We're having an over-supply of wind energy today and the price per kw/h has gone negative. These are the moments that the proponents of wind energy trumpet - however on Friday there was a 'wind drought' during the evening peak with less than one percent of our energy coming from wind. They had to fire up the diesel generators - the very dirtiest and most expensive kind of energy generation.
Interesting to note that at the exact same time (Friday PM peak) there was a 'wind drought' all over the NEM - so the new HV inter-connector from NSW would have been equally useless if NSW was mostly 'renewable' like us here in SA. You have to wonder what will happen when coal isn't there any longer to back it up.
While extensive periods of negative or near zero prices may look great for consumers, such prices discourage further expansion but will drive expansion of storage technology investment.
Diesel gensets will always be part of the mix as they are for most grid's globally to manage extreme periods of high demand and has little to do with the main source of energy. SA has operated diesel for at least 15 years and fortunately for SA, is actually lower / MWh than Coal in CO2 emissions. Additionally a number of diesel generator plants in Australia also run additional scrubbers to remove non CO2 emissions such as NOX and SOX.
Diesel peaking capacity is expensive per MW, however this is because its treated as top peaking capacity and thus used rarely so when they do they rightfully jack the price up for CAPEX recovery.
Its worth noting at the time of SA's "wind drought",
- Vic was sharing SA's "wind drought", no real surprises there.
- Tas's wind was down to about 1/4 during the "wind drought", thus demonstrating geographic diversity is critical when looking at weather related energy sources.
- NSW wind was generating around 60% of nameplate
- Qld wind was operating > 60% of nameplate
[in all cases these are rough estimates of the actual % of nameplate without counting to the nearest MW]
The proposed HV connector into NSW would have tapped into NSW's existing significant hydro and SNOWY 2.0 peaking generation capacity and as it turns out NSW still had a reasonable amount of wind output, but the imported power to SA was rather sourced from Vic and Tas hydro sources. So to state the HV link would have been useless is wishful thinking.