How did wind and solar perform in the recent heat-wave?

There has been a lot of commentary – in conservative media and political circles – about renewables failing during the power crisis.

Detailed inspections suggests the opposite is true. And it is worth clarifying a few points about the operation of power systems to illustrate why.

All power systems have gas plants as backup and most have diesel as well, because the speed of response and low capital cost offset the lower operating cost of coal plants when the gas or diesel plants are used sparingly.

Gas peakers in the US, for example, operate an average of 4% of the time. Even in South Australia, over the last seven days to Wednesday including the heat wave, open cycle gas and diesel plants (the type used for peak demand) have operated at less than 10% capacity factors.

In the good old days before wind and solar were a thing, Eastern Australia had 58GW of coal, gas and hydro to supply an average of 24GW demand and a peak of 35GW. Still, with all this, in February 2009 there was 1,000MW of load shedding.

This year while gas and coal capacity was reduced by some 15 per cent, since the peak and the population had increased by 16 per cent, only 200MW was shed, when more than 1,800 MW of coal was unavailable in Victoria alone.

There is a website called OpenNEM which shows power generation in 5 minute intervals across the NEM. From that data

On Thursday, in spite of the hottest day ever recorded in an Australian capital, South Australia had no lack of generation, although 20,000 people were disconnected because of a substation fault – not a lack of generation. There is 3,400MW of gas and diesel capacity in South Australia. Their maximum combined output together was 2,940 MW at 7PM.

By next summer South Australia will have approximately 400MW of low wind specific wind turbines operating which even in last Thursday’s weather conditions will supply a minimum of 90MW.

It will also have 1,000 MW of new solar and 50-100 MW of new batteries, so while the solar won’t contribute at 8PM the batteries and wind will combine with existing gas to carry the load. South Australia is already a net exporter so that will only increase while gas consumption will continue to fall.

Coal and gas plants were also offline in NSW.. Even though the heat in NSW was significantly less than Victoria, NSW was relying on imports from Queensland.

At 1PM on Friday at the height of Victoria’s power shortage NSW was importing 1,300 MW from Queensland and the NSW coal and gas plants could manage no more than 82% of nameplate capacity. In contrast South Australia exported continuously to Victoria from 6AM to midnight with a peak of 640 MW and an average of 460 MW

Some other useful observations to be made to counter the anti-renewable take on the load-shedding

In the last 30 days wind supplied 6.4% of Victoria’s power. At 11:30 on Friday it supplied 6.4% of the power,

1. In the last 30 days large scale solar supplied 1.4% of Victoria’s power at 11:30 on Friday it was supplying 2.1%.
3. Brown coal  supplied 74.1% of Victoria’s power over the last 30 days but when it was needed it dropped to 31% at 11:30.
5. In the critical 11:30-2:30 time period Victoria energy minister Lily D’Ambrosio was confident that the coal generators, which have had $100’s of millions spent on them over the last 3 years, would perform somewhere near capacity. She was mistaken. 38% of  coal capacity went off line.
7. On Friday from 8:00AM to 8:0 PM wind provided 6.9% of energy in Victoria and utility solar 2.2%  i.e. wind and solar supplied more than their average share. In contrast brown coal which has supplied 74% of Victoria’s power over the last 30 days only managed 34%.
9. Over the critical period of 10:45 to 2:45 Friday in Victoria, solar provided 2%, wind 5.3% of power and brown coal 31.6%. Solar was slightly above average as expected, wind output was 82% of the 30 day 24 hour average although as wind is normally at its lowest between 11 and 4. the wind share at that time was possibly above average also.
11. In contrast coal slumped to 42%  of its 30 day share
13. From 7AM to 9PM wind and solar combined varied between 6 and 11% of supply, vs their monthly average of 7.9%. After the sun went down wind was not less than 10%

If we invested  $1 billion in coal, it may buy a single 250-330 MW brown coal HELE plant but won’t provide any money to fuel, operate or maintain it. For an extra $50-60 million per year it will supply about 1,400 GWh/yr and output will be zero for an average of  300 hours per year

For $1 billion you can build 250 MW of wind 250 MW of tracking solar and  220 MW of pumped hydro which will provide between 400 and 600 MW peak power on a hot day and 1,600 GWh per year. Output will never be zero, and annual operating and maintenance costs will be around $30 m per year.

As for nuclear the 2,200 MW Plant Vogtle is costing US$25 billion plus financing costs, insurance and long term waste storage. It needs at least 6,500 MW of other plants operating at less than 70% capacity to provide spinning reserve.

It will produce about 17 TWh per year. There will be 6 weeks every 18 months when maximum output is 1,100 MW assuming there is no need ever for maintenance shut downs outside of refueling.

For the full cost of US$30 billion, we could build 7,000 MW of wind, 7,000 MW of tracking solar, 10,000 MW of  rooftop solar, 5,000MW of pumped hydro and 5,000 MW of batteries.

Annual output would be between 55 and 65 TWh, minimum output on a hot afternoon will be between 10,000 and 20,000 MW and minimum output at night will be about 6-7,000MW, the spinning reserve is built in. Annual operating cost per MWh will be half that of the nuclear plant.

That is why nuclear is irrelevant in Australia. It has nothing to do with greenies, it’s just about cost and reliability.

Note: Just to show you how fast the transition is happening. The UK went from 42% coal in 2012 to 5% last year. It went without coal altogether for 180 days.

In our case on a sunny windy late spring day, Victoria’s power consumption drops to about 105-110 GWh per day. On a good day now, wind generates 20 GWh. The new wind farms under construction are more effective and will generate about 40 GWh on a windy day i.e. a total of 60 GWh from wind.

Rooftop solar currently supplies around 7-9 GWh. This is expected to increase by 60-70% over the next 2-3 years so we can expect around 14 GWh. Large scale solar in Victoria has only just started. New plants on order will increase output by a factor of 6 or 7 by late spring 2021 output will rise from around 2 GWh per day to around 15 GWh. Thus wind and solar will supply 90GWh+.

If necessary hydro can easily supply 15 GWh in a day and gas 15 GWh so it is quite possible that in two years we could go coal free for days at a time without imports. Given that Tassie will be able to sell us 10 GWh/day and SA 12, it is quite possible that by 2021 Victoria could go fossil fuel free for days at a time.

In reality it won’t happen because we will keep brown coal plants going to undercut NSW black coal generation and gas and hydro will be saved for low wind/solar days. There will however be 70% renewable days and annual renewable share in the 21/22 financial year will be between 41 and 45% of Victorian power consumption.

Peter Farley is a fellow of the Intitution of Engineers for almost 30 years who writes extensively on energy matters.