Independent Review into the Future Security of the National Electricity Market Blueprint for the Future, Jun 2017

8.4 Electric vehicles

Uptake of electric vehicles is likely to increase, associated with the combined impact of declining battery prices and introduction of high range and low price electric vehicles⁴⁷² into the market. Currently, electric vehicles only constitute about 0.3 per cent of Australia’s electric vehicle sales.⁴⁷³ Globally, there were an estimated 1.26 million electric vehicles at the end of 2015.⁴⁷⁴ The right mix of incentives for the uptake of electric vehicles along with a decarbonised electricity grid could help to achieve significant emissions reductions in Australia’s transport sector, which in 2015 accounted for about 18 per cent of Australia’s emissions (or 93 million tonnes of carbon dioxide equivalent).⁴⁷⁵

Electric vehicle uptake could significantly change electricity usage patterns in Australia. Electricity consumption by electric vehicles is estimated to reach nearly 4 per cent of total electricity consumed by FY2036.⁴⁷⁶ Electric vehicle charging can be relatively easily managed to reduce negative impacts on the electricity grid. If properly managed, electric vehicle charging could improve grid utilisation and be a flexible demand absorbing load during periods of high VRE output (less spilled energy).⁴⁷⁷

It is possible, in principle, for electric vehicles to be used as distributed energy storage facilities, releasing energy back to the grid at peak times, and also helping in addressing the management of frequency, reactive power and voltage to improve grid security and reliability. However, the Panel is not aware of any cases where the use of electric vehicles in this way has commenced commercially.

8.5 System security technologies

Chapter 2 discusses some key services that are required to support power system security, such as frequency control services. While many of those services can be sourced from generation or storage technologies, they can also be sourced from other technologies, including synchronous condensers and power conversion electronics.

Synchronous condensers

A synchronous condenser is a machine similar to a synchronous generator or motor, having a large rotating mass that spins at a speed proportional to the grid frequency. It does not produce electricity. Instead its benefit is that, as a synchronous technology, it provides physical inertia to help dampen rapid frequency changes, fault current to help maintain system strength, and the ability to supply or absorb reactive power to help control voltage. Operating a synchronous condenser consumes only a very small amount of energy.

Synchronous condensers can be purchased as new, or reconfigured from decommissioned synchronous generators (such as coal-fired generators). Converting a decommissioned synchronous generator to a synchronous condenser may be an economical alternative to purchasing a new synchronous condenser. Cost-savings are achieved through re-using the existing generator machinery, foundation and building, auxiliary systems and grid connections. However, as system security needs are often location-specific, the viability of such a conversion will depend on the location of the decommissioned generator.

It is also possible to make modifications to synchronous generators that are still in operation, enabling them to be switched between generator mode and synchronous condenser mode. This approach has been employed in Tasmania, where there are 14 hydro generators capable of operating in synchronous condenser mode.⁴⁷⁸

Synchronous condensers are a mature technology. There are a limited number of synchronous condensers in place throughout the NEM, though many have either been retired or are close to retirement, and traditionally were designed for voltage control rather than to provide inertia and fault level contributions.⁴⁷⁹ Their future potential depends less on innovation, than on the creation of better incentive frameworks to value the security services they provide.

Power conversion electronics

Power conversion electronics convert electricity to have different characteristics.⁴⁸⁰ Power conversion electronics are used at many points in the grid, including when converting from DC to AC (or vice versa) for certain transmission lines, generators, storage systems and loads. Power conversion electronics associated with VRE generators and loads convert DC to AC and are called an inverter.

Inverters can be designed and configured so that electricity is sent out from a DC generator (such as solar photovoltaic) or consumed by a load in a way that it provides security services. While generators connected to the power system via inverters are typically not able to provide the same level of inertia associated with synchronous generators, some systems can provide synthetic inertia and other system security services.⁴⁸¹ All technologies using inverters have the potential to provide some frequency response, and in some cases, FFR.⁴⁸² The characteristics and practicality of this function vary between different technologies.⁴⁸³ Wind turbines can provide an inertia-based FFR (also known as synthetic inertia) using the kinetic energy in their rotors. If their generation is curtailed below full capacity they can then provide FFR by increasing generation quickly when needed.⁴⁸⁴ Both wind and solar photovoltaic are able to provide reactive power and voltage control if designed to do so.⁴⁸⁵

A recent example in Australia is Stage 2 of the Hornsdale Wind Farm in South Australia which has been licensed with higher connection standards than required under the National Electricity Rules. In accordance with the licence conditions, the wind turbine inverters installed have the capability to provide frequency control services to the NEM. In addition, the wind farm is designed to better withstand high rates of change of frequency.⁴⁸⁶

8.6 Conclusion

The evolution of power generation, storage and integration technologies continues in Australia and globally. The maturity level and rate of development of these technologies in terms of cost, scalability and operability will vary depending on levels of ongoing investment, the ability to integrate and undertake controlled trials of new developments under realistic conditions and sustained demonstration at scale.

Their inclusion as part of the energy system requires consideration of operating characteristics and other externalities such as emissions intensity, flexibility, scalability and dispatchability and future potential.

It is important that there is ongoing oversight of development progress both nationally and internationally and that appropriate incentives, urgency, support and planning mechanisms exist to ensure timely development of these future options.