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The Sum of Ruinous Green Delusions - by Tim O’Brien for the Australian Quadrant - 07.03.23

Labor says it will reduce 2005 CO2 emissions of 560 million tonnes by 43 per cent come 2030. That brings it down to 57 per cent of 560 = 320 million tonnes. Emissions for 2021 were about 490 million tonnes so it will be reduced by 490 – 320 = 170 million tonnes.

Where does the 43 per cent come from? My guess is the person who selected it was a fan of the late Douglas Adams’ The Hitchhiker’s Guide to the Galaxy, and through a slip of memory thought the answer was 43. The government has now set this target in legislation. Court challenges by emissions-reduction activists to coal or gas expansions, to name a couple, will now have in their armoury this legislation to support their case. The halving of global investment in fossil fuels since 2015 has much to do with the current world energy crisis.

The biggest emitter of CO2 is power generation, at 34 per cent, and that amounted to about 170 million tonnes in 2020. Where is Labor going to find its 170 million tonnes? I don’t know, but if it gets 170 million tonnes of it from power generation, let’s look at the consequences of going 100 per cent renewable at some point in the near future.

If only 80 per cent of coal and gas generation were to be replaced and, importantly, appropriately sized battery back-up is built to support the removed generation, then the cost will be 80 per cent of what I have calculated. If a photovoltaic solar farm of 1 megawatt nameplate capacity ( MW- a million watts) is built, and generates a MW for each hour of the day for a year, it would generate 8760 MWh over 12 months.

By monitoring the actual output over a year and adding up all the MWh, to take account of the 4 seasons, it is found for the typical farm that the yearly total is 1750 MWh. This is 20 per cent, or 0.2 times, the 8760 MWh total. This 0.2 is called the “capacity factor” for the PV solar farms. For the average day, the 1 MW farm produces 1752/365=4.8 MWh. Expressed another way – 24 hours x 0.2 = 4.8 hours it outputs 1 MW. In summer it will beat the average and in a wet winter it will be less than the average.

Now let’s look at the 2880 MW NSW Eraring coal fired power station, which is marked for closures in about three years time. If in a 24-hour day it delivers power as following:

♦ 2700MW for the periods 6am to 9am and 5pm to 9 pm ie 7 hours for 18,900MWh.

♦ 2200MW from 9am to 5 pm ie 8 hours for 17600 MWh.

♦ 1700MW for 9pm to 6am ie 9 hours for 15,300MWh.

This gives 51,800 MWh for the 24-hour period. If this is to be replaced with a solar PV farm, how big does it have to be to produce to match this output in 4.8 hours?

Solar farm output x 4.8 = 51,800 MWh, so farm output = 10,800MW. This is 3.7 times bigger than the 2880 MW plant it is replacing. The 4.8 hours is for an average day. In summer more power will be made than required. In winter there will be brown outs.

In the 9am to 5 pm period the demand is 2200 MW, so 4.8 x 2200 = 10,560 MWh of generated power is consumed. The 51,800 – 10,560 = 41,240 MWh has to be stored in batteries if CO2 emissions from coal and gas turbines are disallowed.

The Eraring announcement, reported in the press, said a 700 MW battery was planned as part of the shift to renewable energy. It did not state for how long this battery could output 700 MW — a typical and annoying failure of reporters to supply the MWh value for batteries. Typically, the Eraring battery could do so for 1.3 hours i.e. 910 MWh versus the 41,240MWh required. This 700MW battery is only good for managing transient variations in supply. Where the 41,240 MWh comes from was not identified. Snowy2.0 perhaps?

Greens leader Adam Bandt clearly does not understand the difference between a firming battery and a transient-response battery because he said “when SA needed to firm it’s supply, it built the worlds biggest battery in under a month”. This Tesla battery was 100MW/130MWh, cost $90 million, and if called upon to firm, the loss of a 1300MW supply, it could do so for six minutes.

If a wind farm were used instead of a solar farm, the typical capacity factor is found to be 0.4 and the calculation becomes wind farm output x 9.6 hour = 51,800MWh. (24 x .4 = 9.6). So the farm output = 5400MW, which is 1.9 times the 2880MW coal power station.

To look at the costs involved, I will use a 50/50 mix of wind and solar farms. They are each going to provide 51,800/2 = 25,900MWh. So the solar farm is 25,900/4.8 = 5400MW and the wind farm is 25,900/9.6 = 2700MW. A total of 8100 MW. The current cost of the solar is $1.7 million/ MW and the land based wind farm is $2 million/MW. So cost comes to $1.7 million x 5400 + $2 million x 2700 equals $14.58 billion.

The battery-storage requirement is complicated because who can know when and at what strength the wind will blow. So I will minimise the storage requirement by saying no wind is blowing when the solar farm is operating. If it did, all the wind output would have to be stored because the solar farm by itself could supply the demand.

So the solar farm outputs 4.8 x 5400 = 25,920 MWh and, as shown above,10,560 MWh is consumed during this time, leaving 15360 MWh to be stored. The wind farm outputs between 6am and 9am and 6pm and 9pm, too good to be true, and 3.6 hours during the night. During those periods the demand is 6 x 2700 + 3.6 x 1700 = 22,320 MWh requiring 25,900 – 22,320 = 3600 MWh be stored. The total to be stored is 3600+15,360 = 18,960MWh or 18.96 GWh (G = billion). The battery efficiency is appropriately 90 per cent, so the batteries have to be rated at 18.96/.9 = 21 GWh. Battery storage costs $500 million per GWh, so the battery cost is $10.5 billion.

Managing the haphazard energy supply from renewables falls upon the power- and process-control engineers. For 21 GWh of storage they may install four assemblies each rated at 3GW/5GWh. When the renewables supply more than the demand, the excess is used to charge a not fully charged assembly and when the renewables is less than demand, an assembly supplies all the demand and all the renewable energy is used for charging.

This brings the cost to $25 billion and the expense of the transmission lines to convey the electricity from the remote solar and wind locations to where it can be connected to a major transmission line, has to be added onto this figure.

$25 billion/2880 MW = $8.7 million/MW replaced is a sobering number.

Coincidentally, WA coal and gas generation is very close to the output of the Eraring power station. So WA has to add 5400 MW of solar and 2700 MW of wind plus 21 GWh of batteries costing $25 billion to go 100 per cent renewable. Add to this the cost of additional transmission lines.

Alinta intends to replace Loy Yang B 1000 MW coal station with an offshore wind farm and pumped hydro. As Jeff Dimery, Alinta CEO, told The Financial Review’s Energy and Climate Summit in October 2022, “What cost me $1 billion to acquire is going to cost me $8 billion to replace, so let’s talk about that and explain to me how energy prices still come down. I am missing something”.

I don’t have a price on a transmission line cost/km, but Labor’s Chris Bowen sees an urgent need to spend $20 billion on major transmission lines on the National Energy Grid for the eastern states plus SA. Include $4 billion for Snowy 2.0, and an extra 10,000 km of minor transmission lines required to replace coal and gas generation with renewables and $4 million/km is probably a fair ballpark figure.

The National Energy Grid has approximately 35,000MW of coal plus gas generation capacity. WA, which is not part of the National Energy Grid, will increase this amount by about 2500 MW, to 37,500MW. So, for the whole country, we are looking at 37,500/2880 = 13 Erarings. And 13 x $25 billion = $325 billion, plus the cost of transmission lines for 105 GW of wind and solar, 2.8 times the 37.5 GW and 270 GWh of batteries and pumped hydro.

The above calculation indicates 2.8 times more renewables MWs replacing the coal and gas MWs. To suggest that, when renewables are generating more than the grid demands, this is the time to divert that excess to making green hydrogen by electrolysis, doesn’t hold water. If you want to make green hydrogen under my scenario, start adding more GWs to the 105GW total.

As the level of renewables climbs, I expect the unreliability of wind and solar will have become so obvious that the shutting down of gas-fired generation will be suspended. Gas generates 400g of CO2/kWh versus 1000g of CO2/kWh from coal. (I acknowledge my numbers don’t factor in the growth in energy consumption over time).

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The Sum of Ruinous Green Delusions - by Tim O’Brien for the Australian Quadrant - 07.03
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BA ‘Tim’ O’Brien is a retired metallurgist

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