A zero-carbon transport sector needs more than electric vehicles

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Decarbonising Australia’s transport systems will take more than a transition to electric vehicles. Understanding how and when owners like to charge their cars is important. Our researchers are examining how we might persuade the increasing electricity demand to meet the time-dependent renewable energy supply.

How many people do you know who own an electric vehicle? Most Australians still drive petrol-fuelled cars. But the proportion of electric vehicles (EVs) on our roads is set to boom in coming years, particularly if the government’s plans to introduce a fuel efficiency standard prove successful.

Transport researchers at the University of Melbourne Faculty of Engineering and Information Technology have studied the expectations EV owners have for charging – and what they think of policies and technologies that aim to shape EV charging behaviours.

Why we need to prepare Australia for electric vehicles

Cars account for 10 per cent of Australia’s total greenhouse gas emissions. Electric vehicles are a major solution that will lead to a zero-carbon transport sector. But electric vehicles are power-hungry.

“The main issue is that electric vehicles could add significant electrical load to the grid at the wrong time. And there may be parts of the grid, especially in the distribution networks – which is like the edge of the grid in a way – that may already be congested,” says Professor Pierluigi Mancarella, Chair of Electrical Power Systems at the Melbourne Energy Institute.

Electricity use already peaks at around 6 pm. The added load from masses of commuters plugging in their vehicles at once would strain the grid – and complicate Australia’s transition to renewable energy.

However, intelligent management of electric vehicle charging can bridge gaps in the renewable energy supply. EVs could charge from solar cells during the day and feed electricity back to the home or the grid in the evening.

“Electric vehicles can be hugely beneficial while we make our grid smarter and more sustainable,” says Professor Mancarella.

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Understanding how electric vehicles could affect our electricity supply

The EV Integration project, led by the University of Melbourne, explored the impacts of Australia’s EV transition on our energy grid – and proposed strategies for how to manage them. The project brought together energy and transport researchers as well as industry partners from Energy Networks Australia and the Centre for New Energy Technologies.

Transport researcher Dr Patricia Lavieri says the collaboration opened her eyes to challenges and opportunities in the energy sector.

“In transport, we make assumptions about energy, and they make assumptions about transport,” says Dr Lavieri.

“They will say ‘Oh, nobody is at home in the middle of the day. So let’s not try to have residential charging in the middle of the day.’

“But the truth is that if you analyse transport demand, you can see there is a segment of consumers that has their cars parked at home in the middle of the day and other groups that could have. Knowing this, we can design integrated transport and energy demand management strategies that encourage people to charge their cars mid-day,” says Dr Lavieri.

The strength of the EV Integration project was in this cross-disciplinary research approach, which has given the industry partners varied options to consider for managing electric vehicle uptake in Australia.

“The research team from the University of Melbourne worked very well with our industry working group team to achieve the objectives of the project,” says Dr Monaaf Al-Falahi, Technical Program Coordinator at Energy Networks Australia.

“The outcomes of the project were very insightful, with a list of recommendations for the industry to consider maximising hosting capacity of EVs with minimal impact on the electricity grid.”

Why we need to understand electric vehicle charging behaviour

Since reinforcing the entire energy network to handle increased loads would be a long and costly process, strategic planning is crucial.

Researchers must understand when EVs will be drawing power from the grid – especially as Australia transitions to weather-dependent renewable energy.

“Being able to shape behaviour is fundamental, because you’re going to need to convince your demand to behave in a way that meets your supply,” says Dr Lavieri.

Most electric vehicle owners would prefer to charge their cars at home in the evening, Dr Lavieri found. Current owners – who tend to have higher incomes – are more motivated by convenience than by electricity prices. But future EV owners may be more sensitive to price.

“People are living on budgets, and they are trying to minimise their costs,” says Dr Lavieri.

Monetary incentives could guide charging behaviours. These include free public charging and time-of-use tariffs – discounts for charging at off-peak times.

Smart chargers, which have a data connection that provides real-time information about the electricity price and supply, are the most reliable method to control demand. They can be controlled either by the user or the supplier, with the latter giving energy companies the most control over energy demand.

“Users preferred the user-controlled smart charging, because … they are concerned about the risks. They are concerned about whether they're going to have their vehicle charged or not. They're concerned about their privacy on sharing this data continuously,” says Dr Lavieri.

But giving owners the opportunity to override supplier control might increase user acceptance of supplier-controlled smart charging.

The time to prepare is now

At this early stage of EV adoption in Australia, we have the opportunity to create policies to shape the charging behaviour of EV owners to the benefit of our energy systems.

Dr Lavieri’s research is revealing groups of consumers that could be targeted with policy packages tailored to their circumstances.

An emerging opportunity to expedite Australia’s zero-carbon transition is to encourage coupling the adoption of electric vehicles with solar cells for the home. Dr Lavieri found that a surprising number of prospective EV owners would be willing to charge their vehicles in the off-peak period in the middle of the day, as opposed to the common midnight off-peak period.

“Australia is the leading country in per capita adoption of rooftop solar, and it's just growing with all the incentives and so forth. It's really an opportunity that can't be missed,” Dr Lavieri says.