Over the next two decades, Australia will be racing to reach net zero emissions.
There are different theories about how to get there, but one of the most prominent is the idea known as "electrify everything".
This idea will probably determine how you stay warm, how you heat your water, and how you drive from one place to another.
So, here's what it means – and what it would involve.
A nationwide home renovation project
In the world of energy and climate policy, Saul Griffith is an emerging star.
The Australian entrepreneur and inventor has founded multiple companies, won a MacArthur "genius" grant, mapped the enormously complex US energy system, advised the President and is currently celebrating the passage of landmark US climate legislation.
He's also an advocate for electrify everything – recently setting up a non-profit, Rewiring Australia, to push for exactly that.
Dr Griffith sees decarbonisation as largely a problem of having the wrong machines.
He calculates that Australia has about 101 million of them.
If it can simply swap them out, it'll be well on the way towards net zero by 2050.
Simple, right?
It makes the apparently complex process of decarbonisation sound like something you could get done in a suburban hardware store.
To work, most of those 101 million machines need to be replaced with electric versions at the end of their life.
Amongst other things, net zero amounts to a collective nationwide home renovation project.
What are these machines?
They're generally the cars and appliances most Australians use every day.
Things like gas house-heaters and gas water-heaters. Small, everyday machines owned by households and small businesses that burn fossil fuels.
Then there's the much larger, usually corporate-owned, machines used in industries like manufacturing, construction and mining.
Some of these generate or supply energy for household and commercial use – they're machines like coal-fired power plants, or diesel-electric trains.
According to Dr Griffith, there are about 1 million of these larger machines and 100 million of the smaller ones.
We're focusing on the smaller machines, because they're easier to electrify.
Here's how many machines of each type make up the total.
The "miscellaneous" machines (ie the lawnmower icon) are lots of different types. Don't worry about them for the moment.
Let's focus on the machines up the top: gas space heaters, gas hot water systems, gas cooking appliances, and light vehicles.
If 6 million gas heaters were placed in single file, they'd stretch from Sydney, through Wagga Wagga, all the way to Adelaide.
If 2.6 million gas cooktops were stacked on top of each other at St Kilda beach, the tower would soar into space.
If the gas distribution lines that feed these appliances were untangled and connected, the single pipe could wrap around the Earth twice.
You get the point: there's a lot of machines to replace.
These snaking lines of gas heaters and leaning towers of gas cooktops are the legacy of decades of cheap fossil fuels and unrestrained emissions.
But, of course, we're not really interested in the physical scale of the machines, but the emissions associated with each type.
This is where it gets interesting: three types of machines are responsible for most of the emissions.
What machines emit the most?
If we ignore emissions associated with electricity, the household machines that generally emit the most are the petrol-or-diesel car, the gas hot water system, and the gas space heater.
Together they accounted for about 95 per cent of average household emissions, said Professor Andrew Blakers from the Australian National University.
Gas used for cooking and other purposes was a negligible amount, he added.
Gas water heaters can emit relatively little compared to electric water heaters that run on electricity generated by fossil fuels.
But when the electricity is generated by renewables, the gas hot water systems are comparatively much dirtier.
"Getting rid of your gas water heater and gas space heater is equivalent to buying an EV in terms of emissions impact," Professor Blakers said.
(NB: This depends on how much you drive, and how cold it is where you live.)
If we compare just gas heating and land transport, cars are by far the main contributor to national household emissions.
One reason emissions from transport are so high is not all households use gas, but pretty much all have cars (the average house has 1.8 cars).
For households with gas water heating and space heating, the ratio of blue flames to petrol drops will be much closer to being even.
How's it going with electrifying cars?
There are about 20 million vehicles registered in Australia, and the vast majority of them burn fossil fuels.
Only about 60,000 of these registered vehicles are EVs.
So there's a long way to go.
According to government modelling, by 2030 that figure will be 3.8 million.
In general terms, taking 3.8 million petrol and diesel cars off the road would be equivalent to replacing about 11 million gas water heaters.
How long would it take?
To replace all these machines within 25 years, Australia will need to swap them out at a rate of about one every 10 seconds, or six a minute.
So, like any home renovation, it would have to be done in a hurry.
Fortunately, all the machines that need to be replaced are going to have to be replaced anyway – most of them won't last another decade.
The average age of cars in Australia is about 10 years, while gas water heaters and gas heaters tend to be replaced every 10-15 years.
The trick, Professor Blacker said, will be replacing them with the right machines.
That means buying an EV when you get your next car, or an electric heat pump (ie reverse-cycle air conditioners) when the gas heater dies.
"It's easy. We just have to stop like-for-like replacement," he said.
Dr Griffith agreed.
"Next time your gas hot water heater kicks the bucket, we need the replacement to be electric. And that's just the reality."
What about emissions from power generation?
Substituting electricity for fossil fuels raises other issues, such as beefing up renewable power generation, plus storage.
About one-third of annual electricity generation for the the National Electricity Market (NEM) comes from renewable sources.
The federal government is targeting 82 per cent renewables in the NEM by 2030.
As part of this shift to renewables, Dr Griffith is advocating for a massive uptake of rooftop solar and batteries.
About 3 million households currently have rooftop solar, leaving 7 million without.
If each of these 7 million households had a standard 5kW system, the combined output would be an additional 35GW – which is a lot.
In generation capacity, it would be roughly equivalent to giving every player at this year's AFL Grand Final their own coal-fired power plant.
Electrification would cost money upfront, but save money in the long-term through energy efficiency, Dr Griffith said.
And it was still the cheapest way of cutting emissions now, he added.
In the ACT, newly built suburbs won't have gas mains. The territory has also banned the sale of petrol-engine cars after 2035.
And this month, Victoria released a roadmap for phasing out gas.
In the US, the Inflation Reduction Act, which President Biden signed into law last month, includes billions in funding for home electrification.
These are encouraging signs for advocates, but it's early days.
The biggest challenges were political not technical, Dr Griffith said.
"Unless we figure out how to bring everyone along, the political project fails," he said.
"You don't half-solve climate change."
Hear more about climate change solutions in the podcast WHO'S GONNA SAVE US? a collaboration between triple j Hack and the Science team at RN.
