DOE standards improve efficiency for battery backup power

Posted on by
Chris Granda

On December 28, 2016, the US Department of Energy (DOE) issued new energy efficiency standards for the relatively obscure, but important, class of products know as uninterruptible power supplies or UPS.  UPS provide critical protection from outages or fluctuations in electricity supply for sensitive electronic devices, particularly desktop computers (laptops usually have their own batteries built in). Battery backup power from a UPS instantly kicks in when power delivery from the electric utility is disrupted, allowing a computer to be shut down normally without losing data. The surprisingly large energy and economic savings and emissions reductions from the new UPS standard make it the sleeper success story among DOE’s 2016 efficiency standards.

DOE estimates that UPS meeting the new standards will save .94 quadrillion BTUs over 30 years of UPS sales, or about 87 billion kilowatt hours, resulting in net savings of $1-3 billion for U.S. consumers and businesses. This reduction in energy consumption will also prevent the emission of an estimated 49 million metric tons of CO2 over the same period. To put this in perspective, the energy saved is equivalent to the annual electricity consumption of 7 million US homes, and the CO2 reductions are equivalent to the emissions of 10.3 million cars in the US in one year. 

In its analysis for the new standard DOE identified six energy efficiency improvements which UPS manufacturers can use to help meet the new standards including better semiconductors, improved capacitors and more efficient cooling fans.  DOE did not evaluate “transformer-less” UPS design, which has recently gained market share and provides yet another way for manufacturers to meet the new standards.  Had DOE included transformer-less design in their analysis, we believe even stronger UPS efficiency standards would have been justified.

DOE’s analysis projects that 9.6 million UPS of all kinds will be sold in 2019. DOE also projects that the new standards will not increase the cost for the most common type of UPS (voltage and frequency dependent models) and will cut consumers’ energy costs by about $32 each over the lives of these products. For other UPS types, modest price increases for compliant models will be paid back to consumers through lower utility bills within a few years.

DOE originally proposed standards for UPS as part of a 2012 proposal covering a wide range of battery charger products. However, DOE later determined that the battery charger test procedure did not adequately measure UPS efficiency, and the final battery charger standards published in June omitted UPS.  DOE subsequently published a separate UPS test procedure and proposed standards.  The final standards will come into effect in 2019, completing a multi-year standards development process. The new federal standards will preempt existing state level standards currently in place in California and Oregon but will not be official until published in the Federal Register. Most likely, final publication will be decided by the Trump administration