Добірка наукової літератури з теми "Renewable energy sources – Risk assessment"

Abstract The article analyzes the development trends for renewable energy sources in 2010-2021. The growing use of renewable energy sources in the global energy balance in developed and developing countries was revealed. The share of renewable sources in the production of electricity in 2021 was determined. The results presented in the form of approaches to the integration of renewable sources in order to replenish the production processes for the provision of energy services are based on an extensive assessment of scientific Russian and foreign literature. Integration of renewable energy sources will contribute to the sustainability of existing technologies and risk neutralization. The integrated approach will contribute to the interconnected provision of electricity, heat, cold and mobility

Transient stability affected by renewable energy sources integration due to reductions of system inertia and uncertainties associated with the expected generation. The ability to manage relation between the available big data and transient stability assessment (TSA) enables fast and accurate monitoring of TSA to prepare the required actions for secure operation. This work aims to build a predictive model using Gaussian process regression for online TSA utilizing selected features. The critical fault clearing time (CCT) is used as TSA index. The selected features map the system dynamics to reduce the burden of data collection and the computation time. The required data were collected offline from power flow calculations at different operating conditions. Therefore, CCT was calculated using electromagnetic transientsimulation at each operating point by applying self-clearance three phase short circuit at prespecified locations. The features selection was implemented using the neighborhood component analysis, the Minimum Redundancy Maximum Relevance algorithm, and K-means clustering algorithm. The vulnerability of selected features tends to result great variation on the best features from the three methods. Hybrid collection of the best common features was used to enhance the TSA by refining the final selected features. The proposed model was investigated over 66-bus system.

This paper argues that energy systems are becoming increasingly complex, and illustrates how new types of hazards emerge from an ongoing transition towards renewable energy sources. It shows that the energy sector relies heavily on risk assessment methods that are analytic, and that systemic methods provide important additional insights. A case study of the Dutch gas sector illustrates this by comparing the hazard and operability study (HAZOP, analytic) with the system-theoretic process analysis (STPA, systemic). The contribution is twofold. This paper illustrates how system hazards will remain underestimated by sustained use of only analytic methods, and it highlights the need to study the organization of safety in energy transitions. We conclude that appropriate risk assessment for future energy systems involves both analytic and systemic risk assessments.

AbstractA simulation model to evaluate risks in Power Systems including green energy sources to generate electricity for electro mobility use is presented in the paper. The model allows to calculate risk indicator that characterize the performance of the Power Systems. The model considers the additional risks of wind and solar variability in the Power Systems, through wind farms and PV farms, respectively. Also, in the recent years, the number of electric vehicles (EVs) on the road have been rapidly increasing. Charging this increasing number of EVs is expected to have an impact on the power grid especially if high charging powers and opportunistic charging are used. Multiple papers have observed that the charging stations are used by multiple users during the day. In a context where electric mobility is gaining increasing importance as a more sustainable solution for urban environments, this work presents the optimization of charging profiles of the potential users of these charging stations. We analyzed the charging profiles in a power grid with renewables sources of energy and we determine the optimal charging profiles for the power grid based on maximizing the energy delivered by renewable sources of energy.

Abstract Based on the characteristics of the renewable energy sources (RES), current states and also Russia uses the analysis of emerging risks and their management methods for avoiding this problem. The analysis of methodological approaches to assessing emerging risks in the implementation of electricity generation projects based on various types of renewable energy sources is carried out. The problems of assessing the natural resource risks of using renewable energy in the Russian Federation in relation to the climatic regionalization of the territory are examined. The most representative parameters of the ecological and geographical component for assessing the degree of risk by using renewable energy are highlighted. The authors propose a methodology for assessing the degree of risk for using solar resources based on the characteristics calculated of the influx variability for solar radiation to the earth's surface, by assessing and mapping the level of natural resource risks. The levels of resource risks in solar energy development for some regions of Russia were estimated. The paper presents maps of areas with different risk levels in Russia.

Energy poverty is a problem that affects all member states of the European Union to a varying degree, including Poland, where about 9% of the population is at risk of energy poverty. The article aims to show the changes in energy poverty in Poland in 2010–2018. The specific goal, however, is to evaluate government measures aimed at reducing energy poverty through investments based on renewable energy sources. To present changes in the level of energy poverty in 2010–2018, the authors proposed a new synthetic measure that unifies several different measures used by researchers and allows for a comprehensive assessment of this phenomenon. The conducted research showed that in 2010–2018 there was a slow but visible decrease in the level of energy poverty in Poland. In addition, the article indicates investments in renewable energy sources that may have a positive impact on reducing the scale of energy poverty in Poland. The programs implemented with national and EU public funds, which finance investments in renewable energy sources in Poland, are also presented.

Oil is one of the most important sources of energy, about 25 percent of which comes from offshore sources. As a result, the transportation of oil tankers, and the construction of offshore oil platforms and subsea pipelines have increased, to facilitate offshore oil exploitation. However, most oil spill risk assessments analyze the impact of one risk source, and rarely consider multiple risk sources in the study area. This paper focuses on three risk sources that may cause oil spills in a certain area, and establishes an oil spill risk assessment model through a fuzzy inference system. Oil spill probabilities for different risk sources are calculated through the model. According to the definition of oil spill risk, the risk probability of multiple risk sources in the study area is obtained, which can provide technical support for regional oil spill emergency capacity and emergency resource allocation.

Stable and reliable integrated energy systems are one of the major issues related to sustainable regional and national energy development. Because most existing studies are conducted on whole countries, few address the effects of regional interaction and renewable energy. Therefore, a natural disaster risk assessment model (NDRAM) combined with spatial models is used as a general systematic tool to assess and resolve regional energy security, based on a framework of resources, generation, transmission, marketing and consumption, with 17 metrics. In particular, energy systems were treated as organic connected-units and their security status was regarded as a combined result of potential hazard and system vulnerability. The proposed method was applied to evaluate and classify the security situation of 31 Chinese provinces in 2016. The results showed that transmission had the most significant impact among five major risk sources. The closer grid connections have a stronger ability to deal with risks among regions, where renewables consumption could be better stimulated cross-regionally. In terms of a regional perspective, there is still a gap among different regions, and eastern China presented higher energy risk status. The most energy-hazard provinces are mainly in the east provinces with well-developed levels in Beijing, Tianjin and Shanghai. The least energy-vulnerable provinces are mainly in the abundant natural resources regions such as Inner Mongolia, Sichuan and Xinjiang. The NDRAM-based general model provides a systematic tool for quantitative assessment of regional energy security with a full accounting of regional interaction and renewable energy issues, which may help to develop clean energy, optimize system infrastructure and improve scientific management.

The growth of the industry and population of South Africa urges to seek new sources of electric power, hence the need to look at alternative power sources. Power output from some renewable energy sources is highly volatile. For instance power output from wind turbines or photovoltaic solar panels fluctuates between zero and the maximum rated power out. To optimize the overall power output a model was designed to determine the best trade-off between production from two or more renewable energy sources putting emphasis on wind and solar. Different measures of risk, such as coefficient of variation (CV) and value at risk (VAR), were used to determine the best hybrid renewable energy system (HRES) configuration. Depending on the investors’ expected returns (demand) and risk averseness, they will be able to use the model to choose the best configuration that suites their needs. In general it was found that investing in a diversified HRES is better than investing in individual power sources.

Les entreprises du secteur de l’énergie sont confrontées à la nécessité de transformer leur modèle économique pour intégrer les préoccupations écologiques et assurer une transition énergétique (TE). Selon la littérature sur les transitions, la prise en compte des risques de ce processus nécessite des approches novatrices orientées vers le long terme, ainsi qu'une conception adaptative des politiques. Dans ce cadre, l'approche de l'écosystème d’affaire joue un rôle important dans la découverte de nouvelles solutions liées à la TE. L'objectif principal de cette thèse est d'examiner l’apport de l'application de l'approche de l'écosystème dans la réduction des risques sous-jacents de ce processus. Par le biais d'entretiens approfondis et une revue de littérature exhaustive, d'un engagement étendu des parties prenantes et d'une interrogation sur les caractéristiques des acteurs de l'énergie dans une série de contextes, le potentiel du rôle de l'écosystème émergent des énergies renouvelables (EEnR) dans la réduction des risques de la TE est étudié. La recherche menée donne un aperçu de la nature holistique de la relation entre les acteurs de l'énergie et explore les obstacles communs rencontrés tels que l'acceptabilité sociale, les risques du marché et la gestion des parties prenantes. Les résultats suggèrent que les entreprises sont conscientes du potentiel d'un EEnR émergent. De nombreuses caractéristiques de ce EEnR ont été trouvées dans les stratégies de partenariat actuelles des acteurs interrogés. Plus largement, une cartographie de cet écosystème émergent a été présentée
Energy companies are faced with the need to transform their business model to integrate environmental concerns and ensure an energy transition. According to the transitions literature, addressing the risks of this process requires innovative, long-term oriented approaches, as well as thoughtful and adaptive policy design. In this framework, the business ecosystem approach plays an important role in the discovery of new solutions during the energy transition. The main objective of this thesis is to examine the contribution of applying the ecosystem approach in reducing the underlying risks of this process. Through exhaustive in-depth interviews and literature reviews, extensive stakeholder engagement, and interrogation of the characteristics of energy actors in a range of contexts, the potential for the role of the emerging renewable energy ecosystem in reducing the risks of the energy transition is explored. The research conducted provides insight into the holistic nature of the relationship between energy actors and explores common barriers encountered such as social acceptability, market risks and stakeholder management. The results suggest that companies are aware of the potential of an emerging renewable energy ecosystem and that most companies view the ecosystem approach positively. Many characteristics of this potential ecosystem, which is in its nascent stage, were found in the current partnership strategies of the interviewed stakeholders. More broadly, a mapping of the emerging renewable energy ecosystem was presented

Thesis (PhD (School of Public Leadership))--University of Stellenbosch, 2012.
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ENGLISH ABSTRACT: Technology assessment has changed in nature over the last four decades. It changed from an analytical tool for technology evaluation, which depends heavily on quantitative and qualitative modelling methodologies, into a strategic planning tool for policy-making concerning acceptable new technologies, which depends on participative policy problem analysis. The goal of technology assessment today is to generate policy options for solutions of organisational and societal problems, which at the operational level, utilise new technologies that are publicly acceptable; that is, viable policy options. Energy technology assessment for sustainability is inherently a complex and dynamic process that requires a holistic and transdisciplinary approach. In the South Africa context, specifically, there is no formal and coherent approach to energy technology assessment from a sustainability perspective. Without a formal comprehensive or well integrated technology assessment approach to evaluate the sustainability of any technology, the policy-makers, technology designers, and decision-makers are faced with difficulty in terms of making reasoned decisions about the appropriate technology options. This study developed a framework that incorporates a technology assessment approach, namely, system dynamics, within the broader scope of technology development for sustainability. The framework, termed the Systems Approach to Technology Sustainability Assessment (SATSA), integrates three key elements: technology development, sustainable development, and a dynamic systems approach. The study then provides a guiding process of applying the framework to energy technology assessment theory and practice within the context of sustainable development. Biodiesel, a cleaner burning replacement fuel, argued to potentially contribute to sustainable development, is used for the demonstration. Biodiesel development entails complex interactions of actors such as the technology developers, government at different levels, communities, as well as the natural environment. Different actions or responses in the greater system might hinder or undermine the positive effects of such a development. Based on the SATSA framework, a Bioenergy Technology Sustainability Assessment (BIOTSA) model was developed. The BIOTSA model was used to test the outcomes of a proposed biodiesel production development in the Eastern Cape Province of South Africa on selected sustainability indicators. In addition, some policy scenarios were tested to compare how they assist in improving the selected indicators. The BIOTSA model results are useful in comparing dynamic consequences resulting from a proposed biodiesel production development and the respective policies and decisions that may arise from such a development. The testing and validation of the BIOTSA model was carried out based on structural validity, behavioural validity, and expert opinion. Potential policy scenario outcomes and their implication, on the selected sustainability indicators, were also tested. The opinions of the selected stakeholders indicated that the BIOTSA model was useful in providing an understanding of the potential impacts of the biodiesel development on selected sustainability indicators in the Eastern Cape Province. Thus, the SATSA framework can be applied for assessing sustainability of other renewable energy technologies. In addition, system dynamics provide a useful and a feasible dynamic systems approach for energy technology sustainability assessment. Finally, the model building process and transdisciplinary nature of this study enabled the identification of the potential problems that could arise during the biodiesel production development. In addition, gaps in data and knowledge were identified and the recommendation for future work in this field is highlighted. Nevertheless, the findings of the BIOTSA model could inform policy- and decision-making in biodiesel production development in South Africa. The development of similar models for other renewable energy development efforts is thus recommended. The current efforts to facilitate the large-scale roll out of concentrated solar thermal technologies in Southern Africa, for example, would require the development of a Solar Thermal Technology Sustainability Assessment (SOTTSA) model.
AFRIKAANSE OPSOMMING: Die aard van tegnologie assessering het in die afgelope vier dekades verander. Dit het verander ten opsigte van ’n analitiese hulpmiddel vir tegnologie evaluering, wat hoofsaaklik staatmaak op kwalitatiewe en kwantitatiewe modelleringsmetodiek, na ’n strategiese beplanningshulpmiddel vir beleidvorming met betrekking tot nuwe aanvaarbare tegnologieë, wat afhanklik is van ’n deelnemende beleidsprobleem analise. Vandag se doel vir tegnologie assessering is om beleidsopsies vir oplossings van organisatoriese en sosiale probleme te genereer, wat op operasionele vlak gebruik maak van nuwe tegnologieë wat deur die publiek aanvaar is; met ander woorde, lewensvatbare beleidsopsies. Energie tegnologie assessering vir volhoubaarheid is sonder twyfel ’n komplekse en dinamiese proses wat ’n holistiese en transdisiplinêre benadering benodig. In die Suid- Afrikaanse konteks is daar geen formele en samehangende benadering tot tegnologie assessering vanaf ’n volhoubaarheidsperspektief nie. Beleidsmakers, tegnologie ontwerpers en besluitnemers mag sukkel om beredenerende besluite te neem oor die toepaslike tegnologie opsies sonder ’n formele omvattende of goed geïntegreerde tegnologie assesseringsbenadering om die volhoubaarheid van enige tegnologie te evalueer. Hierdie studie het ’n raamwerk ontwerp wat die tegnologie assesseringsbenadering inkorporeer binne die breë bestek van tegnologiese ontwikkeling vir volhoubaarheid naamlik, stelsel dinamika. Die raamwerk, genoem die Sisteem Benadering tot Tegnologie Volhoubaarheidsassessering (SBTVA) integreer drie sleutelelemente: tegnologiese ontwikkeling, volhoubaarheidsontwikkeling, en ʼn dinamiese stelsels benadering. Verder verskaf die studie ’n leidende proses te opsigte van die toepassing van die raamwerk tot energie tegnologie assesseringsteorie en praktyk binne die konteks van volhoubaarheidsontwikkeling. Biodiesel word gebruik vir die demonstrasie omdat dit gereken word as ’n skoner plaasvervanger vir brandstof en daar aangevoer word dat dit ’n potensiële bydraer tot volhoubaarheidsontwikkeling is. Die ontwikkeling van biodiesel behels komplekse interaksie tussen verskeie akteurs soos tegnologiese ontwikkelaars, die regering op verskillende vlakke, gemeenskappe asook die natuurlike omgewing. Verskeie aksies of reaksies in die groter sisteem mag dalk die positiewe effek van so ontwikkeling ondermyn of verhinder. ’n Biodiesel Tegnologiese Volhoubaarheidsassessering (BIOTVA) model is ontwerp gebaseer op die SBTVA raamwerk. Die BIOTVA model is gebruik om die uitkomste op geselekteerde volhoubaarheidsaanduiders van ’n voorgestelde biodiesel produksie ontwikkeling in die Oos- Kaap Provinsie van Suid-Afrika te toets. Buiten vir die voorafgaande is sekere beleidtoekomsblikke ook getoets om te vergelyk hoe hulle sal help om die geselekteerde aanwysers te verbeter. Die BIOTVA model resultate is behulpsaam in die vergelyking van dinamiese gevolge wat voortspruit uit die voorgestelde biodiesel produksie ontwikkeling asook die onderskeie beleide en besluite wat mag ontstaan van so ’n ontwikkeling. Die toetsing en bekragtiging van die BIOTVA model was uitgevoer gebaseer op strukturele geldigheid, gedragsgeldigheid, en kundige opinie. Potensiële beleidtoekomsblikke uitkomste en die nagevolge, ten opsigte van die geselekteerde volhoubaarheidsaanduiders, is ook getoets. Die opinies van die geselekteerde aandeelhouers het aangedui dat die BIOTVA model bruikbaar is om ’n beter begrip te verskaf ten opsigte van die potensiële impak wat die biodiesel ontwikkeling op geselekteerde volhoubaarheidsaanduiders in die Oos-Kaap Provinsie sal hê. As gevolg hiervan kan die SBTVA raamwerk toegepas word om die volhoubaarheid van ander herwinbare energie tegnologieë te assesseer. Buiten die voorafgaande kan stelsel dinamika ’n bruikbare en uitvoerbare dinamiese stelselbenadering vir energie tegnologie volhoubaarheidsassessering verskaf. Ten slotte, die model bouproses en transdisiplinêre aarde van die studie het gehelp om potensiële probleme wat kan voorkom tydens die biodiesel produksie ontwikkeling te identifiseer. Daarby is gapings in data en kennis ook geïdentifiseer en die aanbevelings vir verdere studie in die veld is uitgelig. Nieteenstaande kan die bevindings van die BIOTVA model beleidmakers en besluitnemers in die biodiesel produksie ontwikkeling van Suid- Afrika inlig. Die ontwikkeling van soortgelyke modelle vir ander herwinbare energie ontwikkelingspogings word aanbeveel. As voorbeeld sal die huidige pogings om die grootskaalse uitrol van gekonsentreerde son termiese tegnologieë in Suider-Afrika te fasiliteer die ontwikkeling van ’n Son Termiese Tegnologie Volhoubaarheidsassesering (SOTTVA) model benodig.

This research investigates the potential for employing solar energy as a sustainable power generation source in the Kingdom of Saudi Arabia (KSA). The work maps the availability of solar energy throughout the country, and investigates the feasibility of implementing the technology at two case study locations. These are the existing power generation grid sites of Wadi Aldawasir (located 20° 23′ 22.00″ N 45° 12′ 32.00″ E), and Shuaibah (located 20° 37′ 22.84″ N 39° 33′ 44.02″ E). The first case study site, Wadi Aldawasir, covers an area of 48,900 m2, where parabolic trough solar thermal technology is proposed for power generation. The second case study site, Shuaibah power plant is one of the largest desalination and fossil fuel plants in the world with a 1,030,000 m3/ day capacity. Both case studies were assessed in terms of site specifications with selection based on Direct Normal Irradiation (DNI). A feasibility study examining Concentrated Solar Power (CSP) potential was conducted for both locations, with analysis of weather data, particularly monthly and annual, global horizontal and beam normal irradiation data. From these data, a reasonable estimate of CSP potential, and viability of the technology was determined. Simulation was then performed using Solar Advisor Model (SAM) and Renewable Energy Technology Screen (RETScreen) software, taking into account the location weather data, (DNI, dry-bulb and dew-point temperatures, relative humidity, barometric pressure, and wind speed), technical specification, (solar field, Solar Multiple (SM) Solar collector Assemblies (SCAs), power cycle and thermal storage) and economic parameters (energy unit cost, maintenance, etc.). Simulation evaluated annual energy performance (solar radiation resource of the solar field, electrical energy delivered by solar thermal plant, system losses, required solar field area), levelised cost of unit of power generated, CO2 emissions savings, and other financial feasibility indicators. The work shows that the energy yield of the new solar power plants using proposed CSP technology in both case studies is feasible.

The huge natural energy resources available in the world’s oceans are attracting increasing commercial and political interest. In order to evaluate the status and the degree of acceptability of future Ocean Energy (OE) schemes, it was considered important to develop an Integrated Assessment Methodology (IAM) for ascertaining the relative merits of the competing OE devices being proposed. Initial studies included the gathering of information on the present status of development of the ocean energy systems on wave, OTEC and tidal schemes with the challenges faced for their commercial application. In order to develop the IAM, studies were undertaken for the development and standardization of the assessment tools focussing on: • Life Cycle Assessment (LCA) on emission characteristics. • Energy Accounting (EA) studies. • Environmental Impact Assessment (EIA) over different environmental issues. • Resource captures aspects. • Defining economy evaluation indices. The IAM developed from such studies comprised of four interrelated well defined tasks and six assessment tools. The tasks included the identification of the modus operandi on data collection to be followed (from industry) for assessing respective OE devices, and also advancing relevant guidelines as to the safety standards to be followed, for their deployment at suitable sites. The IAM as developed and validated from case studies in ascertaining relative merits of competing OE devices included: suitable site selection aspects with scope for resource utilisation capability, safety factors for survivability, scope for addressing global warming & energy accounting, the environmental impact assessment both qualitatively and quantitatively on different environmental issues, and the economic benefits achievable. Some of the new ideas and concepts which were also discovered during the development of the IAM, and considered useful to both industry and researchers are given below: • Relative Product Cost (RPC) ratio concept- introduced in making an economic evaluation. This is considered helpful in sensitivity analysis and making design improvements (hybridising etc) for the cost reduction of OE devices. This index thus helps in making feasibility studies on R&D efforts, where the capital cost requirement data and life span of the device is not well defined in the primary stages of development. • Determination of the threshold limit value of the barrage constant - considered useful in determining the efficacy of the planning process. The concept ascertained the relative efficiency achieved for various barrage proposals globally. It could also be applied to suggest the revisions required for certain barrage proposals and also found useful in predicting the basin area of undefined barrage proposal for achieving economic viability. • Estimations made on the future possibility of revenue earnings from the by-products of various OTEC types, including the scope of chemical hubs from grazing type OTEC plants. • Determination of breakeven point- on cost versus life span of wave and OTEC devices studied, which is useful in designing optimum life of the concerned devices. The above stated multi-criterion assessment methodology, IAM, was extended leading to the development of a single criterion model for ascertaining sustainability percent achievable from an OE device and termed IAMs. The IAMs was developed identifying 7 Sustainability Development Indices (SDI) using some the tools of the IAM. A sustainability scale of 0-100 was also developed, attributing a Sustainability Development Load Score (SDLS) percentage distribution pattern over each SDIs, depending on their relative importance in achieving sustainability. The total sum of sustainability development (SD) gained from each SDI gave the IAMs (for the concerned device), indicating the total sustainable percentage achieved. The above IAMs developed, could be applied in ranking OE devices alongside the unsustainable coal power station. A mathematical model of estimating the IAMs was formulated, in order to ascertain the viability to the sustainable development of any energy device. The instruments of IAM and IAMs which have been developed would be helpful to the OE industry in ascertaining the degree of acceptability of their product. In addition it would also provide guidelines for their safe deployment by assessing the relative merits of competing devices. Furthermore, IAM and IAMs would be helpful to researchers undertaking feasibility studies on R&D efforts for material development research, ‘hybridization studies’ (as also new innovations), cost reduction, the performance improvement of respective devices, and any economic gains. With future advancements in OE systems and the availability of field data from large scale commercial applications, the specific values/data of the IAM & IAMs may be refined, but the logic of the models developed in this research would remain the same.

The modern day power grid is a highly complex system; as such, maintaining stable operations of the grid relies on many factors. Additionally, the increased usage of renewable energy sources significantly complicates matters. Attempts to assess the current stability of the grid make use of several key parameters, however obtaining these parameters to make an assessment has its own challenges. Due to the limited number of measurements and the unavailability of information, it is often difficult to accurately know the current value of these parameters needed for stability assessment. This work attempts to estimate three of these parameters: the Inertia, Topology, and Voltage Phasors. Without these parameters, it is no longer possible to determine the current stability of the grid. Through the use of machine learning, empirical studies, and mathematical optimization it is possible to estimate these three parameters when previously this was not the case. These three methodologies perform estimations through measurement-based approaches. This allows for the obtaining of these parameters without required system knowledge, while improving results when systems information is known.
Ph. D.

Current hydro-turbines aim to capture the immense energy available in tidal movements, however commonly applied technologies rely on principles more applicable in hydroelectric dams. Tidal stream currents, such as in Coastal Georgia, are not strong enough to make such turbines both efficient and economically viable. This research proposes a novel low-energy vortex shedding vertical axis turbine (VOSTURB) to combat the inefficiencies and challenges of hydro-turbines in low velocity free tidal streams. Some of the energy in tidal streams is extracted naturally from vortex shedding; as water streams past a bluff body, such as pier, low pressure vortices form alternatively on each side, inducing a rhythm of pressure differentials on the bluff body and anything in its wake. VOSTURB aims to capture this energy of the vortices by installing a hydrofoil subsequent to the bluff body. This foil, free to oscillate, translates the vortex energy into oscillatory motion, which can be converted into a form of potential energy. The presented research will act as a 'proof of concept.' It aims to assess such foil motion, or the ability of VOSTURB to capture vortex energy, and begin to assess the amount of tidal energy that can be theoretically harnessed. In this study a small scale model of VOSTURB, a cylindrical bluff body with a hammer shaped hydrofoil, was tested in a hydraulic flume for various mean flow speeds. Tangential accelerations of the foil's center of gravity were obtained through the use of an accelerometer. The acceleration data was analyzed utilizing Fourier analysis to determine the fundamental frequency of the wing oscillations. The available power to be harnessed from the oscillatory motion was then estimated utilizing this fundamental frequency. Ultimately it was found that the frequency of the VOSTURB foil oscillations corresponded highly with the theoretical frequency of vortex shedding for all moderate to high flow speeds. Low speeds were found to produce inconsistent and intermittent small oscillations. This signifies at moderate to high flow speeds, VOSTURB was able to transform some vortical energy into kinetic. The maximum average power obtained 8.4 mW corresponded to the highest flow velocity 0.27 m/s. Scaled to Rose Dhu prototype conditions this represented 50 W at a flow velocity of 0.95m/s, the maximum available at Rose Dhu. Although it was ascertained that VOSTURB could consistently capture some of the vortical energy; the percentage of which could not be calculated with certainty. Thus, the average kinetic power assessments of the foil were compared to the available power of the mean flow for each flow speed calculated by two methods: (1) over the foil's swept area; (2) the area of fluid displaced by the bluff body immediately in front of the foil. The maximum efficiency of the foil, found for the fastest flow speed was at 18% and 45% respectively. It was found that both average foil power, available flow power, and efficiency all decreased with a decrease in flow velocity. This study can serve as only a preliminary study for the effectiveness of VOSTURB as a hydro-turbine for tidal power. In the experiments, the foil was allowed to oscillate freely with little resistance. Future testing of VOSTURB needs to observe whether the vortex energy can overcome the resistive torque introduced by a generator to induce oscillatory motion as well as further optimize the foil design. While the testing in this project assesses the kinetic energy or power of the vortex shedding, this future testing will provide insight into the actual work that can actually be converted into potential energy or power. Complementing this research, both a Harmonic Analysis of Least Squares (HAMELS) and a Complex Empirical Orthogonal Function (CEOF) Analysis was conducted on available surface height and current velocity data separately from an available Regional Ocean Modeling System (ROMS) model of Coastal Georgia. Such analysis were conducted to observe spatial and temporal tidal patterns advantageous to a possible prototype installation of a tidal turbine such as VOSTURB. The more conventional HAMELS analysis, which isolates components of a signal with a certain frequency, identified temporal and spatial patterns attributed to tidal constituents. CEOF analysis, where major patterns of variance are identified not according to prescribed frequencies, was employed to identify any patterns possible not attributed to the tidal constituents. This study was also in part to observe whether the CEOF analysis could identify any patterns of tidal propagation that could not be resolved by the HAMELS analysis. The CEOF and HAMELS analysis of the surface height output produced very similar results: major modes of surface height variation due to the diurnal and semidiurnal tidal constituents propagating up the estuary. The CEOF results did not produce any additional information that could not be found through the HAMELS analysis of the constituents and presented such results in an arguably more convoluted manner. In addition, the surface height analysis provided no direct insight into areas more advantageous to tidal power. The CEOF analysis of the vector current velocity data however did provide some insight. The CEOF of the current data was able to isolate patterns of variance corresponding to the tidal constituents. However, the CEOF was also able to identify local 'hotspots' of high current magnitudes not resolved by HAMELS. These local areas of high current magnitudes, most likely due to changes in hydrodynamic conditions such as channel constrictions, are advantageous for tidal power applications. These general areas could serve as a starting point for the location selection process for a possible prototype installation of VOSTURB if the area was refined more. Ultimately for a prototype installation of VOSTURB, further experimentation and analysis is required for both the turbine design and placement, such as a power conversion methodology for the turbine and a more spatially resolute set of data to perform a CEOF analysis on. With these tasks completed, the prototype installation will be part of a larger effort between the Georgia Institute of Technology and the Girl Scouts of America to create completely sustainable "Eco-Village" on Rose Dhu Island, GA. With an extensive community outreach planned to educate the public, Rose Dhu, along with championing hydrokinetic energy, will serve as a paradigm for sustainable design and energy.

Diploma thesis deals with analysis of internal microclima of the building , evaluation of its thermal and technical properties and it also deals with its energy comsumption. With using simuation programm, there was designed solutions which will lead not only to lowering of energy consumption but also to improvemnt of komfort for students and tachers.

The increasing demand for energy and the increased depletion rate of nonrenewable energy resources call for research on renewable alternatives. Mapping the availability of these resources is an important step for development of energy conversion projects. For this purpose, the wave power potential along the Atlantic coast of the southeastern USA, and the tidal stream power along the coast of Georgia are investigated in this study. Wave power potential is studied in an area bounded by latitudes 27 N and 38 N and longitudes 82 W and 72 W (i.e. North Carolina, South Carolina, Georgia, and northern Florida). The available data from National Data Buoy Center wave stations in the given area are examined. Power calculated from hourly significant wave heights and average wave periods is compared to power calculated using spectral wave energy density. The mean power within 50 km of the shore is determined to be low, whereas higher power is available further offshore beyond the 3500 m contour line. The tidal stream power potential along the coast of the state of Georgia is evaluated based on the NOAA tidal predictions for maximum tidal currents and three dimensional numerical modeling of the currents with Regional Ocean Modeling System (ROMS). The modeling results are validated against the available measurements. This region has low to moderate average tidal currents along most of the coast, but with the possibility of very strong local currents within its complex network of tidal rivers and inlets between barrier islands. Tidal stream power extraction is simulated with a momentum sink in the numerical models at the estuary scale to investigate effect of power extraction on the estuarine hydrodynamics. It is found that different power extraction schemes might have counterintuitive effects on the estuarial hydrodynamics and the extraction efficiency. A multi-criteria method that accounts for the physical, environmental and socioeconomic constraints for tidal power conversion schemes is proposed to select favorable locations and to rank them according to their suitability. For this purpose, the model results are incorporated into a Geographical Information System (GIS) database together with other geospatial datasets relevant to the site selection methodology. The methodology is applied to the Georgia coast and the candidate areas with potential are marked.

AbstractA holistic response and adaptation to climatic vicissitudes and extreme conditions as well as their associated risks to human and ecological sustainability must adequately cater for energy needs and optimization. An interventional approach should, among other measures, seek to improve the resilience of existing and prospective energy systems to climate change. The structured and policy-driven nature of adaptation measures require a bottom-up proactive approach that envisages the performance and efficiency of these systems, especially in terms of their sensitivity and vulnerability to changing climate conditions. Therefore, this chapter seeks to scrutinize various sources of energy concerning their resistance capabilities to climate change in the face of increasing global energy demands and consumption. Renewable and conventional energy sources are co-examined and compared vis-à-vis the current trends and predictions on climatic factors that are bearing on their principles of production, supply, and distribution. Findings from this chapter will serve as assessment tools for decision makers and corroborate other ongoing discourse on climate actions towards socioeconomic development and a sustainable environment.

Abstract The energy transition from fossil fuels to renewable or cleaner energy sources is upon us. There is also a global focus on reducing atmospheric carbon dioxide emissions. Several major companies are placing an emphasis on solutions such as hydrogen and carbon capture and sequestration or reuse. While this will provide new business opportunities for the pipeline industry, there are inherent risks, especially as they are scaled up to meet societal demand. Therefore, there is a need to assess the potential for harm to people and the environment. Hydrogen is a flammable gas with the potential for both fire and explosion. Carbon dioxide is an asphyxiant at high concentrations and can dissolve in water, having unintended environmental effects. Traditional oil dispersion models have been used by the oil and gas sector and pipeline industry for decades to investigate overland, downstream, and in water movement, behavior, and potential effects of hypothetical and real-world releases. Atmospheric dispersion models have been used to assess vapor transport, resulting potential impacts (e.g., asphyxiation and or toxic effects) to humans and the environment, and risk of fire and explosion. Based upon our experience with the current regulatory environment, the scrutiny placed upon operators by regulators and intervenors (especially with other products such as oil), and the large amount of time required to plan, permit, construct, and operate pipelines, we believe these comprehensive and quantitative assessments will be at the forefront of decision making. The use and potential adaptation of these existing modeling tools will be crucial in assessing risk from transport, storage, and use to ensure safety of each project through all phases of its life cycle (e.g., prior to permitting, construction, operation, and decommissioning) during this energy transition.

Climate change is often considered in terms of its macroscale implications. For example, many governments and non-governmental organizations are engaged in the development of policy frameworks that could influence different societal actions and behavioral scenarios. But such macroscale policy decisions may also significantly impact the localized design of products and services in different business ecosystems. Unfortunately, products and services are generally designed only taking into account local influences. An approach that ties macroscale frameworks to localized product- or system-level design metrics is lacking. For example, the cost of upgrading the entire U.S. electrical system has been estimated to be on the order of $200 billion, and recent U.S. policy discussions in the area outline options such as “smart” grid upgrades, distributed and/or on-site renewable energy systems including solar and wind energy, infrastructural support for plug-in of electric and hybrid vehicles etc. But most existing electricity generation and thermal performance models of power generating stations or cogeneration plants fail to provide any indication of the environmental impacts associated with distributing electricity from generator to point-of-use. It is thus not intuitive how the direction of localized plant or system design should be altered given the different macro-level initiatives. This paper attempts to fill this gap by exploring a methodology that combines engineering economics, probabilistic risk assessment, and thermodynamic (2nd Law) analysis to evaluate different policy choices. Specifically, a framework that could allow quick estimation of the comparative consumption, operational power requirements, relative thermal performance and environmental footprint associated with different proposals on upgrading the grid is developed. The approach is demonstrated in the context of a representative segment of a hypothetical electrical grid distribution system located between two electric power generating stations (EPGS) facing overload as additional customer demands are projected to be integrated with renewable sources in the near-term future.

Abstract Energy shortages and environment pollution are among the most important problems all over the world. As a clean and renewable energy carrier, hydrogen is expected to be one of the most promising alternative solutions to the energy and environmental problems in the near future. However, the safety issues in hydrogen production, transport and storage have to be thoroughly addressed before commercialization of hydrogen energy to give authorities confidence and to eliminate the public fear of using hydrogen. Accurate knowledge of the dispersion characteristics of unintended hydrogen releases in the atmosphere is essential to developing good standards and codes for hydrogen safety. This paper presents a numerical study on the indoor hydrogen leakage risk assessment and numerical simulation. The physical and mathematical model of hydrogen leakage and diffusion process are established. Based on computational fluid dynamics, the numerical simulation of hydrogen leakage process is studied. The effects of leakage source height and direction on hydrogen leakage and diffusion in indoor space are analyzed. The results show that the hydrogen leakage in the laboratory space is initially diffused by jet. With the development of time, the leaked hydrogen with different height and direction of leakage source forms different forms of vortex in the space, which affects the speed and amount of hydrogen accumulation in the space. When the hydrogen leakage source is low, the leakage direction is downward and back to the vent, the safety risk is greater.

Abstract There is a growing interest in electrification of offshore production assets using renewable energy devices. Typical configurations have arrays of power generating devices, located a short distance away from the platform and linked by subsea cables. To date, floating offshore wind turbines and wave energy converters have been trialed as sources of electrical power. With hulls, moorings and cables set out in close proximity, there is a unique station keeping risk profile that needs to be managed, to ensure fitness for service through the life of the field. When developing electrification schemes, there is a body of relevant research that can be accessed to help identify and control mooring risks. In the early days of North Sea floating production, the industry encountered multiple instances of accelerated mooring line degradation. The causes and mitigations were researched through joint industry projects, leading to the publication of operating guidance through OGUK, the HSE, ISO and others. This guidance, along with a series of milestone papers, offers a valuable body of learning that is available to electrification projects. In this paper, the authors survey the integrity threats and challenges affecting moorings in electrification schemes that are based around small arrays of wind turbines or wave energy converters. Through qualitative risk assessment, comparison is made to mooring integrity issues in the floating production sector. The relevance of guidance from oil and gas is reviewed. Consideration is given to the consequences of a line failure, and how in some cases these may represent intolerable risks. It is argued that a through-life integrity risk assessment is essential for successful deployments; also, that existing OGUK guidance on mooring integrity be extended, to reflect the specifics of electrification projects.

Abstract Despite the growing share of renewable sources, the world energy matrix still depends heavily on fossil fuels, especially oil. The exploration of this product brings severe challenges and risks which must be managed during all phases of an oil well’s lifetime. Analysis methodologies have already been developed and established to contribute to safety; however, with the growing complexity of the system, these methodologies may need a more structured way to identify some arising loss scenarios. The System-Theoretic Accident Model and Process (STAMP) deals with this problem. STAMP is a causality model that, attacking the problem from different paradigms, treats safety as a control problem, shifting emphasis from preventing failures to enforcing safety constraints. Based on a system model that spells out the control levels of a system and the control and feedback interactions between them, named SCS (Safety Control Structure), it focuses on preventing those interactions that lead the system to a hazardous condition, making it vulnerable to losses. This paper presents an analysis technique built on STAMP named System Theoretic Process Analysis (STPA), applied in the case of a submarine oil well at the production phase to highlight the benefits of using STAMP as a complement to more traditional analysis methodologies. The results conclude that STPA analysis can identify safety breaches from different sources. The first relevant source relates to the component failure events — also covered by more conventional methods such as PRA (Probabilistic Risk Assessment). The most significant contribution relates to safety breaches related to components interaction, managerial decisions, organizational factors, and others. The latter are manageable by structuring the loss scenario generation, which is the primary goal of STAMP.

The energy crisis triggered globally in the last quarter of 2021, forced Romania to go through a winter with liberalized electricity and gas prices, a period unprecedented in terms of consumer prices, accentuated by the result of closing energy targets that coalfired operations as a result of the imposition of EU conditions for the restructuring of the mining and energy sector. The year before, 2020, the COVID-19 pandemic, with restrictions imposed, produced a decrease in electricity demand, a decline in coal-fired power consumption, greatly reduced the share of gas in the energy mix, using preferential renewable energy sources. Subsequently, Russian gas prices have risen to record highs and, as a result, coal-fired power generation has returned to the European Union in 2021, although coal became more expensive and emission allowance prices doubled. In the context of the armed conflict between Russia and Ukraine, major price increases are expected worldwide, generating new risks of exposing the economy and new challenges in terms of ensuring Romania's independence and energy security. Against this background of these situations, can Romania still respect the European commitments of the Green Pact, meet these challenges and respond to the needs of the communities affected by the projected programs? The present paper aims at a critical assessment of the current situation of the Romanian coal mining and future trends of using a �clean coal� as a variant to respond to the requirements of the environmental concerns.

The Synthesis Report (SYR) distils and integrates the findings of the three Working Group contributions to the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), the most comprehensive assessment of climate change undertaken thus far by the IPCC: Climate Change 2013: The Physical Science Basis; Climate Change 2014: Impacts, Adaptation, and Vulnerability; and Climate Change 2014: Mitigation of Climate Change. The SYR also incorporates the findings of two Special Reports on Renewable Energy Sources and Climate Change Mitigation (2011) and on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (2011).

There is an innate and critical relationship between energy and weather, water, and climate. As the deployment of renewable energy, particularly wind and solar energy, increases, so too does dependence on weather and weather variability. Understanding, accounting for, and communicating weather and climate variables is therefore critical for the planning and optimization of the energy system. This puts increasing pressure on the scientific community, and particularly those working on the weather and climate aspects of renewables, to provide the right information to meet the key decision-making needs of the energy sector. This study is the second of two pilot projects on the provision of actionable information for decision-making through the tailored and targeted assessment of weather and climate science. This study confirmed that excellent progress is being made on a variety of fronts associated with renewable energy, which is critically important as we move to increase use of renewables. A consistent theme in the discussions under this study, however, is the need to bring together many disparate types of data, modeling, and analyses toward convergent tools that adequately address the complex interconnectedness of a national power system built on renewable sources. In many ways, the most significant finding of this study is the need for major convergence research efforts to build the necessary historical reanalysis datasets, integrated weather-energy forecast models, and policy and regulatory frameworks that can leverage current disciplinary research efforts.

In the path towards decarbonization, rechargeable lithium-ion batteries are critical for the widespread adoption of electric vehicles and renewable energy storage systems. To meet the growing demand for this mineral, various sources of lithium are being explored. This study evaluated the technical and economic feasibility of direct lithium extraction (DLE) from flowback and produced waters (FPW) of the Duvernay shale reservoir development near Fox Creek, Alberta and the Montney tight reservoir development in Northeast British Columbia using ion-exchange sorbents. Results indicate that lithium extraction from FPW using DLE technology is a viable option, with fluid pH, temperature, total suspended solids, and organic carbon affecting extraction efficiencies. In the assessment of Duvernay-based FPW fluids processed at a selected centralized facility, approximately 93 tonnes of lithium carbonate, or 105 tonnes of lithium hydroxide monohydrate could be produced annually, based on an average lithium content of 45.1 mg/L and a capacity of approximately 475,000 m3 per year. A discounted cash flow analysis determined the after-tax and royalty internal rate of return of 22% in the production of lithium carbonate (Li2CO3), and 38% in the production of lithium hydroxide monohydrate (LiOH·H2O) from the Duvernay development area. Comparatively, in the assessment of Montney brine fluids processed at a modelled centralized facility, approximately 117 tonnes of lithium carbonate or 134 tonnes of lithium hydroxide monohydrate could be produced annually, based on an average lithium content of 57.7 mg/L and a capacity of approximately 475,000 m3 per year. A discounted cash flow analysis determined the after-tax and royalty internal rate of return of 29% in the production of lithium carbonate and 48% in the production of lithium hydroxide monohydrate from the Dawson Creek Montney development area. These findings demonstrate the economic feasibility of extracting and refining lithium into battery-grade products from a novel source based on forecasted commodity prices and the development of a domestic battery supply chain system. Further investigation of DLE technology, a strategic resource sampling and analysis program, and investigation into the minimum scale of lithium extraction development are recommended.

The accelerating impacts of climate change, the need to adapt to changing economic and political realities, and the recent energy crisis have made the green transition something that most Nordic citizens acknowledge. However, especially rural areas and their communities are at risk of being reduced to passive instruments of national green transition measures featuring heavy land-use. These conditions make it very difficult to create a sense of justness in green transitions, leading to growing sense of alienation and resentment and putting the national climate goals in danger. From this starting point, the case studies of the research project “Just Green Transition on Rural Areas: Local Benefits from Value Creation” set out to examine what kind of benefits would generate value from green transition measures in the direct impact zone of new energy projects. The case studies took place in three Nordic countries and six locations: in Northern Ostrobothnia and Northern Central Finland of Finland, involving wind power and land use planning; in Nord-Fron and Nord-Odal in Norway, involving both wind power and strategic sustainability work; and in Skive and Bornholm of Denmark, involving a hybrid mix of renewable energy sources in the context of industrial park development. The results highlight the importance of local involvement and trust in green energy transitions in Nordic rural areas. Neglecting local needs can cause resistance to renewable projects. Early engagement, transparent communication, and ensuring local benefits are vital. While monetary benefits attract attention, relying solely on them can create community divisions. A blend of community engagement, environmental benefits, and local ownership of projects fosters trust and a deeper sense of justice in these transitions.

This rapid review provides insight into the effects of climate change in the Republic of Yemen (Yemen), with particular attention on key sectors of concern, including food security, water, energy and health. Many contextual and background factors are relevant when discussing climate-related impacts and potential priorities in Yemen. Limited studies and tools that provide climate data for Yemen exist, and there is a clear lack of recent and reliable climate data and statistics for past and future climates in Yemen, both at the national and more local levels (downscaled). Country-level information in this report is drawn mostly from information reported in Yemen’s UNFCCC reporting (Republic of Yemen, 2013, 2015) and other sources, which tend to be donor climate change country profiles, such as a USAID (2017) climate change risk profile for Yemen and a Climate Service Center Germany (GERICS) (2015) climate fact sheet on Yemen. Many of these are based on projections from older sources. Studies more commonly tend to look at water scarcity or food insecurity issues in relation to Yemen, with climate change mentioned as a factor (one of many) but not the main focus. Regional information is taken from the latest Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6) report in relation to the Arabian Peninsula (and hence Yemen). Academic sources as well as donor, research institutes and intergovernmental organisations sources are also included. It was outside the scope of this report to review literature in the Arabic language.

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.