South Australia power generation type 2009/2010 (data sourced from https://www.aemo.com.au/media/Files/Other/planning/0400-0013%20pdf.pdf)
In 2009 the South Australian grid consisted predominantly of fossil fuel generation technologies, with coal and natural gas generation being the main base loaded power generation supply in the state.
Based on South Australia's ambition to reduce carbon intensity, renewable power generation developments were given financial incentives such as tax rebates, and electricity retailers were required to source a proportion of energy from renewable resources, which encouraged a surge in green field wind and solar projects.
The levelized cost of electricity (LCOE) of renewable energy sources are approximated at $3-6 US cents/ kWhr per (as cited by Lazard Levelized Cost of Electricity Analysis version 13) for large scale wind and solar generation projects. This has forced base loaded generators dependent on fossil fuels such as coal and gas power generation to switch from a base loaded power profile, to a midmerit, cyclic profile as a result of not being able to compete on an LCOE basis, especially when there is a surplus of a renewable power generation.
This phenomenon was experienced in South Australia, which gained a surplus of power generation, especially during daylight hours, forcing older coal fired power stations that were not able to be subjected to cyclic loading profiles due to maintenance impacts to be duly decommissioned. Existing large base loaded gas fired generation technologies were also not able to compete on an LCOE basis due to high costs of fuel gas ($8-9 USD/GJ yielding LCOE of $8-$12 US cents/kWhr for existing plants), forcing them to transition to a peaking generation profile with multiple starts per day. This resulted in the transition of the power generation portfolio in SA.
South Australia Generation Type 2016/2017 (data source: AEMO)
The South Australian power grid became highly dependent on renewable energy resources, predominantly wind energy. This incentivized power producers to invest in new solar and wind generation projects, while minimal investment was made on transmissions networks, or grid firming and peaking technologies to accommodate a grid with high renewable energy penetration.
This inadvertently made the South Australian state more dependent on the Victorian interconnector for power shortfalls during grid events. In a scenario where the Victorian interconnector is disconnected, the South Australian region would be islanded, which would require the region to be self-sufficient for base loaded power generation.
It's not an uncommon problem. See how utilities and operators must constantly fill the gap between supply and demand, and how GE can help.
In September 2016, torrential weather resulted in South Australian transmissions lines and pylons being damaged, causing a contingency event on the grid due to voltage depressions below allowable limits based on protection settings of various wind farms. This caused certain wind farms to be disconnected from the grid, resulting in a shortfall of power generation. Historically, in such events, spinning synchronous generation technologies such as gas and coal generation allow enough time for load shedding to automatically take place in the South Australian region to avoid a complete system blackout. However, with the region heavily reliant on renewable energy generation during the contingency event which could not supply the equivalent amount of inertia, the rate of change of frequency exceeded the response capability of load shedding systems to avoid a system blackout. As a result, South Australia went into a complete state blackout for more than four hours.
Since the South Australian event in September 2016, many measures have been taken to increase grid stability and to allow better management of grid events whilst still maintaining high levels of renewable energy generation.This includes battery storage systems, fast start peaking and also grid firming dispatchable power plants, which have made the South Australian network more resilient against statewide blackouts.
The learnings from the South Australian region are being discussed and applied to other regions in Australia to ensure grid resilience during the transition to a high renewable energy grid. The lessons learned, and measures taken, are applicable to other regions around the world that are also forecasted to be heavily reliant on renewable power generation. The result of this is the emergence of the peaking, grid firming, and energy storage segment. GE's aeroderivative gas turbines are a great fit for these segments. In the next two sections, you'll find out why.