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Economic and Environmental Benefits of CHP-based District Heating Systems in Sweden
Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Future energy systems and thus the climate are affected by many factors, such as energy resources, energy demand, energy policy and the choice of energy technologies. Energy systems of the future are facing three main challenges; the steady growth of global energy demand, the energy resource depletion, as well as the increasing emissions of carbon dioxide (CO2) and other greenhouse gases and their impact on climate change. To meet the mentioned challenges with sustainability in mind, actions that increase energy efficiency and choosing an energy-efficient energy system which is cost efficient will be essential. Combined heat and power (CHP) plants and district heating and cooling could contribute greatly to increased system efficiency by using energy otherwise wasted.

The aim of this study is to increase the understanding of how CHP-based district heating and cooling systems using different primary energy sources can contribute to more cost-efficient energy systems, which reduce global CO2 emissions, and to highlight the impact of some important parameters and measures on Swedish municipal district heating systems. An important assumption in this study is the estimation of CO2 emissions from electricity production, which is based on marginal electricity perspectives. In the short term, the marginal electricity is assumed to come from coal-fired condensing power plants while in the long term it consists of electricity produced by natural gas-fired combined cycle condensing power plants. This means that the local electricity production will replace the marginal electricity production. The underlying assumption is an ideal fully deregulated European electricity market where trade barriers are removed and there are no restrictions on transfer capacity.

The results show that electricity generation in CHP plants, particularly in higher efficiency combined steam and gas turbine heat and power plants using natural gas, can reduce the global environmental impact of energy usage to a great extent. The results confirm, through the scenarios presented in this study, that waste as a fuel in CHP-based district heating systems is fully utilised since it has the lowest operational costs. The results also show how implementation of a biogas-based CHP plant in a biogas system contributes to an efficient system, as well as lowering both CO2 emissions and system costs. The results show that replacing electricity-driven (e.g. compression) cooling by heat-driven cooling using district heating (e.g. absorption chillers) in a CHP system is a cost-effective and climate friendly technology as electricity consumption is reduced while at the same time the electricity generation will be increased. The results of the study also show that there is potential to expand district heating systems to areas with lower heat density, with both environmental and economic benefits for the district heating companies.

The results reveal that the operation of a studied CHP-based district heating system with an imposed emission limit is very sensitive to the way CO2 emissions are accounted, i.e., local CO2 emissions or emissions from marginal electricity production. The results show how the electricity production increases in the marginal case compared with the local one in order to reduce global CO2 emissions. The results also revealed that not only electricity and fuel prices but also policy instruments are important factors in promoting CHP-based district heating and cooling systems. The use of electricity certificates has a large influence for the introduction of biogas-based cogeneration. Another conclusion from the modelling is that present Swedish policy instruments are strong incentives for cogeneration with similar impact as applying external costs.

Abstract [sv]

Framtidens energisystem och därmed även klimatet påverkas av många faktorer, såsom energitillgångar, efterfrågan på energi, energipolicy och valet  av energitekniska lösningar. De framtida energisystemen står inför tre viktiga utmaningar: den ständigt växande efterfrågan på energi i världen, problemet med minskande energitillgångar samt den ökande koldioxidhalten i atmosfären och utsläppen av andra växthusgaser och deras påverkan på klimatförändring. Det blir alltmer angeläget att möta de nämnda utmaningarna med hållbarhetsbegreppet i åtanke, att agera för att öka energieffektiviteten och att välja ett energieffektivt energisystem som också är kostnadseffektivt. Fjärrvärme och fjärrkyla baserade på kraftvärme (CHP) kan i hög grad bidra till ökad effektivitet genom användning av energi som annars skulle gå till spillo.

Syftet med denna studie är att öka förståelsen för hur CHP-baserad fjärrvärme och fjärrkyla som använder olika energikällor kan bidra till mer kostnadseffektiva energisystem som även ger minskade globala koldioxidutsläpp samt att belysa effekterna av vissa viktiga parametrar för svenska fjärrvärmesystem. Ett viktigt antagande i denna studie är beräkningarna av koldioxidutsläppen från elproduktion som är baserade på marginalelsperspektiv. På kort sikt antas marginalelen komma från koleldade kondenskraftverk, medan den på lång sikt utgörs av el som produceras av naturgas i gaskombi-kondenskraftverk. I beräkningarna antas den lokala elproduktionen ersätta marginalelsproduktionen. Det underliggande antagandet är en ideal, helt avreglerad, europeisk elmarknad där handelshindren är borta och det inte finns några begränsningar i överföringskapaciteten.

Resultaten visar att elproduktion i kraftvärmeverk, speciellt i högeffektiva kraftvärmeverk med en kombination av ång- och gasturbiner med naturgas, kan minska den globala miljöpåverkan av energianvändningen avsevärt. Resultaten bekräftar också, genom de scenarier som presenteras i denna studie, att avfall utnyttjas fullt ut som bränsle i kraftvärmebaserade fjärrvärmesystem eftersom det har de lägsta driftskostnaderna. Resultaten visar också hur införande av ett biogasbaserat kraftvärmeverk i ett biogassystem bidrar till ett effektivt system för att minska koldioxidutsläppen och systemkostnaderna. Resultaten visar att det är kostnadseffektivt och klimatvänligt att byta ut eldrivna kompressorkylmaskiner mot värmedrivna absorptionskylmaskiner i ett CHP-system eftersom elanvändningen minskas och elproduktionen samtidigt kommer att öka. Resultaten av studien visar också att det finns potential att bygga ut fjärrvärmesystem till områden med lägre värmetäthet med både miljövinster och ekonomiska fördelar för fjärrvärmeföretagen.

Resultaten visar att driften av ett studerat CHP-baserat fjärrvärmesystem där olika gränsvärden för utsläpp införs är mycket känsligt för hur koldioxidutsläppen redovisas, d v s som lokala koldioxidutsläpp eller utsläpp från marginalel. Resultatet visar hur elproduktionen ökar i marginalelsfallet jämfört med det lokala fallet för att minska de globala koldioxidutsläppen. Resultaten visade också att inte bara el- och bränslepriserna, utan också styrmedlen är viktiga för att främja kraftvärmebaserad fjärrvärme och fjärrkyla. Elcertifikat har t ex stor inverkan på införandet av biogasbaserad kraftvärme. En annan slutsats från modelleringarna är att de styrmedel som finns i dagens Sverige utgör starka incitament för kraftvärme och har en liknande effekt som att använda externa kostnader.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013. , 108 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1524
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-92807ISBN: 978-91-7519-604-6 (print)OAI: oai:DiVA.org:liu-92807DiVA: diva2:622636
Public defence
2013-06-10, C3, C-huset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2013-05-22 Created: 2013-05-22 Last updated: 2013-05-22Bibliographically approved
List of papers
1. Modelling and optimisation of electricity, steam and district heating production for a local Swedish utility
Open this publication in new window or tab >>Modelling and optimisation of electricity, steam and district heating production for a local Swedish utility
2006 (English)In: European Journal of Operational Research, ISSN 0377-2217, Vol. 175, no 2, 1224-1247 p.Article in journal (Refereed) Published
Abstract [en]

District heating may help reduce environmental impact and energy costs, but policy instruments and waste management may influence operations. The energy system optimisation model MODEST has been used for 50 towns, regions and a nation. Investments and operation that satisfy energy demand at minimum cost are found through linear programming. This paper describes the application of MODEST to a municipal utility, which uses several fuels and cogeneration plants. The model reflects diurnal and monthly demand fluctuations. Several studies of the Linköping utility are reviewed. These indicate that the marginal heat cost is lower in summer, a new waste or wood fired cogeneration plant is more profitable than a natural-gas-fired combined cycle, material recycling of paper and hard plastics is preferable to waste incineration from an energy-efficiency viewpoint, and considering external costs enhances wood fuel use. Here, an emission limit is used to show how fossil-fuel cogeneration displaces CO2 from coal-condensing plants. © 2005 Elsevier B.V. All rights reserved.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-43950 (URN)10.1016/j.ejor.2005.06.026 (DOI)75220 (Local ID)75220 (Archive number)75220 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-05-22
2. Internalising external costs of electricity and heat production in a municipal energy system
Open this publication in new window or tab >>Internalising external costs of electricity and heat production in a municipal energy system
2007 (English)In: Energy Policy, ISSN 0301-4215, Vol. 35, no 10, 5242-5253 p.Article in journal (Refereed) Published
Abstract [en]

Both energy supply and waste treatment give rise to negative effects on the environment, so-called external effects. In this study, monetary values on external costs collected from the EU′s ExternE project are used to evaluate inclusion of these costs in comparison with an energy utility perspective including present policy instruments. The studied object is a municipal district heating system with a waste incineration plant as the base supplier of heat. The evaluation concerns fuels used for heat production and total electricity production, for scenarios with external costs included and for a scenario using the present policy instrument.

Impacts of assumptions on marginal power producers (coal or natural gas power plants) are investigated, since locally produced electricity is assumed to replace marginal power and thus is credited for the avoided burden. Varying levels of external costs for carbon dioxide emissions are analysed. The method used is an economic optimisation model, MODEST.

The conclusion is that present policy instruments are strong incentives for cogeneration, even when external costs are included. Waste is fully utilised in all scenarios. In cases where coal is the marginal power producer, more electricity is produced; when natural gas is the marginal power producer, less is produced. There are several uncertainties in the data for external costs, both methodological and ethical. In the ExternE data, not all environmental impacts are included. For waste incineration, ashes are not included, and another difficulty is how to treat the avoided burden of other waste treatment methods.

Keyword
External costs, Combined heat and power, Waste incineration
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-14206 (URN)10.1016/j.enpol.2007.04.026 (DOI)
Available from: 2007-01-04 Created: 2007-01-04 Last updated: 2013-05-22
3. European perspective on absorption cooling in a combined heat and power system: A case study of energy utility and industries in Sweden
Open this publication in new window or tab >>European perspective on absorption cooling in a combined heat and power system: A case study of energy utility and industries in Sweden
2007 (English)In: Applied Energy, ISSN 0306-2619, Vol. 84, no 12, 1319-1337 p.Article in journal (Refereed) Published
Abstract [en]

Mankind is facing an escalating threat of global warming and there is increasing evidence that this is due to human activity and increased emissions of carbon dioxide. Converting from vapour compression chillers to absorption chillers in a combined heat and power (CHP) system is a measure towards sustainability as electricity consumption is replaced with electricity generation. This electricity produced in Swedish CHP-system will substitute marginally produced electricity and as result lower global emissions of carbon dioxide. The use of absorption chillers is limited in Sweden but the conditions are in fact most favourable. Rising demand of cooling and increasing electricity prices in combination with a surplus of heat during the summer in CHP system makes heat driven cooling extremely interesting in Sweden. In this paper we analyse the most cost-effective technology for cooling by comparing vapour compression chillers with heat driven absorption cooling for a local energy utility with a district cooling network and for industries in a Swedish municipality with CHP. Whilst this case is necessarily local in scope, the results have global relevance showing that when considering higher European electricity prices, and when natural gas is introduced, absorption cooling is the most cost-effective solution for both industries and for the energy supplier. This will result in a resource effective energy system with a possibility to reduce global emissions of CO2 with 80%, a 300% lower system cost, and a 170% reduction of the cost of producing cooling due to revenues from electricity production. The results also show that, with these prerequisites, a decrease in COP of the absorption chillers will not have a negative impact on the cost-effectiveness of the system, due to increased electricity production.

Keyword
Absorption cooling, European electricity prices, Natural gas, Carbon dioxide, Global emissions
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-14161 (URN)10.1016/j.apenergy.2006.09.016 (DOI)
Available from: 2006-11-27 Created: 2006-11-27 Last updated: 2013-05-22
4. Assessment of the natural gas potential for heat and power generation in the County of Ostergotland in Sweden
Open this publication in new window or tab >>Assessment of the natural gas potential for heat and power generation in the County of Ostergotland in Sweden
2009 (English)In: Energy Policy, ISSN 0301-4215, Vol. 37, no 2, 496-506 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this study is to investigate the potential use of natural gas for heat and power production for the municipality of Linkoping, Norrkoping and Finspang in the County of Ostergotland, Sweden.

The results of the study revealed that these three municipalities with the present heating demand can convert 2030 GWh/year of the present fuel mixed to natural gas. The expansion of natural gas provides the possibility to increase the electricity generation with approximately 800 GWh annually in the County of Ostergotland. The global emissions of CO2 reduce also by approximately 490 ktonne/year by assuming the coal condensing power plant as the marginal power plant. The total system cost decreases by 76 Mkr/year with the present electricity price which varies between 432 and 173 SEK/MWh and with 248 Mkr/year if the present electricity price increases to 37% which is approximately corresponding to European electricity prices.

Sensitivity analysis is done with respect to the different factors such as price of electricity, natural gas, etc. The findings show that increased price of electricity and increased district heating demand increases the profitability to convert to natural gas using CHP plant.

Keyword
Natural gas, CO2 emissions, Combined heat and power
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-16971 (URN)10.1016/j.enpol.2008.09.080 (DOI)
Available from: 2009-03-01 Created: 2009-02-27 Last updated: 2013-05-22
5. Possibilities and consequences of deregulation of the European electricity market for connection of heat sparse areas to district heating systems
Open this publication in new window or tab >>Possibilities and consequences of deregulation of the European electricity market for connection of heat sparse areas to district heating systems
2010 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 87, no 7, 2401-2410 p.Article in journal (Refereed) Published
Abstract [en]

The objective of the study is to analyse the conditions for connection of residential buildings in heat sparse areas to district heating systems in order to increase electricity production in municipal combined heat and power plants. The European electricity market has been assumed to be fully deregulated. The relation between connection of heat sparse areas, increased electricity and heat production as well as electricity prices, fuel prices and emissions rights is investigated. The results of the study show that there is potential to expand the district heating market to areas with lower heat concentrations in the cities of Gavle, Sandviken and Borlange in Sweden, with both economic and environmental benefits. The expansion provides a substantial heat demand of approximately 181 GWh/year, which results in an electricity power production of approximately 43 GWh/year. Since the detached and stand-alone houses in the studied heat sparse areas have been heated either by oil boiler or by direct electricity, connection to district heating also provides a substantial reduction in emissions of CO2. The largest reductions in CO2 emissions are found to be 211 ktonnes/year assuming coal-fired condensing power as marginal electricity production. Connection of heat sparse areas to district heating decrease the system costs and provide a profitability by approximately 22 million EURO/year for the studied municipalities if the price of electricity is at a European level, i.e. 110 EURO/MWh. Sensitivity analysis shows, among other things, that a strong relation exists between the price of electricity and the profitability of connecting heat sparse areas to district heating systems.

Place, publisher, year, edition, pages
Elsevier Science B.V., Amsterdam., 2010
Keyword
Combined heat and power; Heat sparse areas; CO2 emissions; District heating; Deregulated electricity market
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-58385 (URN)10.1016/j.apenergy.2010.02.002 (DOI)000278675100034 ()
Note
Original Publication: Shahnaz Amiri and Bahram Moshfegh, Possibilities and consequences of deregulation of the European electricity market for connection of heat sparse areas to district heating systems, 2010, Applied Energy, (87), 7, 2401-2410. http://dx.doi.org/10.1016/j.apenergy.2010.02.002 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2010-08-13 Created: 2010-08-11 Last updated: 2017-12-12
6. Simulation and introduction of a CHP plant in a Swedish biogas system
Open this publication in new window or tab >>Simulation and introduction of a CHP plant in a Swedish biogas system
2013 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 49, no SI, 242-249 p.Article in journal (Refereed) Published
Abstract [en]

The objectives of this study are to present a model for biogas production systems to help achieve a more cost-effective system, and to analyse the conditions for connecting combined heat and power (CHP) plants to the biogas system. The European electricity market is assumed to be fully deregulated. The relation between connection of CHP. increased electricity and heat production, electricity prices, and electricity certificate trading is investigated. A cost-minimising linear programming model (MODEST) is used. MODEST has been applied to many energy systems, but this is the first time the model has been used for biogas production. The new model, which is the main result of this work, can be used for operational optimisation and evaluating economic consequences of future changes in the biogas system. The results from the case study and sensitivity analysis show that the model is reliable and can be used for strategic planning. The results show that implementation of a biogas-based CHP plant result in an electricity power production of approximately 39 GW h annually. Reduced system costs provide a profitability of 46 MSEK/year if electricity and heat prices increase by 100% and electricity certificate prices increase by 50%. CO2 emission reductions up to 32,000 ton/year can be achieved if generated electricity displaces coal-fired condensing power.

Place, publisher, year, edition, pages
Elsevier, 2013
Keyword
Biogas system, CO2 emissions, Energy systems optimisation, Combined heat and power plant, Marginal electricity
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-85624 (URN)10.1016/j.renene.2012.01.022 (DOI)000309902000051 ()
Available from: 2012-11-26 Created: 2012-11-26 Last updated: 2017-12-07

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