Louise Trygg - Academia.edu (original) (raw)

Papers by Louise Trygg

Energies, Oct 31, 2019

Linköping municipality has managed biogas driven buses in the regional transport system since 199... more Linköping municipality has managed biogas driven buses in the regional transport system since 1997 and all buses in the municipality have run on biogas since 2015. Biogas is a renewable fuel and by replacing fossil fuels it can help to lower net CO2 emissions. However, Internal Combustion Engines (ICE) in buses still have a rather low efficiency, in the range of 15-30%. If the combustion of biogas instead takes place in a combined cycle gas turbine (CCGT) efficiency could be higher and heat losses reduced. This could be a feasible solution if the transport system instead used electric buses charged with electricity generated by the CCGT. This article has a top-down perspective on the regional transport system and the regional district heating system (DHS) in Linköping municipality. Two alternative systems are compared regarding CO2 emissions, electricity production and component efficiencies. The first system that is studied is in operation today and uses locally produced biogas in the ICE buses. In parallel the combined heat and power (CHP) system delivers electricity and heat to households in the region. The second system that is studied is a system with electric buses and a CHP system that uses biogas in the CCGT to deliver electricity and heat to the regional power grid and DHS. The study shows that emissions would be reduced if biogas use is changed from use in ICE buses to use in the CCGT in the CHP-DHS. Improved biogas use could lower CO2-eq emissions by 2.4 million kg annually by using a better fuel-energy pathway.

Applied Energy, Nov 1, 2009

Current knowledge of the potential for an increased use of industrial district heating (DH) due t... more 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. 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 studied 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.

Applied Energy, Mar 1, 2012

Ethanol can be produced with little impact on the environment through the use of polygeneration t... more Ethanol can be produced with little impact on the environment through the use of polygeneration technology. This paper evaluates the potential of integrating a lignocellulosic ethanol plant into a district heating system by case study; the plant has an ethanol capacity of 95 MW with biogas, electricity and heat as by-products. Stockholm's district heating system is used as the case study, but the results may be relevant also for other urban areas. The system has been studied using MODEST-an optimisation model framework. The results show that introducing the plant would lead to a significant reduction in the cost of heat production. The income from the biofuels and electricity produced would be about €76 million and €130 million annually, respectively, which is an increase of 70% compared to the income from the electricity produced in the system today. Assuming that the electricity produced will replace marginal electricity on the European electricity market and that the biofuel produced will replace gasoline in the transport sector, the introduction of the polygeneration plant in the district heating system would lead to a reduction of global CO 2 emissions of about 0.7 million tonnes annually.

Journal of Cleaner Production, Dec 1, 2016

Denmark has a national political goal of a 100% renewable energy supply in 2050. This requires a ... more Denmark has a national political goal of a 100% renewable energy supply in 2050. This requires a comprehensive transition of the energy system. For some decades, district heating in Denmark has been contributing to high fuel efficiency as well as to the integration of the electricity and heating sectors. Largescale compression heat pumps would improve the integration between the district heating and power sectors by utilising the fluctuations in the supply from wind power, solar photo voltaic and other sources. Previous studies indicate that the introduction of heat pumps in Denmark will have a positive impact on the total costs for energy supply in the transition towards 100% renewable energy. In this paper, this is further investigated to assess the feasibility of heat pumps in the Danish energy system. The assessment is made by applying two different energy system analysis tools, named EnergyPLAN and MODEST. The comparison and discussion of these tools is a secondary purpose of the study. In general, the results show a potential for introducing heat pumps in Denmark between 2 and 4 GW-thermal power and a total potential benefit around 100 M€/year in 2025.

Journal of Cleaner Production, Apr 1, 2014

Integration of biofuel production into district heating-part I: an evaluation of biofuel producti... more Integration of biofuel production into district heating-part I: an evaluation of biofuel production costs using four types of biofuel production plants as case studies,

Energy Policy, Jul 1, 2008

Decreased energy use is crucial for achieving sustainable energy solutions. This paper presents c... more Decreased energy use is crucial for achieving sustainable energy solutions. This paper presents current and possible future electricity use in Swedish industry. Non-heavy lines of business (e.g. food, vehicles) that use one-third of the electricity in Swedish industry are analysed in detail. Most electricity is used in the support processes pumping and ventilation, and manufacturing by decomposition. Energy conservation can take place through e.g. more efficient light fittings and switching off ventilation during night and weekends. By energy-carrier switching, electricity used for heat production is replaced by e.g. fuel. Taking technically possible demand-side measures in the whole lines of business, according to energy audits in a set of factories, means a 35% demand reduction. A systems analysis of power production, trade, demand and conservation was made using the MODEST energy system optimisation model, which uses linear programming and considers the time-dependent impact on demand for days, weeks and seasons. Electricity that is replaced by district heating from a combined heat and power (CHP) plant has a dual impact on the electricity system through reduced demand and increased electricity generation. Reduced electricity consumption and enhanced cogeneration in Sweden enables increased electricity export, which displaces coal-fired condensing plants in the European electricity market and helps to reduce European CO 2 emissions. Within the European emission trading system, those electricity conservation measures should be taken that are more cost-efficient than other ways of reducing CO 2 emissions. The demand-side measures turn net electricity imports into net export and reduce annual operation costs and net CO 2 emissions due to covering Swedish electricity demand by 200 million euros and 6 Mtonne, respectively. With estimated electricity conservation in the whole of Swedish industry, net electricity exports would be larger and net CO 2 emissions would be even smaller.

Cleaner engineering and technology, Aug 1, 2022

Energies, Jul 12, 2017

In the European Union's Energy Performance of Buildings Directive, the energy efficiency goal for... more In the European Union's Energy Performance of Buildings Directive, the energy efficiency goal for buildings is set in terms of primary energy use. In the proposal from the National Board of Housing, Building, and Planning, for nearly zero energy buildings in Sweden, the use of primary energy is expressed as a primary energy number calculated with given primary energy factors. In this article, a multi-dwelling building is simulated and the difference in the primary energy number is investigated when the building uses heat from district heating systems or from heat pumps, alone or combined with solar thermal or solar photovoltaic systems. It is also investigated how the global CO 2 emissions are influenced by the different energy system combinations and with different fuels used. It is concluded that the calculated primary energy number is lower for heat pump systems, but the global CO 2 emissions are lowest when district heating uses mostly biofuels and is combined with solar PV systems. The difference is up to 140 tonnes/year. If the aim with the Swedish building code is to decrease the global CO 2 emissions then the ratio between the primary energy factors for electricity and heat should be larger than three and considerably higher than today.

Energy Conversion and Management, Aug 1, 2012

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.

Energy Policy, Feb 1, 2009

A vital measure for industries when redirecting the energy systems towards sustainability is conv... more 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 coalcondensing power is assumed to be the marginal electricity source.

Energy Procedia, Sep 1, 2018

District heating networks are commonly addressed in the literature as one of the most effective s... more District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand-outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations.

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.