By Fred
(An insight to the staggering ballpark numbers needed to achieve NZ by 2050).
Out of idle curiosity I got to wondering how big the NZ 2050 challenge is if the renewables source energy was electricity. Fossil fuels (coal, oil and gas) accounted for 91% of Australia’s primary energy mix in 2021-22. Oil accounted for the largest share of Australia’s primary energy mix in 2021-22, at 37%, followed by coal (28%) and gas (27%).
Only Wind, Solar and Nuclear sources were considered in isolation, although it is expected a mix including biomass will also be used on the path to NZ. The numbers used are averages and do not make allowance for “outages” (maintenance, failures, extended lack of sun or wind, local variations to capacity factor [1] etc.). Practical solutions using renewables will require extra capacity, location diversity and significant storage due to the “peakiness” of renewables supply. One of the challenges is in determining where to put the renewable wind or solar farms given climate change has already altered weather patterns that will continue to change.
Australia consumed 5,762 PetaJoules (PJ) of energy in 2022[2] that included 512 PJ from renewables, leaving 5250 PJ to be transitioned away from fossil fuels, which is one of the “elephants in the room” not usually discussed in the ongoing “power prices” bun-fight at federal level.
This averages out to: 5250 / 365 = 14.384 PJ per day
(Remembering that 1 PetaJoule = 1E15 Joules and 1 Watt = 1 Joule per second, therefore 1 GWh = 1E9 * 60 * 60 = 1E9 * 3,600 = 3.6E12 Joules. Conversion of 1 PJ to GWh = 1E15 /3.6E12 GWh = 277.78 GWh.)
Converting fossil fuel energy consumption to GWh: 14.384 * 277.78 = 4000 GWh per day
Calculating the nameplate capacity able to meet consumption:4000 / 24 = 166.67 GW.
By way of comparison to current electricity generation capacity, the combined output of “Loy Yang A” and “Loy Yang B” is 3.3 GW which meets 50% of Victoria’s requirements, whereas “Eraring”, rated at 2.9 GW, supplies approximately 25% of New South Wales requirements. It is a significant step up to 166.67 GW.
Nuclear
Supposedly has a “capacity factor” of 100% and delivers its nameplate rated output continuously, i.e.: a 1 GigaWatt large nuclear plant produces 1 GW 24 hours per day each day. (Note: I’m ignoring the real annual downtime of 7% in the USA and 25% in the United Kingdom! [3], which is classified as part of the “availability factor”. So much for base load power.)
If 167 GW capacity is supplied solely by nuclear it would require:
- 167 of 1 GW large nuclear reactors, or
- 556 of 300 MW SMR reactors = (one near you)
The cost to build would be prohibitive at $9.2B per GW for large nuclear reactors. A program to build 167 LNRs would cost $1.5 Trillion. If implemented, it would put the USA to shame which has 92 commercial reactors with a net capacity of 94.7 GW supplying 20% of the total electricity load.
Solar
Gives variable output during daylight hours and the system output is nameplate capacity times the effective hours per day. Average daily output for a 1 kiloWatt solar system is dependent on location, i.e. typical values are 3.5 kiloWatt hours (kWh) in Hobart and 5 kWh hours in Alice Springs yielding capacity factors of 14.6% and 20.8% respectively.
To deliver 24 GWh per day via solar the base system nameplate capacity required is correspondingly larger, i.e. 24 /5 = 4.8 GW for Alice Springs and 24/3.5 = 6.86 GW for Hobart.
Given solar panel efficiencies are around 20% at 1,000 W per square meter (m2) irradiance, the panel area required for 4.8 GW nameplate at Alice Springs would be: 4.8E9 / (1000 * 20%) = 24,000,000 m2 = 24 square km (km2). A practical solar farm would be bigger by approximately 25%.
I’m trying to visualise a 6 km by 4 km block of land/sand covered entirely by solar panels using silicon wafers 100µm thick (= 2,400 cubic metres of silicon = 5,589,804 kg at $50 to $100 per kg, say $100 = approximately $560M). The cost of silicon for solar cells is expected to fall significantly [7] to a few $ per kg.
By way of comparison to fossil fuel generators, the solar panel sizes to replace “Loy Yang A” and “Loy Yang B”, are 3.3 * 24 km2 = 79 km2 and “Eraring” 2.9 * 24 = 69 km2 respectively. The land space required to replace coal fired with solar is supposedly comparable if the mine is included. [4].
If the entire transition energy was supplied by solar located at Alice Springs, the panel area is:
Required system capacity: 4,000/5 = 800 GW
Panel size: 800 E9 / (1,000 * 0.2) = 4 E9 m2 = 4,000 km2.
To put this in context, this is an area 1.7 times the size of the Australian Capital Territory or 1/6th the size of “Anna Creek”, Australia’s largest cattle station.
As a rough rule of thumb at $1 per watt for solar installed, the cost is $800B + transmission lines + storage.
Wind
Power derived from wind is, like solar, location dependent but also wind speed constrained as the turbines have a minimum and maximum speed. The best location for a wind farm has low gust, continuous wind able to drive the turbine to maximum output all day every-day. The larger the turbine the more efficient it is.
The “power density” (MW per km2) of onshore windfarms is variable [5]. Modelling of the terrain, typical wind speed and direction can help to optimise, however when wind turbines are placed together in a windfarm, they produce less energy than when placed in isolation. The harvesting of wind energy leads to the formation of wind turbine wakes, a region with reduced wind speed, behind each turbine. These wind turbine wakes affect the performance of downstream turbines in the farm. In addition, large wind farms act as additional resistance to the atmospheric boundary layer (ABL) which mostly determines the performance, rather than by direct interactions among the turbines. Therefore, the potential for layout optimisations of large arrays is limited and more numerous smaller arrays yield higher efficiency.
Off-shore tends to have a better capacity factor than onshore due to more consistent wind. The UK has 30+ GW of wind turbine split roughly down the middle for on-shore and off-shore achieving an overall capacity factor of 32% in 2023. Australia doesn’t have any offshore windfarms due to lack of governance by the LNP, with over a decade of opportunity for offshore windfarm policy and process development wasted.
For onshore wind in Australia, there is a website [6] that tracks the combined output of 80+ windfarms spread from Tasmania through South Australia and New South Wales to Queensland with a total combined nameplate output of 11,409 MW. As can be seen below, some days (20/07/24) the output is better than others (7,644 MW = 67% capacity factor), however on average wind farms in south-east Australia operate at a capacity factor of around 30-35%.
Australia’s largest windfarm is the MacIntyre Wind Precinct60km west of Warwick, which is set to cost $2 billion and produce up to 1,026 megawatts of energy from 180 of 5.7 MW wind turbines.
If a 30% capacity factor is used, the effective cost per GW is $2 B/30% = $6.667 B. If the transition was entirely based on use of wind, the total cost would be $6,667 B * 167 =$1.113 T+ transmission lines + storage.
Note: The “Herries Range Wind Farm” (1,000MW) expansion project to the above has been announced, doubling the capacity to 2 GW and the cost to over $4 billion.
Noise
The nuclear “debate” shouldn’t exist. Anybody with google and a few minutes of thought would realise that 8 reactors aren’t going to cut it, nuclear is expensive, takes a long time to implement and has questions about safety in the post 9/11 world. It is likely the combined effect of a number of developments over the almost 20 years since 9/11 have limited new building to only four reactor construction starts in the US (of which two were abandoned) and two in the EU. As for Small Modular Reactors that produce around 300 MW, the costs and construction timescales have blown out making them uneconomic. If the coal fired Eraring power station, scheduled for closure, was replaced by SMRs it would take 10 units, if SMRs ever become a reality.
The other “elephant” is that as we change energy sources away from fossil fuels, the equipment they power must also be changed to/replaced with electrically actuated, which comes at significant cost.
If we are going to produce solar panels in Australia, we had better get on with it – there’s a lot to do.
As for meeting NZ 2050…
References
1) The net “capacity factor” or “capability factor” is the unitless ratio of actual electrical energy output over a given period of time to the theoretical maximum electrical energy output over that period. The theoretical maximum energy output of a given installation is defined as that due to its continuous operation at full nameplate capacity over the relevant period.
2) Energy Consumption, Department of Climate Change, Energy, the Environment and Water.
3) Unit Capacity Factor, Power Reactor Information System.
4) For land use efficiencies of various power sources see: Land use of energy sources per unit of electricity.
5) Understanding wind farm power densities, Cambridge.
6) Wind Energy, Anero.
7) Simple Nano Trick Purifies Silicon for Energy Applications, Spectrum.
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