Load balancing (electrical power)

Load balancing, load matching, or daily peak demand reserve refers to the use of various techniques by electrical power stations to store excess electrical power during low demand periods for release as demand rises. The aim is for the power supply system to have a load factor of 1. Grid energy storage stores electricity within the transmission grid beyond the customer. Alternatively, the storage can be distributed and involve the customer, for example in storage heaters running demand-response tariffs such as the United Kingdom's Economy 7, or in a vehicle-to-grid system to use storage from electric vehicles during peak times and then replenish it during off peak times. These require incentives for consumers to participate, usually by offering cheaper rates for off peak electricity. Telephone exchanges often have arrays of batteries in their basements to power equipment and in the past metro systems such as the London Underground had their own power stations, not only giving some redundancy but also using the grid for load balancing. Today these supplies often have been replaced by direct supply from the grid and so are no longer available for the purpose of load balancing. Solutions to the load balancing problem focus on "smart grid" technology, in which many consumer and industrial appliances would communicate with the utility using digital means, and could be switched on and off by the utility to run at off-peak hours. In a very basic demand balancing system, the power company sends a signal down the line or by a dedicated phone chip to turn on a special circuit in the home. Typically, a storage device for space heating or a water heater will be connected to this circuit. The electricity is turned on after the evening peak demand, and turned off in the morning before the morning peak demand starts. The cost for such power is less than the "on-demand" power which makes it worthwhile for the user to subscribe to it. A nuanced system is possible with benefits for the power company and the electricity user.