Seite - 154 - in Water, Energy, and Environment - A Primer

Theyare separatedbyasolidceramicbarrier that servesas the electrolyte. It was developed in the 1960s by the Ford Motor Company and subsequently sold to the Japanese company NGK. It has nowbeenwidely demonstrated in Japan, andmore than 270MWof peak shaving capacity has been installed. US utilities are beginning to explore the technology for peak shaving, backup power, firming up intermittent wind power, andother applications. 9.2.1.3 Nickel–cadmium Nickel–cadmium (Ni–cad) batteries have been in commercial production since 1910. They are a traditional battery type that, while not known for high energy density or low first cost, provides a simple-to-manage, long-lived and reliable electricity storage option. For many years, in small battery form, they were aprimary electricity source formobile devices. 9.2.1.4 Lithium-ion Most battery attention today is focused on a relatively new development, lithium-ion (Li-ion) batteries. They were first developed in Japan and released to the market in 1991. Initial applications were in consumer markets, but today many companies are examining the use of large collections of Li-ion battery cells for use in other energy storage applications. These include their use in passenger electric vehicles (3–3.5 miles of travel per kWh of stored energy), residential and business storage of solar-generated electricity, and multi-megawatt containerizedbatteries for utility applications. Li-ionbatteries arewidelyused todaybecause theyhavehigh energy density: ‘pound for pound they’re some of the most energetic rechargeable batteries available.’For example, it takes six kilograms of lead–acid battery to store the same energy as one kilogramofLi-ion battery. They also hold their chargewell (today’s Li-ion batteries lose about 5% per month), have no Water,Energy, andEnvironment–APrimer154