| 11. |
- Fröling, Morgan, 1966, et al.
(författare)
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Is there a role for district heating in future cities with low energy buildings?
- 2008
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Ingår i: 11th International Symposium on District Heating and Cooling, August 31 to September 2, 2008, Reykjavik, ICELAND.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The district heating sector is challenged in its traditionalway of doing business by buildings increasingly moreenergy efficient (with low heat demand for space heating).This paper reports on work of mapping out suchchallenges connected to passive houses in Sweden. Itshould be noted that the conditions might be different indifferent geographical areas. To gain climate friendlinessin the building sector a system perspective must be usedboth regarding energy and environmental issues. Thelevels of energy use in buildings in Sweden today and inthe future are discussed together with marginal vs.average thinking regarding energy and heat production.From our findings we conclude that it is not necessarilyso that electricity or natural gas should be the option ofchoice for hot water demand or peak loads that need tobe externally covered also in energy efficient buildings.However, it will require active work by district heatingcompanies to stay competitive. It will be increasinglyimportant for district heating companies to communicatewith their customers. It will also be important to identifynew customers and new areas where heat can beutilized; the “district heating villa” in Göteborg, Sweden is an example of investigating new possibilities of heat use.The study reported in this paper has identified a numberof areas where further research and development isneeded for district heating to improve the future marketposition of district heating.
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| 12. |
- Fröling, Morgan, 1966, et al.
(författare)
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Life Cycle Assessment of Second Generation Biodiesel: Biomass to Liquid
- 2008
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Ingår i: Designing Pathways for a Sustainable World: At Scale, in Time, and for All, AGS Annual Meeting, MIT, Cambridge, MA. USA, January 28-30 2008. ; , s. abstract in proceedings-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 13. |
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| 14. |
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| 15. |
- Johansson, Kristin, 1979, et al.
(författare)
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Environmental impact of the EPSPEX system. Part 1: Life cycle assessment of polystyrene insulated district heating systems with PEX fluid pipes
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The EPSPEX system is a distribution system for district heat with media pipes of cross-linked polyethylene (PEX) insulated by blocks of expanded polystyrene (EPS). In this low-pressure distribution system two pipes are used for a space heating circuit, having layers of EVAL to hinder oxygen diffusion, whereas two pipes without diffusion barrier are used for delivery of hot tap water and warm water circulation. The four pipes are placed in the insulating blocks of EPS. Environmental impacts from production, laying and use of an EPSPEX district heat distribution system have been investigated using life cycle methodology. The distribution system is a secondary system developed specially for areas with low heat density. The case studied is the installation and use of an EPSPEX system in Vråen, Värnamo, Sweden. The environmental impacts are described in four categories:climate change, acidification, eutrophication and use of finite resources. Four weighting methods have also been used in the evaluation: EPS2000, Ecoscarcity, ExternE and EcoIndicator99. While carefully considering the precise circumstances of this study, the findings can be adapted for using the EPSPEX district heat distribution systems in other areas.During this study the question was raised of how this district heat delivery system compares with systems that use conventional district heating pipes. This has beenfurther investigated and is reported in the second part of this report: Miljöbelastning från EPSPEX-systemet. Del 2: Konventionella twinrör eller EPSPEX vad är bäst urmiljösynpunkt. In the second part the environmental impacts from the EPSPEX system have been compared with the impacts from conventional twin pipes (polyurethane insulated steel media pipes) used in a comparable setting. A discussion on the environmental choice between media pipes of PEX and steel can also be found in the second part. It should be noted that the two systems for district heat distribution are not fully comparable in function. The EPSPEX system has stricter limitations regarding pressure and temperature compared with the conventional system. The EPSPEX system is also limited in use for well drained ground conditions above the water table. Conventional district heating pipes do not have this limitation. The most important possibility to decrease the environmental impacts from the EPSPEX system is to increase the insulation, this even though the distribution systemis comparably well insulated to start with. The environmental life cycle impacts of the distribution pipe system production, laying and use are predominated by the extra heat that has to be generated to cover the heat losses from the system. When this report was written, measurements from systems in use to confirm the model calculation of heat losses are still lacking. More fine-tuned results can be achieved when studies of the EPSPEX system in use have been concluded.Among different components in the EPSPEX system the impacts from production and transport of EPS-blocks make the major impact. Thus, it is important to utilize the polystyrene material as efficiently as possible, minimizing spillage, and to ensure that unavoidable spillage is recycled as material. However, the environmental impacts from production of the insulating blocks are well outweighed by the decreased environmental impacts gained by using the insulation. In product development it is thus important to ensure that the insulating capacity of the EPSPEX system is never decreased.Machines used for excavating the pipe trenches combust diesel oil, and the production and use of this diesel oil generates a substantial part of the environmental impacts byseveral of the assessment methods used. If possible, it is desirable to further minimize the excavation work and to use mini excavators and low emitting machines (especially regarding nitrous oxides). The brass swaged coupling used to connect the PEX-pipes, gives a strong impact regarding acidification and the two weighting methods EPS2000 and Ecoscarcity, especially when compared to the very small volume fraction these devices constitute. It would be advisable to study if the devices could be made from other material or from recycled material.
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| 16. |
- Johansson, Kristin, 1979, et al.
(författare)
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Environmental impact of the EPSPEX system. Part 2: Traditional twin pipes or EPSPEX for district heat distribution - what is best from an environmental point of view?
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this study the life-cycle environmental impacts from an EPSPEX system for distribution of district heat (a four-pipe system with centrally generated hot tap water) are compared with the environmental impacts of a twin-pipe system with steel media pipes, if installed in the same area. A life cycle assessment of the EPSPEX system constructed in Vråen, Värnamo, Sweden, has been reported in Miljöbelastning från EPSPEX-systemet. Del 1: Livscykelanalys av polystyrenisolerat fjärrvärmesystemmed PEX-mediarör [1]. In that study the question was raised of how the EPSPEX system compares with a conventional twin-pipe system with polyurethane-insulated steel media pipes.In the present study the EPSPEX system in Vråen is compared with a hypothetical construction of a conventional twin pipe system in the same area. Two different fuel mixes for district heat generation have been studied to increase the understanding of the environmental performance of district heat distribution systems; the fuel mix used in Vråen (heat delivered from Värnamo Energi) and Swedish average district heat. How media pipes from the two different materials (PEX and steel) compare is discussed in a separate part. There are technical differences that must be kept in mind when the systems are compared in this way. The EPSPEX system is designed for low-pressure district heat systems and could only be used in such context. It is unadvisable to install the EPSPEX system below the ground water table; this is not a restriction for the twin pipe system. Under the conditions of this study the environmental performance of the EPSPEX system is better than the twin pipe system.The heat loss from the EPSPEX system is approximately 60% of the heat loss for a comparable twin pipe system. This is caused by a combination of thick insulation for the EPSPEX system and the possibility to summertime shut down the district heating circuit for this system and only use the hot tap-water circuit. Note, however, that the heat loss from the EPSPEX system is more uncertain compared to the twin-pipe system. From the characterization methods used, the production of the EPSPEX system gives a higher environmental impact compared to the twin pipe system. This heavily depends on the large amount of insulating material used. However, the environmental impacts from production of the insulation are more then outweighed by the emissionsavoided from heat generation due to lower heat loss. District heating sub centrals generates a notable part of the total environmental impact when using the weighing method EPS2000. Note that sub centrals are not technicallynecessary in low-pressure district heat systems, as the EPSPEX system. The comparison between different fuel mixes for heat generation indicates clearly that the heat generation is an important parameter for environmental performance for all district heating. It is further indicated that also biofuels must be used with sensible andenvironmentally friendly methods. The media pipes of PEX seem to give lower environmental impacts compared withmedia pipes of steel. However, the results differ between assessment methods used.
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| 17. |
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| 18. |
- Luterbacher, Jeremy S., et al.
(författare)
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High yield methane generation from wet biomass and waste
- 2007
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Ingår i: Pathways to our common future - Proceedings of The Alliance for Global Sustainability Annual Meeting 2007, 18-21 March, Barcelona, Spain.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 19. |
- Luterbacher, Jeremy S., et al.
(författare)
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Hydrothermal Gasification of Waste Biomass: Process Design and Life Cycle Asessment
- 2009
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:5, s. 1578-1583
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Tidskriftsartikel (refereegranskat)abstract
- A process evaluation methodology is presented that incorporates flowsheet mass and energy balance modeling, heat and power integration, and life cycle assessment. Environmental impacts are determined by characterizing and weighting (using CO2 equivalents, Eco-indicator 99, and Eco-scarcity) the flowsheet and inventory modeling results. The methodology is applied to a waste biomass to synthetic natural gas (SNG) conversion process involvingacatalytic hydrothermal gasification step. Several scenarios are constructed for different Swiss biomass feedstocks and different scales depending on logistical choices: large-scale (155 MWSNG) and small-scale (5.2 MWSNG) scenarios for a manure feedstock and one scenario (35.6MWSNG) for awoodfeedstock. Process modeling shows that 62% of the manure’s lower heating value (LHV) is converted to SNG and 71% of wood’s LHV is converted to SNG. Life cycle modeling shows that, for all processes, about 10% of fossil energy use is imbedded in the produced renewable SNG. Converting manure and replacing it, as a fertilizer, with the process mineral byproduct leads to reduced N2O emissions and an improved environmental performance such as global warming potential: -0.6 kgCO2eq./MJSNG vs -0.02 kgCO2eq./MJSNG for wood scenarios.
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| 20. |
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