult to achieve continuity in the thermal insulation layer. In this paper thermal bridges are investigated in the first one-family low-energy house in Latvia. The proportion of the overall heat loss due to thermal bridging is determined based on the results from a numerical calculation method described in the standard LVS EN ISO 10211 and from the simplified calculation method given in the standard LVS EN ISO 14683. In this paper the software tool THERM is used for two-dimensional thermal bridge model simulations. The results suggest that 7.7 % of the total heat transmission losses occur due to thermal bridges.

Study of Hygrothermal Processes in External Walls with Internal Insulation

Abstract Being an important contributor to the final energy consumption, historic buildings built before 1945 have high specific heating energy consumption compared to current energy standards and norms. However, they often cannot be insulated from the outside due to their heritage and culture value. Internal insulation is an alternative. However internal insulation faces challenges related to hygrothermal behaviour leading to mold growth, freezing, deterioration and other risks. The goal of this research is to link hygrothermal simulation results with experimental results for internally insulated historic brick masonry to assess correlation between simulated and measured data as well as the most influential parameters. The study is carried out by both a mathematical simulation tool and laboratory tests of historic masonry with internal insulation with four insulation materials (mineral wool, EPS, wood fiber and granulated aerogel) in a cold climate (average 4000 heating degree days). We found disparity between measured and simulated hygrothermal performance of studied constructions due to differences in material parameters and initial conditions of materials. The latter plays a more important role than material parameters. Under a steady state of conditions, the condensate tolerating system varies between 72.7 % and 80.5 % relative humidity, but in condensate limiting systems relative humidity variates between 73.3 % and 82.3 %. The temperature between the masonry wall and all insulation materials has stabilized on average at +10 °C. Mold corresponding to Mold index 3 was discovered on wood fiber mat.

System Dynamics Modeling of Households' Electricity Consumption and Cost-Income Ratio: a Case Study of Latvia

Abstract Increased energy efficiency of the building sector is high on the list of priorities for energy policy since better energy efficiency would help to reduce impact on climate change and increase security of energy supply. One aim of the present study was to find a relative effect of growth of demand for energy services due to changes in income, energy consumption per unit of demand due to technological development, changes in electricity price and household income on household electricity consumption in Latvia. The method applied included system dynamics modeling and data from a household survey regarding the relationship between electricity saving activities and the electricity cost-income ratio. The results revealed that, in direct contrast to the expected, a potential reduction of the electricity consumption is rather insensitive to electricity price and electricity cost-income ratio, and that the efficiency of technologies could be the main drivers for future electricity savings. The results suggest that support to advancement of technologies and faster replacement of inefficient ones rather than influencing the energy price could be effective energy policy measures. The model, developed in the study could be used in similar assessments in other countries.

Analysis of Green Investment Scheme for Energy Efficiency Measures in Latvia

Latvia has the unprecedented opportunity to be the first country in the world to sell assigned amount units under Article 17 of the Kyoto Protocol – International Emissions Trading. Negotiations are ongoing with a number of buyers for pilot transactions with a cumulative volume of 8–10 million assigned amount units (AAUs) out of 40 million AAUs earmarked by Latvia’s government for total sales. Signed agreements are expected in 2009. Latvia’s government has indicated their interest in exploring options to sell the full volume of available AAUs by the end of 2012. The main goal of these activities is “greening” – increasing the market value of Latvia’s AAUs and alleviating buyers’ concerns regarding the environmental integrity of transactions. The Latvian government has agreed to “green” the transaction and channel the revenues to projects or programmes with environmental benefits. The Ministry of Environment, representing the government, has indicated its interest to buyers in pursuing greening during the pilot transaction in the following areas: biomass and biogas heating, energy efficiency improvements in public sector buildings and residential buildings. Pilot transactions will be followed by other transactions for other renewable energy sources.

Influence of Heat Gains on Typical Apartment House Heat Energy Consumption in Latvia, Simplified Calculation Method

Influence of Heat Gains on Typical Apartment House Heat Energy Consumption in Latvia, Simplified Calculation Method The existing calculation method for heat gains and building energy balance, which has been approved in Latvian legislation, uses approximately 70 equations and formulas to calculate heat gains. By carrying out a study on apartment building heat gains it was concluded that these heat gains for different types of buildings are located in relatively narrow range. This means that it is possible to simplify heat gain calculation method while making buildings energy balance. By using standard ISO 13790:2008 a simplified calculation method which describes heat gains in typical apartment buildings in Latvia was developed. This calculation method consists of one equation.