Uninterruptable Power Supplies (UPS) based on Grid Energy Storage Power grids began in the pre-computer era as manually-controlled networks, often relying on guesswork and rule-of-thumb methods to keep them operating. Grids were inefficient and frequently unpredictable; blackouts and frequency runaways were common – this is still the case today in many developing economies. Today the digital economy is critically dependent on the continuous supply of reliable power at a very specific frequency. Grids are now computer controlled and vast resources are devoted to maintaining grid stability. Grid operators pay power stations to provide ancillary services (e.g. spinning reserve and frequency regulation). Power stations are paid to operate below rated power (in a position to quickly add extra power to the grid) or paid to “spin” (i.e. burn fuel) poised to step in should there be a failure in another part of the grid. Grid faults still occur though, and many businesses install uninterruptable power supply technology to allow them time to save important data during short blackouts. Critical services (hospitals, data centres etc) may use large-scale uninterruptable power supply systems to allow them to operate normally throughout a long blackout. These often include diesel generators but, since the first seconds are critical and diesel generators cannot switch on instantly, it is common to see batterybased UPS systems – essentially grid energy storage applications. Large banks of rechargeable lead acid batteries can operate very effectively as UPS systems – they are an energy storage solution that can immediately substitute for grid power in a grid fault event. Traditional deep-cycle rechargeable lead acid batteries have always been capable of providing an offset to grid faults. However, despite their wider potential as energy storage solutions for all sorts of applications, they sit idle – as a sunk cost to the business, operating only as insurance against potential grid interruptions. Recent advances in lead acid battery design has made them tolerant of continuous partial discharge and partial recharge cycles, opening the door to their use as true grid energy storage applications – or more excitingly, as mini power stations, offering to the grid the spinning-reserve and frequencyregulation services that are today usually provided by fossil fuel generators, while at the same time providing uninterruptible power supply in case of a grid failure. These spinning-reserve and frequency regulation services are very valuable to grid operators – hence the battery bank has the potential to be not a sunk cost but a profit centre.
Resource Box/Author Box: Ecoult delivers complete energy storage solutions and modules powered by the breakthrough UltraBattery technology – a hybrid lead-acid energy storage device containing both an Ultracapacitor and a battery in a common electrolyte. Ecoult’s storage solutions manage intermittencies, smooth power and shift energy in a safe, reliable and environmentally sound way – the energy storage of choice for grid ancillary services, wind and solar farms, remote Microgrid Energy Storage, dual purpose and diesel microgrid efficiency applications.
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