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In the electricity industry no two words instil a greater sense of fear or failure as load shedding.
The term might not seem like much to the average punter who only wants to know that the lights will come on when they flick the switch.
But its implications are clear and cold enough — it means blackouts.
And the mere spectre of it is often a sign of an electricity system in distress.
What is load shedding?
According to the Australian Energy Market Operator (AEMO), which runs the National Electricity Market (NEM) on the east coast, load shedding is a way of keeping the system stable.
In truth, there are many ways the operator can keep the system stable, but load shedding is the most extreme tool at its disposal.
Electricity is like most other commodities in that it is about supply and demand, the latter of which is known as "load" in industry jargon.
But unlike just about any other good, supply of electricity has to match demand almost perfectly at all times. Margins of error are tiny.
Such rigour is required because power, while so essential, can also be dangerous to people and appliances.
Think of the electricity system as a generator at one end, a user at the other end, and a highwire in between.
The aim of the game is to keep the highwire perfectly stable by exactly matching the user's needs with the generator's output.
Too little supply and the wire will drop.
Too much power and the wire could overload.
Either way, the consequences of failure are serious.
They inevitably trigger safeguards at the generator that force it to switch off, or trip, to prevent even more drastic consequences such as an explosion, for example.
A grid such as the NEM, which services more than 10 million customers in the eastern states, is at a vastly bigger scale.
But the principles are the same.
In order to avoid circumstances where supply and demand become dangerously out of whack the market operator can cut power to big numbers of customers to restore balance — it sheds the load.
This can be done by telling users, such as industrial players, to pare back or switch off.
Or it can be done at what is known as the distribution level, where entire suburbs are switched off and households have to pitch in to keep the system stable.
Why is there a risk of load shedding?
Across the east coast, but but particularly in Queensland and NSW, a shortage of supply has run headlong into spike in demand as people increase their energy use during a cold snap.
The causes of the supply squeeze are many and various.
For starters, along the eastern seaboard a number of coal-fired power stations are offline.
These include generating units at AGL's Bayswater and Liddell coal plants in NSW and Loy Yang A asset in Victoria, along with the Queensland government's Callide C power plant.
On top of this Australia's largest coal-fired power plant, the 2,880-megawatt Eraring plants in NSW owned by Origin Energy, has been hit by a shortage of coal supply.
Some of these outages were expected — plants are periodically taken offline for maintenance — but others were not.
And when you tally up the capacity of the missing coal units it is a big chunk of the generation in the NEM that would normally be available.
To add to the supply woes, Russia's invasion of Ukraine and the consequent ructions to global energy markets has put a rocket under coal and gas prices.
For many of the generators operating in the east coast, which is one of the world's biggest exporters of both commodities, the turmoil has left them heavily exposed to soaring fuel prices.
A final straw is related to both of those factors and came to a head on Monday when AEMO issued its dire warning about the risks of blackouts.
Under the NEM's rules, price caps for generators can be imposed when costs in the wholesale power market breach maximum thresholds.
In what's believed to be a first, that threshold was breached on Monday in Queensland, and then New South Wales, where wholesale prices have been soaring in response to the supply crunch.
Perversely, however, the imposition of a price cap prompted a bunch of so-called peaking power providers such as fast-start gas and diesel-fired plants to pull back from the market over concerns the high cost of those fuels would lead them to run at a loss.
By pulling back from the market and risking blackouts, the generators helped trigger extraordinary powers that allow AEMO to instruct them to run but also provide for greater levels of compensation.
What can be done to avoid blackouts?
In the short term, the best option available to the market operator is to simply get the coal plants that are offline back into service.
That would instantly provide big licks of extra generation capacity and deal with the immediate crisis and threat of blackouts.
Governments at a state and federal level could also apply pressure on gas producers to send more of their supplies to the domestic market to ease record prices.
To that end, the new federal Labor government has flagged changes to sharpen up the so-called gas trigger that is supposed to give the Commonwealth the power to order the companies to hand over supplies.
And, of course, consumers are already being asked to use less energy where they can to help take pressure off the grid.
Realistically, though, authorities such as AEMO will have to work with the powers they already have to stave off any repeat of this week's troubles.
And by anyone's admission, that is far from ideal. The powers are costly and were only ever meant to be used as a last resort.
Solving the problems bedevilling Australia's largest power network will require longer-term solutions, according to experts in the field.
What the overall fix looks like is still up for debate.
But one way or another, Australia is in desperate need of the extra short and long-term storage and transmission that will be necessary to connect the extra renewable energy inexorably coming to replace the nation's ageing fleet of coal-fired power stations.
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