1,000 research outputs found
Optimizing district heating networks: Exploring the solution space: Transporting geothermal energy to consumers in Delft
No full textSociety is facing a huge challenge in switching the energy sectors dependence on fossil fuels into an energy sector using mostly renewable energy sources. The switch towards using more sustainable energy sources is known as the energy transition. The goal of the energy transition is to lower the greenhouse gas (GHG) emissions emitted by the energy sector. Lowering the GHG emissions helps society limit the global warming caused by GHG [3]. 17.5 % of the global energy usage comes from the energy use in buildings [50]. It is thus very important that the energy use in buildings transitions towards using more sustainable energy sources. One of the renewable energy sources that is ought promising in the energy transition for energy use in buildings is geothermal energy [3]. Geothermal energy is energy that is captured in reservoirs of hot water in the earth’s crust. The hot water captured in the hot water pockets is pumped to the surface, to use it in spatial heating. The return pipe returns the cooled water to the geothermal well, where it can heat up again over a certain period of time [63] [23].In some cases, geothermal energy is applied using a district heating network. A district heating network is an example of a system that provides heating and/or cooling capacities to a group of buildings [65]. A district heating network is a network of pipelines that transport the hot water from the geothermal well to the buildings in the district. A geothermal well in combination with a district heating network is developed in Delft [27]. The district heating network will deliver energy to the TU Delft campus, two neighborhoods in Delft and industry at the Schieweg in Delft [28].Besides the district heating network in Delft, it is expected that district heating networks will be applied more often to accelerate the energy transition. Yun-Chao and Chen (2012) concluded that most optimization techniques optimize the whole system with its components. Less optimization techniques are applied to the sole components. Besides the fact that most optimization methods optimize the system as a whole, most optimization objectives only include optimizing the cost of the system. Also, effective optimization techniques are required as optimizing large graphs may be computationally time consuming [36]. In literature there are also clear signals that state that the trade-off between thermal comfort, and efficiency with respect to cost has to be tackled [53]. In this research, optimizing district heating networks for cost is compared to optimizing district heating to maximize thermal comfort or efficiency.In this research two models are developed: a model that calculates the cost of the district heating network, and a model that calculates the thermal losses of the district heating network. Both models are applied to a district heating networks that is developed in a street network. Furthermore, multiple heuristics are applied to come up with better district heating networks. The optimization technique is tested on 100 small, randomly generated district heating networks. After that, the district heating network in Delft is optimized. The differences in cost, efficiency, etc. will be evaluated. Besides, the performances of the district heating networks are evaluated by introducing energy deficits under different conditions.Optimizing the district heating networks for cost led to a very consistent result: When compared to their individual starting point, the district heating networks became cheaper and more efficient. A moderate-strong correlation is found between the the increase in efficiency and the decrease in cost while optimizing the district heating networks. In contrast to that, the networks that maximize efficiency are much more expensive than their cost optimized alternative, while the increase in efficiency is in most cases moderate. However, there are rare cases where the efficiency is increased much at a moderate increase in cost. This phenomenon is also found in Delft. Given the result that the efficient district heating network also performed much better than the cheapest alternative during energy deficits, in this research it is shown that choosing an objective function has a very large impact on the characteristics of the network. Therefore it is shown that for future district heating network optimization, it is important to trade off cost against efficiency.Complex Systems Engineering and Management (CoSEM
Outcome novelty in Exploratory Modellingand Analysis: A research into the value of novelty search for exploratory modelling
No full textNovelty search is a state-of-the-art approach focusing on behavioural novelty, rewarding diverging, as opposed to pursuing static objectives. This is relevant for exploratory modelling and analysis, which focuses on exploration of model through open exploration or directed search. Novelty search as an open exploration strategy is being tested against proven methods such as latin hypercube sampling. Using existing evolutionary algorithms and a developed novelty function, the experiments focus on comparisson, impact of the number of functional evaluations and the impact of the goals of the evolutionary algorithm. Finally it can be concluded that novelty search finds novelties in the lake problem, which makes it a relevant search strategy, but not suited for indiviual exploration. That means that it would still be advised to use latin hypercube sampling for earlier exploration.Engineering and Policy Analysi
Bridging the Attitude-Behaviour Gap in Household Energy Consumption
No full textThe attitude-behaviour gap in energy consumption refers to the imparity between people's environmental values (and attitudes) and their actual behavior in consumption. This paper calls for the facilitation of the behaviour change process that is implementable in the context of one's everyday life to address the attitude-behaviour gap in household energy consumption. Two interrelated intervention design constructs are proposed based on the results of literature review, namely (1) providing consumers accurate information about actionable suggestions in the specific context of their everyday life, and (2) fostering consumers' motivation to engage in the behavior change process towards energy conservation. Smart Grid technologies are instrumental in both intervention types.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.System Engineerin
Managing Violations in Service Level Agreements
No full textA Service Level Agreement (SLA) represents an agreement between a service user and a provider in the context of a particular service provision. SLAs contain Quality of Service properties that must be maintained by a provider. These are generally defined as a set of Service Level Objectives (SLOs). These properties need to be measurable and must be monitored during the provision of the service that has been agreed in the SLA. The SLA must also contain a set of penalty clauses specifying what happens when service providers fail to deliver the preagreed quality. Although significant work exists on how SLOs may be specified and monitored, not much work has focused on actually identifying how SLOs may be impacted by the choice of specific penalty clauses. The participation of a trusted mediator may be necessary to resolve conflicts between involved parties. The main focus of the paper is on identifying particular penalty clauses that can be associated with an SLA
Compliance in Resource-based Process Models
Get PDFpeer reviewedExecution of business processes often requires resources, the use of which is usually subject to constraints. In this paper, we study the compliance of business processes with resource usage policies. To this end, we relate the execution of a business process to its resource requirements in terms of resources consumed, produced or blocked by tasks of the business process. Policies specifying constraints on resource usage are specified in the form of obligations and the verification of whether a business process complies with a given resource usage policy is formally studied
Simulating the flexibility potential of demand response with heat pumps in the Netherlands
No full textThe growth of electricity generated by renewables increases the intermittency of the Dutch electricity production. To deal with this, the Dutch power system requires a higher amount of flexibility in the future. Demand response with heat pumps is one of the options with a high potential to provide flexibility, because it offers the potential to store energy close to demand. In this thesis, the potential for electricity cost reduction with demand response with heat pumps for space heating by using the thermal inertia of buildings in the Netherlands is investigated. The effect of different heat load profiles, seasonality, and different comfort requirements on the economic potential demand response with heat pumps is analysed. An existing Matlab model is revised and expanded to perform simulations with different cluster types, seasons and predefined comfort limits. The model simulates the DR algorithm, R.E.X., and shifts the load of clusters based upon their thermal demand and the EPEX market prices within the predefined technical and consumer flexibility constraints, to analyse the potential of operational cost reductions of DR with heat pumps. Therefore, the key input parameters of the model are: (1) the thermal demand, (2) electricity market prices, and (3) the flexibility constraints. The key output parameters are: (1) the operational savings in euro, (2) the operational savings in percentage, and (3) the amount of shifted load. The model design, behaviour and results are validated with an expert validation.It is concluded, that DR with heat pumps can facilitate flexible balancing of supply and demand by aggregators in the Netherlands. The potential of DR with heat pumps for different stakeholders can increase depending upon the penetration of RES-E, heat pumps and EVs. Current obstacles for the development of DR of heat pumps are the high share of fixed energy taxes and the reduced efficiency and lifetime of the heat pump when DR is used. Designing flexible tariffs and a focus on flexibility in the re-design of heat pumps can take these obstacles away.Complex Systems Engineering and Management (CoSEM
Energy resilience through self-organization
No full textPower systems are large-scale, complex socio-technical systems that provide modern society with one of its most indispensible assets: electricity. Electricity supply is not only an irreplaceable asset in daily activities, it is also vital for operation of other critical infrastructures of the technological age. Crucial socio-economic systems depend on electricity supply to support infrastructures such as telecommunications, transportation, water and natural gas supply, as well as financial and healthcare services. Therefore, ensuring secure and reliable operation of power systems as an enabling infrastructure is crucial...
Harnessing Heterogeneity: Understanding Urban Demand to Support the Energy Transition
No full textThis thesis demonstrates that heterogeneous spatio-temporal demand profiles are required for a realistic representation of urban energy systems. This is needed to prepare them for the energy transition. Therefore, existing and future urban energy system models should be expanded with more detailed spatio-temporal local demand data that account for both household and non-household consumers, in particular for the thus far omitted service sector consumers. This thesis describes methods and approaches that allow for such detailed modelling of urban demand profiles based on the few publicly available data sources. Using the developed detailed spatio-temporal demand profiles, this thesis provides new insights in the impact of renewable energy resources in realistic, heterogeneous urban areas. The presented results can support governments, communities, and companies in theirendeavours to bring the energy transition to fruition.System Engineerin
The Effects of Open Data Communities on Open Data Benefits and Barriers
No full textGovernmental organisations worldwide are working on their open data strategies and are openly sharing their data with the public. Recently also open data communities have been set up by several national governments. The effects of setting up these data communities on open data benefits and barriers and whether an effect exists at all is not yet clear, because there has been little scientific research into data communities. This thesis therefore focuses on the effects of setting up open data communities. A single-unit case study was conducted to gather qualitive information of the effects of data communities. The case study focussed on the Dutch open data community and consisted of two parts, a document analysis and in-depth interviews. The results of the analysis show how the Dutch community contributes to enhancing open data benefits, including (indirectly) creating more informed citizens, increasing the access to capacity and resources outside of the data publishing organisation and a higher problem-solving capacity. Furthermore, the interview participants agree to a large extent that communities contribute to intragovernmental collaboration and the use of collective intelligence to solve public problems. According to the interviewees, the community also (potentially) mitigates open data barriers such as the lack of interest in using open data (by governmental organisations). The interviewees stated that the community managers made sure every question that was posted got a sufficient answer within a reasonable amount of time and therefore the barrier stating that the data provider ignores requests and suggestions of data users could also be mitigated, as well as difficulties in the interaction with the data provider. Both researchers and most community users and managers argued that the community could also contribute to mitigating low engagement of public managers with open data and increasing the knowledge and skills of employees to use the open data. Lastly, according to the interview participants, the community can decrease difficulty in discovering/locating data and not being able to combine and connect datasets. The interviewees were also questioned about how institutional instruments could increase the value of the open data community. Although the participants concluded that the contribution of formal instruments (such as rules) is limited, they indicated informal rules (such as norms) and enforcing instruments (such as rewards) can contribute to the value that is created by an open data community. The community-specific challenges identified in the analysis can contribute to the process of designing an open data community, because policy makers can compare scope and design choices with the empirical experiences. This thesis also provides an exploratory scientific contribution: this research provides insight into how open data communities can contribute to enhancing open data benefits and the mitigation of open data barriers. Although the results are promising, certain limitations are applicable to the research. The thesis only studied one open data community and the full list of open data benefits and barriers was reduced based upon an assessment of the author of the thesis. Last of all, the interviews focused on qualitative data. Combining the results of this thesis with other case studies can improve generalisability. Complex Systems Engineering and Management (CoSEM
Enhancing Dutch Energy Safety: Unleashing Redundancy for Cyber-Resilient Industrial Operations at Gate terminal
No full textCritical infrastructures, such as the energy sector, are vital for the proper functioning of society. It is crucial to protect these infrastructures against cyberattacks on their operational technology, ensuring their operational performance, and safeguarding energy safety. There is a lack of existing research on improving cybersecurity in operational technology for increasing operational performance in liquefied natural gas infrastructure in the Netherlands, specifically when it comes to increasing redundancy in the system. In an attempt to fill this knowledge gap, this thesis implements agent-based modelling to answer the following main research question:“To what extent does the implementation of redundancy enhance the operational performance of operational technology in the industrial processes of Gate terminal in the face of cyber threats, in order to maintain the availability of business services?”The thesis shows that the key determinants for the effectiveness of a redundancy strategy are the criticality of the redundantly implemented element, and the degree of diversity applied. Additionally, a trade-off between the advantages of redundancy the inevitably increased attack surface can be observed: when implementing an ineffective redundancy strategy, overall system performance may degrade in comparison to the initial system conditions. The importance of an effective incident response cycle must not be overlooked. A redundancy strategy is only as effective as the capability of the system operator to prevent and deal with incidents. Future research can build on this thesis, exploring more explicit redundancy strategies, types of attacks, and strategic defense systems, as well as the optimization of the redundancy trade-off. These research directions can help in further analyzing and understanding the impact of redundancy on system operational performance.Engineering and Policy Analysi
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