Renewable energy means a grid overhaul. But what does that look like?

The grid that powers our homes, industries and communities is at straining point. With more electric cars, heaters, and ovens, along with changes to the way the system works due to an increase in renewable energy, there’s plenty that needs to be done to make our grid fossil fuel free.

And with the Australian government announcing this week that it will subsidise more renewable and ‘dispatchable’ energy, it’s worth understanding how this will affect transmission.

What does a grid running entirely on renewables look like?

Blackouts are not always about a shortage of energy

Think of our energy grid like a well-connected railway system. 

Energy needs to travel from the place it’s created – for example a wind or solar farm, or a coal fire power station – to the place it’s used – like your house or a factory.

In between there are transmission lines. They can be high voltage transmission lines that can transport large amounts of energy long distances, or your local street poles transporting small amounts of energy.

On all types of transmission lines there is usually only a small amount of energy travelling along the cables.

But on incredibly hot days, or other days where more energy is needed, the transmission lines push the maximum amount of energy through them.

High voltage transmission lines are built to accommodate that hottest or most power intensive day, but if planners get it wrong, the system can have black outs.

This is why people are asked (or forced) to turn off their air conditioners or other appliances on extremely hot days – energy companies are trying to stop a complete black out of the system.

Why do we need so many new transmission lines?

Experts have noted that to decarbonise by 2050, Australia will need more than 10,000 kilometres of new high-voltage powerlines. But why are so many required?

As well as requiring more energy for our electrical appliances, more transmission lines are needed because the way we are producing energy is changing.

Coal fired power stations and other traditional fossil fuel power sources have their own infrastructure, from the power station itself into cities and the larger grid. But where power stations are located is not usually the best place for new solar or wind farms.

Projects like the HumeLink – a 500kV transmission line connecting Wagga Wagga, Bannaby and Maragle – will allow renewables like Snowy 2.0 to be able to be transported into the grid.

There have been issues with people not wanting the transmission lines in their area, and this has slowed down some projects.

There are other options – some groups are suggesting more small power systems that don’t require huge grid like infrastructure.

Can the grid be run entirely on renewables?

There’s another potential hiccup with the push for renewables – how dispatchable it is.

The grid needs to be carefully managed so just enough energy is scheduled for people to use. Too much or too little leads to blackouts.

While the sun shines and the wind blows this isn’t really a problem. Even if there’s too much, it’s easy to quickly stop the blades of a turbine moving or unplug a solar panel so energy no longer comes into the system.

Renewables are much better than coal or gas power stations at being flexible in the way they dispatch power, but they’re not as ‘firm’, and can’t usually be ‘turned up’ if already running at full capacity due to the wind or sun.

With the right mix of renewables, the grid will run on fossil fuel free power almost the entire time. But for those few days in the year where there’s not enough wind or solar, another form of dispatchable power is required.

This is regularly suggested to be gas (which is a fossil fuel), but greener options include batteries or other forms of energy storage like hydro. Even electric vehicles have been suggested as a type of battery to fill up when energy is abundant, and use like a house battery when it’s needed.

There’s also potential for consumers to make a difference.  If we were more aware of when there was less energy in the system – and it’s therefore more expensive – people might be more likely to use their washing machine or charge their electric car at a different time.

This also helps the transmission lines problem – reducing peak hours.