Renewable energy resources are increasingly being used to cover the demand in the electricity grids in many countries. A question that is currently for most grids rather theoretical, although interesting in introducing a long-term perspective, pertains to what an energy supply from exclusively renewable energy resources could look like. This question has to be answered individually for each grid. The objective of the present paper is to scrutinize the specific challenges that a 100% renewable energy scenario brings for the Java-Bali grid. This objective is achieved by designing power generation time series such that they match a given load time series. An important challenge for a 100% renewable energy supply is the very high dependency on solar energy, which generates an enormous primary power generation fluctuation on both a daily and an annual timescale. In particular the seasonal fluctuations come along with high storage demand, which is the greatest challenge involved in a 100% renewable energy supply. There are strategies that may be used to considerably reduce the storage demand: the installed photovoltaic (PV) capacity can be increased, bioenergy can be used for seasonal balancing, and special long-term storage can be added. These options are considered in the present paper.

Currently, many countries try to satisfy their energy needs with an increasing usage of renewable resources. The general motivations, with varying weighting in the different countries, are ecological reasons, concerns about energy security, and economical considerations. A for now rather theoretical question, although interesting for opening a long-term perspective, is how an energy supply from exclusively renewable energy resources could look like. This question has to be answered individually for any specific energy supply system. The present paper has the objective to present and evaluate a scenario for an electricity supply only from renewable energy resources for the Java-Bali grid. After designing a load time series for the year 2050 for the Java-Bali grid, a scenario is developed how to cover the load with electricity from renewable energy resources alone. Assumptions about the usable energy sources are made as well as assumptions about the available power plant capacity or energy potential. A specific challenge is the fact that solar energy must be the main source in such a renewable-energy based system, which comes with the need for a large storage capacity to match the power supply at any time with the load. Several possibilities are presented how to bring down the storage capacity: the increment of the installed PV capacity, the usage of bioenergy for seasonal balancing, and the complementation of the proposed short-term storage with an additional long-term storage. The study shows some of the specific challenges that a gradual transformation of the current electricity supply system on Java and Bali into a renewable-energy-based one would face and gives some hints about how to cope with these challenges. Scenarios like the one designed in this study are an important tool for decision-makers who face the task to scrutinize the consequences of choosing between different development paths. Article History: Received: August 15th 2017; Received: October 18th 2017; Accepted: January 14th 2018; Available onlineHow to Cite This Article: Günther, M., Ganal, I. and Bofinger, S. (2018) A 100% Renewable Electricity Scenario for the Java-Bali Grid. Int. Journal of Renewable Energy Development, 7(1), 13-22.https://doi.org/10.14710/ijred.7.1.13-22

An energy supply system consists of a system of power plants and transmission anddistribution systems that supply electrical energy. The present project is limited to the modellingof the generation system. Its objective is the design and implementation of a web-basedapplication for simulating energy supply systems using the Laravel framework. The projectfocuses on six modules representing geothermal energy, solar energy, biopower, hydropower,storage, and fossil-based energy that are allocated to satisfy a given power demand. It isexecuted as a time series modelling for an exemplary year with hourly resolution. Thedevelopment of the software is divided into four steps, which are the definition of the userrequirements, the system design (activity, use case, system architecture, and ERD), the softwaredevelopment, and the software testing (unit testing, functionality testing, validity testing, anduser acceptance testing). The software is successfully implemented. All the features of thesoftware work as intended. Also, the software goes through validity testing using three differentinput data, to make sure the software is accurate. The result of the testing is 100% accuracy withrespect to the underlying model that was implemented in an excel calculation.