IEST6911 – M ANAGING GREENHOUSE GAS EMISSIONS A SSIGNMENT 3 Large-scale 100% renewable electricity systems can be reliable withoutbase-load power stations and without vast amounts of storage.2 | P a g e Proposed Solutions To address the above-mentioned issues some solutions such as geographical diversification of power generation sites, ionic liquids storages, pumped hydro reserves, electric thermal storage, flywheel energy storage system and vehicle-to-grid options can be adopted. Electric Thermal Storage (ETS) Electric thermal storage (ETS) units are used as temperature regulator for environmental profile for both commercially and domestically.
These units are heat accumulator within them, which can be used later as required for temperature control in the environment. ETS in combination with wind and hydro can be used for meeting the electricity requirements of a small grid. Refer to case study conducted by Wong and Pinard, 2017) on Yukon Electric Grid (YEG), in which wind and ETS were used to achieve required load.3 | P a g e Figure 1 Optimization model for wind and ETS source (Wong and Pinard, 2017) Ioinic Liquids (IL) Ionic Liquids (ILs) can be defined as their melting points are lower than 100 °C.
some examples of application of Ionic liquids are LI/NA Ion Battery Electrolytes, Lithium €’ Sulfure (Li€’S) Battery Electrolytes, Lithium €’ Oxygen (Li€’O2) Battery Electrolytes, Fuel Cell Electrolytes, Electroactive Carbons from Ionic Liquids. As per Watanabe et al., 2017, ILs cab be very suitable Because of its distinctive properties namely non-volatility, high thermal stability and high ionic conductivity, ILs are appropriate for the storage of energy (Watanabe et al., 2017). Thermal Storage and Molten Salt Batteries: Water in steam form can be used to generate electricity and thus water is one of the thermal energy storage material. One of the common usages for thermal storage is that of Molten Salt batteries, which have a high melting temperature. In this case, molten salts do not change their state and the thermal energy gets stored in them. Later, once the heated salt is pumped through a steam generator, electricity is generated from the steam produced. A step further, Molten Salt batteries and solar thermal power can contribute to 100% Renewable energy system.  Renewable Power Methane (RPM) Renewable power methane is made using the excess electricity during the process of methanation, an alternate Natural and renewable Gas (SNG). There are numerous usage of these gases for instances it can be used for heating, alternate to fossil fuels. MRESOM (Multi-Region Energy System Optimization Model) developed by (Pleџmann et al., 2014) has effectively used the above process in its RE100 model. The figure below is an illustration of the model.4 | P a g e Block Diagram for RE100 model of MRESOM source (Pleџmann et al., 2014) Flywheel Energy Storage System (FESS) Flywheel Energy Storage System (FESS) stores energy in kinetic form. They have longer life than batteries(Wicki and Hansen, 2017). Added significant use for FESS is its application with wind turbine as it can be used for variable-speed wind generators for increasing the dynamic working of the FESS (Cimuca et al., 2010). Refer to (Arani et al., 2017) for various applications. It is argued that FESS can be successfully used in conjunction with solar generation units, wind turbine as well as Photo Voltoic Cells.. FESS application with Wind Turbine(Arani et al., 2017) FESS application with PV (Arani et al., 2017)5 | P a g e Power system with pumped hydro storage (Kapsali and Anagnostopoulos, 2017) Vehicle to Grid (V2G) The Vehicle to Grid is based on the ability of bi-directional energy movement between electric vehicles and the electricity grid. In a Vehicle to Grid system, additional battery capacity offered by a vehicle is used to retain electricity equilibrium grid among peak and off-peak periods. At off peak time, electricity flows from the grid to the electric vehicle whereas during the peak hours when electricity demand is high, excess energy stored in vehicle battery is sent back to the electricity grid. In this way, an electric vehicle is essentially converted to an energy capacity resource instead of being a load on the energy grid. With the advent of larger capacity battery electric vehicles a greater flexibility has become available for analyzing the pure electricity arbitrage using V2G, rather than energy arbitrage between transport fuels (Deane et al., 2010). Figure below illustrates simplified schematics of a standard Vehicle to Grid system.6 | P a g e Simplified Vehicle-to-Grid (V2G) Schematic (Deane et al., 2010)7 | P a g e and bio-fueled gas turbines, photovoltaic (PV) cells and wind. The use of these technologies exhibited that a base load power plant is not required even during the peak hours. Also, all these simulations resulted in achieving the reliability standards set by NEM. Later, a further study was performed for comparing least cost scenarios for 100% renewable electricity with low emission fossil fuel scenarios in the Australian National Electricity Market by (Elliston et al., 2014). This study established that most of the fossil fuel scenarios cannot contest the financial affordability of a 100% renewable. Conclusion In nutshell, with the help of above detailed discussion it would be safe to say that as world is shifting towards renewable energy sources, researchers are focusing on eliminating the use of base load power stations running on fossil fuels and their investigations have successfully used different technologies to meet the peak load energy requirements. Thus, it is evident that 100% renewable energy system can perform without the support a base load power station. References  NEJAT, P., JOMEHZADEH, F., TAHERI, M. M., GOHARI, M. & ABD. MAJID, M. Z. 2015. 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