Optimisation of hybrid off-grid energy systems by linear programming

Energy, Sustainability and Society, Dec 2012

Background In this study, a general model of a hybrid off-grid energy system is developed, which can be adjusted to reflect real conditions in order to achieve economical and ecological optimisation of off-grid energy systems. Methods Using linear programming methods in the General Algebraic Modeling System (GAMS) environment, the optimal configuration of the electrical power supply system following characteristic restrictions as well as hourly weather and demand data is found. From this model, the optimal mix of solar- and wind-based power generators combined with storage devices and a diesel generator set is formed. Results The operation of this model was tested in two real off-grid energy systems, a cluster of villages in India and Titumate in Colombia. Both optimisation processes resulted in hybrid energy systems, utilising photovoltaics (PV), lead-acid batteries and a diesel generator as a load-balancing facility. Conclusions With respect to small off-grid energy systems, it was found that renewable energy in combination with electrical storage devices help to reduce the cost of energy compared to stand-alone diesel generator sets. The optimal solutions strongly depend on the particular load demand curve. As both PV and wind energy benefit from energy storage, the costs of the battery can be shared and the two technologies complement each other. Finally, although the optimised capacity of the diesel generator remains nearly constant, its contribution to the total power generation is being substituted by renewable energy sources, which serve as fuel-saving technologies.

A PDF file should load here. If you do not see its contents the file may be temporarily unavailable at the journal website or you do not have a PDF plug-in installed and enabled in your browser.

Alternatively, you can download the file locally and open with any standalone PDF reader:

https://link.springer.com/content/pdf/10.1186%2F2192-0567-2-7.pdf

Optimisation of hybrid off-grid energy systems by linear programming

Fabian Huneke 0 Johannes Henkel 0 Jairo Alberto Benavides Gonzlez 1 Georg Erdmann 0 0 Department of Energy Systems, Technische Universitt Berlin , Einsteinufer 25 (TA8), Berlin , 10587, Germany 1 Equitel Organization, Av. Ciudad de Cali No. 11-22, Bogot, Colombia Background: In this study, a general model of a hybrid off-grid energy system is developed, which can be adjusted to reflect real conditions in order to achieve economical and ecological optimisation of off-grid energy systems. Methods: Using linear programming methods in the General Algebraic Modeling System (GAMS) environment, the optimal configuration of the electrical power supply system following characteristic restrictions as well as hourly weather and demand data is found. From this model, the optimal mix of solar- and wind-based power generators combined with storage devices and a diesel generator set is formed. Results: The operation of this model was tested in two real off-grid energy systems, a cluster of villages in India and Titumate in Colombia. Both optimisation processes resulted in hybrid energy systems, utilising photovoltaics (PV), lead-acid batteries and a diesel generator as a load-balancing facility. Conclusions: With respect to small off-grid energy systems, it was found that renewable energy in combination with electrical storage devices help to reduce the cost of energy compared to stand-alone diesel generator sets. The optimal solutions strongly depend on the particular load demand curve. As both PV and wind energy benefit from energy storage, the costs of the battery can be shared and the two technologies complement each other. Finally, although the optimised capacity of the diesel generator remains nearly constant, its contribution to the total power generation is being substituted by renewable energy sources, which serve as fuel-saving technologies. - Background One major issue associated with the challenge of the worlds increasing demand for energy is the electrification for approximately two billion people [1] in developing countries that do not currently have access to electricity. The worlds population is expected to reach nine billion people in 2050. Most of this expected population growth will take place in developing countries and emerging nations [1]. Additionally, policies in emerging nations are concerned with increasing the supply of energy, as energy consumption per capita has become one of the major indicators for the developmental progress of a country. These two factors mainly determine the growth in energy demand. Many of the places with limited or no connection to the national grid are rural communities. The question is how to provide these off-grid energy systems. A common solution for off-grid power supply in small and medium-sized energy systems is a fuel generator set [2]; however, the following current developments have sought to improve the competitiveness and desirability of alternative off-grid energy systems: Steeply decreasing production costs of renewable energy technologies like solar, wind and biomass caused a boom in the respective technologies in developed countries, Expanding research in electric storage devices sparked by the plans of several countries to use electric vehicles in the future, Increasing environmental concerns and awareness of climate change provoked by CO2 emissions produced by the combustion of fossil fuels and Increasing operation costs for fuel generator sets due to rising oil prices. The following section provides a review of literature on the topic, leading to the presentation of the research questions. In [1], integrated energy farms, which aim to bring power and food to rural communities, are discussed. The supply of electricity is integrated in an independent and decentralised energy supply concept under consideration of sustainable development of remote areas by empowering the residents to take care of their own needs. The study of Nfah et al. [3] is concerned with the optimisation of off-grid energy systems at rural communities in Cameroon focussing on hydro and solar resources. Another more general steady-state modelling approach is done in [4] under consideration of hybrid energy systems consisting of a micro-hydro, a biogas, a biomass, a back-up diesel generator and a photovoltaic (PV) array. The optimal dispatch strategy, as well as the optimal sizing, especially of the PV array is calculated simultaneously by linear programming. The performance of another type of hybrid energy system is investigated in [5]. Here, the interaction between an existing wind/diesel energy system and a leadacid battery bank is examined. The optimal sizing of such a wind-diesel hybrid energy system is discussed in [6] under consideration of the minimum long-term electricity production cost. In [7], the life cycle costs of stand-alone diesel generator sets and PV battery systems are compared. The benefit from linking different solar home systems by installing an off-grid (...truncated)


This is a preview of a remote PDF: https://link.springer.com/content/pdf/10.1186%2F2192-0567-2-7.pdf

Fabian Huneke, Johannes Henkel, Jairo Alberto Benavides González, Georg Erdmann. Optimisation of hybrid off-grid energy systems by linear programming, Energy, Sustainability and Society, 2012, pp. 7, Volume 2, Issue 1, DOI: 10.1186/2192-0567-2-7