Browsing by Department "Department of Energy Technology"
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Item Accomplishing rural electrification for over a billion people: Approaches towards sustainable solutions(Aalto University, 2014) Rahman, Mizanur Md.; Paatero, Jukka, Dr., Aalto University, Department of Energy Technology, Finland; Energiatekniikan laitos; Department of Energy Technology; Energy Economics and Power Plant Engineering; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, FinlandAccess to electricity appears to be a prerequisite to materialize social, economic, and human development in the underprivileged rural areas. However, 1.1 billion rural people in the world, almost all of them living in developing countries, still do not have access to electricity. Although the rural electrification process poses more challenges than urban electrification, rural areas are blessed with abundant and relatively evenly distributed renewable energy resources. To facilitate electricity access to this huge population, it is essential to deal with the rural electrification task by considering its challenging features and the potential merits of renewable resources. The objective of this thesis is to present policy and techno-economic frameworks for sustainable and accelerated rural electrification for over a billion people in developing countries. This thesis considers grid expansion as the primary option for rural electrification, and renewable resource based off-grid options were considered as the alternative where grid expansion is not feasible. Grid-based rural electrification policies were examined by focusing on one case program (the Bangladesh rural electrification program) in light of challenges that are generic for developing countries. The assessment of the potentials and techno-economic viability of renewable resources were performed by utilizing analytical methodologies and well-established computer tools (HOMER and RETScreen). The evaluation of choices among rural electrification alternatives has been illustrated with the help of the Stochastic Multicriteria Acceptability Analysis (SMAA) tool. The evaluation methods and tools are illustrated by employing case data obtained mainly from Bangladesh. This thesis observed that some key policy elements influence the performance of a grid-based rural electrification program. These policy elements guide the rural electrification program towards success through addressing distinct rural electrification challenges. Agricultural residues have the potential to generate electricity to meet household-level demands in rural areas of many developing countries. Hybrid biogas and solar resources can serve both clean-cooking and electricity loads in rural households with achieving benefit (saving) more than the cost. The multicriteria decision support technique enables a rural electrification program to choose decision options from different alternatives based on sustainability criteria.Item Advances in Humidity Measurement Applications in Metrology(Aalto University, 2015) Sairanen, Hannu; Heinonen, Martti, Dr., VTT Technical Research Centre of Finland, Finland; Energiatekniikan laitos; Department of Energy Technology; Applied Thermodynamics; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, FinlandA significant part of the development of humidity measurement applications in metrology is carried out due to the climate change. Within this thesis metrology tools for humidity measurements in energy gases were developed. In addition, a new method and apparatus for radiosonde calibrations were developed and constructed to provide traceability to the System of Units (SI) and thus improve the quality of radiosonde measured humidity data. Metrology tools for humidity measurements of energy gases were developed by studying the water vapour enhancement factor for methane. A new hygrometer-based calibration method was developed and a set-up was assembled for calibrations of liquid microflows from syringepumps. Metrological validation for the set-up including uncertainty analysis was carried outfor flow rates from 0.1 ul min-1 to 10 ul min-1. The set-up was applied in development and construction of a novel apparatus to measure the enhancement factor. The apparatus was metrologically validated by air and methane measurements for pressures up to 6 MPa and dew/frost-point temperatures from -50 °C to +15 °C. Utilising this apparatus, new experimental enhancement factor data was measured. Along with literature data on equilibrium states of water vapour in methane, new literature-based enhancement factors were calculated. The experimental and the calculated data were combined and an equation expressed as a function of pressure and dew-pointe temperature was fitted to the data. The equation covers dew/frost-point temperature range from -23 °C to +20 °C and pressures below 7 MPa and its expanded uncertainty (k = 2) is 0.23 in the whole range. Radiosondes operate over a wide range of humidity, temperature and pressure values and thus their calibrations should also cover these conditions. However, calibrations performed with traditional methods at cold temperatures and low humidity require a lot of time and therefore a customized apparatus was developed and constructed. The new apparatus enables significantly shorter calibration times within the temperature range from -80 °C to +20 °C and the dew/frost-point temperature range between -90 °C and +10 °C. The apparatus fulfils the requirements set by Global Climate Observing System (GCOS) and its GCOS Reference Upper-Air Network (GRUAN).Item Assessing energy efficiency potential in the building stock: Method for estimating the potential for improvements and their economic effects(Aalto University, 2015) Tuominen, Pekka; Tuomaala, Mari, Dr., Gasum Ltd., Finland; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, FinlandBuildings, representing more than a third of global energy consumption, have long remained one of the focal points for the efforts to increase energy efficiency. The residential sector in particular has had more energy-related policies put in place than any other sector in the IEA countries. Therefore, the question which policies will have the greatest effect over time is very relevant to the policymakers. The main objective of this thesis is to develop a method for calculating the en-ergy efficiency potential of the building stock and to assess the economic effects of the realization of the potential in terms of changes in GDP, employment and external costs. Even though the method is meant to be applicable to different building stocks, the Finnish building stock was mostly studied as the method was developed over time. Similar but more limited analysis was also conducted for a number of EU member states. During the course of the study, a calculation tool called REMA was developed based on the methods used. The purpose of REMA is to allow conducting similar analyses in the future with relative ease in a systematized way. REMA is a bottom-up engineering model of energy use in the building stock. Future developments are estimated using annual rates of new construction, renovations and removals from the building stock. The selected approach entails selecting representative building types, also called archetypes, for estimating the energy consumption in different segments of the building stock. The scenarios calculated concerning the Finnish case indicate that a few per-cent rise in annual construction and renovation investments can decrease total primary energy consumption 5–7% of the country by 2050 compared to a baseline scenario. On the short term a slight decrease in the level of GDP and employment is expected. On the medium to long term, however, the effects on both would be positive. Furthermore, a significant drop in harmful emissions and hence external costs is anticipated. Overall, a clear net benefit is expected from improving energy efficiency. For other EU countries studied, typically energy savings of about 20% were estimated to be achievable by 2030 with cost-effective renovation investments in the building stock analysed. Overall, major economically sound energy efficiency potentials were identified, but the realization of these potentials is rather slow due to the limited renewal rates present in building stocks.Item Assessing the uncertainties of climate policies and mitigation measures. Viewpoints on biofuel production, grid electricity consumption and differentiation of emission reduction commitments(VTT Technical Research Centre of Finland, 2012) Soimakallio, Sampo; Savolainen, Ilkka, Professor, VTT Technical Research Centre of Finland; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of Engineering; Syri, Sanna, Professor, Energy Economics, Department of Energy Technology, School of Engineering, Aalto University, FinlandAmbitious climate change mitigation requires the implementation of effective and equitable climate policy and GHG emission reduction measures. The objective of this study was to explore the significance of the uncertainties related to GHG emission reduction measures and policies by providing viewpoints on biofuels production, grid electricity consumption and differentiation of emission reduction commitments between countries and country groups. Life cycle assessment (LCA) and macro-level scenario analysis through top-down and bottom-up modelling and cost-effectiveness analysis (CEA) were used as methods. The uncertainties were propagated in a statistical way through parameter variation, scenario analysis and stochastic modelling. This study showed that, in determining GHG emissions at product or process level, there are significant uncertainties due to parameters such as nitrous oxide emissions from soil, soil carbon changes and emissions from electricity production; and due to methodological choices related to the spatial and temporal system boundary setting and selection of allocation methods. Furthermore, the uncertainties due to modelling may be of central importance. For example, when accounting for biomass-based carbon emissions to and sequestration from the atmosphere, consideration of the temporal dimension is critical. The outcomes in differentiation of GHG emission reduction commitments between countries and country groups are critically influenced by the quality of data and criteria applied. In both LCA and effort sharing, the major issues are equitable attribution of emissions and emission allowances on the one hand and capturing consequences of measures and policies on the other. As LCA and system level top-down and bottom-up modelling results are increasingly used to justify various decisions by different stakeholders such as policy-makers and consumers, harmonization of practices, transparency and the handling of uncertainties related to methodological choices, parameters and modelling must be improved in order to avoid conscious misuse and unintentional misunderstanding.Item Biomass Gasification(Aalto University, 2011) Kouhia, Mikko; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of EngineeringThere is great interest in the utilization of biomass in high efficiency power generation and in the production of high quality synthetic fuels and chemicals. Gasification, among biochemical conversion, is one way to achieve this goal. In this report the operational principle of gasification is reviewed, an analysis of different biomasses is presented and the main gasifier types are examined. The product gas composition, cleaning and utilization are examined and the commercial status of gasification is studied. There are many ways to gasify biomass, but the most common way in medium-to-large scale is to use atmospheric circulating fluidized bed gasifiers; downdraught fixed bed gasifiers are used in a smaller scale. Gasification has not yet achieved extensive usage, but it is likely to be utilized increasingly in the future as an environmentally friendly way to produce power, fuels and chemicals.Item Combining Simulation and Optimisation for Dimensioning Optimal Building Envelopes and HVAC Systems(Aalto University, 2012) Hamdy, Mohamed; Hasan, Ala, Dr., Aalto University, Finland; Energiatekniikan laitos; Department of Energy Technology; HVAC Technology; Insinööritieteiden korkeakoulu; School of Engineering; Sirén, Kai, Prof., Aalto University, FinlandResponding to the international calls for high energy performance buildings like nearly-zero energy buildings (nZEB), recent years have seen significant growth in energy-saving and energy-supply measures in the building sector. A detailed look at the possible combinations of measures indicates that there could be a huge number (possibly millions) of candidate designs. In exploring this number of designs, looking for optimal ones is an arduous multi-objective design task. Buildings are required to be not only energy-efficient but also economically feasible and environmentally sound while adhering to an ever-increasing demand for better indoor comfort levels. The current thesis introduces suitable methods and techniques that attempt to carry out time-efficient multivariate explorations and transparent multi-objective analysis for optimizing such complex building design problems. The thesis’s experiences can be considered as seeds for developing a generic simulation-based optimisation design tool for high-energy-performance buildings. Case studies are made to illustrate the effectiveness of the introduced methods and techniques. In all the studies, IDA-ICE is used for simulation and MATLAB is implemented for optimisation as well as supplementary calculations. A new program (IDA-ESBO) is used to simulate renewable energy source systems (RESs). Using detailed simulation programs was important to investigate the impact of the energy-saving measures (ESMs) and the RESs as well as their effects on the thermal and/or energy performance of the studied buildings. The case studies yielded many optimal design concepts (e.g., the type of heating/cooling (H/C) system is a key element to achieve environmentally friendly buildings with minimum life cycle cost. The cost-optimal implementations of ESMs and RESs depend significantly on the installed H/C system). On building regulations, comments are taken. For instance, in line with the cost-optimal methodology framework of the European Energy Performance of Buildings Directive (EPBD-recast 2010), our study showed that the Finnish building regulation D3-2012 specifies minimum energy performance requirements for dwellings, lower than the estimated cost-optimal level by more than 15%. The adaptive thermal comfort criteria of the Finnish Society of Indoor Air Quality (FiSIAQ-2008) are strict and do not allow for energy-efficient solutions in standard office buildings. The thesis shows that it is technically possible to speed up the optimisation resolution of the building and HVAC design problems and to reach an optimal or close-to-optimal solution set. A simulation-based optimisation approach with a suitable problem setup and resolution algorithm can efficiently explore the possible combinations of design options and support informative, optimal results for decision-makers.Item Comparison of Indirect CO2-emissions of Different Renewable Transport Fuels(2015) Holmberg, Henrik; Siitonen, Sari; Laukkanen, Timo; Tuomaala, Mari; Niskanen, Tuomas; Department of Energy TechnologyThe European Union's goal is to increase the share of renewable energy sources to 20 per cent and that of liquid biofuels for transport to at least 10 per cent by 2020. Liquid biofuels for transport are, for example, biodiesel and bioethanol. Their use is not assumed to increase CO2-emissions in the atmosphere. However, production processes of transport fuels need energy causing indirect CO2-emissions. To evaluate the environmental burden of these biofuels it is important to consider indirect CO2-emissions in analyses, too. This study defines indirect CO2-emissions for Digestion process, Bioethanol process, FT-process (Fischer-Tropsch-process) and Bio-SNG-process and compares their environmental burden.Item Consumer Demand of Renewable Energy Services - Case Studies on Finland, Germany, Great Britain, USA and China(Aalto University, 2014) Hast, Aira; McDermott, Liisa; Syri, Sanna; Järvelä, Marja; Huuskonen, Maija; Alimohammadisagvand, Behrang; Cross, Sam; Syrjämäki, Eija; Energiatekniikan laitos; Department of Energy Technology; Energy Efficiency and Systems; Insinööritieteiden korkeakoulu; School of EngineeringKULMA project investigated consumer demand of so-called green energy products in various countries to understand better the motivations and preferences of consumers and the societal prerequisites and barriers of renewable energy. In addition to Finland, the target countries were Germany, Great Britain, USA and China, i.e. important export countries for the Finnish Cleantech industry. KULMA project was realised during 2012-2014 by Aalto University, Department of Energy Technology, and Jyväskylä University, Department of Social Sciences. The main funding came through the Strategic research openings instrument of Tekes, the Finnish Funding Agency for Innovation. We investigated the green electricity products available for consumers in the selected European countries, their popularity, origin and typical prices compared to standard electricity products. In the USA, we investigated the situation of renewable energy and local attitudes via sociological methods in Texas and in West Virginia. We found that transparent and clear information about the impacts of a green energy product are essential, when offering them to consumers. Local strategies are important with view to promoting consistent political will and stakeholder involvement for advancing renewable energy. Renewable energy has beneficial effects especially if the production of the technology or the fuel is local. The new industry must also have local acceptance. Previous know-how and industrial tradition often help in the creation of new local industry.Item Curriculum planning in energy engineering education(2015) Mälkki, Helena; Paatero, Jukka V.; Department of Energy Technology; Department of Civil and Environmental Engineering; Department of Built EnvironmentItem Development and application of a multicriteria decision support framework for planning or retrofitting district heating systems(Aalto University, 2013) Wang, Haichao; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, Finland; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, FinlandCHP-based, combined district heating (DH) systems with gas-fired boilers for peak heating load compensation have several advantages compared to traditional DH systems. They have a relatively high level of energy and environmental efficiency. However, there is a lack of a decision support system aiding in the planning or retrofitting of them. Therefore, the aim of this dissertation is to demonstrate how these kinds of DH systems are designed and operated as well as to develop a decision support framework not only from an economic viewpoint, but also in relation to energy, technology, and environment issues. First, the excessive heat supply rate (EHSR), which indicates the thermal maladjustment extent of heat substations, is presented to determine the installation strategy of peak shaving gas-fired boilers. On this basis, the combined heating alternatives to be addressed are constructed with a different basic heat load ratio; moreover, the design and operation of the system is discussed extensively. Then, the dissertation presents an application-oriented, multi- criteria decision support framework for evaluating different combined heating alternatives in a real-life DH system in Daqing, China. Before doing the multicriteria decision analysis (MCDA), a corresponding criteria aggregation system is developed, based on which criteria weights can be elicited using fuzzy AHP in combination with the concept of a 'complementary judgment matrix' (CJM) and hypothesis test. A feasible weight space instead of a deterministic weight vector is then proposed and utilized in the MCDA. Subsequently, the techno-economic performance, atmospheric environmental impact, reliability, and energy efficiency of the systems are modeled respectively in order to obtain the criteria measurements needed for decision support. Stochastic multicriteria acceptability analysis (SMAA) is implemented to synthetically handle the problem. The results indicate that combined district heating systems consisting of CHP and gas-fired boilers can be economically more feasible and sustainable, and it is environmentally efficient to use gas-fired boilers for peak heating load compensation. The most preferred basic heat load ratio in the demonstration case should be between 0.66 and 0.77, with relatively high confidence factors. In all, the present decision support system can be useful for planning or retrofitting and operating the combined district heating system. Nevertheless, it can be extended and applied to other energy supply systems as well.Item Driving and hindering factors for rural electrification in developing countries: Lessons from Bangladesh(2013-10) Rahman, Md. Mizanur; Paatero, Jukka V.; Poudyal, Aditya; Lahdelma, Risto; Department of Energy Technology; Department of Applied Physics; Department of Mechanical EngineeringItem Economic Evaluation of a Synthetic Natural Gas Production Plant using Indirect Gasification of Lignocellulosic Biomass(Aalto University, 2014) Kakkonen, Jukka; Syri, Sanna; Energiatekniikan laitos; Department of Energy Technology; Energy Efficiency and Systems; Perustieteiden korkeakoulu; School of ScienceThe report examines the profitability and business prospects of a bio-SNG plant with fuel power of 100 MW. The plant produces SNG via indirect gasification of woody biomass. This study examines the Nth plant of the same kind, which is expected to be completed in 2020. The report includes three scenarios with alternative energy price outlooks in 2020 with one scenario to extend to 2040. These energy prices are used in the profitability analysis. The profitability calculations include results from the process simulation of different plant constructions. Studied end-use cases are energy production in Finland and transportation use in Sweden. The report also recognizes the national and EU legislation with impact on bio-SNG industry, as well as the different possible support mechanisms the plant might be subjected to. A preliminary business plan, which takes into account all of the above, is a key part of the work. In this report we show that in 2020 bio-SNG production using indirect woody biomass gasification can be a viable technology. The profitability of a bio-SNG plant is, nevertheless, highly sensitive to the future energy prices and the potential support mechanisms. We found that a bio-SNG production plant would be profitable if it was initially subsidized with support mechanisms that are enacted already today, or in markets with higher gas prices, such as the studied case on transportation use in Sweden. In addition to financial aspects, the bio-SNG technology offers several other benefits compared to using imported natural gas such as meeting the energy and climate targets and supporting domestic employment, economy and energy independency.Item An efficient algorithm for bi-objective combined heat and power production planning under the emission trading scheme(Elsevier, 2014) Rong, Aiying; Figueira, José Rui; Lahdelma, Risto; Department of Energy Technology; Energiatekniikan laitos; Energy Efficiency and Systems; Insinööritieteiden korkeakoulu; School of EngineeringThe growing environmental awareness and the apparent conflicts between economic and environmental objectives turn energy planning problems naturally into multi-objective optimization problems. In the current study, mixed fuel combustion is considered as an option to achieve tradeoff between economic objective (associated with fuel cost) and emission objective (measured in CO2 emission cost according to fuels and emission allowance price) because a fuel with higher emissions is usually cheaper than one with lower emissions. Combined heat and power (CHP) production is an important high-efficiency technology to promote under the emission trading scheme. In CHP production, the production planning of both commodities must be done in coordination. A long-term planning problem decomposes into thousands of hourly subproblems. In this paper, a bi-objective multi-period linear programming CHP planning model is presented first. Then, an efficient specialized merging algorithm for constructing the exact Pareto frontier (PF) of the problem is presented. The algorithm is theoretically and empirically compared against a modified dichotomic search algorithm. The efficiency and effectiveness of the algorithm is justified.Item Energiatehokkuuden mittarit ja potentiaalit(Aalto University, 2012) Tuomaala, Mari; Ahtila, Pekka; Haikonen, Turo; Kalenoja, Hanna; Kallionpää, Erika; Rantala, Jarkko; Tuominen, Pekka; Shemeikka, Jari; Rämä, Miika; Sipilä, Kari; Pursiheimo, Esa; Forsström, Juha; Wahlgren, Irmeli; Lahti, Pekka; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of EngineeringThe first objective of the research ‘Energy Efficiency Metrics and Improvement Potentials’ was to study how energy efficiency is measured in different sectors. The second objective was to study how energy efficiency improvement potential could be evaluated on a sectoral basis, and more comprehensively in society as a whole. The research covered five sectors: communities, buildings, transportation and logistics, (process) industry and energy production. According to the Energy Service Directive 2006/32/EC (EC, 2006), energy efficiency is defined as “a ratio between an output of performance, service, goods or energy, and an input of energy”. The output of performance, service, goods or energy covers a wide range of subjects. This results in a variety of energy efficiency metrics. Sometimes it is useful to provide a broader perspective on energy efficiency measurement(e.g. kWh/m3, kWh/m2, etc. in the construction and real estate sector). Sometimes explanatory metrics are also needed, e.g. ‘the capacity utilisation rate’ in the process industry sector. In the analysis of efficiency, one must make decisions about how to set the balance boundary and how to take the life-cycle aspects into account. It is worthwhile to compare only objects which have been defined in a similar way. Energy is used in different forms: as fuel, electricity and heat. Different forms of energy should not be aggregated until they have been transformed into a comparable form. This is made using so-called primary energy factors. There are varying practices in the use of primary energy factors, and the ways in which they are calculated is not well established. Energy efficiency and energy efficiency potential should be studied primarily using energy units. Carbon dioxide (or greenhouse gas) efficiency can be used as a supporting and complementary evaluation criterion. Energy efficiency improvement potential means a difference in energy consumption between the current situation and the reference situation. Defining the reference situation, i.e. the target state, is one of the challenges in calculating the potential. Such a target state can be the best known reference (such as BAT), or ideal performance. No common method exists to define the target state, so practices vary between the sectors. For example, the concept ‘ideal state’ is not even suitable in communities and logistics. A case study was carried out during the late part of the research to calculate the energy efficiency potential of an example area. The study was made in the Kalasatama district near the city centre of Helsinki. The case study verified for example, that metrics from different sectors can be combined in a single study. Based on the study it can be said that the methods being used are still undeveloped, and much research is needed in this area. In practical work, emphasis should be put on reaching agreements concerning the standardisation of energy efficiency calculation methods.Item Energy-efficient city planning - The role and importance of actionable regulations(Aalto University, 2016) Hedman, Åsa; Kazi, Abdul Samad (Sami), Prof., VTT Technical Research Centre of Finland Ltd, Finland; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof., Aalto University, Department of Energy Technology, FinlandThis thesis focuses on energy efficient urban planning and the role of legislation within that context. The objective of this thesis is to analyse if energy efficiency of districts is improved by a regulative approach into planning, if proper tools and guidelines to support the planning are available. The thesis is based on four journal articles and one conference paper. The thesis examines the advantages of a holistic approach in the planning of energy systems both when building new districts as in renovating old ones. It also examines the importance of supportive tools for city planners and planners of energy systems. The results of the analysis show that a holistic approach and supportive tools enable more energy efficient solutions. The key to developing sustainable city plans are for different disciplines to work closely together throughout the whole planning process. Such collaboration might require certain regulative measures to become reality since stakeholders will work towards a common goal that might differ from their individual ones. The energy-efficiency of city plans would benefit from a higher degree of regulation by enabling a push of energy efficient solutions to be realised. Solutions and regulations need to be adapted to local contexts. A regulative approach is beneficial when long term solutions are sought, that doesn't bring short term economic benefits but serve the society well on a longer time perspective. The challenge is to have regulation on a level that both steers the development towards the overall optimised solutions without hindering new innovative solutions to be born. The thesis gives concrete recommendations for how to improve the regulations in the city planning process to enable a more energy efficient built environment.Item Energy-efficient renovation of residential districts. Cases from the Russian market(VTT Technical Research Centre of Finland, 2014) Paiho, Satu; Kazi, Abdul Samad (Sami), Prof. Dr., VP, VTT Technical Research Centre of Finland, Finland; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of Engineering; Lahdelma, Risto, Prof. Dr., Aalto University, Department of Energy Technology, FinlandThe energy-efficiency of Soviet-era residential districts in cold urban Russian regions is poor. It could be improved by renovating buildings to be more energy-efficient and by reducing the losses in the related energy infrastructure. This dissertation deals with the energy-efficient renovation of such Russian districts. The idea of holistic district renovations is introduced, including both renovations of the buildings and modernization of the related energy and water infrastructures. Based on case studies, solutions are presented and analyzed for renovating upscale Russian residential districts into more energy-efficient ones. Holistic renovation concepts were developed both for individual apartment buildings and for typical residential districts. For the II-18 Soviet-standard type building, the energy saving potential was up to 68% for heating energy and up to 26% for electricity. In the district considered, using different district modernization scenarios, up to 72% of the heating demand and up to 34% of the electricity demand could be saved. CO2-equivalent, SO2-equivalent, and TOPP-equivalent (tropospheric ozone precursor potential) emissions, as well as particulates of the different district energy production scenarios, were also analyzed. In view of CO2-equivalent and TOPP-equivalent emissions in the case district, changing a CHP plant from natural gas to biogas would be favorable. Considering also SO2-equivalent emissions and particulates, only the most advanced energy production scenarios could be recommended. The costs of different renovation packages for the type apartment building varied between €125/m2 and €200/m2, depending on the extent of the selected renovation package. Repairing the external walls formed around 35–40% of the total costs in all renovation packages. If the whole district was renovated (both the buildings and the related energy and water infrastructures), the costs per inhabitant varied between €3,360 and €5,200. The costs per inhabitant of additional alternatives, including renewable energy production solutions, were over €6,090. In addition, business models for such district renovations were analyzed. Developing a completely new business model for the Russian district renovations may be needed, since none of the identified models as such is suitable. Since some ESCO (Energy Service Company) activities have been realized in Russia, adapting modified Western ESCOs with well-defined financial guarantees could work in Russia.Item Evaluating k-epsilon with One-Equation Turbulence Model(ELSEVIER SCIENCE BV, 2013) Rahman, M.M.; Meriläinen, Arttu; Islam, A. K. M. Sadrul; Lampinen, M. J.; Department of Energy Technology; Islamic University of Technology; Islam, AKMS; Amin, R; Ali, MAn extended version of the isotropic one-equation model is proposed to account for the distinct effects of low-Reynolds number (LRN) and wall proximity. The turbulent kinetic energy k and the dissipation rate epsilon are evaluated using the R (= k(2) / (epsilon) over tilde) transport equation together with some empirical relations. The eddy viscosity formulation maintains the positivity of normal Reynolds stresses and the Schwarz' inequality for turbulent shear stresses. The model coefficients/functions preserve the anisotropic characteristics of turbulence in the sense that they are sensitized to rotational and nonequilibrium flows. The model is validated against a well-documented flow case, yielding predictions in good agreement with the direct numerical simulation (DNS) data. Comparisons indicate that the present model offers some improvement over the Spalart-Allmaras one-equation model.Item Evaluating local and overall thermal comfort in buildings using thermal manikins(Aalto University, 2012) Foda, Ehab; Energiatekniikan laitos; Department of Energy Technology; Insinööritieteiden korkeakoulu; School of Engineering; Sirén, Kai, Prof.Evaluation methods of human thermal comfort that are based on whole-body heat balance with its surroundings may not be adequate for evaluations in non-uniform thermal conditions. Under these conditions, the human body's segments may experience a wide range of room physical parameters and the evaluation of the local (segmental) thermal comfort becomes necessary. In this work, subjective measurements of skin temperature were carried out to investigate the human body's local responses due to a step change in the room temperature; and the variability in the body's local temperatures under different indoor conditions and exposures as well as the physiological steady state local temperatures. Then, a multi-segmental model of human thermoregulation was developed based on these findings to predict the local skin temperatures of individuals' body segments with a good accuracy. The model predictability of skin temperature was verified for steady state and dynamic conditions using measured data at uniform neutral, cold and warm as well as different asymmetric thermal conditions. The model showed very good predictability with average absolute deviation ranged from 0.3-0.8 K. The model was then implemented onto the control system of the thermal manikin 'THERMINATOR' to adjust the segmental skin temperature set-points based on the indoor conditions. This new control for the manikin was experimentally validated for the prediction of local and overall thermal comfort using the equivalent temperature measure. THERMINATOR with the new control mode was then employed in the evaluation of localized floor-heating system variants towards maximum energy efficiency. This aimed at illustrating a design strategy using the thermal manikin to find the optimum geometry and surface area of a floor-heater for a single seated person. Furthermore, a psychological comfort model that is based on local skin temperature was adapted for the use with the model of human thermoregulation. The latter combination was used with a virtual thermal manikin on a CFD code for the evaluation of indoor thermal conditions and was experimentally validated using human subjects' tests. The results showed that these two approaches with the physical and virtual thermal manikins, using the introduced control mode, can produce a very reasonable predictability of the local and overall thermal comfort for sedentary activities. The average absolute deviation from subjective data for these two approaches was in a range from 0.25-0.5 on the thermal comfort scale. The thermal manikin with the new control mode may be used to optimize the design of HVAC systems towards energy-efficiency along with thermal comfort.Item Evaluation of choices for sustainable rural electrification in developing countries: A multicriteria approach(2013-08) Rahman, Md. Mizanur; Paatero, Jukka V.; Lahdelma, Risto; Department of Energy Technology; Department of Mechanical EngineeringRural electrification (RE) can be modelled as a multifactorial task connected to a large number of variables: decision makers need to choose the appropriate options by considering not only the techno-economic competitiveness but also socio-cultural dynamics and environmental consequences, making the task intricate. Many rural electrification projects have failed due to lack of attention to the issues beyond financial and technical dimensions. This paper presents a standardized approach for decision making concerning the extension of electricity services to rural areas. This approach first determines whether the supply provision should be grid expansion or off-grid on the basis of levelized cost of delivered electricity. If the grid expansion is found nonviable over off-grid options then a multicriteria decision aiding tool, SMAA-2 (Stochastic Multicriteria Acceptability Analysis), will evaluate off-grid technologies by aggregating 24 criteria values. While applying this approach, the delivered costs of electricity by the grid in remote areas within the 1-25. km distances vary in a range of 0.10-7.85 US$/kW. h depending on the line lengths and load conditions. In the off-grid evaluation, the solar PV (photovoltaic) and biogas plants are found as the most preferable alternatives with 59% and 41% acceptability in their first rank, respectively.Item Extension of energy crops on surplus agricultural lands: A potentially viable option in developing countries while fossil fuel reserves are diminishing(2014-01) Rahman, Md. Mizanur; B.Mostafiz, Suraiya; Paatero, Jukka V.; Lahdelma, Risto; Department of Energy Technology; Department of Mechanical Engineering; University of HelsinkiThe rapid depletion of fossil fuel reserves and environmental concerns with their combustion necessitate looking for alternative sources for long term sustainability of the world. These concerns also appear serious in developing countries who are striving for rapid economic growth. The net biomass growing potential on the global land surface is 10 times more than the global food, feed, fiber, and energy demands. This study investigates whether the developing countries have sufficient land resource to meet the projected energy demand towards 2035 by planting energy crops on surplus agricultural land after food and feed production. The annual yields of four commonly grown energy crops specifically jatropha, switchgrass, miscanthus, and willow have been used to make scenarios and estimate land requirements against each scenario. This paper first performs literature reviews on the availability of land resource, past and future trends in land use changes, demand of lands for food production, and potential expansion of croplands. The energy demands towards 2035 are compiled from energy scenarios derived by the International Energy Agency (IEA) and the British Petroleum (BP). This paper also reviewed bio-physiological characteristics of these energy crops to determine whether they are cultivable under tropical climatic conditions in developing regions. This paper found that projected energy demand through 2035 in developing regions could be provided by energy crops grown on a portion of surplus croplands or upgraded grasslands (27% and 22% respectively for miscanthus scenario). Sustainable land management practices, improved agricultural productivity, and adopting suitable energy crops cultivation can potentially supply increasing energy demands.
