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Steel is an indispensable material for the sustainable maintenance and progress of modern civilization. Its versatility in terms of mechanical and thermal characteristics, corrosion resistance, raw material availability, energy consumption and recyclability provides a clear advantage in a fast-changing technological landscape. In order to adapt to the changing needs, steel production methods have been evolving and improving over time. One such improvement opportunity in terms of energy efficient production is the ”heat pipe assisted annealing” concept. The cold rolling of steel is a process where the steel strip is cold-worked by means of rolls to achieve thickness reduction and better uniformity. This results in the strain hardening of steel. To reduce the hardness of steel and to render it more workable, it is thermally treated by heating it to a target soaking temperature and then cooling it down. This process is called annealing and it is an energy intensive process. Conventionally, heating is achieved with natural gas fired furnaces, whereas cooling is done using convective gas cooling. With this setting, the thermal energy extracted from the steel strip during the cooling stage is not used in any way. Moreover, none of the energy that is introduced during the heating stage is retained in the final product.An alternative technology for the annealing of steel was developed at Tata Steel IJmuiden R&D with the objective of recovering and using some of the heat removed during the cooling stage and thus, achieving more energy efficient annealing. With this technology called heat pipe assisted annealing, the cooling strip is thermally linked to the heating strip with multiple rotating heat pipes. In this way, each heat pipe transfers a certain amount of heat from the cooling strip to the heating strip. Only final heating and cooling of the steel strip is carried out in a conventional way. This concept is applicable to relatively low temperature (sub-critical) annealing where the cooling rate is not crucial. Therefore, packaging steel is a good candidate for the application of this technology.A rotating heat pipe is a highly efficient heat transfer device which is a wickless hollow cylindrical vessel rotating around its symmetric axis and containing a fixed amount of working fluid. The working fluid acts as a thermal energy carrier, transporting heat from one end of the heat pipe to the other. This basically occurs in four steps: (i) heat added to the evaporator part of the heat pipe causes the evaporation of the liquid, (ii) vapor travels to the condenser end of the heat pipe due to pressure difference, (iii) vapor condenses in the condenser section where heat is removed from the heat pipe, (iv) liquid returns to the evaporator with the help of the static pressure head and the centrifugal force induced by rotation. The heat pipe assisted annealing concept has been patented and subsequently further studied by Tata Steel Europe R&D. A water-filled rotating heat pipe test rig integrated with steel strips provided the bulk of the prior work. This test rig served as the proof-of-principle installation and it showed that heat can be transported from a hot strip to a cold one with a rotating heat pipe. In this context, several gaps have been identified to further acquire the knowledge on the system components, the concept performance and feasibility.This thesis focuses on four main aspects of the fundamentals and the feasibility of the heat pipe assisted annealing concept: (i) contact heat transfer between the steel strip and the rotating heat pipe, (ii) computationally efficient modelling of the interior dynamics of a rotating heat pipe, (iii) applicable working fluids for the high temperature range, (iv) behavior of the heat pipe assisted annealing system as a whole. These aspects are studied through a thermal engineering perspective. The heat pipe assisted annealing concept relies on the effective transfer of heat from the strip to the rotating heat pipe and vice versa. Therefore, it is important to understand the underlying physics governing this heat transfer and to be able to predict the heat transfer rate for possible configurations. In this context, in Chapter 2 of this thesis, the contact heat transfer between a steel strip and a rotating heat pipe is investigated both experimentally and numerically. The numerical model is based on first principles. It finds the thickness and the pressure of the gas layer between the strip and the heat pipe and subsequently considers different heat transfer mechanisms. The experimental work was carried out on the proof of- principle test rig. The model is validated with the experimental results. The contact heat transfer coefficient in the uniform region varied between 4,000 to 20,000 W/(m2.K). It showed an increase in the contact heat transfer with decreasing strip velocity and increasing radial stress. For the considered cases, conduction through the gas layer was the dominant heat transfer mechanism. Additionally, a simplified expression has been developed for the calculation of contact heat transfer through multiple regression analysis. The modelling of a rotating heat pipe is a crucial step for the detailed study of the heat pipe assisted annealing technology. Although modelling of rotating heat pipes has been the subject of many studies in the literature, these models are not computationally efficient enough to allow for the simultaneous modelling of multiple heat pipes linked to each other with strips. On this ground, in Chapter 3, a novel computationally efficient engineering model describing the transient behavior of the heat pipe is developed. In this model, the liquid and the vapor cells are allowed to change size radially in order to allow for the tracking of the liquid / vapor interface without the need for fine meshing or re-meshing. The model is also adapted to capillary-driven heat pipes. The model is validated with experimental and numerical studies from the literature. The deviation is computed to be around 2% with the numerical and analytical studies and around 6% with the experimental study.The heat pipe assisted annealing concept requires the operation of heat pipes within a temperature range of 25 °C to 700 °C. In order to operate within this range, different working fluids need to be used for different temperature ranges due to constraints of vapor pressure, life time, performance and safety. These working fluids are studied in Chapter 4. First, a selection of the working fluids is made based on a literature review. This selection yielded water, Dowtherm A, phenanthrene and cesium. Then, a life time test has been carried out with thermosyphons to test the stability of phenanthrene. At the end of a 3 months long test at 460 °C, thermal decomposition of phenanthrene was observed. However, these tests should be repeated with better initial vacuum and at multiple temperatures. Finally, Dowtherm A has been used in a rotating heat pipe setup to test its applicability and performance. It has been shown that Dowtherm A is suitable to be used in a rotating heat pipe at the designated temperature range in terms of performance, provided that annular flow is avoided. With the knowledge gathered from the previous chapters of this thesis, a model of the heat pipe assisted annealing line has been developed in Chapter 5. The aim of this model is to quantify the energy efficiency advantage brought by the concept for different number of heat pipes and to understand the behavior of the system as a whole. The simulations were run for a fixed plant layout with varying number of heat pipes and an average wrap angle of 104°. The energy recoveries for the simulations run for a strip of 0.25 mm and a line speed of 6.133 m/s were 76.5%, 73.4%, 69.4% and 63.9% for a total number of 90, 75, 60 and 45 heat pipes, respectively. From the simulation results it follows that cesium heat pipes are more efficient than organic heat pipes. Finally, the simulation results showed that the thermal cycle requirements can be satisfied with this new technology. Large Scale Energy Storage

A membrane assisted process for green hydrogen production from a bioethanol derived feedstock is here developed and evaluated, starting from the conventional Steam Methane Reforming (SMR) process. Such a process is suitable for centralized hydrogen production, and is here analyzed for a large-scale H2 production unit with the capacity of 40.000 Nm3/h. The basic Steam Ethanol Reforming (SER) process scheme is modified in a membrane assisted process by integrating the Pd-membrane separation steps in the most suitable reaction steps. The membrane assisted process, configured in three alternative architectures (Open architecture, Membrane Reactor and Hybrid architecture) was evaluated in terms of efficiencies and hydrogen yields, obtaining a clear indication of improved process performance. The alternative membrane assisted process architectures are compared to the basic SER process and to the benchmark SMR process fed by natural gas, for an overall comparative assessment of the efficiency and specific CO2 emissions and for an economic analysis based on the operating expenditures.

In the UK electricity market, generators are obliged to produce part of their electricity with renewable energy resources in accordance with the Renewable Obligation Order. Since 2009 technology banding has been added, meaning that different technologies are rewarded with a different number of certificates. We analyze these two different renewable obligation policies in a mathematical representation of an electricity market with random availabilities of renewable generation outputs and random electricity demand. We also present another, alternative, banding policy. We provide revenue adequate pricing schemes for the three obligation policies. We carry out a simulation study via sampling. A key finding is that the UK banding policy cannot guarantee that the original obligation target is met, hence potentially resulting in more pollution. Our alternative provides a way to make sure that the target is met while supporting less established technologies, but it comes with a significantly higher consumer price. Furthermore, as an undesirable side effect, we observe that a cost reduction in a technology with a high banding (namely offshore wind) leads to more CO2 emissions under the UK banding policy and to higher consumer prices under the alternative banding policy.

In the current situation with the unprecedented deployment of clean technologies for electricity generation, it is natural to expect that storage will play an important role in electricity networks. This paper provides a qualitative methodology to select the appropriate technology or mix of technologies for different applications. The multiple comparisons according to different characteristics distinguish this paper from others about energy storage systems. Firstly, the different technologies available for energy storage, as discussed in the literature, are described and compared. The characteristics of the technologies are explained, including their current availability. In order to gain a better perspective, availability is cross-compared with maturity level. Moreover, information such as ratings, energy density, durability and costs is provided in table and graphic format for a straightforward comparison. Additionally, the different electric grid applications of energy storage technologies are described and categorised. For each of the categories, we describe the available technologies, both mature and potential. Finally, methods for connecting storage technologies are discussed.

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Biomass is a sustainable energy source which, through thermo-chemical processes of biomass gasification, is able to be converted from a solid biomass fuel into a gas mixture, known as syngas or biosyngas. A solid oxide fuel cell (SOFC) is a power generation device that directly converts the chemical energy of a fuel to electricity. Therefore, biomass-powered SOFCs could be highly efficient. Typically, in addition to carbon dioxide and water vapor, the major components of syngas produced from biomass gasification include hydrogen, carbon monoxide and methane which are potential fuels for SOFCs, which make integration possible between SOFCs and biomass gasifiers. However, the syngas is also comprised of trace species such as tars, H2S, HCl, and alkali compounds, among others, which could be detrimental to SOFCs if they are contained within the feeding syngas stream. Therefore, the syngas must be pretreated in order to reduce these trace species to a level that SOFCs are able to tolerate. With various gas treatments, the overall system performance would fluctuate, and therefore, the influence of the gas treatment methods on the system performance must be understood. The most prominent among the trace species is tar. The effect of tars on the performance of SOFCs has yet to be studied, however, it is known that, even though tar can possibly poison the fuel cell through carbon deposition, it may also become a fuel for SOFCs. Furthermore, SOFC systems are currently designed in general for employing natural gas. Due to the fact that SOFC systems are very sensitive to the fuel types, it is necessary to completely understand the system response when switching from natural gas to biosyngas to enable a better controllability for future experiments. The research scope of this thesis is limited to the aforementioned issues. The objective of this thesis is to provide a fundamental study to ensure a safe and efficient system integration. The study is limited to an existing downdraft fixed-bed gasifier and a 5 kWe SOFC CHP system due to these two units entering the commercial market. The approach utilized, however, could be further adopted for the large scale power plants based on biomass gasifiers and SOFCs. The research begins with the evaluation of technologies involved biomass-powered SOFCs in chapter 2. Technologies regarding biomass gasification, gas cleanup and fuel cells are discussed based on literature surveys. The review begins by briefly summarizing conventional gasifiers including fixed-bed and fluidized bed gasifiers, which are implented for biomass gasification. Following that, details are indicated for SOFC performance affected by the trace species such as particulates, H2S and available cleaning technologies. The combination of biomass gasifiers with fuel cells including proton exchange membrane fuel cells (PEMFC), molten carbonate fuel cells (MCFC), and SOFCs is then reviewed with an emphasis on the development of SOFC technology and the study of integration between biomass gaisifers and SOFCs. Chapter 3 presents a thermodynamic study of the influence of cleaning technology on the energetic and exergetic performance of the integrated gasifier–SOFC system with distinctive system configurations. Two gas cleaning systems, specifically, a combined high and low temperature gas cleaning system and a high temperature gas cleaning system are considered to connect the gasifier with the SOFC system. The influence of the steam addition for the suppression of carbon deposition and various heat sources for steam generation on the system performance is evaluated. The performance of the SOFC system operating with natural gas and biosyngas is also compared. The installed SOFC system, particularly the embedded pre-reformer and anode off-gas recirculation was initially designed for natural gas. This design is desirable as it effectively uses the steam in the anode off-gas and the heat generated in the stack. As SOFC performance is very sensitive to gas composition and operating conditions, both of which are affected by the anode recirculation, an evaluation of the recirculation behavior on safety issues regarding carbon deposition and nickel oxidation and system performance are presented in chapter 4. An important finding is that, by not implementing the recirculation, the biosyngas-fueled SOFC system effectuates a much higher net electrical efficiency, less initial investment and simpler system configuration in comparison to that when recirculation is implemented. Tolerance of SOFCs to the trace species from biomass gasification is not yet fully understood. The influence of biomass gasification tars on SOFC performance and mitigation of carbon deposition are experimentally evaluated in chapter 5&6. Well-controlled operational conditions assist in the suppression of carbon deposition. Chapter 5 presents the influence of operating conditions including steam levels, current density and time on stream on the performance of SOFCs with Ni–YSZ anodes fueled by tar-containing biosyngas at 800 °C. Changes in impedance spectra and polarization curves of SOFCs following tar exposure were analyzed to assess the cell performance. The biosyngas composition and the tar concentration employed in these measurements were identical to those measured from the commercial air-blown biomass gasifier that is to be connected to the studied SOFC system. Operating this type of SOFC with the tar concentrations could result in severe damage to the cell due to carbon formation on the anodes. Scanning Electron Microscopy (SEM) indicated carbon deposition which affected the performance of the SOFC, as is exhibited by the impedance spectra and anode polarization curves of the cells after exposure to tars. However, the risk of carbon deposition could be alleviated by increasing steam levels and current loads. Chapter 6 presents a similar study of the effects of tar on SOFC performance, but possesses a focus on Ni–GDC anodes and various operating temperatures levels (700, 800 and 900 °C) under both dry and wet conditions. Polarization behavior, electrochemical impedance spectroscopy, and cell voltage degradation were analyzed to evaluate the cell performance. It is most likely that the cells with Ni–GDC anodes did not suffer from carbon deposition under the wet conditions studied. Dry tar-containing syngas for SOFCs is unlikely to cause carbon formation under a mild current load; however, it may induce carbon formation at open circuit. The effect of carbon dioxide that is capable of suppressing carbon deposition was experimentally investigated, and an enhanced performance was observed under the conditions studied. Under carbon risk-free operating conditions, the cell voltage increases when raising the feeding tar concentration, indicating that tar performs as fuel for SOFCs. Numerical simulation is an efficient tool for the evaluation of SOFCs’ response when switching fuels. Chapter 7 presents such a numerical study with the focus on the evaluation of kinetic models for methane steam reforming for SOFCs operation with multiple fuels. Three frequently employed kinetic models were selected in order to examine their impacts on the performance of a tubular SOFC. The resulting thermo-electrochemical behaviors derived from these models were compared. It was discovered that all three kinetic models are reasonably accurate in terms of the polarization behavior, but they significantly affected the local thermo-electrochemical performance. A more rapid kinetic model was adopted based on the evaluation of these three kinetic models in order to evaluate the performance of the tubular SOFC in terms of local electrochemical performance, anode oxygen partial pressure and overall SOFC performance when performing with multiple fuels. Chapter 8 draws the conclusions regarding the work presented in this dissertation, and recommendations are suggested for future research activities.

Owing to the complexity of the sector, industrial activities are often represented with limited technological resolution in integrated energy system models. In this study, we enriched the technological description of industrial activities in the integrated energy system analysis optimisation (IESA-Opt) model, a peer-reviewed energy system optimisation model that can simultaneously provide optimal capacity planning for the hourly operation of all integrated sectors. We used this enriched model to analyse the industrial decarbonisation of the Netherlands for four key activities: high-value chemicals, hydrocarbons, ammonia, and steel production. The analyses performed comprised 1) exploring optimality in a reference scenario; 2) exploring the feasibility and implications of four extreme industrial cases with different technological archetypes, namely a bio-based industry, a hydrogen-based industry, a fully electrified industry, and retrofitting of current assets into carbon capture utilisation and storage; and 3) performing sensitivity analyses on key topics such as imported biomass, hydrogen, and natural gas prices, carbon storage potentials, technological learning, and the demand for olefins. The results of this study show that it is feasible for the energy system to have a fully bio-based, hydrogen-based, fully electrified, and retrofitted industry to achieve full decarbonisation while allowing for an optimal technological mix to yield at least a 10% cheaper transition. We also show that owing to the high predominance of the fuel component in the levelled cost of industrial products, substantial reductions in overnight investment costs of green technologies have a limited effect on their adoption. Finally, we reveal that based on the current (2022) energy prices, the energy transition is cost-effective, and fossil fuels can be fully displaced from industry and the national mix by 2050.