| 1. |
- Dodoo, Ambrose, 1979-, et al.
(author)
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Primary energy benefits of cost-effective energy renovation of a district heated multi-family building under different energy supply systems
- 2018
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In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 143, s. 69-90
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Journal article (peer-reviewed)abstract
- The European Union's Directive on energy performance of buildings emphasizes the need to take cost-effectiveness into account when measures are implemented for improved building energy efficiency. In this study, we investigate cost-effective energy renovation measures for a district heated building under different contexts, including varied locations, energy supply systems and economic scenarios. We determine the final and primary energy savings of cost-effective energy renovation packages for the building in the different contexts. The measures analysed include: improved insulation for attic floor, basement walls, and exterior walls; improved windows and doors; resource-efficient taps; heat recovery of exhaust ventilation air; energy-efficient household appliances and lighting. We consider three existing Swedish energy supply systems of varying district heat production scale and tariffs, and also plausible renewable-based energy supply systems. Our analysis calculates the final energy savings of the measures including the cost-effective renovation packages on hourly basis and links these to the different energy supply systems. The cost-effectiveness analysis is based on a double-stage optimization method, considering total and marginal investment costs of renovation measures as well as associated net present values of total and marginal cost savings. The results show that significant final and primary energy savings can be achieved when energy renovation measures are implemented for the building in the different contexts. This study shows that heat demand in existing Swedish building could be about halved while electricity use may be reduced considerably with cost-effective energy renovation measures. The economic viability of the renovation measures is sensitive to the economic regimes especially discount rates and energy price increase.
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| 2. |
- Gustavsson, Leif, 1954-, et al.
(author)
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Bioenergy pathways for cars : Effects on primary energy use, climate change and energy system integration
- 2016
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In: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 115:3, s. 1779-1789
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Journal article (peer-reviewed)abstract
- Different pathways and technologies can be used to convert woody biomass to transport services, but the biomass use and climate implications vary strongly between the alternatives. This study focuses on primary energy use and climate change effects of using bioenergy for transportation in the context of a renewable-based energy system. Integrated pathways to improve the energy efficiency of power and transportation sectors and integrated intermittent renewable energy are considered. The results show that the bioenergy pathway that produces biomotor fuels to replace fossil fuels leads to high primary energy use and instantaneous biogenic CO2 emission per km of driving distance, thus increasing global warming during the first 40e50 years, compared to fossil alternatives. The electric vehicle pathway using bioelectricity from combined heat and power plants leads to immediate global cooling and much greater climate benefits in the long run compared to biomotor fuels. Climate change effects of light-duty vehicles could be strongly reduced by changes in technology together with system integration that links the transport sector to the electricity and heating sectors. The use of biomass should be considered in the context of the overall integrated energy system, and in relation to the development of energy conversion technologies between different sectors.
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| 3. |
- Gustavsson, Leif, 1954-, et al.
(author)
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Climate change effects of forestry and substitution of carbon-intensive materials and fossil fuels
- 2017
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In: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 67:January, s. 612-624
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Journal article (peer-reviewed)abstract
- We estimate the climate effects of directing forest management in Sweden towards increased carbon storage in forests with more land set-aside for protection, or towards increased forest production for the substitution of carbon-intensive materials and fossil fuels, relative to a reference case of current forest management. We develop various scenarios of forest management and biomass use to estimate the carbon balances of the forest systems, including ecological and technological components, and their impacts on the climate in terms of radiative forcing. The scenario with increased set-aside area and the current level of forest residue harvest resulted in lower cumulative carbon emissions compared to the reference case for the first 90 years, but then showed higher emissions as reduced forest harvest led to higher carbon emissions from energy and material systems. For the reference case of current forest management, increased harvest of forest residues gave increased climate benefits. The most climatically beneficial alternative, expressed as reduced cumulative radiative forcing, in both the short and long terms is a strategy aimed at high forest production, high residue recovery rate, and high efficiency utilization of harvested biomass. Active forest management with high harvest levels and efficient forest product utilization will provide more climate benefit, compared to reducing harvest and storing more carbon in the forest.
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| 4. |
- Gustavsson, Leif, et al.
(author)
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Climate effects of bioenergy from forest residues in comparison to fossil energy
- 2015
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In: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 138, s. 36-50
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Journal article (peer-reviewed)abstract
- Forest residues can be left at the harvest site to gradually decompose, or can be collected for energy purposes. This study analyzes the primary energy and climate impacts of bioenergy systems where forest residues are collected and used for electricity, heat and transportation, compared to fossil-based energy systems where fossil fuels provide the same services while forest residues are left on site to decompose. Time profiles are elaborated of primary energy use and carbon dioxide emissions from various energy applications fulfilled by bioenergy or fossil energy systems. Different biological decay functions are considered based on process-based modeling and inventory data across various climate zones. For all scenarios, the changes in cumulative radiative forcing (CRF) are calculated over a 300-year period, to evaluate the short- and long-term contributions of forest residue to climate change mitigation. A life cycle perspective along the full energy chains is used to evaluate the overall effectiveness of each system. The results show largest primary energy and climate benefits when forest residues are collected and used efficiently for energy services. Using biomass to substitute fossil coal provides greater climate change mitigation benefits than substituting oil or fossil gas. Some bioenergy substitutions result in positive CRF, i.e. increased global warming, during an initial period. This occurs for relatively inefficient bioenergy conversion pathways to substitute less carbon intensive fossil fuels, e.g. biomotor fuel used to replace diesel. More beneficial bioenergy substitutions, such as efficiently replacing coal, result immediately in reduced CRF. Biomass decay rates and transportation distance have less influence on climate benefits.
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| 5. |
- Gustavsson, Leif, et al.
(author)
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Effects of different bioenergy pathways on primary energy efficiency, climate mitigation and energy system integration
- 2015
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In: The 10th Conference on Sustainable Development of Energy, Water and Environment Systems – SDEWES 2015. September 27- October 3, 2015, Dubrovnik, Croatia.
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Conference paper (peer-reviewed)abstract
- Woody biomass is an important renewable energy resource that can be used directly or indirectly in the electricity, heat and transport sectors. Different technologies and conversion pathways can be used to convert woody biomass to supply different types of energy services. The primary energy and climate implications of bioenergy systems depend on which conversion technologies and pathways are used to produce the energy services, as well as how the services would have been supplied without the bioenergy system. Here, we focus on bioenergy for transportation in the context of a total renewable-based energy system. We contrast two different pathways: (i) biomotor fuel production in stand-alone plants and (ii) bioelectricity production in standalone plants and district heating systems with CHP plants and heat storage capacity for electric and plug-in hybrid vehicles. We quantify the primary energy use and the instantaneous biogenic CO2 of the two alternatives, per km of driving distance. We consider both commercially available technologies and emerging technologies for biomass-based conversion systems. Furthermore, for the two alternatives we discuss potential benefits of integration between the electricity, heating and transport sectors, to enable a better use of infrastructure. The results show that primary energy use and instantaneous biogenic CO2 emission vary strongly between the alternatives. The primary energy efficiency is much higher and gives less instantaneous biogenic CO2 emission for electric and plug-in hybrid vehicles compared to vehicles using biomotor fuels. Furthermore, the potential integration benefits between the electricity, heating and transport sectors are much larger due to the integration potential of heat storage capacity in DHS and battery storage capacity in electric and plug-in hybrid vehicles, as well as an improved overall integration capacity between the sectors. This study suggests that use of biomass should be considered in the context of the overall energy system, and in relation to the development of energy conversion technologies and integration potential between different energy sectors, to find primary energy efficient alternatives giving climate benefits in both a short- and long-term perspective.
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| 6. |
- Sathre, Roger, et al.
(author)
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Climate effects of electricity production fuelled by coal, forest slash and municipal solid waste with and without carbon capture
- 2017
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In: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 122, s. 711-723
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Journal article (peer-reviewed)abstract
- We analyse the climate implications of producing electricity in large-scale conversion plants using coal, forest slash and municipal solid waste with and without carbon capture and storage (CCS). We calculate the primary energy, carbon dioxide (CO2) and methane (CH4) emission profiles, and the cumulative radiative forcing (CRF) of different systems that produce the same amount of electricity. We find that using slash or waste for electricity production instead of coal somewhat increases the instantaneous CO2 emission from the power plant, but avoids significant subsequent emissions from decaying slash in forests or waste in landfills. For slash used instead of coal, we find robust near- and long-term reductions in total emissions and CRF. Climate effects of using waste instead of coal are more ambiguous: CRF is reduced when CCS is used, but without CCS there is little or no climate benefits of using waste directly for energy, assuming that landfill gas is recovered and used for electricity production. The application of CCS requires more fuel, but strongly reduces the CO2 emissions. The use of slash or waste together with CCS results in negative net emissions and CRF, i.e. global cooling.
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| 7. |
- Truong, Nguyen Le, 1976-, et al.
(author)
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Climate effects of biomass use in integrated energysystems
- 2017
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In: ECEEE Summer Study proceedings 2017. - : European Council for an Energy Efficient Economy (ECEEE). - 9789198387803 - 9789198387810 ; , s. 911-920
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Conference paper (peer-reviewed)abstract
- Biomass is a key resource in a society based on renewable energy, but is a limited resource and the use of biomass in one sector will influence its availability for other sectors. The global energy system is heavily dependent on fossil fuels, and the climate impacts of CO2 occur regardless of the source of emissions. As a result, the climatic effects of biomass use in an energy system depend largely on which biomass feedstock and bioenergy pathway is being used, and what type of fossil fuel pathway is being replaced. In this study, we evaluate the CO2 emissions and climate effects of woody biomass and fossil fuel use. We analyse the potential production of electricity, heat or transport distance when using one kWh of woody biomass and fossil energy system designed to provide the same service to society as the most energy efficient bioenergy systems. The fuel cycle inputs are included in the analyses and are based on different state-of-the art as well as emerging technologies for energy conversion. We quantify the primary energy use and annual CO2 emission of different bioenergy and fossil alternatives. We then calculate the cumulative CO2 emission and climate effects in terms of cumulative radiative forcing for the fossil and bioenergy systems. The results show that primary energy use, CO2 emission, and cumulative radiative forcing vary strongly between the studied alternatives. The use of bioelectricity and electric vehicles instead of biomotor fuel-based vehicles gives about twice the transport distance per unit of consumed woody biomass. Integrated energy systems that supply a package of energy services including electricity, heat and transport distance reduce the primary energy use and increase the climate benefits of woody biomass. The replacement of coal for heat and electricity production by the here studied woody biomass gives large climate benefits immediately.
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| 8. |
- Truong, Nguyen Le, 1976-, et al.
(author)
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Co- and polygeneration of district heat, electricity and/or biomotor fuels in renewable-based energy systems
- 2019
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In: The 14th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES 2019), Dubrovnik, Croatia, October 1-6, 2019.
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Conference paper (peer-reviewed)abstract
- The co- or polygeneration benefits of energy products from a system vary and depends on several factors including how each individual product is otherwise produced and used. In a Nordic renewable based energy system, district heating system using woody biomass could be used for the production of several products and for the integration of electricity, heat and transportation sectors. Energy-efficient systems for the production of different wood based energy services, including efficient end-use system, will reduce the need for woody biomass that could be used in other sectors with less other renewable alternatives including aviation, shipping and material production. However, the scale and the annual variation of heat demands for single district heating systems are key factors that influence co- or polygeneration benefits of such systems. In this study, we analyse district heating systems with annual heat demands between 100 to 1000 GWh. Several technical configurations of co- or polygeneration of heat, electricity and/or biomotor fuels are analyzed, considering different standalone production options, woody biomass fuel prices and integration costs of intermittent energy resources. The development of several state-of-the-art technologies shows that there are co- or polygeneration benefits in district heating systems. System configuration varies with the scales of district heat production as does the use of biomass to generate the same amount of products and both depend on the context of the overall energy system. Electric-based solution for transportation as well as electric-based option for small-scale district heating systems together with cogeneration of heat and electricity in larger district heating system reduce the use of biomass and help to integrate wind power in the overall energy system. Further studies are needed to understand how deep energy-renovation of buildings may influence the configuration of co- or polygeneration system in district heating systems and the potential saving of woody biomass.
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| 9. |
- Truong, Nguyen Le, 1976-
(author)
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Costs and primary energy use of energy supply options to buildings of different energy efficiency levels
- 2016
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In: 2016 ACEEE Summer Study on Energy Efficiency in Buildings. - : American Council for an Energy Efficient Economy.
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Conference paper (peer-reviewed)abstract
- An appropriate energy solution for buildings depends on the scale of demand and the availability of the surrounding technical infrastructure. Building energy demand can be altered by the application of various energy efficiency measures whereas the performance of the energy supply system can be changed by the involvement of various technologies. As a result, optimal energy supply options could depend on various parameters that depend on specific contexts. In this study, different options to supply energy to apartment buildings of different energy efficiency levels in Sweden are investigated. Different renewable-based alternatives to produce heat and electricity based on various state-of-the-art technologies are considered. The optimizations are based on the hourly variation throughout the year of energy demand and of different energy supply systems that change with the ambient conditions such as temperature and solar radiation. The results prove that optimal options for a building depend on its scale of energy demand and on the availability of technologies in the market. Also, there is a tradeoff between monetary costs and primary energy use in supplying energy to apartment buildings. This study shows that it is essential to consider the interaction between energy demand and supply to estimate the costs and primary energy use for energy supply alternatives. A heating system with an electric heat pump shows to be primary energy efficient option whereas that with a wood pellet boiler is a more cost efficient once. However, an energy supply option based on a combined heat and power unit using fuel cell technology could potentially be the most cost- and primary energy efficient option for buildings with low energy demand.
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| 10. |
- Truong, Nguyen Le, 1976-, et al.
(author)
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Costs and primary energy use of heating new residential areas with district heat or electric heat pumps
- 2019
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In: Innovative Solutions for Energy Transitions. - : Elsevier. ; , s. 2031-2038
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Conference paper (peer-reviewed)abstract
- The choice of a heat supply option in new residential areas depends on various factors including available local energy resources and the scale and density of the heat demand in the areas. Here, we study costs and primary energy use of using district heat (DH) and ground-source electric heat pump (EHP) for heating a residential area being developed. We consider different architecture layouts and exploitations of the area along with different building energy efficiency standards which give different heat demand densities and profiles for this residential area. The analysis shows that for existing fuel-based energy supply systems, using DH is more primary energy efficient than using EHP to supply heat to the new residential area. However, if the future production of marginal electricity is based on state-of-the art technologies utilizing renewable energy resources, using EHP can be more primary energy efficient than using DH. The initial investment costs are much lower for options using DH than for options using ground-source EHP for the different exploitation alternatives. Also, the marginal heat cost for suppling DH to the residential area, excluding the sunk capital costs, is significantly lower than the heat cost for supplying heat with ground-source EHPs. The potential use of local ground-source heat linked to the exploitation level of residential area and energy performance of the buildings should be further analyzed in comparison to the use of other types of heat sources such as ambient air or ventilation air.
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