Battery Energy Storage Systems (BESS)

Completed in November 2003 and operational in December 2003, the BESS is one of Golden Valley Electric Association (GVEA)’s initiatives to improve the reliability of service to GVEA members. In the event of a generation- or transmission-related outage, it can provide 25 megawatts of power for 15 minutes or up to 40 megawatts (MW) for less time. Being able to produce 40 MW makes GVEA’s BESS one of the most powerful battery energy storage systems in the world in terms of MW output. One of the requirements for construction of the Intertie was a reactive power supply capable of delivering power, should generation fail. As shown below, the BESS has been meeting those needs.

BESS at Work for You

Here’s how the BESS works: When GVEA brings power up the Intertie from Anchorage utilities and one of their generators loses power, some of our members experience an outage. The same happens if we lose one of our own generators. But with the BESS, we can cover 25 megawatts of power instantly. This gives GVEA time to start up local generation, resulting in fewer outages. In 2019, the BESS responded to 49 events, preventing approx. 252,300 outages per meter.

Outage Prevented

Year Total Number of Outages* Average Number of Outages Prevented Per Meter
2003 3 Less than one
2004 56 7
2005 34 5.6
2006 82 7.5
2007 65 9
2008 25 2.3
2009 28 2.6
2010 40 3.9
2011 18 1.7
2012 43 2.6
2013 60 6.9
2014 78 6.1
2015 52 7.1
2016 69 6.3
2017 72 6.1
2018 59 6.7
2019 49 5.4
2020 55 4.4
2021 57 4.5
2022 76 8.1

*Outages covered include both local generation and transmission outages and outages due to loss of power from Anchorage via the Intertie.

The BESS can’t help in all situations. For example, if a tree falls in a line near your house, you’re cut off from the electrical system until the tree is removed and the line is repaired.

We anticipated a 60% reduction in power-supply-type outages, and we’re exceeding that number. The Outages Prevented Chart above shows how the BESS has been preventing outages for our members. As planned, the operation is so seamless, members don’t even know the BESS is at work.


At the heart of one of the world’s most powerful energy storage battery are two core components: the Nickel-Cadmium (Ni-Cad) batteries, developed by Saft, and the converter, designed and supplied by ABB. The converter changes the batteries’ DC power into AC power, so it’s ready for use in GVEA’s transmission system.


  • ABB – primary design and controls engineering
  • Saft – constructed the Ni-Cad batteries at their Swedish facilities – This will be a cradle-to-grave operation, as Saft is fully responsible for the recycling and/or disposal of each battery
  • City Electric – general contractor for ABB

Awards Received

  • ABB was awarded the Platts 2003 Global Energy Award for their design and development of the BESS converter
  • The Electric Power Research Institute Technology Award for the BESS Project at the National Rural Electric Cooperative Association Annual Meeting on February 15, 2004
  • Guinness World Record certificate acknowledging that the BESS is the world’s most powerful battery on December 10, 2003 – During a test of its maximum limit, it discharged 46 megawatts for 5 minutes

Funding – $35 million

  • Golden Valley Electric Association


  • 13,760 liquid electrolyte-filled NiCad cells
  • Each battery is roughly the size of a large PC and weighs 165 pounds
  • Total BESS weight – 1,500 tons
  • Batteries have an anticipated life of 20 to 30 years