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Systemic humanitarian, environmental, and socio-political problems are impeding current and future generations from meeting their very basic needs. The speed and scope of mainstream responses to the world’s most pressing problems are limited by agency failures and by the ‘rules of the game’. In this context, this research contributes to theory and practice by formulating and exploring the concept of Sustainability Hacking, a particularly advantageous change driver in situations where information is limited, resources are scarce, stakes are high, and decision-making is urgent. This research was conducted through 3 sequential stages. First, the researcher has systematically reviewed the literature on sociotechnical system change for sustainability. This review exposed and discussed 15 theoretical foundations that shape what changes are perceived as desirable and attainable, as well as how to navigate between all the coexisting pathways to drive positive change. By examining these foundations, it became possible to pinpoint opportunities for future contributions. Among them was the idea of investigating the meaning, characteristics and potential implications of Hacking as a change driver of sociotechnical systems. These were revealed in the 2nd research stage, after interviewing self-declared Hackers and cybersecurity experts to understand how they used the term and how they pursued their desired systemic changes. This stage provided the definition, as well as 9 dominant characteristics of System Hacking. The term refers to exploring unconventional solutions to a problem within sociotechnical systems. ‘Unconventional’ here means deviating from embedded institutions, i.e. the rules of the game in a society. Institutions represent sources of stability, coherence, and continuity of systems, while simultaneously shaping public expectations of what changes are viable and the heuristics of how they should be pursued. Differently from conventional approaches, system Hackers are not aiming at changing rules, neither are they passively complying with them. Instead, they work around the ‘rules of the game’ to accomplish ‘good-enough’ results promptly. The 3rd research stage consisted of investigating and working with Sustainability Hacks, i.e. System Hacks addressing pressing sustainability problems. This was performed through a combination of Action Research and Case Studies. Benefitting from a diverse database of 19 cases, the researcher conducted a cross-case analysis, which provided comprehensive observations on the 15 main similarities and 10 differences that constitute the key analytical variables of Sustainability Hacking. Furthermore, the analysis derived 5 Archetypes that can be used as frames of reference to provide guidance for practitioners evaluating possibilities of addressing pressing sustainability problems, as well as to support future academic contributions in this nascent field of research. Gates Cambridge

Large-scale energy storage systems typically withdraw electricity from the grid and transform it into another form for storage. When the grid is unable to meet demand, the process is reversed and the stored energy is transformed back into electricity. Instead of this traditional approach, the following thesis explores the concept of ‘generation-integrated energy storage’, in which a generator’s existing energy conversion pathway is used to store energy in an intermediate form. This has two benefits: (i) the hardware used for generation can be exploited to reduce storage costs and (ii) fewer energy transformations are required when compared to traditional ‘electricity-in-electricity-out’ forms of storage. This means a high effective (exergetic) round-trip efficiency can be achieved at low cost. Specifically, this thesis focuses on the integration of thermal energy storage with the feedwater heating system of steam plant. (In modern energy systems this is likely to be nuclear-powered.) In the proposed system, the plant’s electrical output is flexed whilst maintaining constant reactor power. During charge, the plant’s electrical power output is reduced below its normal full-capacity level, and during discharge, it exceeds this level. This approach provides the equivalent of an electricity storage system and facilitates the adoption of a load-following role for nuclear plant. By allowing the reactor to operate constantly at maximum power output, the system also avoids the economic constraints and practical problems of part-load operation, which currently favour the use of nuclear plant for baseload only. An important feature of the proposed system is that the wet steam turbine bleed flows automatically provide good thermal matching with the feedwater temperature profile. This means that heat can ultimately be transferred to and from sensible-heat thermal-storage media with high exergetic efficiency. Various options are discussed for the thermal stores, including pressurised water tanks, thermal oils, and packed beds. This thesis is focused on the engineering research and development of the feedheat- integrated energy storage system and how this technology would be valuable in a modern energy system. The following contributions have been made: (i) Thermodynamic analysis – Detailed thermodynamic analysis is presented for an elec- tricity storage system in which thermal stores are integrated with the feedwater heating system of steam plant. The findings indicate that a round-trip efficiency greater than 80% is likely and that the plant’s power output can be varied between 85–113%. The analysis is also extended for heat cogeneration applications, for which the effective COP is estimated to be approximately 8 for modern district heating and 4 for industrial process heat. (ii) Off-design steam plant operation – A detailed off-design steam plant model is created. It is shown that the plant performs sufficiently well when operated off-design, and is able to efficiently transfer work to heat and then heat back to work. (iii) Capital cost estimation – A comprehensive cost analysis of the proposed system is undertaken, with an emphasis on the marginal cost of oversizing existing compo- nents. Costs for a well-designed system are approximately 250–1000 $/kWe and 15–20 $/kWhe. (iv) Thermo-economic optimisation – Parametric studies and a genetic algorithm optimisa- tion method are used to determine the optimal trade-off between efficiency and cost, and inform best design practices. (v) Steam turbine operation – A streamline equilibrium throughflow method is used to numerically validate Stodola’s ellipse law, and to explore the unusual off-design conditions caused by the storage system. Throughout this thesis, these contributions are routinely placed in the context of the modern energy system. It is demonstrated that integrated systems which perform multiple roles – electricity generation, energy storage, and possibly heat cogeneration – will be highly valuable for the transition to a low-cost, secure, and decarbonised energy system.

Amyloid fibril related diseases include dementia, Alzheimer’s disease and Parkinsons disease and pose an increasingly large burden to global healthcare, due to the presence of an ageing population. Despite many healthcare advances, amyloid fibril diseases remain largely untreatable, with only symptom managements available rather than any disease-modifying treatments. With hundreds of potential drug candidates failing clinical trials, this suggests that something is lacking in current approaches. One such gap is the thermodynamics of amyloid fibrils and how clinical agents modify the stability of fibrils, either positively or negatively. Thus far there has been a focus on the kinetic stability of amyloid fibrils due to the development and availability of kinetic assays. Specifically, the use of Thioflavin-T (ThT) fluorescence monitored growth curves to quantify the kinetics of amyloid growth in a robust, high-throughput manner. The equivalent thermodynamic assays are largely underdeveloped and as such remain underutilised. This thesis aims to fill this gap by developing a thermodynamic assay which can be used to quantify the Gibbs Free Energy (ΔG), enthalpy (ΔH), entropy (ΔS) and heat capacity (ΔCp) of amyloid fibril elongation. The development of this assay is detailed in Chapter 3, with the accompanying fitting script developed in Chapter 4. The assay was developed to be highly accessible in order to promote its uptake and use, with a low resource burden and a high throughput. The application of this assay to amyloid fibril systems is then detailed in chapter 5. Finally, development of a drug screening platform for use in identifying molecules which could modify the thermodynamic stability of amyloid fibrils is investigated in chapter 6. Through this thesis the development of an assay to quantify the thermodynamic stability of amyloid fibrils is described, with the stability of lysozyme, α-synuclein, insulin, tau, silk and amyloid-β fibrils investigated.

Effective decision making to allocate public funds for energy technology research, development, and demonstration (R&D) requires considering alternative investment opportunities that can have large but highly uncertain returns and a multitude of positive or negative interactions. This paper proposes and implements a method to support R&D decisions that propagates uncertainty through an economic model to estimate the benefits of an R&D portfolio, accounting for innovation spillovers and technology substitution and complementarity. The proposed method improves on the existing literature by: (a) using estimates of the impact of R&D investments from one of the most comprehensive sets of expert elicitations on this topic to date; (b) using a detailed energy-economic model to estimate evaluation metrics relevant to an energy R&D portfolio: e.g., system benefits, technology diffusion, and uncertainty around outcomes; and (c) using a novel sampling and optimization strategy to calculate optimal R&D portfolios. This design is used to estimate an optimal energy R&D portfolio that maximizes the net economic benefits under an R&D budget constraint. Results parameterized based on expert elicitations conducted in 2009-2011 in the United States provide indicative results that show: (1) an expert-recommended portfolio in 2030, relative to the BAU portfolio, can reduce carbon dioxide emissions by 46 million tonnes, increase economic surplus by $29 billion, and increase renewable energy generation by 39 TWh; (2) uncertainty around the estimates of R&D benefits is large and overall uncertainty increases with greater investment levels; (3) a 10-fold expansion from 2012 levels in the annual R&D budget for utility-scale energy storage, bioenergy, advanced vehicles, fossil energy, nuclear energy, and solar photovoltaic technologies can be justified by returns to economic surplus; (4) the greatest returns to public R&D investment are in energy storage and solar photovoltaics; and (5) the current allocation of energy R&D funds is very different from optimal portfolios. Taken together, these results demonstrate the utility of applying new methods to improve the cost-effectiveness and environmental performance in a deliberative approach to energy R&D portfolio decision making.

Successful cap and trade programs for SO2 and NOx in the US allocate allowances to large emitters based on a historic base line for a period of up to thirty years. National Allocation Plans in Europe allocate CO2 allowances in an iterative approach first for a three then for a five-year period. The potential updating of the base line creates perverse incentives for operation and investment. Some allowances are also reserved for new entrants further distorting the scheme. We use analytic models and numeric simulations for the UK power sector to illustrate and quantify how these effects contribute to an inflation of the allowance price while reducing utilisation and investment in efficient technologies. The inflated allowance prices are likely to increase the European allowance budget and emissions, e.g. through the Linking Directive. As a result opportunity costs of emitting CO2 are reduced relative to an efficient cap and trade program.

This dissertation reports on several experimental projects studying electronic transport in thin-flm electronic devices. Self-assembly methods and graphene were used to realise devices contacting films of self-assembled PbS quantum dots. The devices have exhibited single-electron tunnelling with a high yield. The electrical properties of the junctions are studied individually and collectively using statistical tools to extract correlations between device geometries and electrical data. The dissertation includes discussion of the theory of relevant electronic transport including numerical simulations. Several initiated projects deriving from this work are introduced. A second device reported in this thesis is a memristive switch. Contacting thin films of Al2O3 with graphene delivered junctions which exhibit memristive behaviour with an ultrahigh on-off conductance ratio. The conduction state of the junctions is correlated with morphological changes in the devices, whereby conductive flament formation in the junction is found to lead to electrically-controllable and reversible gas encapsulation in bubbles in the structure. The device is measured electrically and topographically, and the correlation between the two aspects is studied. A discussion of memristive conduction is included with numerical simulations. A third section reports on a project studying thermoelectricity in self-assembled molecular junctions, as they show potential for improved thermoelectric efficiency for energy harvesting; this is discussed in the dissertation. Strategies to benchmark the studies are presented with relevant devices fabricated and measured. These include the development of a measurement protocol to study thermoelectricity in devices, studies of electrical coupling between various molecular structures and graphene electrodes, molecular-structure dependence of electrical and thermal conductance of junctions. Preliminary results and on-going work are discussed. I want to thank the Semiconductor Physics Group of the Cavendish Laboratory, the Semiconductor Physics Group of the Institute of Physics, the Cambridge NanoDTC, and Fitzwilliam College, Cambridge for their support. I want also to thank the collaborators acknowledged in the thesis for contributions in materials and services.

District energy systems are an alternative to conventional national-scale networks to meet demand in urban areas. Decentralising electricity production reduces distribution losses, while centralising thermal energy production capitalises on economies of scale. Furthermore, geographic proximity facilitates the use of waste heat from electricity production to meet thermal demand. However, it is difficult to assess which configuration of technologies will best suit a cluster of users. Mathematical optimisation techniques have been extensively researched as a method to resolve this, as they can simplify the design of investment portfolios and operation schedules for a given set of geolocated demands. However, they are not yet practically applicable. This thesis uses the open-source, mixed integer linear programming framework Calliope to present three methodological enhancements which address model simplification, parameter uncertainty, and conflicting decision-maker objectives. These enhancements enable the practical design of district energy systems through data-centric workflows which can readily represent real system complexities in a tractable optimisation model. This thesis first examines the impact of parameter simplification in a linear model. Piecewise linearisation is applied to nonlinear part-load energy consumption curves and a pre-processing step is developed to optimise breakpoint positioning along a piecewise curve. Second, a three-step method is proposed to handle demand uncertainty in linear models, using historical demand data. These steps are scenario generation, scenario reduction, and scenario optimisation. Using out-of-sample tests, robustness of optimal investments to unmet demand is quantified. Furthermore, system resilience to unexpected events is explored by introducing interruptions to the national electricity grid availability for a district in Bangalore, India. Scenario optimisation is extended to account for these interruptions as well as to mitigate unfavourably high levels of CO$_2$ emissions in system design. Finally, this thesis identifies eight possible decision makers, who each hold a different objective in the design of a district energy system. Optimal technology configuration and out-of-sample test results are compared across all decision-maker objectives. These methodological enhancements demonstrate the capability of optimisation models to be reflective of reality whilst being transparent concerning the impact of simplifications, uncertainty, and conflicting objectives. Calliope is extended in this thesis to be practically applicable for district energy systems. Moreover, its extensibility facilitates the continuation of development, including possible future work into data validation and spatial dimension simplification. This research was supported by the Engineering and Physical Sciences Research Council (grant EP\L016095\1). This work was performed using resources provided by the Cambridge Service for Data Driven Discovery (CSD3) operated by the University of Cambridge Research Computing Service (http://www.csd3.cam.ac.uk/), provided by Dell EMC and Intel using Tier-2 funding from the Engineering and Physical Sciences Research Council (capital grant EP\P020259\1), and DiRAC funding from the Science and Technology Facilities Council (www.dirac.ac.uk).

Photovoltaic devices have an efficiency limit of 33% set by fundamental loss processes in the semiconductor materials. The largest loss comes about as a result of charges excited far above the bandgap losing their excess energy as they cool to the bandedge, a process known as thermalisation. Carrier multiplication offers a means of reducing thermalisation losses using a system in which excess energy from one electron-hole pair is transferred to produce a second electron-hole pair. Fully harnessing carrier multiplication would raise the efficiency limit of photovoltaic devices to 44%. Typically, various challenges mean the benefits of carrier multiplication have not yet been realised. In quantum dot materials, the fundamental understanding of the carrier multiplication process is still lacking. A more thorough understanding of the cooling and recombination mechanisms is needed to fully exploit this phenomenon. In organic materials, an excited singlet exciton splits to form two triplet excitons on neighbouring molecules. The process in organics is referred to as singlet fission. Producing a device that can make use of the singlet fission process however, has proved difficult, limited in part by the instability of singlet fission materials and also by challenges brought about by the need to couple to another material. In this thesis, we will examine both quantum dot and organic systems. The initial work in this project involved the fabrication of quantum dot devices. Steps were taken to improve the efficiency and reproducibility of the devices with the aim of investigating carrier multiplication in device stacks. However, the devices work showed limited success and the decision was taken to move to ultrafast spectroscopy. In examining quantum dot films using picosecond transient absorption spectroscopy, we found clear signatures of carrier multiplication occurring in films of dots synthesis here. We also found that some of our results were at odds with explanations in the literature. To explain our results, we took data under a range of excitation conditions and compared them to the predicted results of various explanations in the literature. We also used ultrafast spectroscopy to examine singlet fission in diketopyrrolopyrrole-based molecules. Such molecules are much more stable than the polyacenes typically used in singlet fission research. We looked for the slow recombination signature of triplet excitons in films of a diketopyrrolopyrrole-based molecule using transient absorption spectroscopy. We assigned the formation mechanism of these triplet molecules using the timescale of the singlet to triplet transition. In this work, we have considered means of increasing the harvestable energy from photovoltaic devices and improved our understanding of how such efficiency increases may be possible.