La seguente Tesi di Dottorato si articola in cinque saggi che esaminano alcuni importanti aspetti legati all'energia in Africa subsahariana, e in particolare all'interazione tra lo sviluppo socio-economico e le sue implicazioni per l'ambiente a livello regionale e globale. I saggi sono introdotti da un capitolo di avvicinamento generale ai temi trattati. Questo capitolo prepara il lettore offrendo un riassunto delle principali sfide legate all'energia nel contesto subsariano e formulando le domande di ricerca e gli strumenti sui quali si basa la tesi stessa. Le principali implicazioni di ciascuno dei saggi, sia per la ricerca che per i decisori politici, vengono poi presentate in un capitolo di discussione finale. Il primo saggio esamina la problematica dell’accesso all'energia, e in particolare all'elettricità. Viene illustrato il ruolo dei dati satellitari e dell'analisi statistica dei dati geospaziali nel migliorare la comprensione della situazione dell'accesso all'elettricità in Africa subsahariana. Il saggio include un'analisi delle disuguaglianze che caratterizzano la qualità dell'accesso all'elettricità nella regione. Il risultato principale è che, dopo decenni, la disuguaglianza nell'accesso all'energia sta iniziando a diminuire. Essa rimane però prominente, in particolare per quanto riguarda la quantità di energia consumata. Viene stimato che gli sforzi di elettrificazione tra il 2020 e il 2030 debbano triplicare il loro passo per raggiungere l'obiettivo di sviluppo sostenibile SDG 7.1.1. Il secondo saggio consiste di una piattaforma di valutazione della domanda energetica bottom-up spazialmente esplicita per stimare il fabbisogno energetico tra le comunità in cui l'accesso all'elettricità è attualmente carente, come identificato con la metodologia introdotta nel primo saggio. La valutazione non si limita al fabbisogno energetico residenziale, ma include un resoconto dettagliato, basato sugli usi finali, del fabbisogno energetico di scuole, strutture sanitarie, pompaggio dell'acqua per l'irrigazione, lavorazione delle colture e microimprese, i principali motori dello sviluppo rurale. Viene condotto uno studio nazionale per il Kenya per dimostrare l'importanza di considerare molteplici fonti di domanda oltre al residenziale quando l'obiettivo è sviluppare una strategia di elettrificazione che supperisca veramente alla povertà energetica. Si dimostra poi che esiste un notevole potenziale di crescita della produttività e della redditività rurale grazie all'apporto di energia elettrica. In molte aree, questi profitti locali potrebbero ripagare gli investimenti nelle infrastrutture di elettrificazione in pochi anni. Il terzo saggio analizza un aspetto specifico dell'interazione tra pianificazione dell'accesso all'elettricità, domanda di energia residenziale e adattamento ai cambiamenti climatici. Vengono combinati dati e scenari climatici, satellitari e demografici per produrre una stima globale spazialmente esplicita della domanda di circolazione e condizionamento dell’aria non soddisfatta a causa della mancanza di accesso all'elettricità. Sulla base di modelli integrati di elettrificazione climatica-energetica e geospaziale, risulta che in Africa sub-sahariana, l'hotspot globale della povertà energetica, tenere conto del fabbisogno di circolazione e condizionamento dell’aria locale stimato (in aggiunta agli obiettivi di consumo residenziale di base) determini una riduzione sostanziale della quota di sistemi standalone come l'opzione di elettrificazione meno costosa entro il 2030, e un importante aumento della capacità di generazione di elettricità e dei requisiti di investimento. Tali risultati suggeriscono la necessità di una maggiore considerazione delle esigenze di adattamento climatico nella pianificazione dei sistemi energetici dei paesi in via di sviluppo e nella valutazione del trade-off tra l'espansione della rete elettrica centrale e sistemi decentralizzati per raggiungere un’elettrificazione universale. La pianificazione dell'elettrificazione deve essere tecnicamente efficiente, ma deve anche considerare l'ambiente politico-economico in cui gli investimenti vengono canalizzati. Il quarto saggio valuta il ruolo della governance e della qualità regolatoria nel quadro di modellazione dell'accesso all'energia elettrica. In particolare, si introduce un indice di governance dell'accesso all'elettricità basato su più indicatori che viene poi implementato nel modello di elettrificazione IMAGE-TIMER. L’effetto dell’indice viene modellato attraverso il suo effetto modificatore sui tassi di sconto privati (una misura del rischio e della disponibilità ad accettare costi futuri rispetto ai costi attuali). I risultati mostrano che la governance e la qualità regolatoria nell'accesso all'elettricità hanno un impatto significativo sul mix tecnologico ottimale e sui flussi di investimenti privati per raggiungere l'elettrificazione universale in Africa subsahariana. In particolare, un ambiente rischioso scoraggia l’investimento da parte dei fornitori privati di soluzioni di accesso decentralizzato all'energia, con il rischio di lasciare molti senza elettricità anche oltre il 2030. Il quinto e ultimo saggio analizza il settore energetico africano da un punto di vista ‘Nexus’. Il saggio valuta l'affidabilità del sistema energetico nei sistemi energetici dominati dall'energia idroelettrica (come in molti paesi dell'Africa centrale e orientale) e del ruolo che i cambiamenti climatici e gli eventi estremi possono esercitare su di esso. Il lavoro combina analisi qualitative e quantitative per (i) proporre un solido framework per evidenziare le interdipendenze tra energia idroelettrica, disponibilità di acqua e cambiamento climatico, (ii) analizzare sistematicamente lo stato dell'arte sugli impatti previsti dei cambiamenti climatici su l'energia idroelettrica nell'Africa subsahariana e (iii) fornire evidenza empirica sui trend passati e sulle traiettorie di sviluppo futuro del settore. I risultati suggeriscono che il cambiamento climatico influenzerà l'affidabilità e la sicurezza della fornitura elettrica attraverso diversi canali. Ad esempio, molti dei principali bacini idrologici sono stati caratterizzati da una diminuzione del livello idrico nel corso del ventesimo secolo. Si evidenzia come tuttavia una diversificazione del mix di generazione elettrico sia finora stata promossa solo in un numero limitato di paesi. Si suggerisce infine che l'integrazione delle fonti rinnovabili variabili con l'energia idroelettrica possa aumentare la resilienza del sistema. / This dissertation is a collection of five essays examining some important energy-related aspects at the interplay of sub-Saharan Africa (SSA)’s development and its interactions with the regional and global environment. The essays are introduced by a general overview chapter – highlighting the core energy-related challenges of SSA and the scope of this work. The main implications of the essays, both for research and for policymakers, are then considered in the final discussion chapter. The first essay focuses on access to modern energy, and chiefly on electricity. I illustrate the role of satellite data and the statistical analysis of geospatial data in improving the understanding of the electricity access situation in sub-Saharan Africa. The essay includes an analysis of inequality characterising the electricity access quality in the region. The main finding is that after decades, energy access inequality is beginning to decline but it remains prominent in particular as far as the quantity consumed is concerned. I find that electrification efforts between 2020 and 2030 must triplicate their pace to meet Sustainable Development Goal 7.1.1. The second essay develops a spatially-explicit bottom-up energy demand assessment platform to estimate the energy needs among communities where access to electricity is currently lacking, as identified with the methodology introduced in the first essay. The assessment is not restricted to residential energy needs, but it includes a detailed, appliance-based account of power needs for schools, healthcare facilities, water pumping for irrigation, crop processing, and micro enterprises, the key drivers of rural development. I carry out a country-study for Kenya to show the importance of considering multiple demand sources beyond residential when the aim is developing an electrification strategy which truly overcomes energy poverty. I also show that there is considerable potential for rural productivity and profitability growth thanks to the input of electric energy. In many areas, these local profits might pay back the electrification infrastructure investment in only few years. The third essay analyses a specific aspect at the interplay between electricity access planning, household energy demand and climate change adaptation. I combine climate, satellite, and demographic data and scenarios to produce a global spatially-explicit estimate of unmet ACC demand due to the lack of electricity access. Based on integrated climate-energy and geospatial electrification modelling, I find that in sub-Saharan Africa, the global hotspot of energy poverty, accounting for the estimated local ACC needs on top of baseline residential consumption targets determines a substantial reduction in the share of decentralised systems as the least-cost electrification option by 2030, and a major ramp-up in the power generation capacity and investment requirements. My results call for a greater consideration of climate adaptation needs in the planning of energy systems of developing countries and in evaluating the trade-off between the central power grid expansion and decentralised systems to achieve universal electrification. Electrification planning must be techno-economically efficient, but it must also consider the political-economic environment where investment needs to be channelled. The fourth essay evaluates the role of governance and regulatory quality in the electricity access modelling framework. In particular, I introduce an Electricity Access Governance Index based on multiple indicators implement it into the PBL’s IMAGE-TIMER electrification model through its modifier effect on private discount rates (a measure of risk and willingness to accept future costs vis-à-vis present costs). The results show that governance and regulatory quality in electricity access have a significant impact on the optimal technological mix and the private investment flows for reaching universal electrification in sub-Saharan Africa. In particular, risky environment crowd out private providers of decentralised energy access solutions with the risk of leaving many without electricity even after 2030. The fifth and final essay takes a nexus perspective in the analysis of the African power sector. It deals with the reliability of the energy system in hydropower-dominated power systems (such as in many countries in Central and East Africa) and the role that climate change and extreme events can exert on it. The essay combines qualitative and quantitative analysis to (i) propose a robust framework to highlight the interdependencies between hydropower, water availability, and climate change, (ii) systematically review the state-of-the art literature on the projected impacts of climate change on hydropower in sub-Saharan Africa, and (iii) provide supporting evidence on past trends and current pathways of power mix diversification, drought incidence, and climate change projections. I find that climate change can affect supply reliability and security in multiple ways. For instance, several major river basins have been drying throughout the twentieth century. Nonetheless, I highlight that diversification has hitherto only been promoted in a limited number of countries. I suggest how integrating variable renewables and hydropower can increase system resilience.

We have dealt with the problem arising from the incongruity between the evolution of the electricity system for meeting the objectives of economic growth, and the human/societal requirements of inclusive and affordable development, and environmental compliance, within the purview of sustainability. We conceive and define the concept of sustainability in the context of national electricity system and adopt an indicator-based hierarchical framework to assess, measure and track its sustainability. The approach necessitates prioritization, quantification and aggregation of multi-dimensional indicators of sustainability. We evaluate the Indian electricity system using this framework by benchmarking the actual dimensional indicator values against upper and lower threshold levels to compute a national electricity system sustainability index (NESSI) for India. The estimated NESSI value for India in 2013 is a low 0.377 (benchmark value is 1), which suggest that India has a substantial sustainability gap to bridge. The approach and the results imply that India or any other emerging/developing country needs to have a serious relook at (i) the goals and targets set for the electricity system, (ii) the set of prioritized technology and policy interventions, and (iii) the models and approaches adopted for strategic electricity planning. The findings from our research clearly indicate that countries like India need to adopt “minimizing sustainability gap” rather than “increasing GDP growth” as the sole criterion for deciding about the challenges raised above for the electricity system. We strongly believe that this approach will not only meet the economic development objective set for the electricity system but also help achieving the societal aspirations as well as environmental compliance. We establish that Indian electricity system is poised for an imminent transition into a sustainable system. What constitutes the inputs, the processes and the outcomes of this transition are of immense interest and have been widely debated in the literature. We motivate and implement an electricity system generation expansion model with multi-attribute technology characterization to model the sustainability transition of electricity system and understand the feasibility, cost and carbon emission implications of generation augmentation. We build on the state of the art resource and technology characterization. We obtain the expansion planning requirements for Indian electricity system by superimposing the projected incremental increase in demand with the retirement schedule. Further, building on the recent advances in power system modelling, we formulate the electricity system transition problem as a grouped integer generation scheduling and generation expansion planning model. This formulation accounts for plant startups, minimum loads, operating reserves, ramping limits and plant life. We run multiple experiments by varying the system configurations for a planning horizon of 18 years till 2032 and characterize the system on select indicators under three dimensions of sustainability for each year. Within the select scenarios, NESSI value in the terminal year varies from 0.481 to 0.51 relative to the base year value of 0.377.We throw some light on how the important questions concerning technology pathways for electricity system sustainability transition can be queried. The approach adopted for this research is two pronged. First is to formulate and subsequently answer the question: What is and what should be the electricity system of India? The second is to answer: what are the prospects for transition of electricity system into a sustainable state? How do probable technology pathways manifest in terms of national electricity system? Can renewable energy deliver? Our proposition –which we validate through this research – is to formulate and subsequently answer the questions in two phases. The two phases are briefly detailed below: In the first phase, the question we have attempted to first formulate and subsequently answer is: what is and what should be the electricity system for India? We propose to employ an indicator based approach for this part of the research, which attempts to evaluate India’s electricity system using the sustainability framework. The analysis of the indicators belonging to economic, social, environmental and institutional dimensions of sustainability will provide a deeper understanding of the system, identify and quantify the prevailing sustainability gaps and develop specific targets for interventions. We begin with a survey of literature in the domain of sustainability assessment. We identify and briefly discuss the essential concepts, ideas and methods used in sustainability assessment. We observe the emergence of electricity related concerns in the wider sustainability discourse. Next, we survey the literature on electricity systems and discuss the intersection of energy systems with development. Than we define the sustainable national electricity system and bring out the synergies between measurement of sustainable development and assessment of objectives of electricity systems. We observe cross country variations in electricity system planning objectives. While focus for developed nations has historically been economic and has subsequently included environmental concerns of climate change and pollution. In addition to economic and environmental aspects, the low levels of access as well as consumption are a reality for India and other developing nations. This adds another dimension to the status assessment and subsequent planning of national electricity system of India. Synthesis of sustainability assessment and objectives of electricity system planning in this phase culminates with conception and evaluation of National Electricity System Sustainability Index (NESSI) for India. The underlying theme throughout this phase is our attempt to first formulate and subsequently answer: What is and what should be the electricity system for India? In the second phase, a modeling approach has been developed to optimally prioritize the interventions (energy-technology supply chains) in response to the specific targets (from Phase 1) for planning a sustainable electricity system for India. All the possible supply chain interventions tracking the transitions from energy resources to electricity in the bus bar on grid (as modeled by a Reference Energy System) form the inputs for the mathematical model. The output is the optimal set of interventions as trade-off solutions, which meet the targets set by the sustainability goal. The criteria like cost, efficiency of transformation, emission coefficients and energy resource availability form the basis for developing the optimal plan. We begin this phase with survey of literature on power system modelling. Electricity system planning has been undertaken in academic and planning domains for several decades. It is only recent that, driven by the imminent challenges of de-carbonization, affordability, equity and security- which has resulted in coevolution of several possible technological, behavioral and policy intervention proposals-there is demand for coherent assessment of these propositions for electricity system transition. In our work, we have focused on supply side technology interventions. Supply side technology intervention propositions for electricity system transition more often than not involve variable renewable energy, i.e., solar and wind. Variable renewable energy technologies pose significant modelling challenges because of their characteristic intermittency which induces complex dynamics in the complimentary system, i.e., electricity generating technologies other than renewable energy. We identify tremendous activity in the domain of electricity system modelling with focus on model representation of electricity system constituents which has significant implications for the outcomes of the planning exercises undertaken with these models. Literature synthesis in this phase culminates with our attempt at mathematical modelling of generation technology pathways for electricity system in transition. Undertaking this exercise has involved preparation of model feeds: energy resource supply profiles, generation technology specifications and demand projections. We have done a series of numerical experiments to establish validity of the model. Subsequently we have validated various scenarios for Indian electricity system representing different levels of transitions, which provides insights which we expect will be useful for the stakeholders. The underlying theme throughout this phase is our attempt to answer the questions: How does one understand electricity system transition? How do electricity generating technologies interact amongst each other to yield certain set of system outputs? Can renewable energy deliver? In our pursuit of finding answers to several questions raised at various points in this thesis and alluded to above, we have done a systematic systemic diagnosis of Indian electricity system. We have developed a multi-dimensional and multi-hierarchical indicator based framework to measure national electricity system sustainability. We have assessed Indian electricity system with this framework, to understand if Indian electricity system is sustainable and how it can transition towards a more sustainable state. Based on this understanding, we have investigated electricity generation technology pathways for a transitioning electricity system. We have modelled India as a single region with aggregate temporal profiles of resource availability and hourly loads. Building on the recent literature on power system modelling and their application, this thesis is a systematic exposition of how the important questions of supply side technology portfolio concerning electricity system sustainability transition can be queried. The results are based on several instances of data inputs. Main contributions from our work are: 1. Introducing the concept of sustainability of national electricity system and defining it comprehensively for the first time. 2. Conceptualizing, developing and validating a multi-dimensional and multi-hierarchical indicator-based framework for assessing and benchmarking national electricity system sustainability. This framework is generalizable and applicable to the electricity systems of all the countries for assessing the sustainability status. 3. A composite measure of National Electricity System Sustainability Index (NESSI), which can be used to identify and quantify prevailing sustainability gaps in the national electricity system and provide a goal for sustainability transition of the electricity system through higher NESSI target values. The constituents (dimensions, themes and indicators) of NESSI can enable identification of interventions and fixing of targets for such a transition. 4. Conceptualized, developed and validated an integrated mathematical model of generation expansion planning (supply augmentation) and generation scheduling with extensive operational details for electricity system in transition. This included: Enumeration and characterization of reference electricity system (energy resources, electricity generating technologies and demand for electricity). Demand profiling which involved estimating annual peak demand and demand for electricity, consideration of annual retiring capacity and computation of representative demand profiles (load curves) for past and future years using time-series load data. Modelling variable renewable energy (wind, solar and hydro) by developing representative energy resource availability profiles using time-series data. Harmonizing the extracted temporal energy resource availability and load profiles to preserve the chronological correlations. Explicit modelling of capacity utilization by proposing and implementing unit profile inversion. Effectively, it implies that generation from the variable generation capacity, e.g., solar capacity is upper bounded by the representative profile corresponding to that capacity. Optimally selected generation technology interventions for planning sustainable electricity system for India under select scenarios. 5. Juxtaposition of indicator-based macro model of electricity system sustainability assessment with bottom-up mathematical model of generation expansion planning and generation scheduling to evaluate official Indian scenarios of electricity system planning for sustainability transition. In summary, we have developed and demonstrated an empirical instance of an integrated methodology, beginning from a systematic diagnosis of the national electricity system to a meaningful solution. Through this thesis, we have attempted to understand the alternate future electricity supply transitions, their implications for society and environment and how they are influenced by the planning decisions. In conclusion, there is substantial activity in all stakeholder domains: research activity, actions by NGOs and the government but given the long term nature of probable interventions, sustained efforts will be required to reach the desired outcomes. Future of grid is the biggest system level problem, which we believe we have illuminated to some extent and which could benefit from further research. While planning exercises using complex models are useful in their own right given the complexities of real world close monitoring and scrutiny of the evolving electricity system and timely course corrections will be critical