| 1. |
- Cruz, Igor, 1986-
(författare)
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Evaluating the utilisation of industrial excess heat from an energy systems perspective
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sweden aims to achieve climate neutrality by 2045. The need to immediately reduce greenhouse gas emissions in order to achieve climate targets affects industry directly. The pulp and paper sector is responsible for more than 50% of industrial energy use in Sweden. Increased energy efficiency is expected to contribute significantly to the reduction of primary energy use. The recovery and utilisation of industrial excess heat (IEH) has been identified as an important potential contribution to energy efficiency in industry. Previous research based on top-down studies has estimated the availability of IEH for entire sectors, and bottom-up results for many case studies are available. While top-down studies lack detailed information on the profile of the excess heat available, bottom-up studies have limited coverage. Detailed information about excess heat amounts and temperature levels is required for the assessment of the potential of the various heat recovery technologies that are available. The aim of this thesis is to present, in a series of steps, methods to systematically analyse an industrial process to obtain a detailed profile of the excess heat available under various process conditions, to aggregate results that can be generalised to whole industrial sectors, and to obtain IEH recovery potentials using different technologies. The assessment of the utilisation options for IEH recovery is complemented with an analysis of system aspects that could affect profitability and global greenhouse gas (GHG) emissions. An energy-targeting procedure combined with optimisation has been applied to six case studies of kraft pulp and paper mills in Sweden. This method obtained IEH profiles that were used in a regression analysis to estimate the IEH availability and electricity generation potentials from low and medium temperature IEH using organic Rankine cycles (ORC). A comparison of profitability and global GHG emissions between ORC electricity generation using IEH and small-scale combined heat and electricity (CHP) production is presented for three energy markets.The results show that there is a potential to increase electricity generation from low and medium temperature IEH by 7–9% in the kraft mills in Sweden, depending on the level of process integration considered. The utilisation of low and medium temperature IEH for electricity generation has the potential to reduce global GHG emissions in all the energy-market scenarios considered, but if biomass is considered a limited resource, district heating (DH) deliveries can achieve higher global GHG reductions. ORC electricity generation from low and medium temperature IEH is economically viable and showed overall better profitability and GHG emissions reductions than small-scale CHP using ORCs. The economic feasibility of ORC electricity generation is less affected by external conditions and uncertainties than direct DH deliveries.
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| 2. |
- Djuric Ilic, Danica, 1972-
(författare)
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Classification of Measures for Dealing with District Heating Load Variations-A Systematic Review
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:1
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Forskningsöversikt (refereegranskat)abstract
- The highly varying character of district heating (DH) demand results in low capacity utilization of the DH plants, as well as increased use of fossil fuels during peak demand. The aim of this study is to present an overview and a comprehensive classification of measures intended to manage these load variations. A systematic literature review was conducted based on previously defined search strings as well as inclusion and exclusion criteria. Two scientific databases were used as data sources. Based on 96 detected publications, the measures were categorized as (1) complementing DH production in heat-only boilers (HOBs), or geothermal or booster heat pumps (HPs) (usually controlled by the DH company), (2) thermal energy (TE) storage in storage units or in the network (controlled by the company), and (3) demand side measures, which can be strategic demand increase, direct demand response (DR), or indirect DR. While the company has control over direct DR (e.g., thermal storage in the thermal mass of the buildings), indirect DR is based on communication between the customer and the company, where the customer has complete control. The multi-disciplinary nature of this topic requires an interdisciplinary approach.
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| 3. |
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| 4. |
- Johansson, Maria, 1968-, et al.
(författare)
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Review of sustainable development of the road transport sector : Are there geographical differences?
- 2018
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Ingår i: WEENTECH Proceedings in Energy 4 (2018) 67-87. - : WEENTECH Ltd.. ; , s. 67-87
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Konferensbidrag (refereegranskat)abstract
- Even though the share of renewable energy in the transport sector has increased during the last decade, the sector is still highly dependent on fossil fuels. Consequences are for example emissions of greenhouse gases, particulates, carbon monoxide and nitrogen oxides. This is of great concern for the environment, climate change, and human health. This study reviews scientific publications about sustainable development of the road transport sector, published 2005-2018. The aim of the study is to investigate if there are differences in the measures and strategies presented in the publications depending on the geographical areas studied, and to analyse if there are differences depending on year of publication. The authors analysed to what extent local conditions influence the choice of proposed measures and strategies. A system perspective was applied in order to include measures related to the whole life cycle of the road transport, as well as other sectors, which influence or are influenced by the transport sector. A literature review was performed using the search-engine Web of Science. Results show that important local conditions that may influence the research focus within the area of sustainable development of the road transport sector are for example: energy supply security (e.g. availability of biomass and renewable electricity, as well as access to domestic fossil fuel resources), possibilities for developing infrastructure for biofuel supply and charging of electric vehicles, political priorities and approaches, and traditions.
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| 5. |
- Nordenstam, Lena, 1967-
(författare)
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Corporate and city GHG inventories : Impact on global CO2 emissionswhen considering electricity and CHP-based district heating
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One initiative to reduce greenhouse gas (GHG) emissions involves developing standards for GHG inventories. Companies and cities (regions) can use GHG inventories to compile and report their GHG emissions. Standards for corporate and city GHG inventories often claim that GHG inventories can be used for identifying emissions opportunities, building reduction strategies and setting, measuring and reporting emissions targets. Attributional emissions factors are generally used in corporate and city GHG inventories. For purchased electricity, heat and steam, this means using average emission factors for regional or national production of each energy carrier. Also contractual emissions factors can be used. Changes in emissions from affected production elsewhere are not included. For purchased electricity and district heating (DH), a GHG inventory can be improved by lowered purchases or by purchasing a different energy carrier.Furthermore, combined heat and power (CHP) technology can help reduce global GHG emissions in the supply and conversion of energy, as CHP production is more efficient than conventional separate production of electricity and heat. In CHP production, excess heat from electricity production is utilised for heating buildings, hot water, industry processes etc., either directly or through DH systems.This thesis analyses how emissions reduction measures based on corporate or city GHG inventories, carried out using GHG Protocol standards, affect global CO2 emissions when electricity or CHP-based DH is affected. The incentive of a GHG inventory to a company purchasing electricity and DH, and to a city regarding purchases and production of electricity and DH in its region, is analysed. This is done for GHG inventories conducted in a nation where electricity produced within the nation is regarded as CO2-lean (Sweden) and in a nation where it is more CO2-rich (Germany). The indirect incentive to the DH company to change its production, in order to improve the GHG inventory of its customers and of the city where the DH system is located, is also analysed. Consequential analyses are used to assess how global CO2 emissions are affected by changes in purchases or production of electricity and DH that are incentivised by the GHG inventories studied. These consequential analyses include changes in emissions from affected electricity production elsewhere.The results show that the strength of incentive to reduce purchase of electricity or CHP-based DH by a company or in a city can differ between GHG inventories and consequential analysis. This is most clear when electricity produced within the nation is regarded as CO2-lean (Sweden) while affected electricity production elsewhere is CO2-rich. For replacing purchases of CHP-based DH with electricity, or vice versa, the incentive in a GHG inventory can be the reverse of that in a consequential analysis. Moreover, the incentive to lower the use of electricity is lost when contractual emissions factors with zero emissions, such as renewable electricity guarantees of origin (RE-GOs), are used. In addition, purchase of electricity RE-GOs, which have a large surplus and no requirement of additionality, is less likely to cause a corresponding increase in production of renewable electricity.Furthermore, when the highest emission reduction per Euro invested is sought (e.g. when investment resources are limited), the investment ranking of a heat-only boiler and a CHP plant can differ depending on whether the focus is on improving a city GHG inventory or lowering global CO2 emissions. Moreover, if the DH company improves (reduces) the average emissions factor for DH, it improves the GHG inventory of its customers and of the city where they are located. In a DH system based on bio-fuelled CHP production, the average emissions factor for DH improves when CHP electricity production is lowered to the extent that production of heat at the oil-fuelled heat-only boiler (used for peak heat production) is minimised. However, according to consequential analysis, this would lead to an increase in global CO2 emissions.Based on the results of this thesis, it is concluded that measures which include changes in purchases or production of electricity or CHP-based DH can increase global CO2 emissions when based on how corporate or city GHG inventories in general value CO2 emissions of electricity and DH. It is therefore unfortunate that GHG Protocol standards for corporate and city GHG inventories advocate basing emissions reduction decisions on GHG inventories. There is nonetheless an obvious risk of reported and communicated GHG inventories being used as a basis for emissions reductions decisions. If the aim is actual reduction of global CO2 emissions, average or purchased emissions factors should not be used for purchased electricity and CHP-based DH when assessing, reporting or communicating the impact of companies and cities (regions) on CO2 emissions. Instead, a consequential approach should be used for climate evaluation of purchased electricity and DH.
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| 6. |
- Ödlund, Louise, Professor, 1966-, et al.
(författare)
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Sustainable Business Strategies for District Heating
- 2023
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Konferensbidrag (refereegranskat)abstract
- The European Commission has been recognized DH technology of essential importance to reach the sustainability. A flexibility in the fuel mix, and possibilities of industrial waste heat utilization, combined heat and power (CHP) production and energy recovery through waste incineration, are only some of the benefits which characterize DH technology.The aim of this study is to provide an overview of the possible business strategies which would enable for DH to have an important role towards future sustainable energy systems. The study includes a system approach where DH is seen as a part of an integrated system which consists of transport‑, industrial-, and electricity sectors as well.Converting energy for running the industrial processes from fossil fuels and electricity to DH and delivering excess heat from industrial processes, would make the industry less dependent on fossil fuels and fossil fuel-based electricity, as well as increase energy efficiency and reduce production costs. Reducing the electricity use in the industry sector while at the same time increasing the CHP production in the local DH systems would (1) replace fossil-based electricity production with electricity in biomass- or waste-fueled CHP plants, and reduce the capacity requirements from the national electricity grid (i.e. it would reduce the pressure on the bottle necks in the grid). Furthermore, by operating their central controlled heat pumps and CHP plants depending on the intermittent electricity production variation the DH companies may enable an increased share of intermittent electricity production in the national electricity grid.
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