EVs spark current thinking

The family vehicle could double up as a home battery during peak periods.

• By VALENTINO VESCOVI
• 2:01PM MARCH 13, 2019
• NO COMMENTS

The debate over the lack of a national energy policy is centred on ideological and climate change arguments. There is, however, a more immediate and practical problem that’s likely to be detrimental to Australia that has to do with the predicted rapid up-take of electric vehicles (EVs) and their impact on our power grid.

Government and industry need to quickly find a way to work together, otherwise the power blackouts and load shedding that happen occasionally during summer could increase dramatically. There’s a relatively simple solution to this problem.

There are close to 20 million cars in Australia and, by some predictions, within a few years EVs will constitute about 5 million cars, or one quarter of the total Australian car fleet.

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The total electrical power generating capacity in Australia is close to 45 gigawatts, while the peak power usage in the 6-9pm period is typically about 35GW, according to the Australian Energy Regulator.

In the worst-case scenario, if the majority of EV owners charge their vehicles in the evening peak period, and if each charger is rated at 10 kilowatts, the total draw on the grid would be 50GW. This is more than the total generating capacity and is clearly an untenable situation.

While acknowledging that this is an oversimplified worse-case scenario, it shows that uncontrolled EV battery charging has the potential to severely disrupt the electrical power grid.

The AER reports that close to 20 per cent of our nation’s electricity generating capacity comes from solar and wind power, but this contribution reduces as the sun sets just when a large number of EV owners might want to charge their vehicles. The situation can be even worse in some areas on windless evenings. In time, the situation is likely to worsen as EVs are likely to replace most of the internal combustion engine fleet.

Vehicle to grid

Apart from somehow controlling the times at which EV batteries can charge, the situation can be improved by the use of Vehicle to Grid (V2G) technology.

A V2G unit is a bi-directional power converter that can switch between charging mode and inversion mode. In inversion mode, some of the power from the EV’s battery is returned to the grid.

This means the family vehicle can double up as a home battery during peak periods.

It’s a practical solution because a typical Australian home consumes about 18kW of electricity daily, according to statistics from the Department of Environment and Energy.

To put this in perspective, the new EVs entering the market will have batteries with 40-100kW of capacity.

Even if an EV contributed a modest 5kW to the grid, five million V2G-equipped EVs could cut Australia’s current peak electricity demand by 25GW out of a total of 30GW or so.

Clearly even a modest compliance with this idealised situation would make a tremendous difference to the demand/supply situation.

What’s more, the drain on a typical EV battery would only be modest. Assuming the EV feeds 5kW to the grid over a two-hour period, the drawdown will be 10kWh, which is only a fraction of the EV’s battery capacity.

Co-ordinated action

Several assumptions have been made in the examples discussed above, but even if some of these variables are changed, it’s easy to see what a big difference V2G technology can make to the stability and reliability of Australia’s power grid.

Under the right circumstances, V2G has the potential to reduce the need for power generating companies to build more “peaker” power stations. These “peakers” are power plants that are turned on as required during peak demand times. Electricity from such plants is expensive as they are operated infrequently.

However, the adoption and use of V2G technology cannot happen without appropriate incentives and disincentives to ensure EV batteries consume and provide power at the right times.

Making feed-in tariffs at peak periods sufficiently high is one obvious strategy to discourage charging at that time. Conversely, by using a V2G unit to produce power at that time, the EV owner can reduce power bills and run the EV for virtually no cost in electricity as the peak feed-in tariff will offset the consumption cost.

This raises the question of how to control V2G units. Charging and inversion times could be pre-programmed into the units or they could be controlled via the internet, a smart meter or through power lines. It’s hard to see how these issues can be resolved without the government’s direct involvement with other stakeholders in formulating the right policies and conditions-of-use to ensure a smooth transition to an EV dominant future.

Valentino Vescovi is a co-founder and non-executive director of Rectifier Technologie.