EVs take grid positions

Jeremy Chunn Editorial Consultant KANGANEWS

By mid-2023, renewables made up 36 per cent of all electricity generation in Australia, according to Clean Energy Australia. Wind energy accounted for 13 per cent, small-scale solar 9 per cent, utility-scale solar 5 per cent and hydro 7 per cent. In 2000, renewables made up just 1 per cent of the National Electricity Market (NEM).

In the Australian Energy Market Operator (AEMO)’s 2022 integrated system plan (ISP) – a 30-year roadmap for the transition of the NEM to net zero emissions – the market operator anticipated an electrified fleet may have a “strong influence” on the shape of demand for electricity and where it is used.

EVs can load up on solar around noon or on wind overnight – when power demand is at its lowest. If not otherwise being used, they can unload it in the late afternoon peak when electricity is expensive and generators are often pushed to the limit. This is all predicated on the roll-out of smart charging technology, however.

Rewiring Australia’s Melbourne-based executive director, Dan Cass, estimates that charging an EV direct from solar can provide a full “tank” for A$5 (US$3.20). “We need to build more low-cost solar-powered charging infrastructure in our communities and at our workplaces,” Cass says. “A typical EV owner could drive as much as they need and still automatically charge and discharge at the times most suitable to the system to create a more resilient and sustainable energy grid.”

As more buyers choose electric in the years ahead, the legion of batteries-on-wheels will grow. Under the “step change” scenario described in its 2022 ISP, AEMO expects 58 per cent of vehicles on Australian roads to be electric by 2040 and 99 per cent by 2050.

Very few of the models available at the moment are capable of bidirectional charging – but the technology is coming. Tesla, the biggest-selling EV brand in Australia with 59 per cent market share, has indicated it will include bidirectional charging within two years. The technology allows vehicle-to-grid (V2G) or vehicle-to-home (V2H) power supply.

Network operators generally allow 5kW of export capacity from a residential solar system. If a similar allowance is applied to EVs with export capability, the aggregate could be a very large amount of potential generating capacity. Tristan Edis, director, analysis and advisory at Green Energy Markets in Melbourne, notes that 50,000MW is more than total peak demand in the main Australian grid.

The typical EV battery holds about 60kWh, or 12 hours worth of export if fully discharged at 5kW output. The average vehicle commute only requires about 5-10kWh of battery capacity, Edis suggests. “There is huge latent capacity sitting there that will, most of the time, never be used.”

While buyers might select their vehicle based on a 500km range they will only require once or twice a year, most of the time they might cover no more than 30km a day.

Meanwhile, in the decade or two ahead Australia will be generating so much rooftop solar energy that surplus generation will need to be spilled around the noon peak. In SA, this phenomenon means wholesale electricity prices are regularly pushed to zero or below for as long as six hours a day.

“Market outcomes in SA are likely a few years into the future across other states, when there is a large excess of solar,” Edis says. “EVs with V2G capability can provide a way to soak up the excess and provide it back into the home and the wider grid in the evening peak demand period.”

There are also a few weeks of the year where wind and solar output is low for several days in a row. These can be forecast reasonably accurately a week ahead, Edis says. “The message could go out to households in the lead up to make sure their vehicle is charged to full capacity. The charge could then be steadily drawn down over the week and the vehicle owner paid for the service.”

EV owners may also choose to use their vehicle’s battery to power their own home. An EV that covers about 15,000km a year will use about 3MWh, whereas a house might use 4-10 times this amount of energy, says Tim Ryan, Sydney-based energy consultant and founder of Ready Energy. “Consumers fundamentally prefer to save rather than try to make money,” he says. “It will be easier to plug in an EV and power the house – but this is just as valuable to the whole community as a car that is exporting to the grid.”

The relationship between EVs and the grid is not all upside, however. Passenger vehicles and buses have made up the advance guard in EVs but commercial vehicles and articulated, heavy and light trucks are on their way. This last category will be the main drain of all EVs on the grid in 30 years’ time when they charge up after work, according to Cornwall Insight analysis.

Modelling of uncontrolled charging by 2052 forecasts an 8,000MW load around 8pm – a potential disaster for the grid. If truck owners are incentivised to charge overnight, after the evening peak, they can provide a significant improvement by easing pressure on the grid. Truck fleets will be working during the day while passenger vehicles can top up while the sun is shining.

Bjorn Sturmberg, Canberra-based senior research fellow at Australian National University’s battery storage and grid integration programme, has tested the possibilities of bidirectional charging and says there is a long way to go. A trial of 51 government Nissan Leafs in the Australian Capital Territory was hampered by teething issues with bidirectional chargers. The Spanish company that produced the charging unit used in the trial has ceased production while it works on an upgraded version.

The trial, part funded by the Australian Renewable Energy Agency, was designed to test the possibilities for EVs in supporting the grid. The hypothesis remains to be tested, but Sturmberg does not feel defeated. “The immediate focal points of efforts should be around smart charging or managed charging,” he says. “This is the huge opportunity and it is a stepping stone to perhaps doing bidirectional charging in the future.”

The power required to charge an EV is 2-3 times greater than powering a household so it is vital car buyers understand the responsibilities of operating such a piece of kit. “We don’t want a situation where lots of people have EVs and expect to be able to plug them in and charge at full bore at their convenience. If we get to that point it will be hard to convince millions of people to change their behaviour,” Sturmberg adds.

Instead, EVs should be plugged in when not in use, with software used to control charging to optimise stability of the grid and use of renewables, and to minimise emissions. “We know we have to have 100 per cent EVs, and we know they are going to use a lot of power – there is no uncertainty around this,” Sturmberg continues. “We should make sure the technical systems and social expectations are in place from the get go.”

Australia needs much more public charging infrastructure to service EVs, anywhere and everywhere cars are parked. Tariffs should also reflect time of use so a charge is virtually free in the middle of the day and more expensive during the morning or afternoon peaks. Cornwall Insight expects about 200-250MW of “negative demand” throughout the night. The driver of this behaviour is economic, in the sense that the EV battery will have charged using cheaper energy from the daytime so it will be more cost-effective for the consumer to use this energy to power their homes through the night.

The disruption to car ownership and energy supply caused by EVs could in turn be disrupted by driverless vehicles, which can be shared and get by with much smaller batteries. There would be as many cars in motion but very few would be parked and doing nothing. It would be a much more efficient battery configuration relative to need, but there would no longer be a huge fleet of 60kWh powerpacks on call to manage peaks and troughs.