Flow Batteries : Has Really Large Scale Battery Storage Come of Age ?
The market for electrical energy storage (ES) solutions has been mostly limited to relatively small applications of battery uninterruptible power supply systems (UPS’s) and very large site-specific systems such as pumped hydro storage, two completely different types of ES with separate markets. Flow batteries (FBs) are promising to change that by providing a technology that can potentially span this entire range of applications. Flow batteries have demonstrated providing ES from sub-second local power reliability to hourslong load shaping and price arbitrage functions at the large commercial end-user-scale (500 kW, 520 kWh). Several pilot plants have been built at this scale and early results are positive. In addition, pilot utility-scale systems (12 megawatt, 120 megawatt-hour) are being constructed. The scale and variety of these pilots reflects high confidence in this technology by developers. This paper details technical principles of 2 competing flow battery technologies available in the immediate future, compares their market-readiness, and analyzes economics and market potential for this technology to compete with UPSs as well as play into new commercial load management markets.
Modelling an off-grid integrated renewable energy system for rural electrification in India using photovoltaics and anaerobic digestion
This work describes the design optimisation and techno-economic analysis of an off-grid Integrated Renewable Energy System (IRES) designed to meet the electrical demand of a rural village location in West Bengal – India with an overall electrical requirement equivalent to 22 MWh year−1. The investigation involved the modelling of seven scenarios, each containing a different combination of electricity generation (anaerobic digestion with biogas combined heat and power (CHP) and photovoltaics) and storage elements (Vanadium redox batteries, water electrolyser and hydrogen storage with fuel cell). Micro-grid modelling software HOMER, was combined with additional modelling of anaerobic digestion, to scale each component in each scenario considering the systems' ability to give a good quality electricity supply to a rural community. The integrated system which contained all of the possible elements – except hydrogen production and storage presented the lowest capital ($US 71 k) and energy cost ($US 0.289 kWh−1) compared to the scenarios with a single energy source. The biogas CHP was able to meet the electrical load peaks and variations and produced 61% of the total electricity in the optimised system, while the photovoltaics met the daytime load and allowed the charging of the battery which was subsequently used to meet base load at night.
Simulation and control of hybrid renewable energy system connected to the grid
This paper presents a control and simulation of hybrid renewable energy system connected to the grid. The studied system includes a photovoltaic panel, synchronous permanent magnet generator based wind turbine, and a battery for storage energy. The PV array and wind systems are connected to the common DC bus by a boost converter. The battery is connected by a bi-directional DC/DC converter, and then integrated into the AC utility grid via a common DC/AC inverter. In order to extract the maximum energy, a simulation study has been carried out according to the meteorological conditions (wind speed and variable solar irradiance) while maintaining power quality at a satisfactory level. In order to capture the maximum power, a MPPT algorithm is applied for both wind turbine and photovoltaic panel. The modeling and simulation of the whole system has been performed under Matlab/Simulink environment. The obtained results show that the current and the voltage of grid side are sinusoidal and alternative forms, and the power injected to the grid is around the power produced by the hybrid system.