ABSTRACT Heat load variations, daily as well as seasonal, are constraining co-generation of high-... more ABSTRACT Heat load variations, daily as well as seasonal, are constraining co-generation of high-value energy products as well as excess heat utilisation. Integration of heat-driven absorption cooling (AC) technology in a district heating and cooling (DHC) system raises the district heat (DH) demand during low-demand periods and may thus contribute to a more efficient resource utilisation. In Sweden, AC expansion is a potentially interesting option since the cooling demand is rapidly increasing, albeit from low levels, and DH systems cover most of the areas with potential cooling demand. This study aims to assess the potential for cost and CO2 emission reduction due to expansion of DH-driven AC instead of electricity-driven compression cooling in the DHC system of Göteborg, characterised by a high share of low-cost excess heat sources. The DHC production is simulated on an hourly basis using the least-cost model MARTES. Despite recent advances of compression chillers, the results show potential for cost-effective CO2 emission reduction by AC expansion, which is robust with regards to the different scenarios applied of energy market prices and policies. While the effects on annual DHC system results are minor, the study illustrates that an increased cooling demand may be met by generation associated with low or even negative net CO2 emissions – as long as there is high availability of industrial excess heat in the DHC system, or if e.g. new biomass-based combined heat and power capacity is installed, due to the avoided and replaced marginal power generation.
Comfort cooling demand is increasing also in temperate countries. There, the cooling demand is ch... more Comfort cooling demand is increasing also in temperate countries. There, the cooling demand is characterised by strong seasonal as well as daily demand variations. The utilisation of heat-driven absorption chillers instead of conventional electricity-driven compression chillers is decreasing the power used for cooling but this option is mainly of interest where there is low-cost heat available. Thus, within district-heating (DH) systems with large excess heat supplies this might be a particularly attractive solution. In other DH systems this may instead provide the basis for expanded combined heat and power operation. In Sweden, this is a potentially interesting option since cooling demand is rapidly increasing, albeit from low levels, and DH systems cover most of the areas with potential cooling demand. The aim of the study is to analyse the potential CO2 reduction due to increased substitution of compression chillers by DH-driven absorption chillers. The study is a case study using the district heating and cooling (DHC) system of Goteborg, characterised by a high share of industrial and municipal solid waste incineration excess heat. The DHC production is simulated with a detailed time slice division using the least-cost DH supply model MARTES. The heat needed in the absorption chillers is assumed to be supplied by marginally produced DH. The results show that an increased share of absorption cooling capacity can lead to cost-effective CO2 emissions reduction. The simulation results show that the heat used in the absorption chillers mainly is low-cost industrial excess heat. As long as this is available, or if e.g. new biomass-based CHP is installed within the DHC system, an increased cooling demand can be met by generation associated with low net CO2 emissions due to the avoided and replaced marginal power generation.
The use of district heating (DH) in industrial processes is relatively limited compared to other ... more 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 ...
The aim of this thesis is to identify measures which should be taken in DH systems (DHSs) in orde... more The aim of this thesis is to identify measures which should be taken in DH systems (DHSs) in order to contribute to the development of the DHSs and other energy systems (especially transport, industrial and power sectors) toward sustainability.Four business strategies were analysed: delivering excess heat from biofuel production industry to DHSs, conversion of industrial processes to DH, integration of biofuel production in DHSs and integration of DHdriven absorption cooling technology in DHSs. Delivering excess heat from biofuel production industry to DHSs was analysed with a focus on the biofuel production costs for four biofuel production technologies. Integration of biofuel production and integration of DH-driven absorption cooling technology in DHSs were analysed with a focus on Stockholm’s DHS, using an optimisation model framework called MODEST. When the conversion of industrial processes to DH was analysed, DHSs and industrial companies in Vastra Gotaland, Ostergotland and Jonkoping counties were used as case studies; a method for heat load analysis called MeHLA was used to analyse the effects on the local DHSs.The results showed that when considering biomass an unlimited resource, by applying the abovementioned business strategies DH has a potential to reduce global fossil fuel consumption and global GHG emissions associated with power, industrial and transport sectors.DH producers may contribute to the sustainable development of the transport sector by buying excess heat from the biofuel production industry. This business strategy results in lower biofuel production costs, which promotes development of biofuel production technologies that are not yet commercial. Moreover, introduction of large-scale biofuel production into local DHSs enables development of local biofuel supply chains; this may facilitate the introduction of biofuel in the local transport sectors and subsequently decrease gasoline and fossil diesel use. Conversion of industrial processes from fossil fuels and electricity to DH is a business strategy which would make the industry less dependent on fossil fuels and fossil fuelbased electricity. DH may also contribute to the sustainable development of the industry by buying waste heat from industrial processes, since this strategy increases the total energy efficiency of the industrial processes and reduces production costs. Furthermore, DH has a possibility to reduce fossil fuel consumption and subsequently GHG emissions in the power sector by producing electricity in biomass- or waste-fuelled CHP plants.When the marginal electricity is associated with high GHG emissions (e.g. when it is produced in coal-fired condensing power (CCP)) plants, the reduction of the marginal electricity production (due to the conversion of industrial processes from electricity to DH and due to the conversion of compression cooling to DHdriven absorption cooling) results in higher environmental benefits. On the other hand, the introduction of biofuel production into DHSs becomes less attractive from an environmental viewpoint, because the investments in biofuel production instead of in CHP production lead to lower electricity production in the DHSs. The increased DH use in industry and introduction of the biofuel production and DH-driven absorption cooling production into the DHSs lead to increased biomass use in the DHSs. Because of this, if biomass is considered a limited resource, the environmental benefits of applying these business strategies are lower or non-existent.
Global warming, in combination with increasing energy demand and higher energy prices, makes it n... more 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 Linkoping, 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.
A common electricity market in Europe will in all probability lead to a levelling out of the elec... more A common electricity market in Europe will in all probability lead to a levelling out of the electricity price, which implies that Swedish consumers will face higher electricity prices with a European structure. This new market situation will force industry and energy suppliers to take new essential measures as actors in a deregulated European electricity market. In this thesis it is shown how over 30 Swedish small and medium-sized industries can reduce their use of electricity by about 50%. When scaling up the result to include all Swedish industry, the measures will lead to a significant reduction in global CO2 emissions, and a situation where Sweden will have a net export of electricity. Changing industrial energy use towards increased use of district heating will consequently affect the local energy suppliers. As a local energy supplier invests in CHP and co-operates on heat with an industry that has altered its energy use, the system cost will be halved. Considering higher European electricity prices, the benefits will be even higher with possibilities to reduce global emission with over 350%. In Sweden where district heating is very well established, heat driven absorption technology is especially favourable since it will lead to cost effective electricity production and increased utilization time for a CHP plant. Vapour compression chillers have been compared with heat driven absorption cooling for a local energy utility with a district cooling network and for industries in a Swedish municipality with CHP. The results show that the higher the share of absorption technology is, in comparison to compression chillers, the lower the production cost will be for producing cooling. This thesis illustrates measures for Swedish industry and energy suppliers in a fully deregulated European electricity market that will shift the energy systems in the direction of cost-effectiveness and resource effectiveness. The thesis also shows that the benefits of the measures will increase even more when accounting with electricity prices with a higher European structures. To methodically change the use of electricity would be an economical way to increase the competitiveness of Swedish plant in relation to other European plants. Taking advantage of these particularly Swedish conditions will contribute to the creation of lean resource systems, and as a result help the whole EU region to meet its commitment under the Kyoto Protocol. Altering industrial energy use towards less electricity and energy dependence will be a competitive alternative to new electricity production and help secure energy supply in the European Union.
ABSTRACT Heat load variations, daily as well as seasonal, are constraining co-generation of high-... more ABSTRACT Heat load variations, daily as well as seasonal, are constraining co-generation of high-value energy products as well as excess heat utilisation. Integration of heat-driven absorption cooling (AC) technology in a district heating and cooling (DHC) system raises the district heat (DH) demand during low-demand periods and may thus contribute to a more efficient resource utilisation. In Sweden, AC expansion is a potentially interesting option since the cooling demand is rapidly increasing, albeit from low levels, and DH systems cover most of the areas with potential cooling demand. This study aims to assess the potential for cost and CO2 emission reduction due to expansion of DH-driven AC instead of electricity-driven compression cooling in the DHC system of Göteborg, characterised by a high share of low-cost excess heat sources. The DHC production is simulated on an hourly basis using the least-cost model MARTES. Despite recent advances of compression chillers, the results show potential for cost-effective CO2 emission reduction by AC expansion, which is robust with regards to the different scenarios applied of energy market prices and policies. While the effects on annual DHC system results are minor, the study illustrates that an increased cooling demand may be met by generation associated with low or even negative net CO2 emissions – as long as there is high availability of industrial excess heat in the DHC system, or if e.g. new biomass-based combined heat and power capacity is installed, due to the avoided and replaced marginal power generation.
Comfort cooling demand is increasing also in temperate countries. There, the cooling demand is ch... more Comfort cooling demand is increasing also in temperate countries. There, the cooling demand is characterised by strong seasonal as well as daily demand variations. The utilisation of heat-driven absorption chillers instead of conventional electricity-driven compression chillers is decreasing the power used for cooling but this option is mainly of interest where there is low-cost heat available. Thus, within district-heating (DH) systems with large excess heat supplies this might be a particularly attractive solution. In other DH systems this may instead provide the basis for expanded combined heat and power operation. In Sweden, this is a potentially interesting option since cooling demand is rapidly increasing, albeit from low levels, and DH systems cover most of the areas with potential cooling demand. The aim of the study is to analyse the potential CO2 reduction due to increased substitution of compression chillers by DH-driven absorption chillers. The study is a case study using the district heating and cooling (DHC) system of Goteborg, characterised by a high share of industrial and municipal solid waste incineration excess heat. The DHC production is simulated with a detailed time slice division using the least-cost DH supply model MARTES. The heat needed in the absorption chillers is assumed to be supplied by marginally produced DH. The results show that an increased share of absorption cooling capacity can lead to cost-effective CO2 emissions reduction. The simulation results show that the heat used in the absorption chillers mainly is low-cost industrial excess heat. As long as this is available, or if e.g. new biomass-based CHP is installed within the DHC system, an increased cooling demand can be met by generation associated with low net CO2 emissions due to the avoided and replaced marginal power generation.
The use of district heating (DH) in industrial processes is relatively limited compared to other ... more 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 ...
The aim of this thesis is to identify measures which should be taken in DH systems (DHSs) in orde... more The aim of this thesis is to identify measures which should be taken in DH systems (DHSs) in order to contribute to the development of the DHSs and other energy systems (especially transport, industrial and power sectors) toward sustainability.Four business strategies were analysed: delivering excess heat from biofuel production industry to DHSs, conversion of industrial processes to DH, integration of biofuel production in DHSs and integration of DHdriven absorption cooling technology in DHSs. Delivering excess heat from biofuel production industry to DHSs was analysed with a focus on the biofuel production costs for four biofuel production technologies. Integration of biofuel production and integration of DH-driven absorption cooling technology in DHSs were analysed with a focus on Stockholm’s DHS, using an optimisation model framework called MODEST. When the conversion of industrial processes to DH was analysed, DHSs and industrial companies in Vastra Gotaland, Ostergotland and Jonkoping counties were used as case studies; a method for heat load analysis called MeHLA was used to analyse the effects on the local DHSs.The results showed that when considering biomass an unlimited resource, by applying the abovementioned business strategies DH has a potential to reduce global fossil fuel consumption and global GHG emissions associated with power, industrial and transport sectors.DH producers may contribute to the sustainable development of the transport sector by buying excess heat from the biofuel production industry. This business strategy results in lower biofuel production costs, which promotes development of biofuel production technologies that are not yet commercial. Moreover, introduction of large-scale biofuel production into local DHSs enables development of local biofuel supply chains; this may facilitate the introduction of biofuel in the local transport sectors and subsequently decrease gasoline and fossil diesel use. Conversion of industrial processes from fossil fuels and electricity to DH is a business strategy which would make the industry less dependent on fossil fuels and fossil fuelbased electricity. DH may also contribute to the sustainable development of the industry by buying waste heat from industrial processes, since this strategy increases the total energy efficiency of the industrial processes and reduces production costs. Furthermore, DH has a possibility to reduce fossil fuel consumption and subsequently GHG emissions in the power sector by producing electricity in biomass- or waste-fuelled CHP plants.When the marginal electricity is associated with high GHG emissions (e.g. when it is produced in coal-fired condensing power (CCP)) plants, the reduction of the marginal electricity production (due to the conversion of industrial processes from electricity to DH and due to the conversion of compression cooling to DHdriven absorption cooling) results in higher environmental benefits. On the other hand, the introduction of biofuel production into DHSs becomes less attractive from an environmental viewpoint, because the investments in biofuel production instead of in CHP production lead to lower electricity production in the DHSs. The increased DH use in industry and introduction of the biofuel production and DH-driven absorption cooling production into the DHSs lead to increased biomass use in the DHSs. Because of this, if biomass is considered a limited resource, the environmental benefits of applying these business strategies are lower or non-existent.
Global warming, in combination with increasing energy demand and higher energy prices, makes it n... more 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 Linkoping, 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.
A common electricity market in Europe will in all probability lead to a levelling out of the elec... more A common electricity market in Europe will in all probability lead to a levelling out of the electricity price, which implies that Swedish consumers will face higher electricity prices with a European structure. This new market situation will force industry and energy suppliers to take new essential measures as actors in a deregulated European electricity market. In this thesis it is shown how over 30 Swedish small and medium-sized industries can reduce their use of electricity by about 50%. When scaling up the result to include all Swedish industry, the measures will lead to a significant reduction in global CO2 emissions, and a situation where Sweden will have a net export of electricity. Changing industrial energy use towards increased use of district heating will consequently affect the local energy suppliers. As a local energy supplier invests in CHP and co-operates on heat with an industry that has altered its energy use, the system cost will be halved. Considering higher European electricity prices, the benefits will be even higher with possibilities to reduce global emission with over 350%. In Sweden where district heating is very well established, heat driven absorption technology is especially favourable since it will lead to cost effective electricity production and increased utilization time for a CHP plant. Vapour compression chillers have been compared with heat driven absorption cooling for a local energy utility with a district cooling network and for industries in a Swedish municipality with CHP. The results show that the higher the share of absorption technology is, in comparison to compression chillers, the lower the production cost will be for producing cooling. This thesis illustrates measures for Swedish industry and energy suppliers in a fully deregulated European electricity market that will shift the energy systems in the direction of cost-effectiveness and resource effectiveness. The thesis also shows that the benefits of the measures will increase even more when accounting with electricity prices with a higher European structures. To methodically change the use of electricity would be an economical way to increase the competitiveness of Swedish plant in relation to other European plants. Taking advantage of these particularly Swedish conditions will contribute to the creation of lean resource systems, and as a result help the whole EU region to meet its commitment under the Kyoto Protocol. Altering industrial energy use towards less electricity and energy dependence will be a competitive alternative to new electricity production and help secure energy supply in the European Union.
Uploads
Papers by Louise Trygg