Why doesn't Australia need so much storage in the wind and solar grid

How many storages have high grating – 90 percent or more – varying wind and solar requirements to ensure there is enough supply to meet demand?

This is a hot topic inside and outside the energy circle. One common theory – often pushed by the nuclear and fossil fuel lobbies, and the former Coalition government – ​​is that you should match each kW of wind and solar capacity to an equivalent amount of storage.

The CSIRO says the idea is wrong, and Australia will only need to install a fraction of the storage for every kW of renewable energy – between one-fifth and one-third – to meet demand.

“Such a conclusion would substantially overestimate the need for storage capacity,” said CSIRO in an updated version of the GenCost report, a landmark annual document that tracks the costs of comparable energy technologies, and in the case of wind and solar, their storage and transmission. needs too.

The reason for this, says CSIRO, is that although the generation mix is ​​changed, and significantly more wind and solar – in terms of rated capacity – are being built to replace coal, the maximum demand has not changed.

And that means the amount of storage or deliverable generation needed to meet maximum demand doesn’t change either.

“So instead of installing on a kW per kW basis to ensure maximum demand is met, we only need to install a fraction of the kW of storage for each kW of variable renewable energy.”

At lower wind and solar penetration rates – up to 50 percent – ​​virtually no storage is needed because “reserves” are already in place, mostly to support coal generators that fail or cannot scale up fast enough to meet spikes in demand.

“The combined storage, peaking, and other flexible generation capacity only needs to be sufficient to meet maximum demand,” notes CSIRO. “In a high renewable variable system, the maximum demand will be much lower than the installed renewable variable capacity.

“As the share of renewable generation increases, peak summer or winter events may not represent the most critical days for backup generation.

“For example, during peak summer events, solar PV generation is high and as a result storage is relatively full and available for delivery to the evening peak period. A more challenging period for renewable variable systems may be on days of lower demand when cloud cover is high and wind speeds are low.

“Today’s low-cost renewable generation and low storage costs can see the greatest demands on storage, peaking, and other flexible capacities. Thus, the low level of demand on these low renewable generation days may be a more important benchmark in determining the amount of additional spare capacity required.

“The applied modeling approach takes all of these factors into account over nine years of historical weather. The result we found is that, by 2030, NEM will need to have a storage capacity of 0.20kW to 0.34kW for every kW of renewable power generation installed.

“Showing the most extreme case of the 90% share of renewable variables for NEM, Figure 5-7 shows maximum annual demand, current lowest renewable generation demand, storage capacity, peak capacity, other flexible capacities and total variable renewable generating capacity.

Data shows that:

• The demand at the lowest point of renewable generation23 is much lower than the maximum demand
• Existing and new flexible capacities are slightly lower than maximum demand indicating a variety of renewable power plants are available at peak demand (during the nine weather years examined). Flexible capacity exceeds demand at minimum renewable energy generation.
• The existing and new flexible capacity required to support variable renewable energy is a fraction of the total variable renewable capacity.

See also: Integrated wind and solar still cheapest, and green hydrogen costs dropping fast: CSIRO

And: Slow, expensive, and not great for 1.5° targets: CSIRO destroys the Coalition’s nuclear fantasy

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