The seasonality of supply is a big deal, and requires very long duration storage. Our modelling of South Australia shows that 4-10 hour storage supplied by batteries and/or pumped hydro was often full during excess wind and solar periods, and equally was often empty during periods of excess demand. This led to a need for gas or its equivalent to ensure there was no unserved energy demand.
An extremely crude estimate of the firming cost was around $12/MWh and the majority of that cost was the gas capital and operating costs. We note the gas generation capacity already exists.
Gas ended up supplying 7.5% of the energy and so South Australia would have been very low carbon emissions in this scenario. Overall the results suggest that even with the benefit of exports and imports it’s likely some long duration storage will be required NEM wide as VRE penetration increases. However, much more work remains to be done in studying storage duration requirements before we at ITK really know what we are talking about.
The seasonality of wind and solar is a big deal
Recently, ITK looked at the excellent prospects for batteries and the increasing amount of evidence that utility scale batteries are finding a place in the market.
We noted that in the US, where, somehow, ancilliary services and frequency control don’t seem to be the issues that they are in Australia, batteries were starting to be of longer duration. Many of the 2GW of the battery contacts signed by leading US utility NextEra Energy are for four hour duration.
In Australia though, all the grid scale batteries are of 2 hours or less duration.
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