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.