Page - 129 - in Clean Water Using Solar and Wind - Outside the Power Grid

Handling variable production 129 One drawback of the saltwater battery is that it is slightly heavier than a lead-acid battery. The other disadvantage is that it has to be charged and discharged at lower rates than the other battery types. A typical charge time is ten hours and discharge time 20 hours, because the current should not exceed around 14 A. The saltwater battery temperature should not exceed 40°C, which can be a problem in tropical regions. There are still very few manufacturers of saltwater batteries, so as competition increases and with economy of scale these batteries may become much more economically attractive. 10.3.4 Flow batteries A flow battery, also called a redox flow battery is an electrochemical cell. Two chemical components dissolved in liquids are contained in the system and separated by a membrane, Figure 10.2. The chemicals provide chemical energy that is converted to electrical energy via the membrane. There is ion exchange through the membrane, while both liquids circulate in their own respective volumes. The ion exchange is followed by an electric current. The cell voltage typically reaches 1–2.2 V. - + Electrode Catholyte Anolyte Current collectors Pump Ion selective membrane Discharging Figure 10.2 Principle of a redox flow battery. Modified from Akhil et al. (2013). Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user