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District Heating Sensitivity to Heat Demand Reductions and Electricity Market Dynamics
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences. (Built Environment Energy Systems Group (BEESG))
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Sweden and the rest of the EU member states have to reduce primary energy use andemissions of CO2, and increase the use of renewable energy sources according to the EUclimate change package “20-20-20”. To do this, the energy systems need to use less fossilfuel and to utilise energy resources more efficiently. Reduction of energy use in buildings isan important part of this transformation. In Sweden, district heating is the most commontechnique to supply heat for space heating and domestic hot water to multi-family residentialbuildings in urban areas. Efficiency improvements in buildings connected to district heatingsystems should not be counterproductive from a systems perspective, e.g. causing lessefficient total use of resources and increased global CO2 emissions. A reduced electricityproduction in combined heat and power plants, which may be a result of reduced districtheating demand, is sometimes seen as problematic with regards to emissions of CO2, sincethis electricity is normally considered to replace electricity produced in less efficient fossilfuelledcondensing power plants.This licentiate thesis summarises the first part of a PhD project that studies thepossibilities for Swedish district heating systems to adapt to a reduced demand for heating inbuildings, as well as to changes in energy markets. In this thesis the impact of buildingenergy-efficiency improvements and electricity market dynamics on the operation of districtheating systems and CO2 emissions is investigated.The energy system cost-optimisation software MODEST has been used to study theimpact of heat demand changes on the heat and electricity production in the Swedish districtheating systems in Linköping and Uppsala. MODEST optimisations were also used toinvestigate the impact of electricity price fluctuations on the operation of the Uppsaladistrict heating system, and the interaction between the national power system and allSwedish district heating systems collectively.The results show that energy efficiency improvements in buildings that reduce heatdemand by up to 40 % do not increase global CO2 emissions due to production of districtheating. This is because heat-only production is reduced to a larger extent than combinedheat and power production. The results also show that low electricity prices during winterand a large introduction of intermittent wind and solar power generation in the Swedishpower system can be expected to induce use of electricity for district heat production and tohamper co-generation of electricity in combined heat and power plants.

Place, publisher, year, edition, pages
Uppsala universitet, 2012. , 68 p.
National Category
Energy Systems
Research subject
Engineering Science
Identifiers
URN: urn:nbn:se:uu:diva-176407OAI: oai:DiVA.org:uu-176407DiVA: diva2:535146
Presentation
2012-01-16, Å2002, Lägerhyddsvägen 1, Uppsala, 13:15 (Swedish)
Opponent
Supervisors
Available from: 2012-06-27 Created: 2012-06-19 Last updated: 2012-06-27Bibliographically approved
List of papers
1. Optimisation of a Swedish district heating system with reduced heat demand due to energy efficiency measures inr esidential buildings
Open this publication in new window or tab >>Optimisation of a Swedish district heating system with reduced heat demand due to energy efficiency measures inr esidential buildings
2011 (English)In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 39, no 12, 7839-7852 p.Article in journal (Refereed) Published
Abstract [en]

The development towards more energy efficient buildings, as well as the expansion of district heating (DH) networks, is generally considered to reduce environmental impact. But the combined effect of these two progressions is more controversial. A reduced heat demand (HD) due to higher energy efficiency in buildings might hamper co-production of electricity and DH. InSweden,co-produced electricity is normally considered to displace electricity from less efficient European condensing power plants. In this study, a potential HD reduction due to energy efficiency measures in the existing building stock in the Swedish city Linkoping is calculated. The impact of HD reduction on heat and electricity production in the Linkoping DH system is investigated by using the energy system optimisation model MODEST. Energy efficiency measures in buildings reduce seasonal HD variations. Model results show that HD reductions primarily decrease heat-only production.The electricity-to-heat output ratio for the system is increased for HD reductions up to 30%. Local and global CO2 emissions are reduced. If co-produced electricity replaces electricity from coal-fired condensing power plants, a 20% HD reduction is optimal for decreasing global CO2 emissions in the analysed DH system.

Place, publisher, year, edition, pages
Elsevier, 2011
Keyword
Low-energy residentialbuildings District heating Energy efficiencymeasures
National Category
Energy Systems
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-176404 (URN)10.1016/j.enpol.2011.09.031 (DOI)
Available from: 2012-06-19 Created: 2012-06-19 Last updated: 2017-12-07Bibliographically approved
2. Sensitivity of district heating system operation to heat demand reductions and electricity price variations: A Swedish example
Open this publication in new window or tab >>Sensitivity of district heating system operation to heat demand reductions and electricity price variations: A Swedish example
2012 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 41, no 1, 525-540 p.Article in journal (Refereed) Published
Abstract [en]

In the future, district heating companies in Sweden must adapt to energy efficiency measures in buildings and variable fuel and electricity prices. Swedish district heating demands are expected to decrease by 1-2% per year and electricity price variations seem to be more unpredictable in the future. A cost-optimisation model of a Swedish local district heating system is constructed using the optimisation modelling tool MODEST. A scenario for heat demand changes due to increased energy efficiency in buildings, combined with the addition of new buildings, is studied along with a sensitivity analysis for electricity price variations. Despite fears that heat demand reductions will decrease co-generation of clean electricity and cause increased global emissions, the results show that anticipated heat demand changes do not increase the studied system's primary energy use or global CO2 emissions. The results further indicate that the heat production plants and the fuels used within the system have crucial importance for the environmental impact of district heat use. Results also show that low seasonal variations in electricity price levels with relatively low winter prices promote the use of electric heat pumps. High winter prices on the other hand promote co-generation of heat and electricity in CHP plants.

Keyword
District heating, CHP, Building energy efficiency, CO2 emissions, Primary energy use, Electricity price variations
National Category
Engineering and Technology
Research subject
Engineering Science
Identifiers
urn:nbn:se:uu:diva-175624 (URN)10.1016/j.energy.2012.02.034 (DOI)000304076800058 ()
Available from: 2012-06-12 Created: 2012-06-11 Last updated: 2017-12-07Bibliographically approved
3. Impacts of large-scale solar and wind power production on the balance of the Swedish power system
Open this publication in new window or tab >>Impacts of large-scale solar and wind power production on the balance of the Swedish power system
2011 (English)In: Proceedings of the World Renewable Energy Congress, Linköping, May 8-13, 2011, 2011Conference paper, Published paper (Refereed)
National Category
Energy Systems
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-132906 (URN)
Conference
World Renewable Energy Congress 2011
Available from: 2010-10-28 Created: 2010-10-28 Last updated: 2016-04-20

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