The Queensland Energy and Jobs Plan (QEJP) sets an ambitious goal to deliver the Queensland SuperGrid. The SuperGrid is the future electricity system aiming to deliver consumers clean, reliable, and affordable power. As part of the plan, all publicly owned coal-fired power plants are intended to be retired by 2035. The capacity will be replaced by wind, solar, and storage to achieve 50% renewable energy by 2030, 70% by 2032, and 80% by 2035. Since Queensland has strong solar and high-quality wind resources close to existing network infrastructure and loads, the Queensland SuperGrid plan provides tremendous opportunities for renewable investment and Renewable Energy Zone (REZ) development.
This Chart of the week looks at the Marginal Loss Factor (MLF) trends at Darling Downs REZ, incorporating the latest changes from QEJP. The MLF is obtained using our in-house Power System Analysis model and Benchmark Power Curve (BPC) model.
The trends of time-of-day (TOD) annual average loss factors for FY 2025, FY 2027, FY 2034, and FY2038 for Queensland Darling Downs REZ compared with NSW New England REZ are shown in Figure 1.
The TOD loss factor trend of New England REZ can be seen as a ‘typical shape’ for areas with high solar generation and no coal-fired and gas-fired power plants. That is, lower loss factors (i.e., more losses in the network) during the day and higher loss factors (i.e., fewer losses in the network) during the night are observed. The shape of the TOD loss factors is inverse to the solar generation profile. However, very distinct TOD loss profiles can be observed for Darling Downs in all years, mainly due to the impact of the coal-fired and gas-fired plants within Darling Downs REZ, such as Kogan Creek, Tarong and Braemar power stations.
In FY 2024, the TOD factors are inversely correlated to the output levels of the coal-fired plants within the REZ, which have lower generation during the day and higher generation during the night. As a result, the loss factors are higher during the day and lower at night. This profile is beneficial for solar projects around the area, which generate during the day and can thus make the most of higher loss factors when larger fossil-fuel-based generators are not producing. By FY 2027, the time-of-day loss factors are much flatter due to the increase in renewable generation in the Darling Downs REZ. The retirement of coal-fired power plants in Southern Queensland and Central Queensland increases the generation from gas plants in Darling Downs REZ and imports from NSW during the evening peak hours, reducing the loss factors in FY 2034. The shape of the TOD loss factor reduces further in FY 2038, mainly due to the uptake of solar generation in the REZ, resulting in lower loss factors during the daytime.
It can be seen that the TOD loss factors are highly dependent on factors such as the generation profile at the assessed site, the behaviour of nearby generation, loads, and network investment, and can be highly impacted by energy policies such as the SuperGrid plan.
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