The total investments in the global energy system amounted to 1.85 trillion in 2018 [1]. Globally over 400 exajoule [2] was provided to energy consumers. The energy consumption is closely related to the emission of green house gasses [3] [4] [5]. In the Kyoto and Paris agreements the international community formalized the intention to reduce the emission of green house gasses in an effort to mitigate global warming [6] [7]. Economic progress has long been linked to increased energy consumption [8] [9]. Mitigation of green house gasses whilst facilitating economic growth poses one of the major challenge of the twenty first century [10] [11]. Development of climate policy and business strategy that facilitates both the mitigation of global warming and economic growth requires understanding of the energy market. In an effort to expand the understanding of the energy market we examine the historic effects of a country’s wealth on the country’s energy mix by applying a multinomial logit choice model for energy carriers to various sectors on a global scale. We find evidence for ordered wealth effects in sector categories Heavy Industry, Agriculture & Other Industry, Passenger Transport Rail, Freight Transport Rail, Residential Heating & Cooking, and Services.

A novel 2D finite element method (FEM) on unstructured grid for nonlinear time-dependent deformation of materials is developed. The objective is to model the complex deformation behavior of the rock salt, inside which caverns are mined to store green fuels (such as hydrogen). The analyses and the developments of the present work allow for quantification of the state of the stress of the cavern, and assess the safety and reliability of the storage structure over time. The novelty of the approach is in using minimization of the potential energy principle in conjunction with nonlinear creep deformation physics. While the available FEM-based simulators offer tools only for solving linear and non-linear elastic models, the developed simulator takes into account cyclic loading and material’s damage evolution in time with possibility to predict the material’s failure. Apart from that, the stored product (hydrogen) density is taken into account, which affects cavern’s pressure variation with depth. Impurities,causing heterogeneous rock salt properties, are also considered in the developed model. Multivariate Gaussian distribution is utilized to generate distribution of the heterogeneous mechanical properties. Eulerian strains are introduced in the model to take into account deformation of the mesh. As such,the computational grid changes its geometry according to the deformation. Several numerical test cases are studied. Firstly, a consistency (verification) study is performed, to validate the linear elastic model. Remark that the linear elastic deformation model casts the basis of the non-linear model with creep physics. Then, several studies have been performed to analyze, quantify and approximate the deformation of the salt cavern under the gas pressure change, including the time-dependent creep physics.

Fossil fuel based energy systems are the main contributor to global warming. As new regulations come into place, a transition towards a more sustainable energy system must be realised. Hydrogen usage is regarded as the key enabler of such systems. The heart of these hydrogen-based energy systems (HESs) is the hydrogen back-up system (HBS) which is responsible for the production, transport and storage of hydrogen. This study investigated how the power-to-gas efficiency of a HBS is governed by various sources and services. Two services are defined for the HES; Service 1: Constant hydrogen supply for the chemical industry. Service 2: Interruptible hydrogen supply as a fuel for power back-up. Both services can use a wind farm or the power grid as the source. A fully transient mathematical model of the system was built in Matlab Simulink. This model uses a rectifier and a PEM electrolyzer to convert the source power into hydrogen. A transport system, consisting of a pressure control station (PCS) and a 50 kilometre transmission pipeline, delivers the hydrogen to the salt cavern. Here, the hydrogen is injected into a 1000 metre deep cavern by a PCS and an injection pipeline. After a discharge pipeline, a third PCS is installed to adapt the hydrogen temperature and pressure for another 50 kilometre long transmission pipeline. A final PCS adapts the flow properties to the desired service values. All components are able to fully capture the intermittent nature of the cases. Historical data of the spot prices for power and wind speeds of 2017 are used for the sources and services. The resulting production and consumption profiles for 2017 were used to size the HBS for each case, ensuring full use of the cavern capacity without over- or underproduction. Simulations of the defined cases showed that the caverns only completed one full charge-discharge cycle during 2017, showing that all cases demand seasonal storage. The power-to-gas efficiency of both the grid-powered cases is 58%. The wind-powered cases show efficiencies of 44% and 41% for the chemical industry and the power back-up cases, respectively. The main conclusions as to why these difference are present are described below. Wind-powered HBSs lead to roughly 24 – 28% more power losses due to a mismatch between the wind farm power output and the PEME operational power input limits. The most significant losses occur during low wind speeds when the wind farm output is between zero and the minimum PEME operating power. The PEME efficiencies are in the range of 67.5 - 70.1%, making it the largest contributor to the total HBS losses. The transport and storage systems for all cases have an efficiency of roughly 95.0 - 95.5%. The efficiency of wind-powered PEMEs is 2.3 - 2.6 percentage points higher compared to grid-powered. The service has no significant effect on the efficiency as the service pressure for all cases is for large part of the year lower than the transport and storage pressure, resulting in negligible power requirements for the transport system.

“Heating and cooling remain neglected areas of energy policy and technology, but their decarbonisation is a fundamental element of a low-carbon economy.” (IEA, 2012). In The Netherlands the total heat demand needs to be reduced and the heat provision needs to become more sustainable (Kamp, 2015). By 2021, municipalities therefore need to have formulate plans on how they will realize the phase-out of natural gas in all districts in which the phase-out will take-place before 2030. In South Holland, district heating is considered a cost-effective alternative for the current gas based system. However, the Netherlands Environmental Assessment Agency (PBL) and the Province of South Holland (PZH) think differently about how district heating should be implemented and it is currently unclear what these differences exactly are and how they influence municipal policy for the phase-out of natural gas. In this thesis, we have therefore researched what the relevant differences between the two regional transition approaches are with regard to the implementation of district heating at a municipal level for realizing cost-efficient CO2 abatement.
In consultation with the PBL and the PZH, we have developed four scenarios for the development of district heating. To analyse these scenarios, we have adapted an existing model of CE Delft, which can calculate the investment costs and fixed costs of district heating infrastructure. Furthermore, we have developed a dispatch model that can calculate the performance of a district heating system in terms of CO2 abatement and marginal costs of heat production.
Based on this comparison of the approaches, a trade-off appears between cost-effective CO2 abatement, and maximizing the overall reduction of CO2 emissions. In which the scenarios of the PZH in general result in higher levels of CO2 abatement and the scenario of the PBL is more cost-effective. Additionally, in the light of the full phase-out of natural gas the approach of the PZH appears to suffer from higher initial investment risks but also provides better opportunities to realize large-scale district heating. However, the research has also pointed out that there are many uncertainties regarding the development of demand and supply that can average out the relatively small differences between the scenarios.
One of these uncertainties is the willingness and ability of residents to participate in district heating. The decision-mandate lies with the consumer; however, current forecasts and policy processes are not sensitive to this mandate. Therefore, we have researched if Q-methodology can support municipalities in developing communication-and-decision making processes that fit with the need of heat consumers in this transition. The case study and focus group have indicated that Q-methodology can provide relevant and unique insights. However, to truly test the method it is necessary to run a larger case study in which the resulting perspectives are used to design a policy process and where this process is re-evaluated by the participants of the study.