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Gong, M. (2017). Exergy and cost analysis of heating systems with energy storage. In: : . Paper presented at The 3rd International Conference on Smart Energy Systems and 4th Generation District Heating, 12-13 September 2017, Copenhagen, Denmark.
Open this publication in new window or tab >>Exergy and cost analysis of heating systems with energy storage
2017 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

About three quarters of the total final energy consumption is in the form of electricity and district heat and 49 TWh of district heat was used in Sweden in 2015. The energy supply and user demands vary and do not always match. The electricity production depends on the available energy resource that often is renewable, such as wind, solar and hydro power. The heat demand strongly depends on outdoor temperature and the weather conditions. Electricity and thermal storages are needed in order to reduce the losses from the lack of match between production and consumption. The cost of energy examined by others shows that electricity storage is about 100 times more expensive than thermal storage. However, in this study cost of exergy is only 20 times more for electricity than thermal. This study views electricity and district heat from source to end use and analyze the cost of exergy with storage. With a surplus of electricity the most efficient and cheapest way is to use electricity storage, such as battery or hydro storage on the purpose of electricity usage. The advantage of thermal storage depends strongly on the purpose of use, e.g. if it is for heating purposes. Heat pump is a method to convert electricity to district heat with 56% exergy efficiency. This paper will analyze different cases in order to give a more detailed discussion. Further studies of more cases are needed in the future.

Keywords
energy storage, exergy, renewable energy
National Category
Energy Systems
Identifiers
urn:nbn:se:hh:diva-35152 (URN)
Conference
The 3rd International Conference on Smart Energy Systems and 4th Generation District Heating, 12-13 September 2017, Copenhagen, Denmark
Available from: 2017-10-05 Created: 2017-10-05 Last updated: 2017-10-10Bibliographically approved
Averfalk, H., Ingvarsson, P., Persson, U., Gong, M. & Werner, S. (2017). Large heat pumps in Swedish district heating systems. Renewable & sustainable energy reviews, 79, 1275-1284
Open this publication in new window or tab >>Large heat pumps in Swedish district heating systems
Show others...
2017 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 79, p. 1275-1284Article in journal (Refereed) Published
Abstract [en]

Power-to-heat solutions like heat pumps and electric boilers are foreseen to be possible future tools to stabilise international power markets with high proportions of variable power supply. Temporary low cost electricity can be used for heat generation at times with high availability of wind and solar power through substitution of ordinary heat supply, hence contributing to increased energy system sustainability. Power-to-heat installations in district heating systems are competitive due to low specific investment and installation costs for large electric boilers, heat pumps, and heat storages. Several large-scale heat pumps were installed in Swedish district heating systems during the 1980s, since a national electricity surplus from new nuclear power existed for some years. The aim of this paper is to summarise the accumulated operation experiences from these large Swedish heat pumps to support and facilitate planning of future power-to-heat solutions with heat pumps in district heating systems. Gained experiences consider; installed capacities, capacity utilisation, heat sources used, refrigerant replacements, refrigerant leakages, and wear of mechanical components. The major conclusion is that many of the large thirty-year-old heat pumps are still in operation, but with reduced capacity utilisation due to internal competition from waste and biomass cogeneration plants in the district heating systems.

Place, publisher, year, edition, pages
Kidlington: Pergamon Press, 2017
Keywords
Power-to-heat, Heat pumps, District heating, District cooling, Integrated energy systems
National Category
Energy Systems
Identifiers
urn:nbn:se:hh:diva-34097 (URN)10.1016/j.rser.2017.05.135 (DOI)000410011500091 ()2-s2.0-85019691543 (Scopus ID)
Available from: 2017-06-13 Created: 2017-06-13 Last updated: 2019-04-04Bibliographically approved
Gong, M. & Werner, S. (2017). Mapping energy and exergy flows of district heating in Sweden. Energy Procedia, 116, 119-127
Open this publication in new window or tab >>Mapping energy and exergy flows of district heating in Sweden
2017 (English)In: Energy Procedia, ISSN 1876-6102, E-ISSN 1876-6102, Vol. 116, p. 119-127Article in journal (Refereed) Published
Abstract [en]

District heating has been available in Sweden since the 1950s and used more than half of the total energy use in dwelling and no-residential premises in 2013. Energy and exergy efficient conversion and energy resources are key factors to reduce the environmental impact. It is important to understand energy and exergy flows from both the supply and demand sides. The exergy method is also a useful tool for exploring the goal of more efficient energy-resource use. Sankey diagrams together with energy and exergy analyses are presented to help policy/decision makers and others to better understand energy and exergy flows from primary energy resource to end use. The results show the most efficient heating method in current district heating systems, and the use of renewable energy resources in Sweden. It is exergy inefficient to use fossil fuels to generate low quality heat. However, renewable energies, such as geothermal and solar heating with relative low quality, make it more exergy efficient. Currently, about 90% of the energy sources in the Swedish district heating sector have an origin from non-fossil fuels. Combined heat and power is an efficient simultaneous generator of electricity and heat as well as heat pump with considering electricity production. Higher temperature distribution networks give more distribution losses, especially in exergy content. An outlook for future efficient district heating systems is also presented.

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2017
Keywords
District heating, exergy, Sankey diagram, Grassmann diagram, Sweden
National Category
Energy Systems
Identifiers
urn:nbn:se:hh:diva-35151 (URN)10.1016/j.egypro.2017.05.060 (DOI)000406743000011 ()2-s2.0-85028600044 (Scopus ID)
Available from: 2017-10-05 Created: 2017-10-05 Last updated: 2017-10-05Bibliographically approved
Gong, M. & Wall, G. (2016). Exergy Analysis of the Supply of Energy and Material Resources in the Swedish Society. Energies, 9(9), Article ID 707.
Open this publication in new window or tab >>Exergy Analysis of the Supply of Energy and Material Resources in the Swedish Society
2016 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 9, no 9, article id 707Article in journal (Refereed) Published
Abstract [en]

Exergy is applied to the Swedish energy supply system for the period 1970–2013. Exergy flow diagrams for the systems of electricity and district heating as well as for the total supply system of energy and material resources for 2012 are presented. The share of renewable use has increased in both electricity and district heat production. The resource use is discussed in four sectors: residential and service, transportation, industry and agriculture. The resource use is also analyzed with respect to exergy efficiency and renewable share. The total exergy input of energy and material resources amounts to about 2700 PJ of which about 530 PJ was used for final consumption in 2012. The results are also compared with similar studies. Even though the share of renewable resource use has increased from 42% in 1980 to 47% in 2012, poor efficiency is still occurring in transportation, space heating, and food production. A strong dependence on fossil and nuclear fuels also implies a serious lack of sustainability. A more exergy efficient technology and a higher renewable energy share are needed in order to become a more sustainable society.

Place, publisher, year, edition, pages
Basel: M D P I AG, 2016
Keywords
energy, renewable, exergy flow diagram, electricity, district heating, Sweden
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-31926 (URN)10.3390/en9090707 (DOI)000383547900044 ()2-s2.0-84988023651 (Scopus ID)
Available from: 2016-09-05 Created: 2016-09-05 Last updated: 2018-10-22Bibliographically approved
Gong, M. & Werner, S. (2016). Mapping Energy and Exergy Flows of District Heating in Sweden. In: Rolf Ulseth & Kyung Min Kim (Ed.), Proceedings the 15th International Symposium on District Heating and Cooling: September 4th - 7th, 2016, Seoul, South Korea. Paper presented at The 15th International Symposium on District Heating and Cooling September 4-7, 2016, Seoul, Republic of Korea (South Korea) (pp. 96-102).
Open this publication in new window or tab >>Mapping Energy and Exergy Flows of District Heating in Sweden
2016 (English)In: Proceedings the 15th International Symposium on District Heating and Cooling: September 4th - 7th, 2016, Seoul, South Korea / [ed] Rolf Ulseth & Kyung Min Kim, 2016, p. 96-102Conference paper, Published paper (Refereed)
Abstract [en]

District heating has been available in Sweden since the 1950s and used more than half of the total energy use in dwelling and no-residential premises in 2013. Energy and exergy efficient conversion and energy resources are key factors to reduce the environmental impact. It is important to understand energy and exergy flows from both the supply and demand sides. The exergy method is also a useful tool for exploring the goal of more efficient energy-resource use. Sankey diagrams together with energy and exergy analyses are presented to help policy/decision makers and others to better understand energy and exergy flows from primary energy resource to end use. The results show the most efficient heating method in current district heating systems, and the use of renewable energy resources in Sweden. It is exergy inefficient to use fossil fuels to generate low quality heat. However, renewable energies, such as geothermal and solar heating with relative low quality, make it more exergy efficient. Currently, about 90% of the energy sources in the Swedish district heating sector have an origin from non-fossil fuels. Combined heat and power is an efficient simultaneous generator of electricity and heat as well as heat pump with considering electricity production. Higher temperature distribution networks give more distribution losses, especially in exergy content. An outlook for future efficient district heating systems is also presented.

Keywords
District heating, exergy, Sankey diagram, Sweden
National Category
Energy Systems
Identifiers
urn:nbn:se:hh:diva-31984 (URN)
Conference
The 15th International Symposium on District Heating and Cooling September 4-7, 2016, Seoul, Republic of Korea (South Korea)
Available from: 2016-09-13 Created: 2016-09-12 Last updated: 2017-01-13Bibliographically approved
Gong, M. & Werner, S. (2015). An assessment of district heating research in China. Renewable energy, 84, 97-105
Open this publication in new window or tab >>An assessment of district heating research in China
2015 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 84, p. 97-105Article in journal (Refereed) Published
Abstract [en]

The recent growth of the Chinese district heating sector has been very high. No other country in the world can show the same growth rate during the last decades. The heated building area increased six times between 1995 and 2008. China has also enjoyed strong growth of scientific articles and papers about district heating in recent years. One third of all international scientific journal articles and conference papers about district heating came from Chinese scientists during 2010–2012, while Swedish scientists accounted for one quarter according to the Scopus scientific search engine. It is important to identify the Chinese district heating research to judge the potential for future collaborative research on district heating systems between Sweden/Europe and China. The 205 international publications on district heating by Chinese scientists published until 2013 have been mapped and summarised with respect to demand, supply, technology, market and environment. More diversified heat supply with renewable source was grasping the Chinese interest, since many new systems have been established, having more degrees of freedom when choosing various heat supply and technology options. The Chinese district heating systems were compared with sustainable district heating solutions in Sweden. Both countries would benefit from future research cooperation. © 2015 Elsevier Ltd.

Place, publisher, year, edition, pages
Kidlington: Pergamon Press, 2015
Keywords
China, Sweden, District heating, Heat supply
National Category
Energy Systems
Identifiers
urn:nbn:se:hh:diva-29504 (URN)10.1016/j.renene.2015.05.061 (DOI)000362618900011 ()2-s2.0-84936972135 (Scopus ID)
Funder
Swedish Energy Agency, 2013-005290
Note

This work has been financially supported by Fjärrsyn, the Swedish district heating and cooling research program funded by the Swedish Energy Agency and the Swedish District Heating Association.

Available from: 2015-09-23 Created: 2015-09-23 Last updated: 2018-03-22Bibliographically approved
Gong, M. & Werner, S. (2015). Exergy analysis of network temperature levels in Swedish and Danish district heating systems. Renewable energy, 84, 106-113
Open this publication in new window or tab >>Exergy analysis of network temperature levels in Swedish and Danish district heating systems
2015 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 84, p. 106-113Article in journal (Refereed) Published
Abstract [en]

Exergy concept is applied on district heating systems with different network temperature levels in their distribution networks. These district heating systems use a combination of renewables and heat recovery from other primary processes. The aim is to show simplicity and value of using exergy concept when comparing current and future temperature levels. Both the traditional exergy factor and the novel exergy utilisation rate are used in these analyses. Exergy utilisation rate expresses the ratio between the exergy delivered to customer heating systems and the exergy content in heat supply input to the distribution network. The analyses are performed on four different generations of district heating technologies, two national groups of district heating systems in Denmark and Sweden for revealing variations among systems, and two municipal systems for revealing variations within systems. The main conclusions are simplifications can be introduced in order to analyse the network temperature levels, current exergy factors reveal that current temperature levels can be reduced, and that almost two thirds of the exergy content in heat supply input are lost in the heat distribution chain. These conclusion will be vital input in developing the future fourth generation of district heating systems using both renewables and heat recovery. © 2015 Elsevier Ltd.

Place, publisher, year, edition, pages
Kidlington: Pergamon Press, 2015
Keywords
Exergy factor, Exergy utilisation rate, District heating, 4GDH
National Category
Energy Systems
Identifiers
urn:nbn:se:hh:diva-29505 (URN)10.1016/j.renene.2015.06.001 (DOI)000362618900012 ()2-s2.0-84946473498 (Scopus ID)
Available from: 2015-09-23 Created: 2015-09-23 Last updated: 2018-03-22Bibliographically approved
Werner, S. & Gong, M. (2014). District heating research in China. Stockholm: Svensk fjärrvärme AB
Open this publication in new window or tab >>District heating research in China
2014 (English)Report (Other academic)
Abstract [en]

District heating is growing rapidly in China as Chinese building areas is expanding fast giving increased heating and cooling demands. This report gives an overview of the current situation for district heating and the research and development in this sector in China. Possibilities for collaboration between Swedish and Chinese researchers and companies in the field of district heating and cooling are also presented.

Place, publisher, year, edition, pages
Stockholm: Svensk fjärrvärme AB, 2014. p. 76
Series
Fjärrsyn resultatrapport ; 2014:3
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-27363 (URN)978-91-7381-133-0 (ISBN)
Projects
Fjärrvärmeforskning i Kina
Note

Med sammanfattning på svenska. The project is part of the Fjärrsyn research program which is financed by Swedish District Heating Association and Swedish Energy Agency.

Available from: 2014-12-29 Created: 2014-12-29 Last updated: 2018-03-22Bibliographically approved
Gong, M. & Wall, G. (2014). Life Cycle Exergy Analysis of Solar Energy Systems. Journal of Fundamentals of Renewable Energy and Applications, 5(1), Article ID 1000146.
Open this publication in new window or tab >>Life Cycle Exergy Analysis of Solar Energy Systems
2014 (English)In: Journal of Fundamentals of Renewable Energy and Applications, ISSN 2090-4533, E-ISSN 2090-4541, Vol. 5, no 1, article id 1000146Article in journal (Refereed) Published
Abstract [en]

Exergy concepts and exergy based methods are applied to energy systems to evaluate their level of sustainability. Life Cycle Exergy Analysis (LCEA) is a method that combines LCA with exergy, and it is applied to solar energy systems. It offers an excellent visualization of the exergy flows involved over the complete life cycle of a product or service. The energy and exergy used in production, operation and destruction must be paid back during life time in order to besustainable. The exergy of the material that is being engaged by the system will turn up as a product and available for recycling in the destruction stage. LCEA shows that solar thermal plants have much longer exergy payback time than energy payback time, 15.4 and 3.5 years respectively. Energy based analysis may lead to false assumptions in the evaluation of the sustainability of renewable energy systems. This concludes that LCEA is an effective tool for the design and evaluation of solar energy systems in order to be more sustainable.

Place, publisher, year, edition, pages
Foster City, CA: OMICS, 2014
Keywords
Exergy analysis, Sustainable development, Life cycle analysis
National Category
Energy Engineering
Identifiers
urn:nbn:se:hh:diva-27399 (URN)
Available from: 2015-01-05 Created: 2015-01-05 Last updated: 2018-03-22Bibliographically approved
Gong, M. & Werner, S. (2014). On district heating and cooling research in China. In: Proceedings from the 14th International Symposium on District Heating and Cooling: September, 6-10, 2014: Stockholm, Sweden. Paper presented at The 14th International Symposium on District Heating and Cooling, Stockholm, Sweden, 7-9 September, 2014 (pp. 325-332). Stockholm: Swedish District Heating Association
Open this publication in new window or tab >>On district heating and cooling research in China
2014 (English)In: Proceedings from the 14th International Symposium on District Heating and Cooling: September, 6-10, 2014: Stockholm, Sweden, Stockholm: Swedish District Heating Association , 2014, p. 325-332Conference paper, Published paper (Refereed)
Abstract [en]

The growth of the Chinese district heating sector has been very rapid during recent years. No other country in the world can show the same rapid growth of district heating systems during the last decades. Heated building area increased six times between 1995 and 2008 according to the Chinese district heating statistics. China has also enjoyed strong growth of scientific articles and papers published about district heating in recent years. During 2010-2012, one third of all international scientific journal articles and conference papers about district heating came from Chinese scientists, while Swedish researchers accounted for one quarter. It is important to identify the Chinese district heating and cooling research to judge the potential for future collaborative research on district heating systems between Sweden/Europe and China. Until 2013, Chinese district heating and cooling scientists have published 205 international publications on district heating and 36 publications on district cooling. In this paper, these articles are mapped and summarised with respect to topics, active research institutions, and their technology focuses. Another approach is to grasp the Chinese interest for more diversified heat supply, since many new systems are established and thereby have more degrees of freedom when choosing by various heat supply and technology options.

Place, publisher, year, edition, pages
Stockholm: Swedish District Heating Association, 2014
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:hh:diva-26715 (URN)978-91-85775-24-8 (ISBN)
Conference
The 14th International Symposium on District Heating and Cooling, Stockholm, Sweden, 7-9 September, 2014
Note

This work has been financially supported by Fjärrsyn, the Swedish district heating and cooling research program funded by the Swedish Energy Agency and the Swedish District Heating Association.

Available from: 2014-10-13 Created: 2014-10-13 Last updated: 2018-03-22Bibliographically approved
Projects
District heating research in China [P37907-1_Energi]; Halmstad University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-8307-124X

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