Browsing by Author "Syri, Sanna, Prof., Aalto University, Department of Mechanical Engineering, Finland"

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  • Analyzing electricity market efficiency and impacts of renewable electricity
    (2022) Farsaei, Anahita
     School of Engineering | Doctoral dissertation (article-based)
    The EU aims to be climate-neutral by 2050. Achieving net-zero greenhouse gas emissions needsaction in all economic sectors including electricity markets. Electricity market is experiencing a rapid transition to renewable energy especially in the Nordic countries. Although the growing amount of renewables paves the path for climate change mitigation, their effect on market efficiency needs to be studied. Furthermore, in an interconnected multi-national electricity market, local energy policies in one country can affect the other countries. This dissertation examines these possible effects. This dissertation analyses market power potential in the Iranian electricity market as well as in Finland and in the Baltic countries. A new Lerner index is proposed for the pay-as-bid auction. Lerner index and HHI are employed for Finland and the Baltic countries. In addition, the impacts of local energy policies in Finland and Sweden on the neighboring countries are studied in this dissertation. Finland has implemented legislation to phase out coal by 2029. In Sweden, there is an ongoing debate regarding nuclear power. Different scenarios are proposed in this dissertation to analyze the effect of these policies on average electricity prices, CO2 emissions, electricity system cost and electricity trade in Finland, Sweden and the Baltic countries. For this purpose, the models Enerallt and REX are employed to model short-term and long-term future with low CO2 emissions. In the short-term, coal and peat in Finland are replaced with biomass while for 2050, a growing amount of wind power is employed. International transmission expansion is also considered in scenarios for 2050. The results indicate that in Iran market power potential increases during off-peak hours. In Finland, HHI and Lerner index values show that increasing wind power in the electricity market mostly results in less market power potential. However, for the Baltic countries despite the significant entrance of wind power in electricity market, they have a highly concentrated market. Results from analyzing the effects of local policies in interconnected markets on the neighboring countries show that national-level policies have impact on wider regions. In the short-term, phasing out coal in Finland may lead to increased electricity import from the wider Nordic market area and even outside it, mostly from regions with carbon-intensive generation. With this policy, among the studied countries only Finland will face a decrease in CO2 emissions in the region, while the rest of the countries will see a small increase. However, the long-term transition to very low CO2 emissions from the electricity production can benefit the Baltic countries. International transmission expansion by 2050 can provide the Baltic countries with an opportunity to have electricity sufficiency and export more electricity. Achieving this needs significant new investments in wind power capacity.
  • Challenges of an LCA based decision making framework – the case of EU sustainability criteria for biofuels
    (2016) Koponen, Kati
     School of Engineering | Doctoral dissertation (article-based)
    The European Union (EU) has set a 10% target for renewable energy in transportation by 2020 in its Renewable Energy Directive (RED). The EU has also set sustainability criteria for biofuels, including a greenhouse gas (GHG) calculation method to study the emission saving gained by biofuels compared to fossil fuels. Only biofuels accepted by these criteria can contribute to the renewable energy targets and benefit from national support systems. The GHG calculation method is an application of life cycle assessment (LCA) framework, which is often used to study the environmental impacts of biofuels. This thesis aims to analyse how a tool based on LCA framework can support decision making on biofuels in policy context and what are the challenges encountered.  Even though LCA is a widely applied tool for evaluating the environmental im-pacts of products, several challenges remain – for example related to system boundary setting, allocation procedure, and parameter assumptions. In policy context, the needed simplifications of the LCA framework create an extra chal-lenge. The results of this study show that the current RED GHG assessment method cannot alone guarantee the climate change mitigation benefits due to biofuel use. Therefore, several suggestions to develop the RED GHG criteria are given. General clarification of the RED guidelines concerning the interpretation problems, appropriate data, and cut-off criteria is needed. The uncertainty of the GHG results needs to be acknowledged, as LCA always present only an estima-tion of the real world. Economic allocation could be used instead of energy allocation, in order to clarify the economic causality of the analysed systems as well as the double counting rule of the RED for waste and residue based feedstocks. An important addition to the current RED method is to recognize the significance of potential loss of ecosystem carbon stocks and additional carbon sequestration related to bioenergy chains. This can be done by including the land use reference system in bioenergy LCA. The RED sustainability criteria and the EU bioenergy policy should be further developed in order to guarantee the use of most climate beneficial bioenergy options.
  • Consequences of demand-side interventions on the operation efficiency of future energy systems
    (2019) Olkkonen, Ville
     School of Engineering | Doctoral dissertation (article-based)
    National energy systems are in a state of transition. Electricity and heat generation from renewableenergy sources has increased substantially during the past few years in the European Union (EU).The EU member states project ambitious national targets for higher integration of variablerenewable energy (VRE) within electricity markets in particular. In this dissertation, the consequences of demand-side interventions on the energy system operation are examined. Demand-side interventions are studied in energy systems, where future transition is guided by the climate change mitigation policies for reducing greenhouse gas emissions and increasing the shareof renewable energy sources. First, the impact of stakeholder preferences in the evaluation ofdifferent heating choices for new single-family house in Finland are examined. The decisionproblem was analysed using multicriteria analysis considering different technical, economic,environmental and usability criteria. Since energy systems are being further interconnected in theEU through international power markets, the spatial and temporal variations regarding theenvironmental effects of electricity generation are examined in a national and multinational levelanalysis. The temporal variations in marginal electricity generation implicate that the short-termmarginal cost of production can vary significantly according to the time of the day. This means thatthe true cost of consuming electricity varies also depending of the time of use. In this regard, it isexamined how demand response, in this case temporally available shiftable demand affects theenergy system operation in Finland in future scenarios with increased shares of nuclear power andvariable renewable energy. The results indicate that in power markets that are highlyinterconnected, the effects of different demand-side interventions are not necessarily restricted tothe country (or bidding area) where demand-side intervention is committed. This is because theemissions embodied in electricity or system efficiency gains can leak to the neighbouring countriesas a consequence of electricity exchange. In this case, viewing the effects of demand-sideinterventions from a national perspective may be suboptimal. This study thus suggests that the marginal electricity generation in a multi-region system should be considered. Using the long-term perspective is also recommended when estimating the marginal consequences of a demand-side intervention that will influence the energy system in the long-term. Due to the spatial and temporal variations in marginal electricity generation, taking into account the time-varying nature of marginal emissions is recommended in relevant life cycle assessment studies. This variation was found to increase in the future due to the higher VRE integration. Demand response can be utilised to balance short-term variations in residual demand. However, its potential to facilitate higher integration of VRE can be limited by the technical and economic restrictions that constrain thedemand-side resource capacity utilisation. Demand response can therefore only partially replaceflexible conventional supply technologies in the provision of balancing power and energy.
  • Delivering Sustainable Energy in the European Context: Challenges and Solutions
    (2020) Cross, Samuel
     School of Engineering | Doctoral dissertation (article-based)
    Limiting GHG emissions, and thus mitigating climate change, requires radically improving the sustainability of energy systems, most significantly by increasing the share of renewable energy.Reaching this objective requires strong policy actions and planning, in addition to appropriate technology choices made by energy utilities. This thesis considers the question of delivering sustainable energy systems in the European context, focusing on the electricity sector. The scope includes advancing renewable energy but also other measures to increase energy sustainability, such as energy storage. A variety of perspectives are taken, with different geographic and sectoral contexts. The overall aim is to ascertain what are the key measures and best practices for improving energy system sustainability.The starting point is the EU 2009 Renewable Energy Directive (RED I) and its implementation of renewables targets for 2020. The progress of EU Member States towards reaching these targets is assessed, with a regional focus on the Nordic & Baltic states. The results indicate that effective,stable planning and policy support are required to advance renewables and that a broad portfolio of RES technologies is most appropriate, instead of a dominant reliance on a single technology.While the studied countries have met or are on track to meet their 2020 targets, a wider analysis indicates a number of EU Member States will not meet these objectives. This raises the question of the credibility of EU energy policy if these legally binding targets are not properly enforced.A key result with respect to bioenergy is that the future growth of the sector will be limited by the restricted primary biomass resource in the EU and meeting biomass sustainability requirements.Turning to a focus upon islanded power systems, the scope of this research is expanded to improving overall sustainability of energy systems. Beginning with a benchmarking analyses of 28 islanded systems, a range of measures are identified for improving energy system sustainability.These include peak shaving and development of interconnectors, in addition to the development of renewables. This leads directly to an analysis of the use of electrical energy storage (EES) on the island of Jersey. While this analysis is limited to use of EES for the specific objectives of the studied island, the effectiveness of energy storage is also reflected upon for broader objectives such as RES integration. Furthermore, other measures for RES integration are also considered. In summary, delivering sustainable, low carbon energy scenarios requires a wide range of measures, which existing modelling approaches do not always identify in order of cost efficiency.
  • Demand Response in District-heated Buildings
    (2021) Salo, Sonja
     School of Engineering | Doctoral dissertation (article-based)
    Heating and cooling account for approximately half of the total energy consumption in the European Union. That is why the European Commission in its strategy for the heating and cooling sector is emphasising ways to develop energy-saving and greenhouse gas-reducing solutions in buildings. District heating is one of the most efficient heating methods, especially in colder and densely populated areas. The challenges of district heating are large fluctuations in daily and seasonal consumption that are difficult to mitigate in the inflexible centralised production system. Additionally, district heating is mainly produced with fossil fuels and, thus, it is facing a shift towards low-carbon as well as more cost-effective systems. On the other hand, attention is being paid to the indoor air conditions in properties. The latest indoor air classifications focus on the thermal comfort of individuals in buildings that promote not only a healthy environment but also increased work efficiency. Therefore, heating control systems in buildings give priority to the comfort of people. This dissertation investigates the addition of flexibility to the district heating system by using the thermal inertia of building structures, as well as the thermal comfort of individuals during periods of demand response. In this dissertation, demand response refers to control measures for space heating in water-circulating radiator networks as a response for external requirements in demand. This dissertation develops rule-based control algorithms for room-level temperature control via water-circulating radiator thermostats connected to a cloud service. These control algorithms are applied in district-heated office buildings. The system allows for individual thermal comfort while performing optimised and targeted heating control. In addition, a district heating system with dynamic heating pricing was modeled for evaluating demand response by shifting loads in time on the building level and by utilising a centralised thermal energy storage. The results of the dissertation show that individuals report poorer thermal comfort than previously anticipated on days of demand response. Additionally, the modeling results also show that the demand flexibility of district heating utilising the thermal mass of buildings is of little benefit to the district heating company. Thus, demand response itself does not bring savings to the property owner either. However, field studies show that room-based control enables individual heating, which can save energy even in highly energy-efficient office buildings.
  • District heating with low-carbon heat sources and low distribution temperatures
    (2020) Rämä, Miika
     School of Engineering | Doctoral dissertation (article-based)
    Energy supply sector is the largest source of anthropogenic emissions with a share of more than a third in global greenhouse gas (GHG) emissions. In terms of energy demand, the heating and cooling sector corresponds to more than a half of the global final energy consumption. Urban areas have been evaluated to be responsible of 76 % of global energy use and 37-49 % of the GHG emissions. The relevance of cities in the context of climate change mitigation and the significance of the heating and cooling sector imply that solutions for urban areas are an essential part of the mitigation measures needed. This is where district heating (DH) and district cooling (DC) technologies can play an important role. Both DH and DC are energy solutions designed for densely populated areas. This thesis focuses on developing DH systems by studying means for improving their efficiency and integrating more low-carbon heat sources for heat supply. The potential impact of low temperature distribution is also assessed. The heat sources considered in the scope of the presented research are heat pumps (HPs), solar collectors (SCs) and nuclear district heating (NDH). Centralized SCs provide 4-5 times higher heat output than decentralised building-specific units with the same total investment. However, HPs outperform the centralized SCs in Finnish DH systems by producing 9-30 times more heat with the same investment. The feasibility of NDH is strongly linked to the DH demand and distance between the site and the DH system. Low temperature distribution reduces the heat losses and, more importantly, improves the efficiency of connected heat supply. A fair and transparent allocation of benefits and costs is a prerequisite for the transition due to stakeholders involved. The benefits are for heat supply and distribution (DH company) while costs mainly result from required building-level changes (customer). The use of low temperature distribution requires more careful management of the temperature levels, making network simulation tools both in planning and operational phase important. Both HPs and SCs benefit from low distribution temperatures.
  • Effective integration of renewable energy in Northern European energy systems
    (2024) Hyvönen, Johannes
     School of Engineering | Doctoral dissertation (article-based)
    The European Union (EU) has committed to reaching carbon neutrality by 2050 at the latest, with Finland ambitiously pledging to reach net-zero carbon emissions already by 2035. Reaching these targets will require a rapid expansion in renewable energy generation over the next decade, which will mostly be facilitated by market incentives and private investments in the EU. Yet, it is still somewhat unclear what technologies will effectively enable different sectors to be decarbonized in the future, especially as increased energy market uncertainty and high electricity prices have become common in the last years following the war in Ukraine and the EU energy crisis in 2022. This thesis thus aims to provide new insights into how renewable energy use can be increased effectively in both individual and national energy systems in Northern Europe, with Publications I–III assessing the techno-economic feasibility of solar PV and energy storage systems in end-consumer applications in Finland, and Publications IV–VI focusing on how potential risks, limitations, and challenges may impact the transition to clean energy in Northern Europe.  The results of this thesis indicate that both smaller and larger locally installed solar PV systems can effectively increase the share of renewable energy in residential buildings and data centers in northern countries. Yet, in most cases, this necessitates selling surplus electricity to the grid to be cost-effective, as the use of energy storage to balance solar PV systems is shown to generally increase energy-related costs for end-consumers at higher latitudes. Moreover, the results highlight how resource adequacy and power supply security will be crucial in ensuring the effective transition to clean energy in Northern Europe. Notably, potential limitations in critical mineral and biomass availability pose significant risks to reaching national climate and energy policy targets in Finland and Northern Europe, as the global supply of many critical minerals is currently highly concentrated in a few non-EU countries and will have to be expanded considerably to facilitate the global transition to clean energy, and as Finland and similar countries will need to increase forestry carbon removals substantially to meet EU emission reduction targets for 2030 and to stay on track to attain national carbon neutrality targets. Additionally, the presented analysis suggests that new investments into flexible thermal power generation are necessary to cost-effectively balance the growing share of intermittent wind and solar PV generation in the Finnish power system by 2035. Subsequently, this thesis highlights how further action is needed to facilitate renewable energy integration and attain national climate targets in Northern Europe, as well as to guarantee resource adequacy and energy system reliability in the clean energy transition.
  • Energy transition impacts and opportunities in the Nordic electricity and district heating markets
    (2019) Helin, Kristo
     School of Engineering | Doctoral dissertation (article-based)
    An ongoing period of low electricity market price has a negative impact on the profitability of many forms of electricity and heat production in the Nordic energy system. As the share of variable renewable energy increases and climate goals become more stringent, there is worry over how the heating and electricity sectors will adapt to new demands. This dissertation discusses the integration of the heat and electricity sectors for additional flexibility and efficiency in both. We take a market-based view on the integration because it is realised and maintained only if the necessary investment is profitable. We discuss three aspects of sector integration: industrial demand-side management (IDSM), combined heat and power (CHP) production, and large-scale heat pumps (LHPs). The economic IDSM capacity of a case pulp and paper mill differs significantly from the technical capacity due to the costs and risks of demand response actions. Owing to these, the technical capacity may be only partially utilised. The economy of the future use of CHP and LHPs in Nordic district heating has links to the overall electricity demand and electricity production capacities. The use of these technologies improves the efficiency of the energy system when compared with current competing technologies. Model results indicate continuous potential for the use of both past the year 2030, if electricity demand grows according to national forecasts. While we find economic potential for sector integration in all studied cases, there are limits and conditions for them, including the market price of electricity, as well as regulations and taxation. Research and policymaking aiming for increased sector integration should consider the market-based and international operation of the energy business. This will allow the holistic understanding of investment potential in sector integration beyond theoretical feasibility.
  • Integration of variable renewable energy in national and international energy systems: modelling and assessment of flexibility requirements
    (2016) Zakeri, Behnam
     School of Engineering | Doctoral dissertation (article-based)
    National energy policies seek to increase the share of local renewable energy to meet the targets for climate change mitigation and to enhance the energy security. In this respect, large-scale integration of variable renewable energy (VRE) seems to be a predominant option. To cope with the intermittency of VRE, energy systems need to employ different "flexibility" solutions to match energy supply and demand in different time scales.  This dissertation examines the flexibility of an energy system in integration of VRE by employing quantitative energy system modelling methods. First, the maximum flexibility of an energy system is quantified. Then, different flexibility solutions and their system-level benefits are compared. The dissertation examines the market value of flexibility to quantify the profitability of such options from an investor's viewpoint. Since energy systems are being further interconnected through international power markets, the role of such markets in integration of VRE is crucial. To examine this role, this contribution develops a market-based multi-region energy system model. The proposed model is an hourly simulation-optimization model capturing the main operational features of an international power market, as well as the local heat sector in each country.  The results indicate that the flexibility of the Finnish energy system is limited and needs to be improved to accommodate wind integration levels larger than 20% of the total electricity demand. For the examined energy system, large-scale heat pumps in connection with the district heating system and heat storage prove to be techno-economically the most promising flexibility option. The deployment of electrical energy storage is not profitable under today's market compensations, but the monetization of some externalities could make a business model for some storage technologies. The size of these system-level benefits of energy storage is quantified in this study. Last but not the least, the role of international power markets in providing flexibility is analysed. The integration of VRE in neighbouring countries entails overlapping impacts, which may diminish the flexibility of the whole system. The findings of this dissertation inform energy policy on the flexibility of the energy system to achieve the planned targets from high-level integration of VRE.
  • An interdisciplinary assessment of energy security risks in the Finnish energy market
    (2019) Jääskeläinen, Jaakko J.
     School of Engineering | Doctoral dissertation (article-based)
    Climate change is currently one of the most compelling global threats, and energy sector accounts for almost two thirds of all emissions related to the climate change. Therefore, national energy systems face conflicting pressure to supply the ever-increasing demand for energy while decarbonising energy production. Under this pressure, concern over energy security has increased. The most topical energy security concerns in the Finnish energy market are generation adequacy and import dependence. This dissertation examines these themes along with other market-related energy security risks in the Finnish context.  This dissertation analyses energy security in the Finnish energy system by examining various scenarios in investment, the future of combined heat and power (CHP) production, the impacts of a severe drought, and import dependence. The research is done in collaboration with multiple researchers from other disciplines such as law and environmental and political sciences. Generation adequacy in the Finnish energy system is analysed by using the EnergyPLAN simulation tool. The impacts of a severe drought on the Finnish energy system are analysed by combining hydrological and energy system modelling. Generation capacity investment prospects, particularly those of biomass-based CHP production, are analysed by applying the net present value (NPV) and levelised cost of electricity (LCOE) methods. Energy security issues related to a plausible decrease in the Finnish CHP capacity are analysed on a city-level (Helsinki) by applying quantitative modelling, and on national and international levels, by qualitative assessment. Finland's dependence on Russian energy import currently is analysed by applying the interdependence framework, and the future development of the energy-trade is studied by developing and analysing energy policy scenarios until 2040.  The results indicate that the Finnish energy system is currently well prepared against technical faults. Despite the public concern, challenges with generation adequacy due to technical reasons are improbable. A severe, multiyear drought in the Nordic area could affect generation adequacy in Finland particularly via reduced availability of electricity import during peak demand periods. Despite the high thermal efficiency of CHP production, the Finnish energy system would most probably function even if the capacity decreased notably in the 2020s. Finland's notable import dependence on Russian energy import has so far not resulted in any disruptions in security of supply, and the dependence is likely to decrease in the future. However, energy trade between the countries goes beyond techno-economic aspects, and it is difficult to predict the energy security implications of geopolitical and societal trends.
  • Parametric Models for Forest Industry Transformation in Energy Efficiency: Machine Learning Approach
    (2023) Talebjedi, Behnam
     School of Engineering | Doctoral dissertation (article-based)
    This thesis is based on industrial projects with Pulp and Paper industry in a Nordic country. The main focus of the thesis is on the energy efficiency development of the thermomechanical pulp (TMP) mill and optimal integration of the TMP mill and paper machine through heat recovery and the concept of an Energy Hub. Advanced statistical approaches and machine learning methods have been employed to develop refining identification models and advanced energy-saving refining optimization methods for the TMP process. Results prove that an accurate refining identification model could be developed through advanced machine learning methods. The refining identification models to predict the refining energy (such as specific energy consumption) and final pulp quality (such as freeness and fiber length) can be further used to develop a refining control and optimization strategy. The developed optimization strategy based on the integration of Machine learning methods and Genetic optimization algorithm confirms an average reduction of 14 % for the total refining-specific energy consumption. In the following, the optimal integration of the TMP mill and paper machine has been investigated through the Energy Hub (EH) concept. The proposed approach for the cost and energy-efficient design and operation of EH is based on the integration of thermo-economic analysis, reliability and availability analysis, and EH load prediction. The proposed approach was first introduced and evaluated for the energy and cost-efficient design of a combined cooling, heating, and power (CCHP) system that provides the hourly thermal demand of a high-rise residential building. Results prove that by utilizing the proposed method, the system's average total cost could be reduced by 16% during the system's lifespan. As the presented method has shown to be effective in residential EH applications, this method was examined in a second case study (the forest industry) to determine the optimal integration of TMP mill and paper machines. The proposed design method offers a robust design that isn't impacted by penalty rates of unsupplied demand. Depending on the penalty rates, the total system cost could decrease by 14%-28% utilizing the proposed design method.
  • Replacing fossil fuels in district heating - modelling investments, impacts, and uncertainties
    (2024) Lindroos, Tomi J.
     School of Engineering | Doctoral dissertation (article-based)
    Heating and cooling, including industrial heat, consume half of the final energy use in the EU and only 20% of it is produced from renewable sources. District heating (DH) could help decarbonizing heating, but DH sector must reduce its current emission first. In this Thesis, energy system modelling is applied to study investments to fossil-free DH production and related uncertainties. This Thesis uses an existing long-term energy system model TIMES-VTT and develops new more detailed DH models that capture additional real-life constraints and have faster solve times allowing extended uncertainty analysis. The electrification route includes many scalable technologies to replace fossil fuels in DH generation. Large heat pumps were the most robust of the studied investment options unless suffering from high electricity grid fees and taxes. However, local excess heat sources are often significantly smaller than the heat demand, especially in large cities. Ambient heat sources, such as sea water or air, could complement the available heat sources, but this depends highly on local conditions and heat demand density. The biomass route provides a range of well-rounded technologies to replace fossil fuels in district heating. However, this Thesis further strengthens the conclusion that there is not enough biomass available to replace all fossil fuels in DH even in Finland. Increasing biomass demand and decreasing forest sinks in the EU create significant uncertainties over the future availability and price of sustainable biomass. Certain upcoming technologies, such as nuclear district heating and bioenergy with carbon capture and storage, seem promising future decarbonization options, but they need technology development and demonstration units first. In the course of work, large system models proved to be more flexible the more detailed DH models. As a result, large system models indicated faster decarbonization leading to a situation where studies giving background information for climate and energy policies have lower-cost and faster decarbonization of heating sector than what may be achievable. Each modelling study should consider a large range of uncertainties, or they risk drawing flawed conclusions based on too narrow set of modelled cases and assumption ranges. The main sources of uncertainties in the results of this Thesis were related to the variability of electricity generation and price, biomass availability and price, natural gas price, investment costs of new units, breakthrough of new technologies, and the required phase of emission reductions.
  • Sector-Coupling and Renewable Energy Integration in Low-Carbon District Heating: Perspectives of Economics, Environment and Supply Security
    (2024) Javanshir, Nima
     School of Engineering | Doctoral dissertation (article-based)
    In the face of a global climate crisis, the imperative to reduce carbon emissions throughtransforming our energy infrastructure is paramount. This dissertation focuses on decarbonizing District Heating (DH) systems in Finland by integrating power-to-heat (P2H) technologies, including heat pumps and electric boilers, and renewable energy sources such as wind power, considering diverse energy market scenarios. Given the substantial role of heating in Finland's energy demand and the prevalence of DH systems, this topic is pivotal in meeting both national and international environmental objectives. The study encompasses case studies for Finnish cities, analyzing systems including a mid-sized network reliant on local fuels biomass and high-emission fuel peat and the large-scale networks of Helsinki metropolitan region, still dependent on imported fossil fuels, primarily natural gas and coal. This approach covers environmental and economic aspects, considering the fluctuating global fossil fuel prices and the increasing costs associated with carbon dioxide emissions allowances and fuel taxes. This dissertation evaluates the feasibility of partly electrified DH systems under different market conditions, including periods of low, regular, and high energy market prices, including Europe's 2022 energy crisis. This thesis also explores the technical and economic potential of electrified DH systems in the electricity and various balancing markets across different scenarios through modeling and simulation of the case studies. The findings indicate significant environmental benefits as a reduction in carbon dioxide emissions. However, this transition is not without its challenges. Notably, increased reliance on biomass combustion and electricity market volatility were recognized, potentially leading to further environmental and energy security issues. Economically, while electrification offers protection against the volatility of fossil fuel prices and promises long-term economic advantages, the initial investment and potential increases in consumer heating costs present challenges in the short to medium term. The participation of electrified DH systems in balancing markets could provide additional operational profits, yet complexities of system operation and management require careful consideration. DH systems were found to be resilient even under extreme energy prices, however, shutting down combined heating and power plants (CHP) would result in significant losses in potential electricity market income. In conclusion, the electrification of DH systems in Finland presents a promising pathway towards a sustainable heating sector. However, achieving this goal requires a balanced and integrated approach, incorporating technological innovation, strategic planning, and economic incentives.
  • Smart low-carbon district heating networks supporting the energy system transition
    (2019) Wahlroos, Mikko
     School of Engineering | Doctoral dissertation (article-based)
    Heating and cooling sector represents approximately 50% of the total energy consumption in the EU. The European Commission has begun to put more emphasis on the heating and cooling sector by publishing the EU strategy on heating and cooling. District heating (DH) is one of the most efficient heating solutions, especially in the colder regions with high population density. The amount of DH based heat production has remained on a rather stable level during the past decade. Furthermore, DH has been mainly produced with fossil fuels nowadays, and in order to tackle the emissions of heat production, current DH systems are facing a transition towards cleaner and more cost-efficient production. This dissertation investigates increasing smartness in DH networks and assesses the introduction of new heat sources to DH networks. In this context, smart DH networks stand for cost-efficient, low-carbon networks that allow prosumers to gain market access to sell their heat to DH networks. This dissertation models increasing the amount of additional heat supply by heat pumps (HPs), solar thermal production, and data center (DC) waste heat in existing DH networks in Finland. Furthermore, the potential for low-temperature DH networks and dynamic pricing of DH production is studied, as well as the future for biomass based combined heat and power (CHP) production in the EU-27. The results of this thesis indicate that increasing the amount low-carbon DH production technologies decreases utilization of existing units, mainly CHP based heat production and heat-only boilers. Decreasing operational hours of CHP units may decrease the profitability of these units, and the future of CHP is at risk. The current investment environment in the EU does not suggest that biomass CHP would contribute significantly to overall energy efficiency. The results suggest that HPs and DC waste heat would be a suitable alternative for low-carbon DH production, and they could supply heat with high operational hours. DCs can supply heat on a stable level but there are still many barriers slowing down DC waste heat utilization, mainly related to business models between different parties. However, if alternative heat production capacity is not owned by the DH companies, the pricing structure of district heat production should be assessed. Pricing for third-party heat should be transparent so that the utilities can easily assess whether the investment is profitable. Solar thermal production is not feasible for a large-scale DH network in Finland with the current price level, but they could benefit from lower distribution temperatures. Additionally, lower distribution temperatures would increase profitability of HPs and potential for additional low-temperature waste heat supply.
  • Towards effective climate change mitigation: viewpoints of cost efficiency, uncertainty and consumer choice
    (2017) Hast, Aira
     School of Engineering | Doctoral dissertation (article-based)
    In order to limit the concentration of greenhouse gases (GHGs) in the atmosphere and to reach the climate and energy objectives, GHG emission mitigation measures need to be implemented and the share of renewable energy increased in the energy system. In addition to policy actions, consumer energy choices also have an essential effect on the development of GHG emissions and the use of different energy sources. Furthermore, changes in consumer behavior can also be targeted in the policy instruments and the economics of consumers' energy options can be affected through policies. In this dissertation, the analyses were carried out at different levels, sectors and from different viewpoints. Policy measures necessary for meeting the national GHG emission target of Finland with least costs were studied. It was found that there are large differences in the cost-efficiency of different GHG emission mitigation measures. The risks of not meeting the predetermined GHG emission target and exceeding the estimated costs were also evaluated. The results indicate that the costs and achieved GHG emission reductions include large uncertainty, and for example the future oil price development had significant contribution to the uncertainty of GHG emission reduction costs. The progress of electricity from renewable energy sources (RES-E) in Nordic and Baltic countries was also analyzed in this thesis and the development was compared to the RES-E objectives of the countries. The analysis suggests that even if the studied countries are on track to meet their RES-E objectives, some countries are underperforming in the newer RES-E technologies. Also consumer electricity and heating choices were studied in this dissertation. The interaction between policies and consumer behavior was analyzed in particular. It was found that the voluntary green electricity products offered to consumers can include problems weakening the real additional environmental impacts of the green electricity purchase above the legally set requirements. However, especially replacing residential oil heating was one of the most cost-efficient GHG emission mitigation measures in order to meet the Finnish national GHG emission target. This study thus suggests that consumer heating choices are more likely to contribute to the policy objectives than the purchase of differentiated electricity products. It should, however, be noted that the consumer energy choices are influenced by several factors at the same time and they cannot thus be only affected by policies. In addition, the development of market prices like crude oil price can have a large impact on the economics of consumer energy options.
  • Transition towards carbon neutral district heating by utilising low-temperature heat
    (2024) Hiltunen, Pauli
     School of Engineering | Doctoral dissertation (article-based)
    Heating and cooling sector accounts for more than half of the total energy demand in European Union. Traditionally, fossil fuels have had a large share in producing heat to buildings and domestic hot water. Therefore, to mitigate the climate change and achieve European Union's climate goals, decarbonisation of the sector is essential. The war in Ukraine and energy crisis in 2022 increased the pressure to reduce the dependency of imported fossil fuels in heating even more. The transition of old infrastructure to low-carbon heat sources will take decades and will likely happen step-by-step. In this thesis, the transition to carbon-neutral production in Espoo district heating system was investigated. Especially, the role of low-temperature waste heat from the data centres in Espoo during the transition and feasibility of electrified district heating during electricity price shocks were studied. Utilising heat from district heating network's return water to provide heating and improve the energy efficiency were investigated in the campus of Tallinn Technical University was studied in this thesis as well.  Utilising the return water of district heating in low-temperature energy cascades has been discussed as an option to reduce distribution losses in newly built or refurbished areas during the transition to low-temperature district heating. Use of heat from return water reduces the return temperature of the district heating network, which has a positive impact on the energy efficiency of the entire system. Electrification of district heating reduces the consumption of combustible fuels and can help balancing the electricity markets with high share of intermittent power production such as wind or solar power. Furthermore, digitalisation of the society will increase the already high energy demand of IT sector. Cooling of data centres produces large quantities of waste heat, which can be utilised in district heating.  The results of this thesis show that district heating can provide environmentally sustainable alternative to the university campus heated by a natural gas-fired boiler reducing carbon emissions and primary energy consumption. Implementing a sub-network utilising low-temperature heat from the city's district heating network could reduce the emissions and primary energy consumption even more by lowering the heat losses and improving the efficiency of power and heat production in the combined heat-and-power plants. Waste heat from data centres can provide economical heat source for base load production in district heating systems, but it suits poorly for peak demand production during the heating season due to the mismatch between waste heat load and heat demand. Increasing electricity price hinders the profitability of heat pumps priming the low-temperature waste heat. However, heat pumps proved to produce economically viable heat even with high electricity prices, if the costs of fossil fuels are high as well, as it happened in 2021.