| 1. |
- Balderrama, Sergio, et al.
(författare)
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Surrogate models for rural energy planning : Application to Bolivian lowlands isolated communities
- 2021
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 232
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Tidskriftsartikel (refereegranskat)abstract
- Thanks to their modularity and their capacity to adapt to different contexts, hybrid microgrids are a promising solution to decrease greenhouse gas emissions worldwide. To properly assess their impact in different settings at country or cross-country level, microgrids must be designed for each particular situation, which leads to computationally intractable problems. To tackle this issue, a methodology is proposed to create surrogate models using machine learning techniques and a database of microgrids. The selected regression model is based on Gaussian Processes and allows to drastically decrease the computation time relative to the optimal deployment of the technology. The results indicate that the proposed methodology can accurately predict key optimization variables for the design of the microgrid system. The regression models are especially well suited to estimate the net present cost and the levelized cost of electricity (R-2 = 0.99 and 0.98). Their accuracy is lower when predicting internal system variables such as installed capacities of PV and batteries (R-2 = 0.92 and 0.86). A least-cost path towards 100% electrification coverage for the Bolivian lowlands mid-size communities is finally computed, demonstrating the usability and computational efficiency of the proposed framework.
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| 2. |
- Gardumi, Francesco, et al.
(författare)
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Representation of Balancing Options for Variable Renewables in Long-Term Energy System Models : An Application to OSeMOSYS
- 2019
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- The growing complexity and the many challenges related to fast-changing and highly de-carbonised electricity systems require reliable and robust open source energy modelling frameworks. Their reliability may be tested on a series of well-posed benchmarks that can be used and shared by the modelling community. This paper describes and integrates stand-alone, independent modules to compute the costs and benefits of flexible generation options in the open source energy investment modelling framework OSeMOSYS. The modules are applied to a case study that may work as a benchmark. The whole documentation of the modules and the test case study are retrievable, reproducible, reusable, interoperable, and auditable. They create a case to help establish a FAIR-compliant, user-friendly, and low-threshold model and data standards in modelling practices. As is well known, one of the options for balancing high shares of variable renewables is flexible power generation by dispatchable units. The associated costs need to be considered for short-term operational analyses and for long-term investment plans. The added modules contribute to extending the modelling capacity by introducing (a) costs of ramping, (b) non-linear decrease of efficiency at partial load operation, and the cost minimisation objective function of OSeMOSYS. From application to the test case study, two main insights are drawn: costs of ramping and decreased partial load efficiency may influence the competitiveness of generation technologies in the provision of reserve capacity; and refurbishment of existing units may represent attractive investment options for increasing flexibility. Both effects are also seen in the long-term and may impact infrastructure investment decisions to meet decarbonisation targets. These effects would not be captured without the introduction of the modules.
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| 3. |
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| 4. |
- Palombelli, Andrea, et al.
(författare)
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Development of functionalities for improved storage modelling in OSeMOSYS
- 2020
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Ingår i: Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-5442 .- 1873-6785. ; 195
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Tidskriftsartikel (refereegranskat)abstract
- Integrated systems modelling has provided insights on pathways for the sustainable use of energy, land and water resources. Among the existing modelling tools, some have been widely used to engage policy makers, due to their open source and basic structure. Yet, in the attempt of simplifying the representation of integrated systems, essential features significantly influencing the dynamics between systems may have been left aside. This study proposes an improved formulation of the Open Source Energy Modelling System (OSeMOSYS), for a better representation of energy and resource storage processes. In particular, the focus of this work is the storage losses introduction for both dams for hydropower generation and batteries for electricity storage. The modifications were applied to a case study representing key features of both a developed and developing country. The results highlight that, with low additional computational effort, a much more accurate representation of the storage technologies can be achieved. Despite the introduction of losses, renewable energy technologies tend to have a high penetration in the future energy mix thanks to storage applications that remedy their unpredictability and seasonality.
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| 5. |
- Riva, Fabio, et al.
(författare)
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Design and performance evaluation of solar cookers for developing countries : The case of Mutoyi, Burundi
- 2017
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Ingår i: International Journal of Energy Research. - : WILEY. - 0363-907X .- 1099-114X. ; 41:14, s. 2206-2220
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Tidskriftsartikel (refereegranskat)abstract
- Here, we propose an approach for supporting the design and performance evaluation phase of solar cooking technologies, to assess their eventual appropriateness for remote rural contexts, before proposing them for local field tests. The approach is based on (1) local context description and analysis, (2) design and construction of the solar cookers, and (3) thermodynamic performance evaluation. We used the approach to analyse 3 cookers for the area of Mutoyi, Burundi: a parabolic, a panel, and a box cooker. From phases 1 and 2, only panel and box cookers emerged as the technically viable solutions: They were sized, optimized, built, and tested. In phase 3, the thermodynamic evaluation indicated that the box cooker is inappropriate, since water does not reach high enough temperature. Instead, the panel cooker shows a Standardized Cooking Power of 46.85W and a stagnation temperature higher than 75 degrees C, which is able to bring the water to the boil when the environmental temperature is higher than 25 degrees C. The thermal efficiency of the cooker resulted equal to 8.13%, while the mean integral temperature T-m remained around 60 degrees C for all the lab test replicates, higher than the minimum internal temperature to cook legumes. The results of the procedure applied to the case study indicate that the panel cooker can be proposed for local field tests with local food and cooking practices, for assessing its final appropriateness on the field.
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| 6. |
- Riva, Fabio, et al.
(författare)
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Electricity access and rural development: Review of complex socio-economic dynamics and casual diagrams for more appropriate energy modelling
- 2018
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Ingår i: Energy for Sustainable Development. - : Elsevier BV. - 2352-4669 .- 0973-0826. ; 43, s. 203-223
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Forskningsöversikt (refereegranskat)abstract
- The causal relationships between electrification and development of poor, rural communities are complex and contextual. The existing literature focuses mainly on the impact of rural electrification and electricity use on local socio-economic development, while the reverse feedbacks of various social and economic changes on electricity demand and supply have not been fully characterized. Most electricity access impact assessments assume linear, one-way effects and linear growth in electricity demand. However, the projections rarely match the reality, creating challenges for rural utilities. From a modelling perspective, the lack of attention to dynamic complexities of the electricity-development nexus prevents the appropriate modelling of electricity demand over time and, hence, informed planning for and sizing of power plants. With the goal to improve modelling of the electricity-development nexus, we undertake a comprehensive review and extensive analysis of the peer-reviewed literature on electricity access and its impact on rural socio-economic development, and vice versa. We characterize and describe the nexus between electricity access and development through graphical casual diagrams that allow us to capture, visualise and discuss the complexity and feedback loops. Based on this, we suggest guidelines for developing appropriate models able to include and simulate such complexities. Our analysis confirms that electricity use is interconnected through complex casual relations with multiple dimensions of socio-economic development, viz. income generating activities, market production and revenues, household economy, local health and population, education, and habits and social networks. The casual diagrams can be seen as a first step of the conceptualization phase of model building, which aims at describing and understanding the structure of a system. The presence of multiple uncertain parameters and complex diffusion mechanisms that describe the complex system under analysis suggests that systems-dynamic simulations can allow modelling such complex and dynamic relations, as well as dealing with the high uncertainties at stake, especially when coupled with stochastic approaches.
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| 7. |
- Riva, Fabio, et al.
(författare)
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Long-term energy planning and demand forecast in remote areas of developing countries : Classification of case studies and insights from a modelling perspective
- 2018
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Ingår i: Energy Strategy Reviews. - : ELSEVIER SCIENCE BV. - 2211-467X .- 2211-4688. ; 20, s. 71-89
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Forskningsöversikt (refereegranskat)abstract
- More than half a billion people will still lack reliable and affordable electricity in 2040 and around 1.8 billion may remain reliant on traditional solid biomass for cooking. Long-term energy planning could help to achieve the energy access targets in developing countries, especially in remote rural areas. Different studies exist on long-term rural electricity and thermal energy planning, but the different foci, terminology and methodologies make it difficult to track their similarities, weaknesses and strengths. With this work, we aim at providing a critical analysis of peer-reviewed studies on long-term rural energy planning, to help researchers in the field move across the diverse know-how developed in the last decades. The work resulted in the analysis of 130 studies and categorisation of 85 of them that focus on electricity, thermal energy, and oil supply in rural areas, under a number of rules clearly defined in the first part of the paper. We classify the studies in two consecutive steps, first according to their type and afterwards according to the methodology they employ to forecast the energy demand, which is one the most critical aspects when dealing with long-term rural energy planning. The work also provides specific insights, useful to researchers interested in rural energy modelling. Few studies assume a dynamic demand over the years and most of them do not consider any evolution of the future energy load, or forecast its growth through arbitrary trends and scenarios. This however undermines the relevance of the results for the purpose of long-term planning and highlights the necessity of further developing the forecasting methodologies. We conclude that bottom-up approaches, system-dynamics and agent-based models seem appropriate approaches to forecast the evolution of the demand for energy in the long-term; we analyse their potential capability to tackle the context-specific complexities of rural areas and the nexus causalities among energy and socio-economic dynamics.
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| 8. |
- Riva, Fabio, et al.
(författare)
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Soft-linking energy demand and optimisation models for local long-term electricity planning : An application to rural India
- 2019
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 166, s. 32-46
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Tidskriftsartikel (refereegranskat)abstract
- Rural electricity plans are usually designed by relying on top-down rough and aggregated estimations of the electricity demand, which may fail to capture the real dynamics of local contexts. This study aims at soft-linking a bottom-up approach for short- and long-term forecasts of load profiles with an energy optimisation model in a more comprehensive rural energy planning procedure. The procedure is applied to a small Indian community, and it is based on three blocks: (i) a bottom-up model to project households' electrical appliances, which adopts socio-economic indicators to make long-term projections; (ii) a stochastic load profile generator, which employs correlations and users' habits for assessing the coincidence and load factors; (ii) an energy optimisation model based on OSeMOSYS to find the economic optimum. The simulations show that demand models based on socio-economic indicators lead to more structured and less arbitrary scenarios. The soft-link with the energy optimisation model confirms that when accounting for short- and long-term variabilities of electricity demand together, the optimal capacities and costs can vary up to 144% and 50% respectively. Integrating optimisation tools to bottom-up models based on socio-economic indicators for forecasting electricity demand is therefore pivotal to set more reliable investments plans in rural electrification.
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