World's 10 biggest grid-scale batteries

The shelf life of a watt, the basic unit for measuring electric power, is short – very, very short. Electricity travels about 186,000 miles per second.  As a result, it must be used more or less at the same time it is generated – unless it can be stored.

The challenges of matching supply and demand in real time have become significantly more complex with the increased deployment of intermittent or variable resources like wind power or solar photovoltaics on the electric grid.

The vast majority of grid-scale energy storage projects are mechanical systems, especially pumped-hydro storage systems. In 2009, the world boasted more than 100 gigawatts of pumped-hydro storage capacity, including more than 20 gigawatts of capacity in the United States.

To put this in perspective, a 100 watt light bulb consumes one hundred watts of power when turned on. If kept on for an hour, this light bulb would consume a total of 100 watt-hours of energy. A kilowatt (kW) is one thousand watts. A megawatt (MW) is one million watts and a gigawatt is one billion watts, or 1,000 megawatts. Unlike mechanical systems, electrochemical energy storage systems, or batteries, have proven to be more challenging to commercialize.

All things considered, the world’s biggest batteries do not seem especially big.

That is one of the many interesting insights I picked up perusing the U.S. Department of Energy’s Global Energy Storage Database, which includes up-to-date information on grid-connected energy storage projects from around the world. Based on rated power, or the total possible electrical output, the “Sendai Substation Lithium Ion Battery” in northeastern Japan boasts the world’s biggest battery.

Toshiba is developing the project in the city of Sendai for Tohoku Electric Power Company, an investor-owned electric utility that manages the local power grid in the Sendai region.

In a lithium‐ion (li‐ion) battery cell, positively charged lithium ions migrate through a liquid electrolyte (fluids that conduct electricity) while electrons flow through an external circuit. This movement creates energy, which is stored in various compounds, composed of layers of different elements, such as lithium, manganese and cobalt.

Construction began last year on the Sendai system. The project is scheduled to come online in early 2015. The system will be used to regulate frequency change and smooth the impact of grid-connected variable wind and solar resources.

The battery system will have a maximum output of 40 megawatts (MW) and a capacity of 20 megawatt-hours (MWh). In other words, the Sendai battery will be able to provide 40 MW of electricity for about half an hour. As a general matter, one MW of generating capacity can provide power for about 800 homes. The world’s second largest battery by rated power is an advanced lead-acid battery in Goldsmith, TX.

The Notrees Wind Storage Demonstration Project was developed in a joint partnership between Duke Energy and Xtreme Power, a grid-scale energy storage provider that declared bankruptcy on Thursday. The 36 MW battery system is used to manage intermittency at the 153 MW Notrees wind power farm project in western Texas and provides regulation service in the Texas wholesale power market.

http://www.forbes.com/sites/williampentland/2014/01/25/worlds-10-biggest-grid-scale-batteries/2/?ss=businessenergy