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SYNOPSIS In Swaziland policies to alleviate fuelwood shortages have been low on the list of development priorities, as much of the land has extensive bush and tree cover. There are, however, major social and geographical imbalances in biomass resource supply—some areas of Swazi Nation Land are barren due to increasing population pressure and the subsequent demand for fuelwood. This paper will show, in detail, the methodology for the survey which was carried out in Swaziland to investigate the importance of accessibility in linking potential supply to demand. Physical location, land tenure and management practices are generally recognised as important factors to take into consideration when converting potential resources into realistic amounts of fuelwood supply. Guesswork, however, is often used to estimate the impacts of these factors on biomass supplies. A nation-wide study was made in order to obtain more information on the accessibility of resources on privately owned land; results of a household surv...

Abstract Energy system modelling can be used to assess the implications of different scenarios and support improved policymaking. However, access to data is often a barrier to starting energy system modelling in developing countries, thereby causing delays. This article therefore provides data that can be used to create a simple zero order energy system model for Mauritania, which can act as a starting point for further model development and scenario analysis. The data are collected entirely from publicly available and accessible sources, including the websites and databases of international organizations, journal articles, and existing modelling studies. This means that the dataset can be easily updated based on the latest available information or more detailed and accurate local data. These data were also used to calibrate a simple energy system model using the Open Source Energy Modelling System (OSeMOSYS) and two stylized scenarios (Fossil Future and Least Cost ) for 2020-2050. The assumptions used and results of these scenarios are presented in the appendix as an illustrative example of what can be done with these data. This simple model can be adapted and further developed by in-country analysts and academics, providing a platform for future work.

Abstract Post-combustion solvent-based carbon capture is a promising technology that potentially can offset the greenhouse gas emissions from fossil-driven power generation systems. The challenge is that CO2 absorption (similar to other CCS technologies) imposes energetic penalties, and constrains the operational flexibility. In this paper, we build upon our recent contributions in the field (Sharifzadeh et al., 2016; Sharifzadeh and Shah, 2016), and study the dynamic response of such process to the electricity load changes in the power plant. The key research question is to investigate if the steady-state integrated process design and control framework applied in the previous studies, can also ensure controllability under a wide range of disturbances. The present study considers the mutual interactions between the power plant and capture process. Other features of interest include the implications of key design and operational decisions such as reboiler temperature, solvent circulation flow rate, solvent concentration and the rate of power load change or CO2 setpoint tracking for flexible process operation. The results suggest that the capture process exhibits a high degree of flexibility and the integrated design and control framework could be the key enabler for the commercialization of post-combustion solvent-based carbon capture.

[EN] The objective of this article is to compare the behaviour of the most representative domestic hot water systems (DHW) in single-family buildings. The study evaluates the energy consumption, equivalent CO2 emissions and cost for each system over a 15-year life period. This analysis is carried out in four cli- matic zones across Europe to observe the influence of climatic conditions on the results. The four climatic zones are located in the cities of Athens, Madrid, London and Berlin. The analysed systems are: a) natural gas-fired instantaneous water heaters, b) electric storage water heater, c) solar thermal system with gas- fired instantaneous, d) solar thermal system with electric storage water heater, e) air-source heat pump, f) photovoltaic system with electric storage water heater, and g) photovoltaic system with air-source heat pump. This range of technologies covers the most likely solutions to be implemented across domestic buildings in Europe.The heat pump system (HPWH) with PV considering self-consumption shows the lowest environmen- tal impact in all zones, but is not an attractive investment in the coldest zones due to lower natural gas prices. Thermal solar systems have a high purchase and maintenance costs which do not compensate their energy savings. The PV HPWH system has a greater reduction of emissions and a lower cost than HPWH across a 15-year life. The gas boiler system has the lowest cost in a 15-year period in the coldest areas, despite having a greater environmental impact than the heat pump.(c) 2023 Elsevier B.V. All rights reserved.

Abstract Diagnosing the state-of-health of lithium ion batteries in-operando is becoming increasingly important for multiple applications. We report the application of differential thermal voltammetry (DTV) to lithium iron phosphate (LFP) cells for the first time, and demonstrate that the technique is capable of diagnosing degradation in a similar way to incremental capacity analysis (ICA). DTV has the advantage of not requiring current and works for multiple cells in parallel, and is less sensitive to temperature introducing errors. Cells were aged by holding at 100% SOC or cycling at 1C charge, 6D discharge, both at an elevated temperature of 45 °C under forced air convection. Cells were periodically characterised, measuring capacity fade, resistance increase (power fade), and DTV fingerprints. The DTV results for both cells correlated well with both capacity and power, suggesting they could be used to diagnose SOH in-operando for both charge and discharge. The DTV peak-to-peak capacity correlated well with total capacity fade for the cycled cell, suggesting that it should be possible to estimate SOC and SOH from DTV for incomplete cycles within the voltage hysteresis region of an LFP cell.

The evolution of distribution systems (DS) towards the smart-grid concept posses new challenges, triggered by the integration of distributed generation (DG) and the installation of new devices. These challenges raise the need to reconsider the traditional network operation during the planning stage, enabling the DS to be flexible to operate under different network configuration scenarios. In this paper we propose a DS planning methodology for the connection of support feeders in radial networks, explicitly considering reconfiguration options with open-and closed-loop operation. To this end, we propose an efficiency evaluation, based on Data Envelopment Analysis, to assess candidate feeders in terms of expansion costs, energy losses, and lines' chargeability, under a range of demand scenarios that include GD penetration. Additionally, we have developed a method to identify the main feeder in a radial system, obtaining a simplified version of the DS, better suited for analysis. Simulation results on a real urban DS show the effectiveness of the method to identify the best nodes in a main feeder to connect support feeders, further indicating how to divide the network into operation areas for an improved network performance.

Abstract With the widespread application of pulse turbochargers in internal combustion engines, steady or quasi-steady turbine models are no longer qualified for on-engine turbine performance prediction. Pulsatile flow condition caused by the reciprocating nature of the engine results in strong unsteadiness across the turbocharger turbine, which makes the turbine performance departing from that under steady or quasi-steady conditions. Modelling turbocharger turbine through a one-dimensional (1D) method is an important approach to simulate the unsteady performance of the turbine. In this paper, a 1D performance model of turbocharger turbines is presented. The model solves the turbine volute flow with 1D viscous equations, with volute curvature and circumferentially continuously flow exiting at volute outlet considered. The circumferential flow non-uniformity at volute outlet is preserved. The turbine rotor is modeled with multiple meanline models. The model was used to simulate the performance of a mixed-flow turbine and validated by the experimental data. Results show that the performance predictions are in good agreement with the experimental data. Flow parameters at internal points of the turbine predicted by the 1D model were compared with three-dimensional unsteady simulation results and reasonable agreement was observed, which demonstrates the ability of the 1D model in capturing the pulse propagation.

We consider the problem of dispatching a fleet of distributed energy reserve devices to collectively meet a sequence of power requests over time. Under the restriction that reserves cannot be replenished, we aim to maximise the survival time of an energy-constrained islanded electrical system; and we discuss realistic scenarios in which this might be the ultimate goal of the grid operator. We present a policy that achieves this optimality, and generalise this into a set-theoretic result that implies there is no better policy available, regardless of the realised energy requirement scenario. Accepted for publication to the 2018 Power Systems Computation Conference (PSCC)