| 12311. |
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| 12312. |
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| 12313. |
- Rolfsman, Björn, 1971-
(författare)
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Interaction between Energy Systems of Buildings and Utilities in an ever-changing Environment
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The energy system of the building is integrated in a larger energy system. The focus in this thesis is on the interface between the building and the surrounding energy system. Of special interest is how changes in the building energy system or the surrounding system affect each other and how they can interact. Depending on the decision criteria applied by the designer of the building energy system, various strategies can be used vis-a-vis the surrounding energy system. These are discussed as a background to the case studies in the appended papers. The overall objective for most of the case studies is minimisation of cost. One of the papers also deals with an environmental objective. When the Nordic electricity prices are harmonised with the European market, which has a pronounced diurnal variation in spot prices rather than a significant seasonal variation, the energy systems in the Nordic countries have to be run accordingly. This is why short time steps are used throughout the year in some of the models in order to reflect the diurnal variations in the spot price for electricity. All case studies concern buildings within a district heating network, where heat is supplied with combined heat and power plants, and boilers. Some energy conservation measures are also analysed, such as extra wall insulation and new windows. Aspects studied include how life cycle cost is affected by changes in the surrounding energy system, and how the surrounding energy system is affected when the measures on the demand side are compared with investments on the supply side. A number of techniques, for example optimisation models, are developed to analyse these situations. Finally, a suggestion is made as to how the surrounding energy system and the building energy system can interact, when jointly acting on the Nordic electricity market.
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| 12314. |
- Román-Collado, Rocío, et al.
(författare)
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Has electricity turned green or black in Chile? A structural decomposition analysis of energy consumption
- 2018
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Ingår i: Energy. - : Elsevier BV. - 0360-5442. ; 162, s. 282-298
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Tidskriftsartikel (refereegranskat)abstract
- Since 2010, the Chilean government has backed a progressive increase of non-conventional renewable energies sources (NCRES) to put forward the country's energy independence from fossil fuels, and therefore from imports, and to reduce its CO2 emissions. The analysis of the final energy consumptionchanges via a structural decomposition analysis, based on the Input-Output Tables for Chile in the period 2008e2013, enables us to identify the key effects as well as the sectors and energy sources in this process. The results show that the scale and the intensity effects are the main drivers of the final energyconsumption change. There is a significant increase of the final energy sources derived from natural gas (273%), electricity (23%) and oil (8%). The increase of the electricity consumption due to the scale, intensity and demand structure effects reveals a coupling with economic growth, lower energy efficiencyand larger end-use exporter sectors (e.g., mining). Concretely, the use of coal for electricity generation increased in absolute (23,648 Tcal) and relative terms of total fossil fuels (34%). Despite the rapid deployment of NCRES, a short-term analysis suggests that more aggressive policy efforts are needed toeffectively drive the transition towards a low-carbon energy system.
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| 12315. |
- Romanchenko, Dmytro, 1988, et al.
(författare)
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Balancing investments in building energy conservation measures with investments in district heating – A Swedish case study
- 2020
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788. ; 226
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the cost-optimal mix of reduction in the space heating (SH) demand in buildings, achieved through investments in energy conservation measures (ECMs), and investments in the local district heating (DH) system. The work includes three modeling scenarios, which differ with respect to SH demand reduction targets (no supply side targets) for buildings: without a target (only fuel price drives demand reduction); with a total demand reduction (for the building stock); and with a specific demand reduction (to reach a specific kWh/(m2∙y) value for individual buildings). Special emphasis is placed on the choice of ECMs in buildings. For the scenario without a target for SH demand reduction, the least-cost option is a combination of investments in ECMs, heat generation and in storage technologies, yielding a SH demand reduction of 24% already by Year 2030, and thereafter a decrease of 28% up to Year 2050. The reductions are achieved mainly through investments in ventilation heat recovery systems and insulation of roofs. The scenarios that include SH demand reduction targets give similar demand reductions of about 60% by 2050, as compared to 2020. However, the investment cost for fulfilling the specific target scenario is higher than that for the total target scenario.
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| 12316. |
- Romanchenko, Dmytro, 1988, et al.
(författare)
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Flexibility Potential of Space Heating Demand Response in Buildings for District Heating Systems
- 2019
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 12:15
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Tidskriftsartikel (refereegranskat)abstract
- Using an integrated demand-supply optimization model, this work investigates the potential for flexible space heating demand, i.e., demand response (DR), in buildings, as well as its effects on the heating demand and the operation of a district heating (DH) system. The work applies a building stock description, including both residential and non-residential buildings, and employs a representation of the current DH system of the city of Gothenburg, Sweden as a case study. The results indicate that space heating DR in buildings can have a significant impact on the cost-optimal heat supply of the city by smoothing variations in the system heat demand. DR implemented via indoor temperature deviations of as little as +1 degrees C can smoothen the short-term (daily) fluctuations in the system heating demand by up to 18% over a period of 1 year. The smoothening of the demand reduces the cost of heat generation, in that the heat supply and number of full-load hours of base-load heat generation units increase, while the number of starts for the peaking units decreases by more than 80%. DR through temperature deviations of +3 degrees C confers diminishing returns in terms of its effects on the heat demand, as compared to the DR via +1 degrees C.
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| 12317. |
- Romanchenko, Dmytro, 1988, et al.
(författare)
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Impacts of demand response from buildings and centralized thermal energy storage on district heating systems
- 2021
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Ingår i: Sustainable Cities and Society. - : Elsevier BV. - 2210-6707. ; 64
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Tidskriftsartikel (refereegranskat)abstract
- © 2020 The Author(s) Energy use for space heating is a substantial part of total energy end use and heating systems can offer some flexibility in time of use, which should be important in future energy systems to maintain balance between supply and demand. This work applies a techno-economic, integrated, demand-supply optimization model to investigate the combined effect of using demand-side flexibility from buildings, by allowing for indoor temperature deviations (both up- and downward from the set-point), and supply-side flexibility, by applying thermal energy storage (TES), on the operation of district heating (DH) systems. The results indicate that the potential for increased indoor temperature, i.e., demand response (DR), is concentrated to multi-family and non-residential buildings (heavy buildings with high time-constants), while the potential for downregulation of the temperature, i.e., operational energy savings, is utilized to a greater extent by single-family buildings (light buildings). It is also evident that the value of DR diminishes in the presence of a supply-side TES. We show that applying both the demand-side flexibility and a centralized TES is complementary from the heating system perspective in that it results in the lowest total space heating load of the buildings and the lowest running cost for the DH system.
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| 12318. |
- Romanchenko, Dmytro, 1988, et al.
(författare)
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Thermal energy storage in district heating: Centralised storage vs. storage in thermal inertia of buildings
- 2018
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904. ; 162, s. 26-38
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Tidskriftsartikel (refereegranskat)abstract
- Heat load variations in district heating systems lead to increased costs for heat generation and, in most cases, increased greenhouse gas emissions associated with the marginal use of fossil fuels. This work investigates the benefits of applying thermal energy storage in district heating systems to decrease heat load variations, comparing storage using a hot water tank and the thermal inertia of buildings (with similar storage capacity). A detailed techno-economic optimisation model is applied to the district heating system of Göteborg, Sweden. The results show that both the hot water tank and the thermal inertia of buildings benefit the operation of the district heating system and have similar dynamics of utilisation. However, compared to the thermal inertia of buildings, the hot water tank stores more than twice as much heat over the modelled year, owing to lower energy losses. For the same reason, only the hot water tank is used to store heat for periods longer than a few days. Furthermore, the hot water tank has its full capacity available for charging/discharging at all times, whereas the capacity of the thermal inertia of buildings depends on the heat transfer between the building core and its indoor air and internals. Finally, the total system yearly operating cost decreases by 1% when the thermal inertia of buildings and by 2% when the hot water tank is added to the district heating system, as compared to the scenario without any storage.
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| 12319. |
- Romano, Luigi, 1994, et al.
(författare)
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Development of the Vastra Gotaland operating cycle for long-haul heavy-duty vehicles
- 2023
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Ingår i: IEEE Access. - : Institute of Electrical and Electronics Engineers Inc.. - 2169-3536. ; 11, s. 73268-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a complete operating cycle (OC) description is developed for heavy-duty vehicles traveling long distances in the region of Västra Götaland, Sweden. Variation amongst road transport missions is accounted for using a collection of stochastic models. These are parametrized from log data for all the influential road parameters that may affect the energy performance of heavy trucks, including topography, curvature, speed limits, and stop signs. The statistical properties of the developed OC description are investigated numerically by considering some composite variables, condensing the salient information about the road characteristics, and inspired by two existing classification systems. Two examples are adduced to illustrate the potential of the OC format, which enables ease of classification and detailed simulation of energy efficiency for individual vehicles, with application in vehicle design optimization and selection, production planning, and predictive maintenance. In particular, for the track used in the first example, a Volvo FH13 equipped with a diesel engine, simulation results indicate mean CO2 emissions of around 1700 g km-1, with a standard deviation of 360 g km-1; in the second example, dealing with electrical fleet sizing, the optimal proportion shows a predominance of tractor-semitrailer vehicles (70%) equipping 4 motors and 11 battery packs.
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| 12320. |
- Romare, Mia, et al.
(författare)
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Investigating the potential circularity of a phone using Life Cycle Assessment
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report presents a life cycle assessment (LCA) case study of a mobile phone. The work is part of the POLICIA project where the overarching goal is to combine LCA and an economic-based model (POLICA CE model) into an integrated assessment. The aim of this model is to identify market failures and quantify policy effects of efficient combinations along the entire life cycle.The objective of the phone case study work is to enable the impact assessment of the LCA, to be incorporated into the POLICIA CE-model, so that environmental impacts of policies can be directly modelled and optimised. To achieve this, linear and circular variants of products were assessed to identify the components and life cycle stages that influence the environmental impact. The materials and part production stages of the life cycle contribute most to the environmental impact, for all studied impact categories. Specifically, it is the integrated circuit and other electronic components that contribute most. This is turn implies that circular business models aimed at prolonging life or decreasing use of these components can provide the largest impact reductions.
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