Blackouts explained

What Causes a Blackout?

Small, localised power outages can be caused by a wide range of factors, such as lightning, floods, heatwaves, bushfires, high winds, fallen trees, or car accidents.

Large-scale blackouts are less common but can have very severe impacts on human health and economic activity. An independent review of the 2016 SA blackout event found “The causes of a widespread and prolonged power outage can include: extreme weather; terrorism; a criminal act; technical failure; human error; human pandemic; and accidents. Black System events are believed by some to be more likely in the future.”

There are numerous recent international examples of widespread and prolonged blackouts due to a wide range of causes, for example:

• In 2015 more than 700,000 residents on Vancouver Island, Canada lost power due to a storm.
• In 2016 more than 350,000 people in Florida and Georgia in the United States lost power for several days due to impacts on the electricity system from Hurricane Hermine.
• In 2016, 3.5 million people lost power in Puerto Rico due to the failure of two major transmission lines after a fire.
• In 2017, 1.15 million households and businesses in Michigan in the United States lost power (some for up to a week) due to a windstorm.
• In 2017, the entire island of Puerto Rico lost power due to damage to energy infrastructure caused by Hurricane Maria, with parts of the island still without power months later.

Recent Australian Events

In 2016, a severe weather event including multiple tornadoes led to the destruction of 23 transmission towers in South Australia, and ultimately triggered a complete statewide blackout.

Whilst a severe weather event causing a whole state to lose power may be unprecedented in Australia, there have been severe weather-related blackouts to hundreds of thousands of people before in Australia, such as:

• In 2009, more than 500,000 homes without power in Victoria due to heatwave
• In 2011, more than 200,000 houses lost power in Victoria due to storms
• In 2013, almost 250,000 homes in Queensland lost power due to storms
• In 2015, 200,000 business and households in NSW faced extended blackouts of up to a week
• In 2017, 100,000 properties lost power due to Cyclone Debbie

An increase in extreme weather events (such as storms, heatwaves, bushfires)  has serious implications for reliably supplying power to Australian homes.

Fact check: South Australia blackout, September 2016

The whole state of South Australia lost power on 28 September 2016 during a one-in-50 year weather event involving tornadoes , severe thunderstorms, damaging winds, hail and 80,000 lightning strikes. The storm resulted in catastrophic damage to power infrastructure, including the loss of more than 22 transmission towers. As a standard safety response, the South Australian energy system was isolated from the National Electricity Market. Within hours, power was restored to all but 75,000 of the 900,000 homes that lost power.

The Australian Energy Market Operator AEMO (2016), has published four reports into the incident which show the event was triggered by the severe weather causing the loss of three major transmission lines (causing six voltage dips over a 2 minute period).

AEMO advised the Prime Minister at the time of the blackout that the supercharged storm was to blame (SMH 2017).

Former SA Police Commissioner Gary Burns undertook an independent review of the event and identified the significant, severe thunderstorm damage to transmission lines as the chief cause (Burns 2016).