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District Heating and CHP: Local Possibilities for Global Climate Change Mitigation
Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology.
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Global warming, in combination with increasing energy demand and higher energy prices, makes it necessary to change the energy use. To secure the energy supply and to develop sustainable societies, construction of energy-efficient systems is at the same time most vital. The aim of this thesis is therefore to identify how a local energy company, producing district heating (DH), district cooling (DC) and electricity in combined heat and power (CHP) plants, can contribute to resource-efficient energy systems and cost-effective reductions of global carbon dioxide (CO2) emissions, along with its customers. Analyses have been performed on how a local energy company can optimise their DH and DC production and what supply-side and demand-side measures can lead to energy-efficient systems in combination with economic and climate change benefits. The energy company in focus is located in Linköping, Sweden. Optimisation models, such as MODEST and reMIND, have been used for analysing the energy systems. Scenario and sensitivity analyses have also been performed for evaluation of the robustness of the energy systems studied. For all analyses a European energy system perspective was applied, where a fully deregulated European electricity market with no bottlenecks or other system failures was assumed.

In this thesis it is concluded that of the DH-supply technologies studied, the biomass gasification applications and the natural gas combined cycle (NGCC) CHP are the technologies with the largest global CO2 reduction potential, while the biomass-fuelled plant that only produces heat is the investment with the smallest global CO2 reduction and savings potential. However, the global CO2 reduction potential for the biomass integrated gasification combined cycle (BIGCC) CHP and NGCC CHP, the two technologies with highest electricity efficiencies, is highly dependent on the assumptions made about marginal European electricity production. Regarding the effect on the DH system cost the gasification application integrated with production of renewable biofuels (SNG) for the transport sector is the investment option with the largest savings potential for lower electricity prices, while with increasing electricity prices the BIGCC and NGCC CHP plants are the most cost-effective investment options. The economic outcome for biomass gasification applications is, however, dependent on the level of policy instruments for biofuels and renewable electricity. Moreover, it was shown that the tradable green certificates for renewable electricity can, when applied to DH systems, contribute to investments that will not fully utilise the DH systems’ potential for global CO2 emissions reductions.

Also illustrated is that conversion of industrial processes, utilising electricity and fossil fuels, to DH and DC can contribute to energy savings. Since DH is mainly used for space heating, the heat demand for DH systems is strongly outdoor temperature-dependent. By converting industrial processes, where the heat demand is often dependent on process hours instead of outdoor temperature, the heat loads in DH systems can become more evenly distributed over the year, with increased base-load heat demand and increased electricity generation in CHP plants as an outcome. This extra electricity production, in combination with the freed electricity when converting electricity-using processes to DH, can replace marginal electricity production in the European electricity market, resulting in reduced global CO2 emissions.

Demonstrated in this thesis is that the local energy company, along with its customers, can contribute to reaching the European Union’s targets of reducing energy use and decreasing CO2 emissions. This can be achieved in a manner that is cost-effective to both the local energy company and the customers.

Abstract [sv]

Den globala uppvärmningen i kombination med ett ökat energibehov och stigande energipriser gör det nödvändigt att förändra energianvändningen. Energieffektiva system är samtidigt en förutsättning för att kunna säkra energitillförseln och utveckla hållbara samhällen. Fjärrvärme har en viktig roll att fylla i den här omställningen. I fjärrvärmesystemen kan värmeresurser som annars kan vara svåra att nyttiggöras, som till exempel spillvärme och förbränning av avfall tas tillvara. Fjärrvärme kan även bidra till elproduktion i kraftvärmeverk där totalverkningsgraden är högre än vid separat el- respektive värmeproduktion. En omställning av energisystemet till en ökad användning av fjärrvärme och minskad användning av el genom effektiviseringar och konverteringar från olja och el till fjärrvärme kan bidra till att skapa energieffektiva system.

Syftet med den här avhandlingen är att identifiera hur ett lokalt energibolag som producerar fjärrvärme, fjärrkyla och el i kraftvärmeverk kan bidra till att skapa energieffektiva system och kostnadseffektiva globala koldioxidreduktioner tillsammans med sina kunder. Det energibolag som framförallt har studerats i den här avhandlingen är Tekniska Verken i Linköping AB. För att optimera energibolagets fjärrvärme- och fjärrkylaproduktion har energisystemanalyser genomförts, där både åtgärder på tillförsel- och användarsidan har studerats. Genom att se energiförsörjningen ur ett systemperspektiv kan man undvika att ekonomiska och miljömässiga vinster vid en anläggning ersätts av förluster någon annanstans. Optimeringsmodeller, som MODEST och reMIND, har använts för energisystemanalyserna där även scenarier och känslighetsanalyser har inkluderats. För alla energisystemanalyser har ett europeiskt energisystemperspektiv använts där en totalt avreglerad europeisk elmarknad utan flaskhalsar eller andra systemfel antagits.

Slutsatser från analyserna är att det lokala energibolaget kan bidra till kostnadseffektiva globala koldioxidreduktioner genom ett effektivt nyttjande av bränslen i kraftvärmeanläggningar och i bioraffinaderier. Speciellt kraftvärmeanläggningar med hög elverkningsgrad, som t.ex. biomasseförgasning- och naturgaskombianläggningar, har en betydande global koldioxidreduktionspotential. Även biomasseförgasningsanläggningar som är integrerade med produktion av förnybara drivmedel för transportsektorn har visat sig kostnadseffektiva med stor potential att reducera de globala koldioxidutsläppen. Styrmedel har dock en stor påverkan på det ekonomiska utfallet för förgasningsanläggningarna.

Dessutom har studierna visat att energibesparingar kan åstadkommas genom att konvertera el och fossilbränsledrivna industriella processer till fjärrvärme och fjärrkyla. Eftersom fjärrvärme framförallt används för lokaluppvärmning är värmelasten i fjärrvärmesystem säsongsbetonad. Genom att konvertera industriella processer som inte är utetemperaturberoende till fjärrvärme kan fjärrvärmelasten bli mindre säsongsbetonad och mer jämt fördelad över året. En jämt fördelad värmelast är fördelaktig för driften av fjärrvärmeanläggningar och kan bidra till mer elproduktion i kraftvärmeanläggningar. Den extra elproduktionen, tillsammans med den el som blivit tillgänglig efter konvertering av eldrivna processer till fjärrvärme, kan ersätta europeisk marginalelsproduktion vilket kan reducera de globala koldioxidutsläppen.

Det som har framkommit av dessa studier är att det lokala energibolaget, tillsammans med sina kunder, kan bidra till att uppfylla de mål den Europeiska Unionen har angående reduktionen av energianvändningen och koldioxidutsläppen. Dessutom kan detta ske på ett kostnadseffektivt sätt för både energibolaget och dess kunder.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2010. , 77 p.
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1336
Keyword [en]
District heating, combined heat and power, carbon dioxide emissions, optimisation, energy policies
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:liu:diva-58716ISBN: 978-91-7393-325-4 (print)OAI: oai:DiVA.org:liu-58716DiVA: diva2:345085
Public defence
2010-10-08, ACAS, A-huset, Campus Valla, Linköpings universitet, Linköping, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2010-09-01 Created: 2010-08-23 Last updated: 2010-09-01Bibliographically approved
List of papers
1. Pricing district heating by marginal cost
Open this publication in new window or tab >>Pricing district heating by marginal cost
2009 (English)In: ENERGY POLICY, ISSN 0301-4215 , Vol. 37, no 2, 606-616 p.Article in journal (Refereed) Published
Abstract [en]

A vital measure for industries when redirecting the energy systems towards sustainability is conversion from electricity to district heating (DH). This conversion can be achieved for example, by replacing electrical heating with DH and compression cooling with heat-driven absorption cooling. Conversion to DH must, however, always be an economically attractive choice for an industry. In this paper the effects for industries and the local DH supplier are analysed when pricing DH by marginal cost in combination with industrial energy efficiency measures. Energy audits have shown that the analysed industries can reduce their annual electricity use by 30% and increase the use of DH by 56%. When marginal costs are applied as DH tariffs and the industrial energy efficiency measures are implemented, the industrial energy costs can be reduced by 17%. When implementing the industrial energy efficiency measures and also considering a utility investment in the local energy system, the local DH supplier has a potential to reduce the total energy system cost by 1.6 million EUR. Global carbon dioxide emissions can be reduced by 25,000 tonnes if the industrial energy efficiency measures are implemented and when coal-condensing power is assumed to be the marginal electricity source.

Keyword
District heating, Marginal cost, Carbon dioxide emissions
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-16972 (URN)10.1016/j.enpol.2008.10.003 (DOI)
Available from: 2009-03-01 Created: 2009-02-27 Last updated: 2010-09-01
2. Biomass gasification opportunities in a district heating system
Open this publication in new window or tab >>Biomass gasification opportunities in a district heating system
2010 (English)In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 34, no 5, 637-651 p.Article in journal (Refereed) Published
Abstract [en]

This paper evaluates the economic effects and the potential for reduced CO2 emissions when biomass gasification applications are introduced in a Swedish district heating (DH) system. The gasification applications included in the study deliver heat to the DH network while producing renewable electricity or biofuels. Gasification applications included are: external superheater for steam from waste incineration (waste boost, WE), gas engine CHP (BIGGE), combined cycle CHP (BIGCC) and production of synthetic natural gas (SNG) for use as transportation fuel. Six scenarios are used, employing two time perspectives - short-term and medium-term - and differing in economic input data, investment options and technical system. To evaluate the economic performance an optimisation model is used to identify the most profitable alternatives regarding investments and plant operation while meeting the DH demand. This study shows that introducing biomass gasification in the DH system will lead to economic benefits for the DH supplier as well as reduce global CO2 emissions. Biomass gasification significantly increases the potential for production of high value products (electricity or SNG) in the DH system. However, which form of investment that is most profitable is shown to be highly dependent on the level of policy instruments for biofuels and renewable electricity. Biomass gasification applications can thus be interesting for DH suppliers in the future, and may be a vital measure to reach the 2020 targets for greenhouse gases and renewable energy, given continued technology development and long-term policy instruments.

Place, publisher, year, edition, pages
Elsevier Science B.V., Amsterdam., 2010
Keyword
Biomass gasification, District heating, Optimisation, Global CO2 emissions, Energy system, Biorefinery
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-56808 (URN)10.1016/j.biombioe.2010.01.007 (DOI)000277918300007 ()
Note
Original Publication: Kristina Difs, Elisabeth Wetterlund, Louise Trygg and Mats Söderström, Biomass gasification opportunities in a district heating system, 2010, BIOMASS and BIOENERGY, (34), 5, 637-651. http://dx.doi.org/10.1016/j.biombioe.2010.01.007 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2010-06-04 Created: 2010-06-04 Last updated: 2017-12-12Bibliographically approved
3. Absorption Cooling in CHP systems - old technique with new opportunities
Open this publication in new window or tab >>Absorption Cooling in CHP systems - old technique with new opportunities
2008 (English)In: World Renewable Energy Congress and Exhibition,2008, 2008Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-44120 (URN)75681 (Local ID)75681 (Archive number)75681 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2010-09-01
4. Increased use of district heating in industrial processes - Impacts on heat load duration
Open this publication in new window or tab >>Increased use of district heating in industrial processes - Impacts on heat load duration
2009 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 86, no 11, 2327-2334 p.Article in journal (Refereed) Published
Abstract [en]

Current knowledge of the potential for an increased use of industrial district heating (DH) due to conversions of industrial processes to DH is limited. In this paper, a Method for Heat Load Analysis (MeHLA) for exploring industrial DH conversions has been developed. This method can be a helpful tool for analyzing the impact different industrial processes have on the local DH system, when processes that utilize electricity and other fuels, convert to utilizing DH instead. Heat loads for different types of industries and processes are analyzed according to characteristics such as temperature levels and time dependency. MeHLA has been used to analyze 34 Swedish industries and the method demonstrates how conversion of industrial processes to DH can result in heat load duration curves that are less outdoor temperature-dependent and more evenly distributed over the year. An evenly distributed heat load curve can result in increased annual operating time for base load DH plants such as cogeneration plants, leading to increased electricity generation. In addition to the positive effects for the DH load duration curve, the conversions to DH can also lead to an 11% reduction in the use of electricity, a 40% reduction in the use of fossil fuels and a total energy end-use saving of 6% in the industries. Converting the industrial processes to DH will also lead to a potential reduction of the global carbon dioxide emissions by 112,000 tonnes per year.

Keyword
District heating, heat load duration curve, industrial heat load, global CO2
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-17212 (URN)10.1016/j.apenergy.2009.03.011 (DOI)
Available from: 2009-03-11 Created: 2009-03-11 Last updated: 2017-12-13Bibliographically approved
5. Increased industrial district heating use in a CHP system: economic consequences and impact on global CO2 emissions
Open this publication in new window or tab >>Increased industrial district heating use in a CHP system: economic consequences and impact on global CO2 emissions
2009 (English)In: 5th European Conference on Economics and Management of Energy in Industry, 2009Conference paper, Published paper (Other academic)
Abstract [en]

The use of district heating (DH) in industrial processes is relatively limited compared to other fuels and electricity. Hence, the industrial sector has great potential to convert from electricity and fossil fuels to DH. In addition, DH is mainly used for space heating and hot tap water, which makes the DH demand strongly seasonally dependent. By converting industrial processes like cooling, drying and industrial heating to DH, the heat load curve will be more evenly distributed throughout the year, thus utilizing the DH production resources better. This paper analyses how conversions from electricity or other fuels to district heating (DH) in industrial processes will affect an energy system. The effect of a more evenly distributed heat load profile is analysed with different policy instruments, fuel prices and electricity prices. In this study, three CHP plants acting as base load plants, which utilize different fuels (biofuel, waste and natural gas), are analysed. The result shows that when the use of district heating in industrial processes is increased it will lead to reduced system cost in both the biofueled and waste-incinerated combined heat and power system. Furthermore, when considering European electricity production in coal condensing and natural gas power plants, conversion to DH will also lead to possible reduced global CO2 emissions.

Keyword
Combined heat and power, district heating, industrial heat load, heat load duration, energy efficiency audits
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-52014 (URN)
Conference
5th European Conference on Economics and Management of Energy in Industry, 14-17 April, Vilamoura, Portugal
Available from: 2009-11-30 Created: 2009-11-30 Last updated: 2010-09-01
6. Energy conservation measures in buildings heated by district heating - A local energy system perspective
Open this publication in new window or tab >>Energy conservation measures in buildings heated by district heating - A local energy system perspective
2010 (English)In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 35, no 8, 3194-3203 p.Article in journal (Refereed) Published
Abstract [en]

The extensive energy use in the European building sector creates opportunities for implementing energy conservation measures (ECMs) in residential buildings. If ECM are implemented in buildings that are connected to a district heating (DH) system, the operation of DH plants may be affected, which in turn may change both revenue and electricity production in cogeneration plants. In this study a local energy system, containing a DH supplier and its customer, has been analysed when implementing three ECMs: heat load control, attic insulation and electricity savings. This study is unique since it analyses economic and CO2 impacts of the ECMs in both a user and a supplier perspective in combination with a deregulated European electricity market. Results show that for the local energy system electricity savings should be prioritised over a reduction in DH use, both from an economic and a global CO2 perspective. For the DH supplier attic insulation demonstrates unprofitable results, even though this measure affects the expensive peak load boilers most. Heat load control is however financially beneficial for both the DH supplier and the residences. Furthermore, the relation between the fixed and variable DH costs is highlighted as a key factor for the profitability of the ECMs.

Place, publisher, year, edition, pages
Elsevier Science B.V., Amsterdam., 2010
Keyword
Energy conservation measures; District heating; Combined heat and power; Optimisation; Residential buildings
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-58169 (URN)10.1016/j.energy.2010.04.001 (DOI)000280017300008 ()
Note
Original Publication: Kristina Difs, Marcus Bennstam, Louise Trygg and Lena Nordenstam, Energy conservation measures in buildings heated by district heating - A local energy system perspective, 2010, Energy, (35), 8, 3194-3203. http://dx.doi.org/10.1016/j.energy.2010.04.001 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/ Available from: 2010-08-11 Created: 2010-08-09 Last updated: 2017-12-12
7. National energy policies: obstructing the reduction of global CO2 emissions? An analysis of Swedish energy policies for the district heating sector
Open this publication in new window or tab >>National energy policies: obstructing the reduction of global CO2 emissions? An analysis of Swedish energy policies for the district heating sector
2010 (English)In: Energy Policy, ISSN 0301-4215, E-ISSN 1873-6777, Vol. 38, no 12, 7775-7782 p.Article in journal (Refereed) Published
Abstract [en]

The effect of national energy policies on a local Swedish district heating (DH) system has been studied regarding the profitability of new investments and the potential for climate change mitigation. The DH system has been optimised regarding three investments: biomass-fuelled CHP (bio CHP), natural gas-fuelled combined cycle CHP (NGCC CHP) and biomass-fuelled heat-only boiler (bio HOB) in two scenarios (with or without national taxes and policy instruments). In both scenarios EU’s tradable CO2 emission permits are included. Results from the study show that when national policies are included, the most cost-effective investment option is the bio CHP technology. However, when national taxes and policy instruments are excluded, the DH system containing the NGCC CHP plant has 30% lower system cost than the bio CHP system. Regardless of the scenario and when coal condensing is considered as marginal electricity production, the NGCC CHP has the largest global CO2 reduction potential, about 300 ktonne CO2. However, the CO2 reduction potential is highly dependent on the marginal electricity production. Demonstrated here is that national policies such as tradable green certificates can, when applied to DH systems, contribute to investments that will not fully utilise the DH systems’ potential for global CO2 emissions reductions.

Keyword
Energy policies, carbon dioxide emissions, district heating
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-58715 (URN)10.1016/j.enpol.2010.08.037 (DOI)000285032000025 ()
Available from: 2010-08-23 Created: 2010-08-23 Last updated: 2017-12-12

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