Seite - 139 - in Clean Water Using Solar and Wind - Outside the Power Grid

Handling variable production 139 The stored water can also be led into a desalination unit to be upgraded. Excess electric energy can also be used for pumping, desalination and disinfection. 10.7 DIESEL GENERATORS AS BACKUP In many cases an existing diesel generator will be replaced by renewable energy. The old generator can be used as a backup for the intermittent generation, even if this will cost fuel and add to the carbon footprint. However, the advantage of using this backup is that even long-term lack of power can be rectified. 10.8 COST OF ENERGY STORAGE To compare various technologies of energy storage, the concept of levelised cost of storage (LCOS) has been defined. This is usually expressed as a cost of energy storage capacity per kWh. Thus, the LCOS expresses the average cost over the life of the storage, including both capital and operational costs. The huge solar PV and wind energy cost reduction has been achieved through an increasing mass production of PV panels and wind turbines. A similar revolution is apparently coming to energy storage. Worldwide there are massive investments in battery facilities. Energy storage cost has decreased from more than 500 USD/kWh in 2013 to around 200 USD/kWh in 2017 (Lazard, 2016). According to Boston Consulting Group (www.bcg.com) the cost is expected to drop below 100 USD/ kWh in the next five to ten years. 10.9 FURTHER READING There is a huge ongoing effort to develop batteries with larger capacity, smaller size and lower prices. To get acquainted with current storage research we refer to the Joint Center for Energy Storage Research (JCESR) in Argonne, supported by the US Department of Energy, and their webpage http://www.jcesr.org. Sandia Laboratories has issued a handbook on electricity storage with a lot of technical information (Akhil et  al., 2013). IEC has published a white paper on electric storage systems (IEC, 2011); a Downloaded from https://iwaponline.com/ebooks/book-pdf/520710/wio9781780409443.pdf by IWA Publishing user